defmodule Microprints.MicroprintComponent do
  @moduledoc """
  Phoenix Component for rendering microprint SVG visualizations.

  Renders each line of code as a colored horizontal stripe,
  creating a compact visual fingerprint of the file's structure.
  """

  use Phoenix.Component

  alias Microprints.Microprint

  # Pixels per indent level (1 space = 1 indent unit)
  @indent_scale 2
  # Maximum indent in pixels (cap at 40% of width)
  @max_indent_ratio 0.4

  @doc """
  Renders a microprint visualization as an inline SVG.

  ## Attributes

  * `:microprint` - The microprint map with `:lines` (list of line info maps)
  * `:width` - SVG width in pixels (default: 200)
  * `:max_height` - Maximum SVG height in pixels (default: 100)
  * `:clickable` - Whether lines are clickable to highlight (default: false)
  * `:file_path` - File path for click events (required if clickable)
  * `:highlighted_line` - Currently highlighted line number (0-indexed)
  """
  attr :microprint, :map, required: true
  attr :width, :integer, default: 200
  attr :max_height, :integer, default: 100
  attr :clickable, :boolean, default: false
  attr :file_path, :string, default: nil
  attr :highlighted_line, :integer, default: nil

  def microprint(assigns) do
    lines = assigns.microprint.lines
    line_count = length(lines)

    # Each line is 1px, but cap at max_height
    height = min(line_count, assigns.max_height)

    # If we have more lines than max_height, we need to sample
    {displayed_lines, line_mapping} =
      if line_count > assigns.max_height do
        {sample_lines(lines, assigns.max_height),
         sample_line_mapping(line_count, assigns.max_height)}
      else
        {lines, Enum.to_list(0..(line_count - 1))}
      end

    max_indent = trunc(assigns.width * @max_indent_ratio)

    # Find max line length for proportional scaling
    max_length = displayed_lines |> Enum.map(& &1.length) |> Enum.max(fn -> 1 end) |> max(1)

    # Calculate x offset and width for each line
    rendered_lines =
      displayed_lines
      |> Enum.with_index()
      |> Enum.map(fn {line_info, index} ->
        base_x = min(line_info.indent * @indent_scale, max_indent)
        available_width = assigns.width - base_x

        # Map display index to actual line number
        actual_line = Enum.at(line_mapping, index, index)
        highlighted = assigns.highlighted_line == actual_line

        # Build segments for this line
        segments =
          if line_info[:segments] && