Add phx.gen.auth authentication scaffolding

- LiveView-based email/password auth via mix phx.gen.auth
- Auth links removed from public navigation (direct URL access only)
- Accounts context with User schema and token management

app/AGENTS.md

@@ -44,6 +44,37 @@ custom classes must fully style the input
 - Focus on **delightful details** like hover effects, loading states, and smooth page transitions
 
 
+<!-- phoenix-gen-auth-start -->
+## Authentication
+
+- **Always** handle authentication flow at the router level with proper redirects
+- **Always** be mindful of where to place routes. `phx.gen.auth` creates multiple router plugs:
+  - A plug `:fetch_current_scope_for_user` that is included in the default browser pipeline
+  - A plug `:require_authenticated_user` that redirects to the log in page when the user is not authenticated
+  - In both cases, a `@current_scope` is assigned to the Plug connection
+  - A plug `redirect_if_user_is_authenticated` that redirects to a default path in case the user is authenticated - useful for a registration page that should only be shown to unauthenticated users
+- **Always let the user know in which router scopes and pipeline you are placing the route, AND SAY WHY**
+- `phx.gen.auth` assigns the `current_scope` assign - it **does not assign a `current_user` assign**
+- Always pass the assign `current_scope` to context modules as first argument. When performing queries, use `current_scope.user` to filter the query results
+- To derive/access `current_user` in templates, **always use the `@current_scope.user`**, never use **`@current_user`** in templates
+- Anytime you hit `current_scope` errors or the logged in session isn't displaying the right content, **always double check the router and ensure you are using the correct plug as described below**
+
+### Routes that require authentication
+
+Controller routes must be placed in a scope that sets the `:require_authenticated_user` plug:
+
+    scope "/", AppWeb do
+      pipe_through [:browser, :require_authenticated_user]
+
+      get "/", MyControllerThatRequiresAuth, :index
+    end
+
+### Routes that work with or without authentication
+
+Controllers automatically have the `current_scope` available if they use the `:browser` pipeline.
+
+<!-- phoenix-gen-auth-end -->
+
 <!-- usage-rules-start -->
 
 <!-- phoenix:elixir-start -->

app/config/config.exs

@@ -7,6 +7,19 @@
 # General application configuration
 import Config
 
+config :firehose, :scopes,
+  user: [
+    default: true,
+    module: Firehose.Accounts.Scope,
+    assign_key: :current_scope,
+    access_path: [:user, :id],
+    schema_key: :user_id,
+    schema_type: :id,
+    schema_table: :users,
+    test_data_fixture: Firehose.AccountsFixtures,
+    test_setup_helper: :register_and_log_in_user
+  ]
+
 config :firehose,
   ecto_repos: [Firehose.Repo],
   generators: [timestamp_type: :utc_datetime]

app/config/test.exs

@@ -1,5 +1,8 @@
 import Config
 
+# Only in tests, remove the complexity from the password hashing algorithm
+config :bcrypt_elixir, :log_rounds, 1
+
 # Configure your database
 #
 # The MIX_TEST_PARTITION environment variable can be used

app/lib/firehose/accounts.ex

@@ -0,0 +1,297 @@
+defmodule Firehose.Accounts do
+  @moduledoc """
+  The Accounts context.
+  """
+
+  import Ecto.Query, warn: false
+  alias Firehose.Repo
+
+  alias Firehose.Accounts.{User, UserToken, UserNotifier}
+
+  ## Database getters
+
+  @doc """
+  Gets a user by email.
+
+  ## Examples
+
+      iex> get_user_by_email("foo@example.com")
+      %User{}
+
+      iex> get_user_by_email("unknown@example.com")
+      nil
+
+  """
+  def get_user_by_email(email) when is_binary(email) do
+    Repo.get_by(User, email: email)
+  end
+
+  @doc """
+  Gets a user by email and password.
+
+  ## Examples
+
+      iex> get_user_by_email_and_password("foo@example.com", "correct_password")
+      %User{}
+
+      iex> get_user_by_email_and_password("foo@example.com", "invalid_password")
+      nil
+
+  """
+  def get_user_by_email_and_password(email, password)
+      when is_binary(email) and is_binary(password) do
+    user = Repo.get_by(User, email: email)
+    if User.valid_password?(user, password), do: user
+  end
+
+  @doc """
+  Gets a single user.
+
+  Raises `Ecto.NoResultsError` if the User does not exist.
+
+  ## Examples
+
+      iex> get_user!(123)
+      %User{}
+
+      iex> get_user!(456)
+      ** (Ecto.NoResultsError)
+
+  """
+  def get_user!(id), do: Repo.get!(User, id)
+
+  ## User registration
+
+  @doc """
+  Registers a user.
+
+  ## Examples
+
+      iex> register_user(%{field: value})
+      {:ok, %User{}}
+
+      iex> register_user(%{field: bad_value})
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def register_user(attrs) do
+    %User{}
+    |> User.email_changeset(attrs)
+    |> Repo.insert()
+  end
+
+  ## Settings
+
+  @doc """
+  Checks whether the user is in sudo mode.
+
+  The user is in sudo mode when the last authentication was done no further
+  than 20 minutes ago. The limit can be given as second argument in minutes.
+  """
+  def sudo_mode?(user, minutes \\ -20)
+
+  def sudo_mode?(%User{authenticated_at: ts}, minutes) when is_struct(ts, DateTime) do
+    DateTime.after?(ts, DateTime.utc_now() |> DateTime.add(minutes, :minute))
+  end
+
+  def sudo_mode?(_user, _minutes), do: false
+
+  @doc """
+  Returns an `%Ecto.Changeset{}` for changing the user email.
+
+  See `Firehose.Accounts.User.email_changeset/3` for a list of supported options.
+
+  ## Examples
+
+      iex> change_user_email(user)
+      %Ecto.Changeset{data: %User{}}
+
+  """
+  def change_user_email(user, attrs \\ %{}, opts \\ []) do
+    User.email_changeset(user, attrs, opts)
+  end
+
+  @doc """
+  Updates the user email using the given token.
+
+  If the token matches, the user email is updated and the token is deleted.
+  """
+  def update_user_email(user, token) do
+    context = "change:#{user.email}"
+
+    Repo.transact(fn ->
+      with {:ok, query} <- UserToken.verify_change_email_token_query(token, context),
+           %UserToken{sent_to: email} <- Repo.one(query),
+           {:ok, user} <- Repo.update(User.email_changeset(user, %{email: email})),
+           {_count, _result} <-
+             Repo.delete_all(from(UserToken, where: [user_id: ^user.id, context: ^context])) do
+        {:ok, user}
+      else
+        _ -> {:error, :transaction_aborted}
+      end
+    end)
+  end
+
+  @doc """
+  Returns an `%Ecto.Changeset{}` for changing the user password.
+
+  See `Firehose.Accounts.User.password_changeset/3` for a list of supported options.
+
+  ## Examples
+
+      iex> change_user_password(user)
+      %Ecto.Changeset{data: %User{}}
+
+  """
+  def change_user_password(user, attrs \\ %{}, opts \\ []) do
+    User.password_changeset(user, attrs, opts)
+  end
+
+  @doc """
+  Updates the user password.
+
+  Returns a tuple with the updated user, as well as a list of expired tokens.
+
+  ## Examples
+
+      iex> update_user_password(user, %{password: ...})
+      {:ok, {%User{}, [...]}}
+
+      iex> update_user_password(user, %{password: "too short"})
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def update_user_password(user, attrs) do
+    user
+    |> User.password_changeset(attrs)
+    |> update_user_and_delete_all_tokens()
+  end
+
+  ## Session
+
+  @doc """
+  Generates a session token.
+  """
+  def generate_user_session_token(user) do
+    {token, user_token} = UserToken.build_session_token(user)
+    Repo.insert!(user_token)
+    token
+  end
+
+  @doc """
+  Gets the user with the given signed token.
+
+  If the token is valid `{user, token_inserted_at}` is returned, otherwise `nil` is returned.
+  """
+  def get_user_by_session_token(token) do
+    {:ok, query} = UserToken.verify_session_token_query(token)
+    Repo.one(query)
+  end
+
+  @doc """
+  Gets the user with the given magic link token.
+  """
+  def get_user_by_magic_link_token(token) do
+    with {:ok, query} <- UserToken.verify_magic_link_token_query(token),
+         {user, _token} <- Repo.one(query) do
+      user
+    else
+      _ -> nil
+    end
+  end
+
+  @doc """
+  Logs the user in by magic link.
+
+  There are three cases to consider:
+
+  1. The user has already confirmed their email. They are logged in
+     and the magic link is expired.
+
+  2. The user has not confirmed their email and no password is set.
+     In this case, the user gets confirmed, logged in, and all tokens -
+     including session ones - are expired. In theory, no other tokens
+     exist but we delete all of them for best security practices.
+
+  3. The user has not confirmed their email but a password is set.
+     This cannot happen in the default implementation but may be the
+     source of security pitfalls. See the "Mixing magic link and password registration" section of
+     `mix help phx.gen.auth`.
+  """
+  def login_user_by_magic_link(token) do
+    {:ok, query} = UserToken.verify_magic_link_token_query(token)
+
+    case Repo.one(query) do
+      # Prevent session fixation attacks by disallowing magic links for unconfirmed users with password
+      {%User{confirmed_at: nil, hashed_password: hash}, _token} when not is_nil(hash) ->
+        raise """
+        magic link log in is not allowed for unconfirmed users with a password set!
+
+        This cannot happen with the default implementation, which indicates that you
+        might have adapted the code to a different use case. Please make sure to read the
+        "Mixing magic link and password registration" section of `mix help phx.gen.auth`.
+        """
+
+      {%User{confirmed_at: nil} = user, _token} ->
+        user
+        |> User.confirm_changeset()
+        |> update_user_and_delete_all_tokens()
+
+      {user, token} ->
+        Repo.delete!(token)
+        {:ok, {user, []}}
+
+      nil ->
+        {:error, :not_found}
+    end
+  end
+
+  @doc ~S"""
+  Delivers the update email instructions to the given user.
+
+  ## Examples
+
+      iex> deliver_user_update_email_instructions(user, current_email, &url(~p"/users/settings/confirm-email/#{&1}"))
+      {:ok, %{to: ..., body: ...}}
+
+  """
+  def deliver_user_update_email_instructions(%User{} = user, current_email, update_email_url_fun)
+      when is_function(update_email_url_fun, 1) do
+    {encoded_token, user_token} = UserToken.build_email_token(user, "change:#{current_email}")
+
+    Repo.insert!(user_token)
+    UserNotifier.deliver_update_email_instructions(user, update_email_url_fun.(encoded_token))
+  end
+
+  @doc """
+  Delivers the magic link login instructions to the given user.
+  """
+  def deliver_login_instructions(%User{} = user, magic_link_url_fun)
+      when is_function(magic_link_url_fun, 1) do
+    {encoded_token, user_token} = UserToken.build_email_token(user, "login")
+    Repo.insert!(user_token)
+    UserNotifier.deliver_login_instructions(user, magic_link_url_fun.(encoded_token))
+  end
+
+  @doc """
+  Deletes the signed token with the given context.
+  """
+  def delete_user_session_token(token) do
+    Repo.delete_all(from(UserToken, where: [token: ^token, context: "session"]))
+    :ok
+  end
+
+  ## Token helper
+
+  defp update_user_and_delete_all_tokens(changeset) do
+    Repo.transact(fn ->
+      with {:ok, user} <- Repo.update(changeset) do
+        tokens_to_expire = Repo.all_by(UserToken, user_id: user.id)
+
+        Repo.delete_all(from(t in UserToken, where: t.id in ^Enum.map(tokens_to_expire, & &1.id)))
+
+        {:ok, {user, tokens_to_expire}}
+      end
+    end)
+  end
+end

app/lib/firehose/accounts/scope.ex

@@ -0,0 +1,33 @@
+defmodule Firehose.Accounts.Scope do
+  @moduledoc """
+  Defines the scope of the caller to be used throughout the app.
+
+  The `Firehose.Accounts.Scope` allows public interfaces to receive
+  information about the caller, such as if the call is initiated from an
+  end-user, and if so, which user. Additionally, such a scope can carry fields
+  such as "super user" or other privileges for use as authorization, or to
+  ensure specific code paths can only be access for a given scope.
+
+  It is useful for logging as well as for scoping pubsub subscriptions and
+  broadcasts when a caller subscribes to an interface or performs a particular
+  action.
+
+  Feel free to extend the fields on this struct to fit the needs of
+  growing application requirements.
+  """
+
+  alias Firehose.Accounts.User
+
+  defstruct user: nil
+
+  @doc """
+  Creates a scope for the given user.
+
+  Returns nil if no user is given.
+  """
+  def for_user(%User{} = user) do
+    %__MODULE__{user: user}
+  end
+
+  def for_user(nil), do: nil
+end

app/lib/firehose/accounts/user.ex

@@ -0,0 +1,132 @@
+defmodule Firehose.Accounts.User do
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  schema "users" do
+    field :email, :string
+    field :password, :string, virtual: true, redact: true
+    field :hashed_password, :string, redact: true
+    field :confirmed_at, :utc_datetime
+    field :authenticated_at, :utc_datetime, virtual: true
+
+    timestamps(type: :utc_datetime)
+  end
+
+  @doc """
+  A user changeset for registering or changing the email.
+
+  It requires the email to change otherwise an error is added.
+
+  ## Options
+
+    * `:validate_unique` - Set to false if you don't want to validate the
+      uniqueness of the email, useful when displaying live validations.
+      Defaults to `true`.
+  """
+  def email_changeset(user, attrs, opts \\ []) do
+    user
+    |> cast(attrs, [:email])
+    |> validate_email(opts)
+  end
+
+  defp validate_email(changeset, opts) do
+    changeset =
+      changeset
+      |> validate_required([:email])
+      |> validate_format(:email, ~r/^[^@,;\s]+@[^@,;\s]+$/,
+        message: "must have the @ sign and no spaces"
+      )
+      |> validate_length(:email, max: 160)
+
+    if Keyword.get(opts, :validate_unique, true) do
+      changeset
+      |> unsafe_validate_unique(:email, Firehose.Repo)
+      |> unique_constraint(:email)
+      |> validate_email_changed()
+    else
+      changeset
+    end
+  end
+
+  defp validate_email_changed(changeset) do
+    if get_field(changeset, :email) && get_change(changeset, :email) == nil do
+      add_error(changeset, :email, "did not change")
+    else
+      changeset
+    end
+  end
+
+  @doc """
+  A user changeset for changing the password.
+
+  It is important to validate the length of the password, as long passwords may
+  be very expensive to hash for certain algorithms.
+
+  ## Options
+
+    * `:hash_password` - Hashes the password so it can be stored securely
+      in the database and ensures the password field is cleared to prevent
+      leaks in the logs. If password hashing is not needed and clearing the
+      password field is not desired (like when using this changeset for
+      validations on a LiveView form), this option can be set to `false`.
+      Defaults to `true`.
+  """
+  def password_changeset(user, attrs, opts \\ []) do
+    user
+    |> cast(attrs, [:password])
+    |> validate_confirmation(:password, message: "does not match password")
+    |> validate_password(opts)
+  end
+
+  defp validate_password(changeset, opts) do
+    changeset
+    |> validate_required([:password])
+    |> validate_length(:password, min: 12, max: 72)
+    # Examples of additional password validation:
+    # |> validate_format(:password, ~r/[a-z]/, message: "at least one lower case character")
+    # |> validate_format(:password, ~r/[A-Z]/, message: "at least one upper case character")
+    # |> validate_format(:password, ~r/[!?@#$%^&*_0-9]/, message: "at least one digit or punctuation character")
+    |> maybe_hash_password(opts)
+  end
+
+  defp maybe_hash_password(changeset, opts) do
+    hash_password? = Keyword.get(opts, :hash_password, true)
+    password = get_change(changeset, :password)
+
+    if hash_password? && password && changeset.valid? do
+      changeset
+      # If using Bcrypt, then further validate it is at most 72 bytes long
+      |> validate_length(:password, max: 72, count: :bytes)
+      # Hashing could be done with `Ecto.Changeset.prepare_changes/2`, but that
+      # would keep the database transaction open longer and hurt performance.
+      |> put_change(:hashed_password, Bcrypt.hash_pwd_salt(password))
+      |> delete_change(:password)
+    else
+      changeset
+    end
+  end
+
+  @doc """
+  Confirms the account by setting `confirmed_at`.
+  """
+  def confirm_changeset(user) do
+    now = DateTime.utc_now(:second)
+    change(user, confirmed_at: now)
+  end
+
+  @doc """
+  Verifies the password.
+
+  If there is no user or the user doesn't have a password, we call
+  `Bcrypt.no_user_verify/0` to avoid timing attacks.
+  """
+  def valid_password?(%Firehose.Accounts.User{hashed_password: hashed_password}, password)
+      when is_binary(hashed_password) and byte_size(password) > 0 do
+    Bcrypt.verify_pass(password, hashed_password)
+  end
+
+  def valid_password?(_, _) do
+    Bcrypt.no_user_verify()
+    false
+  end
+end

app/lib/firehose/accounts/user_notifier.ex

@@ -0,0 +1,84 @@
+defmodule Firehose.Accounts.UserNotifier do
+  import Swoosh.Email
+
+  alias Firehose.Mailer
+  alias Firehose.Accounts.User
+
+  # Delivers the email using the application mailer.
+  defp deliver(recipient, subject, body) do
+    email =
+      new()
+      |> to(recipient)
+      |> from({"Firehose", "contact@example.com"})
+      |> subject(subject)
+      |> text_body(body)
+
+    with {:ok, _metadata} <- Mailer.deliver(email) do
+      {:ok, email}
+    end
+  end
+
+  @doc """
+  Deliver instructions to update a user email.
+  """
+  def deliver_update_email_instructions(user, url) do
+    deliver(user.email, "Update email instructions", """
+
+    ==============================
+
+    Hi #{user.email},
+
+    You can change your email by visiting the URL below:
+
+    #{url}
+
+    If you didn't request this change, please ignore this.
+
+    ==============================
+    """)
+  end
+
+  @doc """
+  Deliver instructions to log in with a magic link.
+  """
+  def deliver_login_instructions(user, url) do
+    case user do
+      %User{confirmed_at: nil} -> deliver_confirmation_instructions(user, url)
+      _ -> deliver_magic_link_instructions(user, url)
+    end
+  end
+
+  defp deliver_magic_link_instructions(user, url) do
+    deliver(user.email, "Log in instructions", """
+
+    ==============================
+
+    Hi #{user.email},
+
+    You can log into your account by visiting the URL below:
+
+    #{url}
+
+    If you didn't request this email, please ignore this.
+
+    ==============================
+    """)
+  end
+
+  defp deliver_confirmation_instructions(user, url) do
+    deliver(user.email, "Confirmation instructions", """
+
+    ==============================
+
+    Hi #{user.email},
+
+    You can confirm your account by visiting the URL below:
+
+    #{url}
+
+    If you didn't create an account with us, please ignore this.
+
+    ==============================
+    """)
+  end
+end

app/lib/firehose/accounts/user_token.ex

@@ -0,0 +1,156 @@
+defmodule Firehose.Accounts.UserToken do
+  use Ecto.Schema
+  import Ecto.Query
+  alias Firehose.Accounts.UserToken
+
+  @hash_algorithm :sha256
+  @rand_size 32
+
+  # It is very important to keep the magic link token expiry short,
+  # since someone with access to the email may take over the account.
+  @magic_link_validity_in_minutes 15
+  @change_email_validity_in_days 7
+  @session_validity_in_days 14
+
+  schema "users_tokens" do
+    field :token, :binary
+    field :context, :string
+    field :sent_to, :string
+    field :authenticated_at, :utc_datetime
+    belongs_to :user, Firehose.Accounts.User
+
+    timestamps(type: :utc_datetime, updated_at: false)
+  end
+
+  @doc """
+  Generates a token that will be stored in a signed place,
+  such as session or cookie. As they are signed, those
+  tokens do not need to be hashed.
+
+  The reason why we store session tokens in the database, even
+  though Phoenix already provides a session cookie, is because
+  Phoenix's default session cookies are not persisted, they are
+  simply signed and potentially encrypted. This means they are
+  valid indefinitely, unless you change the signing/encryption
+  salt.
+
+  Therefore, storing them allows individual user
+  sessions to be expired. The token system can also be extended
+  to store additional data, such as the device used for logging in.
+  You could then use this information to display all valid sessions
+  and devices in the UI and allow users to explicitly expire any
+  session they deem invalid.
+  """
+  def build_session_token(user) do
+    token = :crypto.strong_rand_bytes(@rand_size)
+    dt = user.authenticated_at || DateTime.utc_now(:second)
+    {token, %UserToken{token: token, context: "session", user_id: user.id, authenticated_at: dt}}
+  end
+
+  @doc """
+  Checks if the token is valid and returns its underlying lookup query.
+
+  The query returns the user found by the token, if any, along with the token's creation time.
+
+  The token is valid if it matches the value in the database and it has
+  not expired (after @session_validity_in_days).
+  """
+  def verify_session_token_query(token) do
+    query =
+      from token in by_token_and_context_query(token, "session"),
+        join: user in assoc(token, :user),
+        where: token.inserted_at > ago(@session_validity_in_days, "day"),
+        select: {%{user | authenticated_at: token.authenticated_at}, token.inserted_at}
+
+    {:ok, query}
+  end
+
+  @doc """
+  Builds a token and its hash to be delivered to the user's email.
+
+  The non-hashed token is sent to the user email while the
+  hashed part is stored in the database. The original token cannot be reconstructed,
+  which means anyone with read-only access to the database cannot directly use
+  the token in the application to gain access. Furthermore, if the user changes
+  their email in the system, the tokens sent to the previous email are no longer
+  valid.
+
+  Users can easily adapt the existing code to provide other types of delivery methods,
+  for example, by phone numbers.
+  """
+  def build_email_token(user, context) do
+    build_hashed_token(user, context, user.email)
+  end
+
+  defp build_hashed_token(user, context, sent_to) do
+    token = :crypto.strong_rand_bytes(@rand_size)
+    hashed_token = :crypto.hash(@hash_algorithm, token)
+
+    {Base.url_encode64(token, padding: false),
+     %UserToken{
+       token: hashed_token,
+       context: context,
+       sent_to: sent_to,
+       user_id: user.id
+     }}
+  end
+
+  @doc """
+  Checks if the token is valid and returns its underlying lookup query.
+
+  If found, the query returns a tuple of the form `{user, token}`.
+
+  The given token is valid if it matches its hashed counterpart in the
+  database. This function also checks whether the token has expired. The context
+  of a magic link token is always "login".
+  """
+  def verify_magic_link_token_query(token) do
+    case Base.url_decode64(token, padding: false) do
+      {:ok, decoded_token} ->
+        hashed_token = :crypto.hash(@hash_algorithm, decoded_token)
+
+        query =
+          from token in by_token_and_context_query(hashed_token, "login"),
+            join: user in assoc(token, :user),
+            where: token.inserted_at > ago(^@magic_link_validity_in_minutes, "minute"),
+            where: token.sent_to == user.email,
+            select: {user, token}
+
+        {:ok, query}
+
+      :error ->
+        :error
+    end
+  end
+
+  @doc """
+  Checks if the token is valid and returns its underlying lookup query.
+
+  The query returns the user_token found by the token, if any.
+
+  This is used to validate requests to change the user
+  email.
+  The given token is valid if it matches its hashed counterpart in the
+  database and if it has not expired (after @change_email_validity_in_days).
+  The context must always start with "change:".
+  """
+  def verify_change_email_token_query(token, "change:" <> _ = context) do
+    case Base.url_decode64(token, padding: false) do
+      {:ok, decoded_token} ->
+        hashed_token = :crypto.hash(@hash_algorithm, decoded_token)
+
+        query =
+          from token in by_token_and_context_query(hashed_token, context),
+            where: token.inserted_at > ago(@change_email_validity_in_days, "day")
+
+        {:ok, query}
+
+      :error ->
+        :error
+    end
+  end
+
+  defp by_token_and_context_query(token, context) do
+    from UserToken, where: [token: ^token, context: ^context]
+  end
+end

app/lib/firehose_web/components/layouts.ex

@@ -9,6 +9,7 @@ defmodule FirehoseWeb.Layouts do
   # The default root.html.heex file contains the HTML
   # skeleton of your application, namely HTML headers
   # and other static content.
+
   embed_templates "layouts/*"
 
   @doc """

app/lib/firehose_web/controllers/user_registration_controller.ex

@@ -0,0 +1,32 @@
+defmodule FirehoseWeb.UserRegistrationController do
+  use FirehoseWeb, :controller
+
+  alias Firehose.Accounts
+  alias Firehose.Accounts.User
+
+  def new(conn, _params) do
+    changeset = Accounts.change_user_email(%User{})
+    render(conn, :new, changeset: changeset)
+  end
+
+  def create(conn, %{"user" => user_params}) do
+    case Accounts.register_user(user_params) do
+      {:ok, user} ->
+        {:ok, _} =
+          Accounts.deliver_login_instructions(
+            user,
+            &url(~p"/users/log-in/#{&1}")
+          )
+
+        conn
+        |> put_flash(
+          :info,
+          "An email was sent to #{user.email}, please access it to confirm your account."
+        )
+        |> redirect(to: ~p"/users/log-in")
+
+      {:error, %Ecto.Changeset{} = changeset} ->
+        render(conn, :new, changeset: changeset)
+    end
+  end
+end

app/lib/firehose_web/controllers/user_registration_html.ex

@@ -0,0 +1,5 @@
+defmodule FirehoseWeb.UserRegistrationHTML do
+  use FirehoseWeb, :html
+
+  embed_templates "user_registration_html/*"
+end

app/lib/firehose_web/controllers/user_registration_html/new.html.heex

@@ -0,0 +1,30 @@
+<div class="mx-auto max-w-sm">
+  <div class="text-center">
+    <.header>
+      Register for an account
+      <:subtitle>
+        Already registered?
+        <.link navigate={~p"/users/log-in"} class="font-semibold text-brand hover:underline">
+          Log in
+        </.link>
+        to your account now.
+      </:subtitle>
+    </.header>
+  </div>
+
+  <.form :let={f} for={@changeset} action={~p"/users/register"}>
+    <.input
+      field={f[:email]}
+      type="email"
+      label="Email"
+      autocomplete="username"
+      spellcheck="false"
+      required
+      phx-mounted={JS.focus()}
+    />
+
+    <.button phx-disable-with="Creating account..." class="btn btn-primary w-full">
+      Create an account
+    </.button>
+  </.form>
+</div>

app/lib/firehose_web/controllers/user_session_controller.ex

@@ -0,0 +1,88 @@
+defmodule FirehoseWeb.UserSessionController do
+  use FirehoseWeb, :controller
+
+  alias Firehose.Accounts
+  alias FirehoseWeb.UserAuth
+
+  def new(conn, _params) do
+    email = get_in(conn.assigns, [:current_scope, Access.key(:user), Access.key(:email)])
+    form = Phoenix.Component.to_form(%{"email" => email}, as: "user")
+
+    render(conn, :new, form: form)
+  end
+
+  # magic link login
+  def create(conn, %{"user" => %{"token" => token} = user_params} = params) do
+    info =
+      case params do
+        %{"_action" => "confirmed"} -> "User confirmed successfully."
+        _ -> "Welcome back!"
+      end
+
+    case Accounts.login_user_by_magic_link(token) do
+      {:ok, {user, _expired_tokens}} ->
+        conn
+        |> put_flash(:info, info)
+        |> UserAuth.log_in_user(user, user_params)
+
+      {:error, :not_found} ->
+        conn
+        |> put_flash(:error, "The link is invalid or it has expired.")
+        |> render(:new, form: Phoenix.Component.to_form(%{}, as: "user"))
+    end
+  end
+
+  # email + password login
+  def create(conn, %{"user" => %{"email" => email, "password" => password} = user_params}) do
+    if user = Accounts.get_user_by_email_and_password(email, password) do
+      conn
+      |> put_flash(:info, "Welcome back!")
+      |> UserAuth.log_in_user(user, user_params)
+    else
+      form = Phoenix.Component.to_form(user_params, as: "user")
+
+      # In order to prevent user enumeration attacks, don't disclose whether the email is registered.
+      conn
+      |> put_flash(:error, "Invalid email or password")
+      |> render(:new, form: form)
+    end
+  end
+
+  # magic link request
+  def create(conn, %{"user" => %{"email" => email}}) do
+    if user = Accounts.get_user_by_email(email) do
+      Accounts.deliver_login_instructions(
+        user,
+        &url(~p"/users/log-in/#{&1}")
+      )
+    end
+
+    info =
+      "If your email is in our system, you will receive instructions for logging in shortly."
+
+    conn
+    |> put_flash(:info, info)
+    |> redirect(to: ~p"/users/log-in")
+  end
+
+  def confirm(conn, %{"token" => token}) do
+    if user = Accounts.get_user_by_magic_link_token(token) do
+      form = Phoenix.Component.to_form(%{"token" => token}, as: "user")
+
+      conn
+      |> assign(:user, user)
+      |> assign(:form, form)
+      |> render(:confirm)
+    else
+      conn
+      |> put_flash(:error, "Magic link is invalid or it has expired.")
+      |> redirect(to: ~p"/users/log-in")
+    end
+  end
+
+  def delete(conn, _params) do
+    conn
+    |> put_flash(:info, "Logged out successfully.")
+    |> UserAuth.log_out_user()
+  end
+end

app/lib/firehose_web/controllers/user_session_html.ex

@@ -0,0 +1,9 @@
+defmodule FirehoseWeb.UserSessionHTML do
+  use FirehoseWeb, :html
+
+  embed_templates "user_session_html/*"
+
+  defp local_mail_adapter? do
+    Application.get_env(:firehose, Firehose.Mailer)[:adapter] == Swoosh.Adapters.Local
+  end
+end

app/lib/firehose_web/controllers/user_session_html/confirm.html.heex

@@ -0,0 +1,57 @@
+<div class="mx-auto max-w-sm">
+  <div class="text-center">
+    <.header>Welcome {@user.email}</.header>
+  </div>
+
+  <.form
+    :if={!@user.confirmed_at}
+    for={@form}
+    id="confirmation_form"
+    action={~p"/users/log-in?_action=confirmed"}
+    phx-mounted={JS.focus_first()}
+  >
+    <input type="hidden" name={@form[:token].name} value={@form[:token].value} />
+    <.button
+      name={@form[:remember_me].name}
+      value="true"
+      phx-disable-with="Confirming..."
+      class="btn btn-primary w-full"
+    >
+      Confirm and stay logged in
+    </.button>
+    <.button phx-disable-with="Confirming..." class="btn btn-primary btn-soft w-full mt-2">
+      Confirm and log in only this time
+    </.button>
+  </.form>
+
+  <.form
+    :if={@user.confirmed_at}
+    for={@form}
+    id="login_form"
+    action={~p"/users/log-in"}
+    phx-mounted={JS.focus_first()}
+  >
+    <input type="hidden" name={@form[:token].name} value={@form[:token].value} />
+    <%= if @current_scope do %>
+      <.button variant="primary" phx-disable-with="Logging in..." class="btn btn-primary w-full">
+        Log in
+      </.button>
+    <% else %>
+      <.button
+        name={@form[:remember_me].name}
+        value="true"
+        phx-disable-with="Logging in..."
+        class="btn btn-primary w-full"
+      >
+        Keep me logged in on this device
+      </.button>
+      <.button phx-disable-with="Logging in..." class="btn btn-primary btn-soft w-full mt-2">
+        Log me in only this time
+      </.button>
+    <% end %>
+  </.form>
+
+  <p :if={!@user.confirmed_at} class="alert alert-outline mt-8">
+    Tip: If you prefer passwords, you can enable them in the user settings.
+  </p>
+</div>

app/lib/firehose_web/controllers/user_session_html/new.html.heex

@@ -0,0 +1,71 @@
+<div class="mx-auto max-w-sm space-y-4">
+  <div class="text-center">
+    <.header>
+      <p>Log in</p>
+      <:subtitle>
+        <%= if @current_scope do %>
+          You need to reauthenticate to perform sensitive actions on your account.
+        <% else %>
+          Don't have an account? <.link
+            navigate={~p"/users/register"}
+            class="font-semibold text-brand hover:underline"
+            phx-no-format
+          >Sign up</.link> for an account now.
+        <% end %>
+      </:subtitle>
+    </.header>
+  </div>
+
+  <div :if={local_mail_adapter?()} class="alert alert-info">
+    <.icon name="hero-information-circle" class="size-6 shrink-0" />
+    <div>
+      <p>You are running the local mail adapter.</p>
+      <p>
+        To see sent emails, visit <.link href="/dev/mailbox" class="underline">the mailbox page</.link>.
+      </p>
+    </div>
+  </div>
+
+  <.form :let={f} for={@form} as={:user} id="login_form_magic" action={~p"/users/log-in"}>
+    <.input
+      readonly={!!@current_scope}
+      field={f[:email]}
+      type="email"
+      label="Email"
+      autocomplete="username"
+      spellcheck="false"
+      required
+      phx-mounted={JS.focus()}
+    />
+    <.button class="btn btn-primary w-full">
+      Log in with email <span aria-hidden="true">→</span>
+    </.button>
+  </.form>
+
+  <div class="divider">or</div>
+
+  <.form :let={f} for={@form} as={:user} id="login_form_password" action={~p"/users/log-in"}>
+    <.input
+      readonly={!!@current_scope}
+      field={f[:email]}
+      type="email"
+      label="Email"
+      autocomplete="username"
+      spellcheck="false"
+      required
+    />
+    <.input
+      field={f[:password]}
+      type="password"
+      label="Password"
+      autocomplete="current-password"
+      spellcheck="false"
+    />
+    <.button class="btn btn-primary w-full" name={@form[:remember_me].name} value="true">
+      Log in and stay logged in <span aria-hidden="true">→</span>
+    </.button>
+    <.button class="btn btn-primary btn-soft w-full mt-2">
+      Log in only this time
+    </.button>
+  </.form>
+</div>

app/lib/firehose_web/controllers/user_settings_controller.ex

@@ -0,0 +1,77 @@
+defmodule FirehoseWeb.UserSettingsController do
+  use FirehoseWeb, :controller
+
+  alias Firehose.Accounts
+  alias FirehoseWeb.UserAuth
+
+  import FirehoseWeb.UserAuth, only: [require_sudo_mode: 2]
+
+  plug :require_sudo_mode
+  plug :assign_email_and_password_changesets
+
+  def edit(conn, _params) do
+    render(conn, :edit)
+  end
+
+  def update(conn, %{"action" => "update_email"} = params) do
+    %{"user" => user_params} = params
+    user = conn.assigns.current_scope.user
+
+    case Accounts.change_user_email(user, user_params) do
+      %{valid?: true} = changeset ->
+        Accounts.deliver_user_update_email_instructions(
+          Ecto.Changeset.apply_action!(changeset, :insert),
+          user.email,
+          &url(~p"/users/settings/confirm-email/#{&1}")
+        )
+
+        conn
+        |> put_flash(
+          :info,
+          "A link to confirm your email change has been sent to the new address."
+        )
+        |> redirect(to: ~p"/users/settings")
+
+      changeset ->
+        render(conn, :edit, email_changeset: %{changeset | action: :insert})
+    end
+  end
+
+  def update(conn, %{"action" => "update_password"} = params) do
+    %{"user" => user_params} = params
+    user = conn.assigns.current_scope.user
+
+    case Accounts.update_user_password(user, user_params) do
+      {:ok, {user, _}} ->
+        conn
+        |> put_flash(:info, "Password updated successfully.")
+        |> put_session(:user_return_to, ~p"/users/settings")
+        |> UserAuth.log_in_user(user)
+
+      {:error, changeset} ->
+        render(conn, :edit, password_changeset: changeset)
+    end
+  end
+
+  def confirm_email(conn, %{"token" => token}) do
+    case Accounts.update_user_email(conn.assigns.current_scope.user, token) do
+      {:ok, _user} ->
+        conn
+        |> put_flash(:info, "Email changed successfully.")
+        |> redirect(to: ~p"/users/settings")
+
+      {:error, _} ->
+        conn
+        |> put_flash(:error, "Email change link is invalid or it has expired.")
+        |> redirect(to: ~p"/users/settings")
+    end
+  end
+
+  defp assign_email_and_password_changesets(conn, _opts) do
+    user = conn.assigns.current_scope.user
+
+    conn
+    |> assign(:email_changeset, Accounts.change_user_email(user))
+    |> assign(:password_changeset, Accounts.change_user_password(user))
+  end
+end

app/lib/firehose_web/controllers/user_settings_html.ex

@@ -0,0 +1,5 @@
+defmodule FirehoseWeb.UserSettingsHTML do
+  use FirehoseWeb, :html
+
+  embed_templates "user_settings_html/*"
+end

app/lib/firehose_web/controllers/user_settings_html/edit.html.heex

@@ -0,0 +1,47 @@
+<div class="text-center">
+  <.header>
+    Account Settings
+    <:subtitle>Manage your account email address and password settings</:subtitle>
+  </.header>
+</div>
+
+<.form :let={f} for={@email_changeset} action={~p"/users/settings"} id="update_email">
+  <input type="hidden" name="action" value="update_email" />
+
+  <.input
+    field={f[:email]}
+    type="email"
+    label="Email"
+    autocomplete="username"
+    spellcheck="false"
+    required
+  />
+
+  <.button variant="primary" phx-disable-with="Changing...">Change Email</.button>
+</.form>
+
+<div class="divider" />
+
+<.form :let={f} for={@password_changeset} action={~p"/users/settings"} id="update_password">
+  <input type="hidden" name="action" value="update_password" />
+
+  <.input
+    field={f[:password]}
+    type="password"
+    label="New password"
+    autocomplete="new-password"
+    spellcheck="false"
+    required
+  />
+  <.input
+    field={f[:password_confirmation]}
+    type="password"
+    label="Confirm new password"
+    autocomplete="new-password"
+    spellcheck="false"
+    required
+  />
+  <.button variant="primary" phx-disable-with="Changing...">
+    Save Password
+  </.button>
+</.form>

app/lib/firehose_web/router.ex

@@ -1,6 +1,8 @@
 defmodule FirehoseWeb.Router do
   use FirehoseWeb, :router
 
+  import FirehoseWeb.UserAuth
+
   pipeline :browser do
     plug :accepts, ["html"]
     plug :fetch_session
@@ -9,6 +11,7 @@ defmodule FirehoseWeb.Router do
     plug :put_layout, html: {FirehoseWeb.Layouts, :app}
     plug :protect_from_forgery
     plug :put_secure_browser_headers
+    plug :fetch_current_scope_for_user
   end
 
   pipeline :api do
@@ -51,4 +54,30 @@ defmodule FirehoseWeb.Router do
       forward "/mailbox", Plug.Swoosh.MailboxPreview
     end
   end
+
+  ## Authentication routes
+
+  scope "/", FirehoseWeb do
+    pipe_through [:browser, :redirect_if_user_is_authenticated]
+
+    get "/users/register", UserRegistrationController, :new
+    post "/users/register", UserRegistrationController, :create
+  end
+
+  scope "/", FirehoseWeb do
+    pipe_through [:browser, :require_authenticated_user]
+
+    get "/users/settings", UserSettingsController, :edit
+    put "/users/settings", UserSettingsController, :update
+    get "/users/settings/confirm-email/:token", UserSettingsController, :confirm_email
+  end
+
+  scope "/", FirehoseWeb do
+    pipe_through [:browser]
+
+    get "/users/log-in", UserSessionController, :new
+    get "/users/log-in/:token", UserSessionController, :confirm
+    post "/users/log-in", UserSessionController, :create
+    delete "/users/log-out", UserSessionController, :delete
+  end
 end

app/lib/firehose_web/user_auth.ex

@@ -0,0 +1,219 @@
+defmodule FirehoseWeb.UserAuth do
+  use FirehoseWeb, :verified_routes
+
+  import Plug.Conn
+  import Phoenix.Controller
+
+  alias Firehose.Accounts
+  alias Firehose.Accounts.Scope
+
+  # Make the remember me cookie valid for 14 days. This should match
+  # the session validity setting in UserToken.
+  @max_cookie_age_in_days 14
+  @remember_me_cookie "_firehose_web_user_remember_me"
+  @remember_me_options [
+    sign: true,
+    max_age: @max_cookie_age_in_days * 24 * 60 * 60,
+    same_site: "Lax"
+  ]
+
+  # How old the session token should be before a new one is issued. When a request is made
+  # with a session token older than this value, then a new session token will be created
+  # and the session and remember-me cookies (if set) will be updated with the new token.
+  # Lowering this value will result in more tokens being created by active users. Increasing
+  # it will result in less time before a session token expires for a user to get issued a new
+  # token. This can be set to a value greater than `@max_cookie_age_in_days` to disable
+  # the reissuing of tokens completely.
+  @session_reissue_age_in_days 7
+
+  @doc """
+  Logs the user in.
+
+  Redirects to the session's `:user_return_to` path
+  or falls back to the `signed_in_path/1`.
+  """
+  def log_in_user(conn, user, params \\ %{}) do
+    user_return_to = get_session(conn, :user_return_to)
+
+    conn
+    |> create_or_extend_session(user, params)
+    |> redirect(to: user_return_to || signed_in_path(conn))
+  end
+
+  @doc """
+  Logs the user out.
+
+  It clears all session data for safety. See renew_session.
+  """
+  def log_out_user(conn) do
+    user_token = get_session(conn, :user_token)
+    user_token && Accounts.delete_user_session_token(user_token)
+
+    if live_socket_id = get_session(conn, :live_socket_id) do
+      FirehoseWeb.Endpoint.broadcast(live_socket_id, "disconnect", %{})
+    end
+
+    conn
+    |> renew_session(nil)
+    |> delete_resp_cookie(@remember_me_cookie, @remember_me_options)
+    |> redirect(to: ~p"/")
+  end
+
+  @doc """
+  Authenticates the user by looking into the session and remember me token.
+
+  Will reissue the session token if it is older than the configured age.
+  """
+  def fetch_current_scope_for_user(conn, _opts) do
+    with {token, conn} <- ensure_user_token(conn),
+         {user, token_inserted_at} <- Accounts.get_user_by_session_token(token) do
+      conn
+      |> assign(:current_scope, Scope.for_user(user))
+      |> maybe_reissue_user_session_token(user, token_inserted_at)
+    else
+      nil -> assign(conn, :current_scope, Scope.for_user(nil))
+    end
+  end
+
+  defp ensure_user_token(conn) do
+    if token = get_session(conn, :user_token) do
+      {token, conn}
+    else
+      conn = fetch_cookies(conn, signed: [@remember_me_cookie])
+
+      if token = conn.cookies[@remember_me_cookie] do
+        {token, conn |> put_token_in_session(token) |> put_session(:user_remember_me, true)}
+      else
+        nil
+      end
+    end
+  end
+
+  # Reissue the session token if it is older than the configured reissue age.
+  defp maybe_reissue_user_session_token(conn, user, token_inserted_at) do
+    token_age = DateTime.diff(DateTime.utc_now(:second), token_inserted_at, :day)
+
+    if token_age >= @session_reissue_age_in_days do
+      create_or_extend_session(conn, user, %{})
+    else
+      conn
+    end
+  end
+
+  # This function is the one responsible for creating session tokens
+  # and storing them safely in the session and cookies. It may be called
+  # either when logging in, during sudo mode, or to renew a session which
+  # will soon expire.
+  #
+  # When the session is created, rather than extended, the renew_session
+  # function will clear the session to avoid fixation attacks. See the
+  # renew_session function to customize this behaviour.
+  defp create_or_extend_session(conn, user, params) do
+    token = Accounts.generate_user_session_token(user)
+    remember_me = get_session(conn, :user_remember_me)
+
+    conn
+    |> renew_session(user)
+    |> put_token_in_session(token)
+    |> maybe_write_remember_me_cookie(token, params, remember_me)
+  end
+
+  # Do not renew session if the user is already logged in
+  # to prevent CSRF errors or data being lost in tabs that are still open
+  defp renew_session(conn, user) when conn.assigns.current_scope.user.id == user.id do
+    conn
+  end
+
+  # This function renews the session ID and erases the whole
+  # session to avoid fixation attacks. If there is any data
+  # in the session you may want to preserve after log in/log out,
+  # you must explicitly fetch the session data before clearing
+  # and then immediately set it after clearing, for example:
+  #
+  #     defp renew_session(conn, _user) do
+  #       delete_csrf_token()
+  #       preferred_locale = get_session(conn, :preferred_locale)
+  #
+  #       conn
+  #       |> configure_session(renew: true)
+  #       |> clear_session()
+  #       |> put_session(:preferred_locale, preferred_locale)
+  #     end
+  #
+  defp renew_session(conn, _user) do
+    delete_csrf_token()
+
+    conn
+    |> configure_session(renew: true)
+    |> clear_session()
+  end
+
+  defp maybe_write_remember_me_cookie(conn, token, %{"remember_me" => "true"}, _),
+    do: write_remember_me_cookie(conn, token)
+
+  defp maybe_write_remember_me_cookie(conn, token, _params, true),
+    do: write_remember_me_cookie(conn, token)
+
+  defp maybe_write_remember_me_cookie(conn, _token, _params, _), do: conn
+
+  defp write_remember_me_cookie(conn, token) do
+    conn
+    |> put_session(:user_remember_me, true)
+    |> put_resp_cookie(@remember_me_cookie, token, @remember_me_options)
+  end
+
+  defp put_token_in_session(conn, token) do
+    put_session(conn, :user_token, token)
+  end
+
+  @doc """
+  Plug for routes that require sudo mode.
+  """
+  def require_sudo_mode(conn, _opts) do
+    if Accounts.sudo_mode?(conn.assigns.current_scope.user, -10) do
+      conn
+    else
+      conn
+      |> put_flash(:error, "You must re-authenticate to access this page.")
+      |> maybe_store_return_to()
+      |> redirect(to: ~p"/users/log-in")
+      |> halt()
+    end
+  end
+
+  @doc """
+  Plug for routes that require the user to not be authenticated.
+  """
+  def redirect_if_user_is_authenticated(conn, _opts) do
+    if conn.assigns.current_scope do
+      conn
+      |> redirect(to: signed_in_path(conn))
+      |> halt()
+    else
+      conn
+    end
+  end
+
+  defp signed_in_path(_conn), do: ~p"/"
+
+  @doc """
+  Plug for routes that require the user to be authenticated.
+  """
+  def require_authenticated_user(conn, _opts) do
+    if conn.assigns.current_scope && conn.assigns.current_scope.user do
+      conn
+    else
+      conn
+      |> put_flash(:error, "You must log in to access this page.")
+      |> maybe_store_return_to()
+      |> redirect(to: ~p"/users/log-in")
+      |> halt()
+    end
+  end
+
+  defp maybe_store_return_to(%{method: "GET"} = conn) do
+    put_session(conn, :user_return_to, current_path(conn))
+  end
+
+  defp maybe_store_return_to(conn), do: conn
+end

app/mix.exs

@@ -41,6 +41,7 @@ defmodule Firehose.MixProject do
   # Type `mix help deps` for examples and options.
   defp deps do
     [
+      {:bcrypt_elixir, "~> 3.0"},
       {:phoenix, "~> 1.8.1"},
       {:phoenix_ecto, "~> 4.5"},
       {:ecto_sql, "~> 3.13"},

app/mix.lock

@@ -1,7 +1,9 @@
 %{
   "bandit": {:hex, :bandit, "1.10.3", "1e5d168fa79ec8de2860d1b4d878d97d4fbbe2fdbe7b0a7d9315a4359d1d4bb9", [:mix], [{:hpax, "~> 1.0", [hex: :hpax, repo: "hexpm", optional: false]}, {:plug, "~> 1.18", [hex: :plug, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}, {:thousand_island, "~> 1.0", [hex: :thousand_island, repo: "hexpm", optional: false]}, {:websock, "~> 0.5", [hex: :websock, repo: "hexpm", optional: false]}], "hexpm", "99a52d909c48db65ca598e1962797659e3c0f1d06e825a50c3d75b74a5e2db18"},
+  "bcrypt_elixir": {:hex, :bcrypt_elixir, "3.3.2", "d50091e3c9492d73e17fc1e1619a9b09d6a5ef99160eb4d736926fd475a16ca3", [:make, :mix], [{:comeonin, "~> 5.3", [hex: :comeonin, repo: "hexpm", optional: false]}, {:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "471be5151874ae7931911057d1467d908955f93554f7a6cd1b7d804cac8cef53"},
   "bunt": {:hex, :bunt, "1.0.0", "081c2c665f086849e6d57900292b3a161727ab40431219529f13c4ddcf3e7a44", [:mix], [], "hexpm", "dc5f86aa08a5f6fa6b8096f0735c4e76d54ae5c9fa2c143e5a1fc7c1cd9bb6b5"},
   "cc_precompiler": {:hex, :cc_precompiler, "0.1.11", "8c844d0b9fb98a3edea067f94f616b3f6b29b959b6b3bf25fee94ffe34364768", [:mix], [{:elixir_make, "~> 0.7", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "3427232caf0835f94680e5bcf082408a70b48ad68a5f5c0b02a3bea9f3a075b9"},
+  "comeonin": {:hex, :comeonin, "5.5.1", "5113e5f3800799787de08a6e0db307133850e635d34e9fab23c70b6501669510", [:mix], [], "hexpm", "65aac8f19938145377cee73973f192c5645873dcf550a8a6b18187d17c13ccdb"},
   "credo": {:hex, :credo, "1.7.17", "f92b6aa5b26301eaa5a35e4d48ebf5aa1e7094ac00ae38f87086c562caf8a22f", [:mix], [{:bunt, "~> 0.2.1 or ~> 1.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:file_system, "~> 0.2 or ~> 1.0", [hex: :file_system, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "1eb5645c835f0b6c9b5410f94b5a185057bcf6d62a9c2b476da971cde8749645"},
   "db_connection": {:hex, :db_connection, "2.9.0", "a6a97c5c958a2d7091a58a9be40caf41ab496b0701d21e1d1abff3fa27a7f371", [:mix], [{:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "17d502eacaf61829db98facf6f20808ed33da6ccf495354a41e64fe42f9c509c"},
   "decimal": {:hex, :decimal, "2.3.0", "3ad6255aa77b4a3c4f818171b12d237500e63525c2fd056699967a3e7ea20f62", [:mix], [], "hexpm", "a4d66355cb29cb47c3cf30e71329e58361cfcb37c34235ef3bf1d7bf3773aeac"},

app/priv/repo/migrations/20260401201722_create_users_auth_tables.exs

@@ -0,0 +1,30 @@
+defmodule Firehose.Repo.Migrations.CreateUsersAuthTables do
+  use Ecto.Migration
+
+  def change do
+    execute "CREATE EXTENSION IF NOT EXISTS citext", ""
+
+    create table(:users) do
+      add :email, :citext, null: false
+      add :hashed_password, :string
+      add :confirmed_at, :utc_datetime
+
+      timestamps(type: :utc_datetime)
+    end
+
+    create unique_index(:users, [:email])
+
+    create table(:users_tokens) do
+      add :user_id, references(:users, on_delete: :delete_all), null: false
+      add :token, :binary, null: false
+      add :context, :string, null: false
+      add :sent_to, :string
+      add :authenticated_at, :utc_datetime
+
+      timestamps(type: :utc_datetime, updated_at: false)
+    end
+
+    create index(:users_tokens, [:user_id])
+    create unique_index(:users_tokens, [:context, :token])
+  end
+end

app/test/firehose/accounts_test.exs

@@ -0,0 +1,397 @@
+defmodule Firehose.AccountsTest do
+  use Firehose.DataCase
+
+  alias Firehose.Accounts
+
+  import Firehose.AccountsFixtures
+  alias Firehose.Accounts.{User, UserToken}
+
+  describe "get_user_by_email/1" do
+    test "does not return the user if the email does not exist" do
+      refute Accounts.get_user_by_email("unknown@example.com")
+    end
+
+    test "returns the user if the email exists" do
+      %{id: id} = user = user_fixture()
+      assert %User{id: ^id} = Accounts.get_user_by_email(user.email)
+    end
+  end
+
+  describe "get_user_by_email_and_password/2" do
+    test "does not return the user if the email does not exist" do
+      refute Accounts.get_user_by_email_and_password("unknown@example.com", "hello world!")
+    end
+
+    test "does not return the user if the password is not valid" do
+      user = user_fixture() |> set_password()
+      refute Accounts.get_user_by_email_and_password(user.email, "invalid")
+    end
+
+    test "returns the user if the email and password are valid" do
+      %{id: id} = user = user_fixture() |> set_password()
+
+      assert %User{id: ^id} =
+               Accounts.get_user_by_email_and_password(user.email, valid_user_password())
+    end
+  end
+
+  describe "get_user!/1" do
+    test "raises if id is invalid" do
+      assert_raise Ecto.NoResultsError, fn ->
+        Accounts.get_user!(-1)
+      end
+    end
+
+    test "returns the user with the given id" do
+      %{id: id} = user = user_fixture()
+      assert %User{id: ^id} = Accounts.get_user!(user.id)
+    end
+  end
+
+  describe "register_user/1" do
+    test "requires email to be set" do
+      {:error, changeset} = Accounts.register_user(%{})
+
+      assert %{email: ["can't be blank"]} = errors_on(changeset)
+    end
+
+    test "validates email when given" do
+      {:error, changeset} = Accounts.register_user(%{email: "not valid"})
+
+      assert %{email: ["must have the @ sign and no spaces"]} = errors_on(changeset)
+    end
+
+    test "validates maximum values for email for security" do
+      too_long = String.duplicate("db", 100)
+      {:error, changeset} = Accounts.register_user(%{email: too_long})
+      assert "should be at most 160 character(s)" in errors_on(changeset).email
+    end
+
+    test "validates email uniqueness" do
+      %{email: email} = user_fixture()
+      {:error, changeset} = Accounts.register_user(%{email: email})
+      assert "has already been taken" in errors_on(changeset).email
+
+      # Now try with the uppercased email too, to check that email case is ignored.
+      {:error, changeset} = Accounts.register_user(%{email: String.upcase(email)})
+      assert "has already been taken" in errors_on(changeset).email
+    end
+
+    test "registers users without password" do
+      email = unique_user_email()
+      {:ok, user} = Accounts.register_user(valid_user_attributes(email: email))
+      assert user.email == email
+      assert is_nil(user.hashed_password)
+      assert is_nil(user.confirmed_at)
+      assert is_nil(user.password)
+    end
+  end
+
+  describe "sudo_mode?/2" do
+    test "validates the authenticated_at time" do
+      now = DateTime.utc_now()
+
+      assert Accounts.sudo_mode?(%User{authenticated_at: DateTime.utc_now()})
+      assert Accounts.sudo_mode?(%User{authenticated_at: DateTime.add(now, -19, :minute)})
+      refute Accounts.sudo_mode?(%User{authenticated_at: DateTime.add(now, -21, :minute)})
+
+      # minute override
+      refute Accounts.sudo_mode?(
+               %User{authenticated_at: DateTime.add(now, -11, :minute)},
+               -10
+             )
+
+      # not authenticated
+      refute Accounts.sudo_mode?(%User{})
+    end
+  end
+
+  describe "change_user_email/3" do
+    test "returns a user changeset" do
+      assert %Ecto.Changeset{} = changeset = Accounts.change_user_email(%User{})
+      assert changeset.required == [:email]
+    end
+  end
+
+  describe "deliver_user_update_email_instructions/3" do
+    setup do
+      %{user: user_fixture()}
+    end
+
+    test "sends token through notification", %{user: user} do
+      token =
+        extract_user_token(fn url ->
+          Accounts.deliver_user_update_email_instructions(user, "current@example.com", url)
+        end)
+
+      {:ok, token} = Base.url_decode64(token, padding: false)
+      assert user_token = Repo.get_by(UserToken, token: :crypto.hash(:sha256, token))
+      assert user_token.user_id == user.id
+      assert user_token.sent_to == user.email
+      assert user_token.context == "change:current@example.com"
+    end
+  end
+
+  describe "update_user_email/2" do
+    setup do
+      user = unconfirmed_user_fixture()
+      email = unique_user_email()
+
+      token =
+        extract_user_token(fn url ->
+          Accounts.deliver_user_update_email_instructions(%{user | email: email}, user.email, url)
+        end)
+
+      %{user: user, token: token, email: email}
+    end
+
+    test "updates the email with a valid token", %{user: user, token: token, email: email} do
+      assert {:ok, %{email: ^email}} = Accounts.update_user_email(user, token)
+      changed_user = Repo.get!(User, user.id)
+      assert changed_user.email != user.email
+      assert changed_user.email == email
+      refute Repo.get_by(UserToken, user_id: user.id)
+    end
+
+    test "does not update email with invalid token", %{user: user} do
+      assert Accounts.update_user_email(user, "oops") ==
+               {:error, :transaction_aborted}
+
+      assert Repo.get!(User, user.id).email == user.email
+      assert Repo.get_by(UserToken, user_id: user.id)
+    end
+
+    test "does not update email if user email changed", %{user: user, token: token} do
+      assert Accounts.update_user_email(%{user | email: "current@example.com"}, token) ==
+               {:error, :transaction_aborted}
+
+      assert Repo.get!(User, user.id).email == user.email
+      assert Repo.get_by(UserToken, user_id: user.id)
+    end
+
+    test "does not update email if token expired", %{user: user, token: token} do
+      {1, nil} = Repo.update_all(UserToken, set: [inserted_at: ~N[2020-01-01 00:00:00]])
+
+      assert Accounts.update_user_email(user, token) ==
+               {:error, :transaction_aborted}
+
+      assert Repo.get!(User, user.id).email == user.email
+      assert Repo.get_by(UserToken, user_id: user.id)
+    end
+  end
+
+  describe "change_user_password/3" do
+    test "returns a user changeset" do
+      assert %Ecto.Changeset{} = changeset = Accounts.change_user_password(%User{})
+      assert changeset.required == [:password]
+    end
+
+    test "allows fields to be set" do
+      changeset =
+        Accounts.change_user_password(
+          %User{},
+          %{
+            "password" => "new valid password"
+          },
+          hash_password: false
+        )
+
+      assert changeset.valid?
+      assert get_change(changeset, :password) == "new valid password"
+      assert is_nil(get_change(changeset, :hashed_password))
+    end
+  end
+
+  describe "update_user_password/2" do
+    setup do
+      %{user: user_fixture()}
+    end
+
+    test "validates password", %{user: user} do
+      {:error, changeset} =
+        Accounts.update_user_password(user, %{
+          password: "not valid",
+          password_confirmation: "another"
+        })
+
+      assert %{
+               password: ["should be at least 12 character(s)"],
+               password_confirmation: ["does not match password"]
+             } = errors_on(changeset)
+    end
+
+    test "validates maximum values for password for security", %{user: user} do
+      too_long = String.duplicate("db", 100)
+
+      {:error, changeset} =
+        Accounts.update_user_password(user, %{password: too_long})
+
+      assert "should be at most 72 character(s)" in errors_on(changeset).password
+    end
+
+    test "updates the password", %{user: user} do
+      {:ok, {user, expired_tokens}} =
+        Accounts.update_user_password(user, %{
+          password: "new valid password"
+        })
+
+      assert expired_tokens == []
+      assert is_nil(user.password)
+      assert Accounts.get_user_by_email_and_password(user.email, "new valid password")
+    end
+
+    test "deletes all tokens for the given user", %{user: user} do
+      _ = Accounts.generate_user_session_token(user)
+
+      {:ok, {_, _}} =
+        Accounts.update_user_password(user, %{
+          password: "new valid password"
+        })
+
+      refute Repo.get_by(UserToken, user_id: user.id)
+    end
+  end
+
+  describe "generate_user_session_token/1" do
+    setup do
+      %{user: user_fixture()}
+    end
+
+    test "generates a token", %{user: user} do
+      token = Accounts.generate_user_session_token(user)
+      assert user_token = Repo.get_by(UserToken, token: token)
+      assert user_token.context == "session"
+      assert user_token.authenticated_at != nil
+
+      # Creating the same token for another user should fail
+      assert_raise Ecto.ConstraintError, fn ->
+        Repo.insert!(%UserToken{
+          token: user_token.token,
+          user_id: user_fixture().id,
+          context: "session"
+        })
+      end
+    end
+
+    test "duplicates the authenticated_at of given user in new token", %{user: user} do
+      user = %{user | authenticated_at: DateTime.add(DateTime.utc_now(:second), -3600)}
+      token = Accounts.generate_user_session_token(user)
+      assert user_token = Repo.get_by(UserToken, token: token)
+      assert user_token.authenticated_at == user.authenticated_at
+      assert DateTime.compare(user_token.inserted_at, user.authenticated_at) == :gt
+    end
+  end
+
+  describe "get_user_by_session_token/1" do
+    setup do
+      user = user_fixture()
+      token = Accounts.generate_user_session_token(user)
+      %{user: user, token: token}
+    end
+
+    test "returns user by token", %{user: user, token: token} do
+      assert {session_user, token_inserted_at} = Accounts.get_user_by_session_token(token)
+      assert session_user.id == user.id
+      assert session_user.authenticated_at != nil
+      assert token_inserted_at != nil
+    end
+
+    test "does not return user for invalid token" do
+      refute Accounts.get_user_by_session_token("oops")
+    end
+
+    test "does not return user for expired token", %{token: token} do
+      dt = ~N[2020-01-01 00:00:00]
+      {1, nil} = Repo.update_all(UserToken, set: [inserted_at: dt, authenticated_at: dt])
+      refute Accounts.get_user_by_session_token(token)
+    end
+  end
+
+  describe "get_user_by_magic_link_token/1" do
+    setup do
+      user = user_fixture()
+      {encoded_token, _hashed_token} = generate_user_magic_link_token(user)
+      %{user: user, token: encoded_token}
+    end
+
+    test "returns user by token", %{user: user, token: token} do
+      assert session_user = Accounts.get_user_by_magic_link_token(token)
+      assert session_user.id == user.id
+    end
+
+    test "does not return user for invalid token" do
+      refute Accounts.get_user_by_magic_link_token("oops")
+    end
+
+    test "does not return user for expired token", %{token: token} do
+      {1, nil} = Repo.update_all(UserToken, set: [inserted_at: ~N[2020-01-01 00:00:00]])
+      refute Accounts.get_user_by_magic_link_token(token)
+    end
+  end
+
+  describe "login_user_by_magic_link/1" do
+    test "confirms user and expires tokens" do
+      user = unconfirmed_user_fixture()
+      refute user.confirmed_at
+      {encoded_token, hashed_token} = generate_user_magic_link_token(user)
+
+      assert {:ok, {user, [%{token: ^hashed_token}]}} =
+               Accounts.login_user_by_magic_link(encoded_token)
+
+      assert user.confirmed_at
+    end
+
+    test "returns user and (deleted) token for confirmed user" do
+      user = user_fixture()
+      assert user.confirmed_at
+      {encoded_token, _hashed_token} = generate_user_magic_link_token(user)
+      assert {:ok, {^user, []}} = Accounts.login_user_by_magic_link(encoded_token)
+      # one time use only
+      assert {:error, :not_found} = Accounts.login_user_by_magic_link(encoded_token)
+    end
+
+    test "raises when unconfirmed user has password set" do
+      user = unconfirmed_user_fixture()
+      {1, nil} = Repo.update_all(User, set: [hashed_password: "hashed"])
+      {encoded_token, _hashed_token} = generate_user_magic_link_token(user)
+
+      assert_raise RuntimeError, ~r/magic link log in is not allowed/, fn ->
+        Accounts.login_user_by_magic_link(encoded_token)
+      end
+    end
+  end
+
+  describe "delete_user_session_token/1" do
+    test "deletes the token" do
+      user = user_fixture()
+      token = Accounts.generate_user_session_token(user)
+      assert Accounts.delete_user_session_token(token) == :ok
+      refute Accounts.get_user_by_session_token(token)
+    end
+  end
+
+  describe "deliver_login_instructions/2" do
+    setup do
+      %{user: unconfirmed_user_fixture()}
+    end
+
+    test "sends token through notification", %{user: user} do
+      token =
+        extract_user_token(fn url ->
+          Accounts.deliver_login_instructions(user, url)
+        end)
+
+      {:ok, token} = Base.url_decode64(token, padding: false)
+      assert user_token = Repo.get_by(UserToken, token: :crypto.hash(:sha256, token))
+      assert user_token.user_id == user.id
+      assert user_token.sent_to == user.email
+      assert user_token.context == "login"
+    end
+  end
+
+  describe "inspect/2 for the User module" do
+    test "does not include password" do
+      refute inspect(%User{password: "123456"}) =~ "password: \"123456\""
+    end
+  end
+end

app/test/firehose_web/controllers/user_registration_controller_test.exs

@@ -0,0 +1,50 @@
+defmodule FirehoseWeb.UserRegistrationControllerTest do
+  use FirehoseWeb.ConnCase, async: true
+
+  import Firehose.AccountsFixtures
+
+  describe "GET /users/register" do
+    test "renders registration page", %{conn: conn} do
+      conn = get(conn, ~p"/users/register")
+      response = html_response(conn, 200)
+      assert response =~ "Register"
+      assert response =~ ~p"/users/log-in"
+      assert response =~ ~p"/users/register"
+    end
+
+    test "redirects if already logged in", %{conn: conn} do
+      conn = conn |> log_in_user(user_fixture()) |> get(~p"/users/register")
+
+      assert redirected_to(conn) == ~p"/"
+    end
+  end
+
+  describe "POST /users/register" do
+    @tag :capture_log
+    test "creates account but does not log in", %{conn: conn} do
+      email = unique_user_email()
+
+      conn =
+        post(conn, ~p"/users/register", %{
+          "user" => valid_user_attributes(email: email)
+        })
+
+      refute get_session(conn, :user_token)
+      assert redirected_to(conn) == ~p"/users/log-in"
+
+      assert conn.assigns.flash["info"] =~
+               ~r/An email was sent to .*, please access it to confirm your account/
+    end
+
+    test "render errors for invalid data", %{conn: conn} do
+      conn =
+        post(conn, ~p"/users/register", %{
+          "user" => %{"email" => "with spaces"}
+        })
+
+      response = html_response(conn, 200)
+      assert response =~ "Register"
+      assert response =~ "must have the @ sign and no spaces"
+    end
+  end
+end

app/test/firehose_web/controllers/user_session_controller_test.exs

@@ -0,0 +1,199 @@
+defmodule FirehoseWeb.UserSessionControllerTest do
+  use FirehoseWeb.ConnCase, async: true
+
+  import Firehose.AccountsFixtures
+  alias Firehose.Accounts
+
+  setup do
+    %{unconfirmed_user: unconfirmed_user_fixture(), user: user_fixture()}
+  end
+
+  describe "GET /users/log-in" do
+    test "renders login page", %{conn: conn} do
+      conn = get(conn, ~p"/users/log-in")
+      response = html_response(conn, 200)
+      assert response =~ "Log in"
+      assert response =~ ~p"/users/register"
+      assert response =~ "Log in with email"
+    end
+
+    test "renders login page with email filled in (sudo mode)", %{conn: conn, user: user} do
+      html =
+        conn
+        |> log_in_user(user)
+        |> get(~p"/users/log-in")
+        |> html_response(200)
+
+      assert html =~ "You need to reauthenticate"
+      refute html =~ "Register"
+      assert html =~ "Log in with email"
+
+      assert html =~
+               ~s(<input type="email" name="user[email]" id="login_form_magic_email" value="#{user.email}")
+    end
+
+    test "renders login page (email + password)", %{conn: conn} do
+      conn = get(conn, ~p"/users/log-in?mode=password")
+      response = html_response(conn, 200)
+      assert response =~ "Log in"
+      assert response =~ ~p"/users/register"
+      assert response =~ "Log in with email"
+    end
+  end
+
+  describe "GET /users/log-in/:token" do
+    test "renders confirmation page for unconfirmed user", %{conn: conn, unconfirmed_user: user} do
+      token =
+        extract_user_token(fn url ->
+          Accounts.deliver_login_instructions(user, url)
+        end)
+
+      conn = get(conn, ~p"/users/log-in/#{token}")
+      assert html_response(conn, 200) =~ "Confirm and stay logged in"
+    end
+
+    test "renders login page for confirmed user", %{conn: conn, user: user} do
+      token =
+        extract_user_token(fn url ->
+          Accounts.deliver_login_instructions(user, url)
+        end)
+
+      conn = get(conn, ~p"/users/log-in/#{token}")
+      html = html_response(conn, 200)
+      refute html =~ "Confirm my account"
+      assert html =~ "Keep me logged in on this device"
+    end
+
+    test "raises error for invalid token", %{conn: conn} do
+      conn = get(conn, ~p"/users/log-in/invalid-token")
+      assert redirected_to(conn) == ~p"/users/log-in"
+
+      assert Phoenix.Flash.get(conn.assigns.flash, :error) ==
+               "Magic link is invalid or it has expired."
+    end
+  end
+
+  describe "POST /users/log-in - email and password" do
+    test "logs the user in", %{conn: conn, user: user} do
+      user = set_password(user)
+
+      conn =
+        post(conn, ~p"/users/log-in", %{
+          "user" => %{"email" => user.email, "password" => valid_user_password()}
+        })
+
+      assert get_session(conn, :user_token)
+      assert redirected_to(conn) == ~p"/"
+    end
+
+    test "logs the user in with remember me", %{conn: conn, user: user} do
+      user = set_password(user)
+
+      conn =
+        post(conn, ~p"/users/log-in", %{
+          "user" => %{
+            "email" => user.email,
+            "password" => valid_user_password(),
+            "remember_me" => "true"
+          }
+        })
+
+      assert conn.resp_cookies["_firehose_web_user_remember_me"]
+      assert redirected_to(conn) == ~p"/"
+    end
+
+    test "logs the user in with return to", %{conn: conn, user: user} do
+      user = set_password(user)
+
+      conn =
+        conn
+        |> init_test_session(user_return_to: "/foo/bar")
+        |> post(~p"/users/log-in", %{
+          "user" => %{
+            "email" => user.email,
+            "password" => valid_user_password()
+          }
+        })
+
+      assert redirected_to(conn) == "/foo/bar"
+      assert Phoenix.Flash.get(conn.assigns.flash, :info) =~ "Welcome back!"
+    end
+
+    test "emits error message with invalid credentials", %{conn: conn, user: user} do
+      conn =
+        post(conn, ~p"/users/log-in?mode=password", %{
+          "user" => %{"email" => user.email, "password" => "invalid_password"}
+        })
+
+      response = html_response(conn, 200)
+      assert response =~ "Log in"
+      assert response =~ "Invalid email or password"
+    end
+  end
+
+  describe "POST /users/log-in - magic link" do
+    test "sends magic link email when user exists", %{conn: conn, user: user} do
+      conn =
+        post(conn, ~p"/users/log-in", %{
+          "user" => %{"email" => user.email}
+        })
+
+      assert Phoenix.Flash.get(conn.assigns.flash, :info) =~ "If your email is in our system"
+      assert Firehose.Repo.get_by!(Accounts.UserToken, user_id: user.id).context == "login"
+    end
+
+    test "logs the user in", %{conn: conn, user: user} do
+      {token, _hashed_token} = generate_user_magic_link_token(user)
+
+      conn =
+        post(conn, ~p"/users/log-in", %{
+          "user" => %{"token" => token}
+        })
+
+      assert get_session(conn, :user_token)
+      assert redirected_to(conn) == ~p"/"
+    end
+
+    test "confirms unconfirmed user", %{conn: conn, unconfirmed_user: user} do
+      {token, _hashed_token} = generate_user_magic_link_token(user)
+      refute user.confirmed_at
+
+      conn =
+        post(conn, ~p"/users/log-in", %{
+          "user" => %{"token" => token},
+          "_action" => "confirmed"
+        })
+
+      assert get_session(conn, :user_token)
+      assert redirected_to(conn) == ~p"/"
+      assert Phoenix.Flash.get(conn.assigns.flash, :info) =~ "User confirmed successfully."
+
+      assert Accounts.get_user!(user.id).confirmed_at
+    end
+
+    test "emits error message when magic link is invalid", %{conn: conn} do
+      conn =
+        post(conn, ~p"/users/log-in", %{
+          "user" => %{"token" => "invalid"}
+        })
+
+      assert html_response(conn, 200) =~ "The link is invalid or it has expired."
+    end
+  end
+
+  describe "DELETE /users/log-out" do
+    test "logs the user out", %{conn: conn, user: user} do
+      conn = conn |> log_in_user(user) |> delete(~p"/users/log-out")
+      assert redirected_to(conn) == ~p"/"
+      refute get_session(conn, :user_token)
+      assert Phoenix.Flash.get(conn.assigns.flash, :info) =~ "Logged out successfully"
+    end
+
+    test "succeeds even if the user is not logged in", %{conn: conn} do
+      conn = delete(conn, ~p"/users/log-out")
+      assert redirected_to(conn) == ~p"/"
+      refute get_session(conn, :user_token)
+      assert Phoenix.Flash.get(conn.assigns.flash, :info) =~ "Logged out successfully"
+    end
+  end
+end

app/test/firehose_web/controllers/user_settings_controller_test.exs

@@ -0,0 +1,148 @@
+defmodule FirehoseWeb.UserSettingsControllerTest do
+  use FirehoseWeb.ConnCase, async: true
+
+  alias Firehose.Accounts
+  import Firehose.AccountsFixtures
+
+  setup :register_and_log_in_user
+
+  describe "GET /users/settings" do
+    test "renders settings page", %{conn: conn} do
+      conn = get(conn, ~p"/users/settings")
+      response = html_response(conn, 200)
+      assert response =~ "Settings"
+    end
+
+    test "redirects if user is not logged in" do
+      conn = build_conn()
+      conn = get(conn, ~p"/users/settings")
+      assert redirected_to(conn) == ~p"/users/log-in"
+    end
+
+    @tag token_authenticated_at: DateTime.add(DateTime.utc_now(:second), -11, :minute)
+    test "redirects if user is not in sudo mode", %{conn: conn} do
+      conn = get(conn, ~p"/users/settings")
+      assert redirected_to(conn) == ~p"/users/log-in"
+
+      assert Phoenix.Flash.get(conn.assigns.flash, :error) ==
+               "You must re-authenticate to access this page."
+    end
+  end
+
+  describe "PUT /users/settings (change password form)" do
+    test "updates the user password and resets tokens", %{conn: conn, user: user} do
+      new_password_conn =
+        put(conn, ~p"/users/settings", %{
+          "action" => "update_password",
+          "user" => %{
+            "password" => "new valid password",
+            "password_confirmation" => "new valid password"
+          }
+        })
+
+      assert redirected_to(new_password_conn) == ~p"/users/settings"
+
+      assert get_session(new_password_conn, :user_token) != get_session(conn, :user_token)
+
+      assert Phoenix.Flash.get(new_password_conn.assigns.flash, :info) =~
+               "Password updated successfully"
+
+      assert Accounts.get_user_by_email_and_password(user.email, "new valid password")
+    end
+
+    test "does not update password on invalid data", %{conn: conn} do
+      old_password_conn =
+        put(conn, ~p"/users/settings", %{
+          "action" => "update_password",
+          "user" => %{
+            "password" => "too short",
+            "password_confirmation" => "does not match"
+          }
+        })
+
+      response = html_response(old_password_conn, 200)
+      assert response =~ "Settings"
+      assert response =~ "should be at least 12 character(s)"
+      assert response =~ "does not match password"
+
+      assert get_session(old_password_conn, :user_token) == get_session(conn, :user_token)
+    end
+  end
+
+  describe "PUT /users/settings (change email form)" do
+    @tag :capture_log
+    test "updates the user email", %{conn: conn, user: user} do
+      conn =
+        put(conn, ~p"/users/settings", %{
+          "action" => "update_email",
+          "user" => %{"email" => unique_user_email()}
+        })
+
+      assert redirected_to(conn) == ~p"/users/settings"
+
+      assert Phoenix.Flash.get(conn.assigns.flash, :info) =~
+               "A link to confirm your email"
+
+      assert Accounts.get_user_by_email(user.email)
+    end
+
+    test "does not update email on invalid data", %{conn: conn} do
+      conn =
+        put(conn, ~p"/users/settings", %{
+          "action" => "update_email",
+          "user" => %{"email" => "with spaces"}
+        })
+
+      response = html_response(conn, 200)
+      assert response =~ "Settings"
+      assert response =~ "must have the @ sign and no spaces"
+    end
+  end
+
+  describe "GET /users/settings/confirm-email/:token" do
+    setup %{user: user} do
+      email = unique_user_email()
+
+      token =
+        extract_user_token(fn url ->
+          Accounts.deliver_user_update_email_instructions(%{user | email: email}, user.email, url)
+        end)
+
+      %{token: token, email: email}
+    end
+
+    test "updates the user email once", %{conn: conn, user: user, token: token, email: email} do
+      conn = get(conn, ~p"/users/settings/confirm-email/#{token}")
+      assert redirected_to(conn) == ~p"/users/settings"
+
+      assert Phoenix.Flash.get(conn.assigns.flash, :info) =~
+               "Email changed successfully"
+
+      refute Accounts.get_user_by_email(user.email)
+      assert Accounts.get_user_by_email(email)
+
+      conn = get(conn, ~p"/users/settings/confirm-email/#{token}")
+
+      assert redirected_to(conn) == ~p"/users/settings"
+
+      assert Phoenix.Flash.get(conn.assigns.flash, :error) =~
+               "Email change link is invalid or it has expired"
+    end
+
+    test "does not update email with invalid token", %{conn: conn, user: user} do
+      conn = get(conn, ~p"/users/settings/confirm-email/oops")
+      assert redirected_to(conn) == ~p"/users/settings"
+
+      assert Phoenix.Flash.get(conn.assigns.flash, :error) =~
+               "Email change link is invalid or it has expired"
+
+      assert Accounts.get_user_by_email(user.email)
+    end
+
+    test "redirects if user is not logged in", %{token: token} do
+      conn = build_conn()
+      conn = get(conn, ~p"/users/settings/confirm-email/#{token}")
+      assert redirected_to(conn) == ~p"/users/log-in"
+    end
+  end
+end

app/test/firehose_web/user_auth_test.exs

@@ -0,0 +1,293 @@
+defmodule FirehoseWeb.UserAuthTest do
+  use FirehoseWeb.ConnCase, async: true
+
+  alias Firehose.Accounts
+  alias Firehose.Accounts.Scope
+  alias FirehoseWeb.UserAuth
+
+  import Firehose.AccountsFixtures
+
+  @remember_me_cookie "_firehose_web_user_remember_me"
+  @remember_me_cookie_max_age 60 * 60 * 24 * 14
+
+  setup %{conn: conn} do
+    conn =
+      conn
+      |> Map.replace!(:secret_key_base, FirehoseWeb.Endpoint.config(:secret_key_base))
+      |> init_test_session(%{})
+
+    %{user: %{user_fixture() | authenticated_at: DateTime.utc_now(:second)}, conn: conn}
+  end
+
+  describe "log_in_user/3" do
+    test "stores the user token in the session", %{conn: conn, user: user} do
+      conn = UserAuth.log_in_user(conn, user)
+      assert token = get_session(conn, :user_token)
+      assert redirected_to(conn) == ~p"/"
+      assert Accounts.get_user_by_session_token(token)
+    end
+
+    test "clears everything previously stored in the session", %{conn: conn, user: user} do
+      conn = conn |> put_session(:to_be_removed, "value") |> UserAuth.log_in_user(user)
+      refute get_session(conn, :to_be_removed)
+    end
+
+    test "keeps session when re-authenticating", %{conn: conn, user: user} do
+      conn =
+        conn
+        |> assign(:current_scope, Scope.for_user(user))
+        |> put_session(:to_be_removed, "value")
+        |> UserAuth.log_in_user(user)
+
+      assert get_session(conn, :to_be_removed)
+    end
+
+    test "clears session when user does not match when re-authenticating", %{
+      conn: conn,
+      user: user
+    } do
+      other_user = user_fixture()
+
+      conn =
+        conn
+        |> assign(:current_scope, Scope.for_user(other_user))
+        |> put_session(:to_be_removed, "value")
+        |> UserAuth.log_in_user(user)
+
+      refute get_session(conn, :to_be_removed)
+    end
+
+    test "redirects to the configured path", %{conn: conn, user: user} do
+      conn = conn |> put_session(:user_return_to, "/hello") |> UserAuth.log_in_user(user)
+      assert redirected_to(conn) == "/hello"
+    end
+
+    test "writes a cookie if remember_me is configured", %{conn: conn, user: user} do
+      conn = conn |> fetch_cookies() |> UserAuth.log_in_user(user, %{"remember_me" => "true"})
+      assert get_session(conn, :user_token) == conn.cookies[@remember_me_cookie]
+      assert get_session(conn, :user_remember_me) == true
+
+      assert %{value: signed_token, max_age: max_age} = conn.resp_cookies[@remember_me_cookie]
+      assert signed_token != get_session(conn, :user_token)
+      assert max_age == @remember_me_cookie_max_age
+    end
+
+    test "writes a cookie if remember_me was set in previous session", %{conn: conn, user: user} do
+      conn = conn |> fetch_cookies() |> UserAuth.log_in_user(user, %{"remember_me" => "true"})
+      assert get_session(conn, :user_token) == conn.cookies[@remember_me_cookie]
+      assert get_session(conn, :user_remember_me) == true
+
+      conn =
+        conn
+        |> recycle()
+        |> Map.replace!(:secret_key_base, FirehoseWeb.Endpoint.config(:secret_key_base))
+        |> fetch_cookies()
+        |> init_test_session(%{user_remember_me: true})
+
+      # the conn is already logged in and has the remember_me cookie set,
+      # now we log in again and even without explicitly setting remember_me,
+      # the cookie should be set again
+      conn = conn |> UserAuth.log_in_user(user, %{})
+      assert %{value: signed_token, max_age: max_age} = conn.resp_cookies[@remember_me_cookie]
+      assert signed_token != get_session(conn, :user_token)
+      assert max_age == @remember_me_cookie_max_age
+      assert get_session(conn, :user_remember_me) == true
+    end
+  end
+
+  describe "logout_user/1" do
+    test "erases session and cookies", %{conn: conn, user: user} do
+      user_token = Accounts.generate_user_session_token(user)
+
+      conn =
+        conn
+        |> put_session(:user_token, user_token)
+        |> put_req_cookie(@remember_me_cookie, user_token)
+        |> fetch_cookies()
+        |> UserAuth.log_out_user()
+
+      refute get_session(conn, :user_token)
+      refute conn.cookies[@remember_me_cookie]
+      assert %{max_age: 0} = conn.resp_cookies[@remember_me_cookie]
+      assert redirected_to(conn) == ~p"/"
+      refute Accounts.get_user_by_session_token(user_token)
+    end
+
+    test "works even if user is already logged out", %{conn: conn} do
+      conn = conn |> fetch_cookies() |> UserAuth.log_out_user()
+      refute get_session(conn, :user_token)
+      assert %{max_age: 0} = conn.resp_cookies[@remember_me_cookie]
+      assert redirected_to(conn) == ~p"/"
+    end
+  end
+
+  describe "fetch_current_scope_for_user/2" do
+    test "authenticates user from session", %{conn: conn, user: user} do
+      user_token = Accounts.generate_user_session_token(user)
+
+      conn =
+        conn |> put_session(:user_token, user_token) |> UserAuth.fetch_current_scope_for_user([])
+
+      assert conn.assigns.current_scope.user.id == user.id
+      assert conn.assigns.current_scope.user.authenticated_at == user.authenticated_at
+      assert get_session(conn, :user_token) == user_token
+    end
+
+    test "authenticates user from cookies", %{conn: conn, user: user} do
+      logged_in_conn =
+        conn |> fetch_cookies() |> UserAuth.log_in_user(user, %{"remember_me" => "true"})
+
+      user_token = logged_in_conn.cookies[@remember_me_cookie]
+      %{value: signed_token} = logged_in_conn.resp_cookies[@remember_me_cookie]
+
+      conn =
+        conn
+        |> put_req_cookie(@remember_me_cookie, signed_token)
+        |> UserAuth.fetch_current_scope_for_user([])
+
+      assert conn.assigns.current_scope.user.id == user.id
+      assert conn.assigns.current_scope.user.authenticated_at == user.authenticated_at
+      assert get_session(conn, :user_token) == user_token
+      assert get_session(conn, :user_remember_me)
+    end
+
+    test "does not authenticate if data is missing", %{conn: conn, user: user} do
+      _ = Accounts.generate_user_session_token(user)
+      conn = UserAuth.fetch_current_scope_for_user(conn, [])
+      refute get_session(conn, :user_token)
+      refute conn.assigns.current_scope
+    end
+
+    test "reissues a new token after a few days and refreshes cookie", %{conn: conn, user: user} do
+      logged_in_conn =
+        conn |> fetch_cookies() |> UserAuth.log_in_user(user, %{"remember_me" => "true"})
+
+      token = logged_in_conn.cookies[@remember_me_cookie]
+      %{value: signed_token} = logged_in_conn.resp_cookies[@remember_me_cookie]
+
+      offset_user_token(token, -10, :day)
+      {user, _} = Accounts.get_user_by_session_token(token)
+
+      conn =
+        conn
+        |> put_session(:user_token, token)
+        |> put_session(:user_remember_me, true)
+        |> put_req_cookie(@remember_me_cookie, signed_token)
+        |> UserAuth.fetch_current_scope_for_user([])
+
+      assert conn.assigns.current_scope.user.id == user.id
+      assert conn.assigns.current_scope.user.authenticated_at == user.authenticated_at
+      assert new_token = get_session(conn, :user_token)
+      assert new_token != token
+      assert %{value: new_signed_token, max_age: max_age} = conn.resp_cookies[@remember_me_cookie]
+      assert new_signed_token != signed_token
+      assert max_age == @remember_me_cookie_max_age
+    end
+  end
+
+  describe "require_sudo_mode/2" do
+    test "allows users that have authenticated in the last 10 minutes", %{conn: conn, user: user} do
+      conn =
+        conn
+        |> fetch_flash()
+        |> assign(:current_scope, Scope.for_user(user))
+        |> UserAuth.require_sudo_mode([])
+
+      refute conn.halted
+      refute conn.status
+    end
+
+    test "redirects when authentication is too old", %{conn: conn, user: user} do
+      eleven_minutes_ago = DateTime.utc_now(:second) |> DateTime.add(-11, :minute)
+      user = %{user | authenticated_at: eleven_minutes_ago}
+      user_token = Accounts.generate_user_session_token(user)
+      {user, token_inserted_at} = Accounts.get_user_by_session_token(user_token)
+      assert DateTime.compare(token_inserted_at, user.authenticated_at) == :gt
+
+      conn =
+        conn
+        |> fetch_flash()
+        |> assign(:current_scope, Scope.for_user(user))
+        |> UserAuth.require_sudo_mode([])
+
+      assert redirected_to(conn) == ~p"/users/log-in"
+
+      assert Phoenix.Flash.get(conn.assigns.flash, :error) ==
+               "You must re-authenticate to access this page."
+    end
+  end
+
+  describe "redirect_if_user_is_authenticated/2" do
+    setup %{conn: conn} do
+      %{conn: UserAuth.fetch_current_scope_for_user(conn, [])}
+    end
+
+    test "redirects if user is authenticated", %{conn: conn, user: user} do
+      conn =
+        conn
+        |> assign(:current_scope, Scope.for_user(user))
+        |> UserAuth.redirect_if_user_is_authenticated([])
+
+      assert conn.halted
+      assert redirected_to(conn) == ~p"/"
+    end
+
+    test "does not redirect if user is not authenticated", %{conn: conn} do
+      conn = UserAuth.redirect_if_user_is_authenticated(conn, [])
+      refute conn.halted
+      refute conn.status
+    end
+  end
+
+  describe "require_authenticated_user/2" do
+    setup %{conn: conn} do
+      %{conn: UserAuth.fetch_current_scope_for_user(conn, [])}
+    end
+
+    test "redirects if user is not authenticated", %{conn: conn} do
+      conn = conn |> fetch_flash() |> UserAuth.require_authenticated_user([])
+      assert conn.halted
+
+      assert redirected_to(conn) == ~p"/users/log-in"
+
+      assert Phoenix.Flash.get(conn.assigns.flash, :error) ==
+               "You must log in to access this page."
+    end
+
+    test "stores the path to redirect to on GET", %{conn: conn} do
+      halted_conn =
+        %{conn | path_info: ["foo"], query_string: ""}
+        |> fetch_flash()
+        |> UserAuth.require_authenticated_user([])
+
+      assert halted_conn.halted
+      assert get_session(halted_conn, :user_return_to) == "/foo"
+
+      halted_conn =
+        %{conn | path_info: ["foo"], query_string: "bar=baz"}
+        |> fetch_flash()
+        |> UserAuth.require_authenticated_user([])
+
+      assert halted_conn.halted
+      assert get_session(halted_conn, :user_return_to) == "/foo?bar=baz"
+
+      halted_conn =
+        %{conn | path_info: ["foo"], query_string: "bar", method: "POST"}
+        |> fetch_flash()
+        |> UserAuth.require_authenticated_user([])
+
+      assert halted_conn.halted
+      refute get_session(halted_conn, :user_return_to)
+    end
+
+    test "does not redirect if user is authenticated", %{conn: conn, user: user} do
+      conn =
+        conn
+        |> assign(:current_scope, Scope.for_user(user))
+        |> UserAuth.require_authenticated_user([])
+
+      refute conn.halted
+      refute conn.status
+    end
+  end
+end

app/test/support/conn_case.ex

@@ -35,4 +35,45 @@ defmodule FirehoseWeb.ConnCase do
     Firehose.DataCase.setup_sandbox(tags)
     {:ok, conn: Phoenix.ConnTest.build_conn()}
   end
+
+  @doc """
+  Setup helper that registers and logs in users.
+
+      setup :register_and_log_in_user
+
+  It stores an updated connection and a registered user in the
+  test context.
+  """
+  def register_and_log_in_user(%{conn: conn} = context) do
+    user = Firehose.AccountsFixtures.user_fixture()
+    scope = Firehose.Accounts.Scope.for_user(user)
+
+    opts =
+      context
+      |> Map.take([:token_authenticated_at])
+      |> Enum.into([])
+
+    %{conn: log_in_user(conn, user, opts), user: user, scope: scope}
+  end
+
+  @doc """
+  Logs the given `user` into the `conn`.
+
+  It returns an updated `conn`.
+  """
+  def log_in_user(conn, user, opts \\ []) do
+    token = Firehose.Accounts.generate_user_session_token(user)
+
+    maybe_set_token_authenticated_at(token, opts[:token_authenticated_at])
+
+    conn
+    |> Phoenix.ConnTest.init_test_session(%{})
+    |> Plug.Conn.put_session(:user_token, token)
+  end
+
+  defp maybe_set_token_authenticated_at(_token, nil), do: nil
+
+  defp maybe_set_token_authenticated_at(token, authenticated_at) do
+    Firehose.AccountsFixtures.override_token_authenticated_at(token, authenticated_at)
+  end
 end

app/test/support/fixtures/accounts_fixtures.ex

@@ -0,0 +1,89 @@
+defmodule Firehose.AccountsFixtures do
+  @moduledoc """
+  This module defines test helpers for creating
+  entities via the `Firehose.Accounts` context.
+  """
+
+  import Ecto.Query
+
+  alias Firehose.Accounts
+  alias Firehose.Accounts.Scope
+
+  def unique_user_email, do: "user#{System.unique_integer()}@example.com"
+  def valid_user_password, do: "hello world!"
+
+  def valid_user_attributes(attrs \\ %{}) do
+    Enum.into(attrs, %{
+      email: unique_user_email()
+    })
+  end
+
+  def unconfirmed_user_fixture(attrs \\ %{}) do
+    {:ok, user} =
+      attrs
+      |> valid_user_attributes()
+      |> Accounts.register_user()
+
+    user
+  end
+
+  def user_fixture(attrs \\ %{}) do
+    user = unconfirmed_user_fixture(attrs)
+
+    token =
+      extract_user_token(fn url ->
+        Accounts.deliver_login_instructions(user, url)
+      end)
+
+    {:ok, {user, _expired_tokens}} =
+      Accounts.login_user_by_magic_link(token)
+
+    user
+  end
+
+  def user_scope_fixture do
+    user = user_fixture()
+    user_scope_fixture(user)
+  end
+
+  def user_scope_fixture(user) do
+    Scope.for_user(user)
+  end
+
+  def set_password(user) do
+    {:ok, {user, _expired_tokens}} =
+      Accounts.update_user_password(user, %{password: valid_user_password()})
+
+    user
+  end
+
+  def extract_user_token(fun) do
+    {:ok, captured_email} = fun.(&"[TOKEN]#{&1}[TOKEN]")
+    [_, token | _] = String.split(captured_email.text_body, "[TOKEN]")
+    token
+  end
+
+  def override_token_authenticated_at(token, authenticated_at) when is_binary(token) do
+    Firehose.Repo.update_all(
+      from(t in Accounts.UserToken,
+        where: t.token == ^token
+      ),
+      set: [authenticated_at: authenticated_at]
+    )
+  end
+
+  def generate_user_magic_link_token(user) do
+    {encoded_token, user_token} = Accounts.UserToken.build_email_token(user, "login")
+    Firehose.Repo.insert!(user_token)
+    {encoded_token, user_token.token}
+  end
+
+  def offset_user_token(token, amount_to_add, unit) do
+    dt = DateTime.add(DateTime.utc_now(:second), amount_to_add, unit)
+
+    Firehose.Repo.update_all(
+      from(ut in Accounts.UserToken, where: ut.token == ^token),
+      set: [inserted_at: dt, authenticated_at: dt]
+    )
+  end
+end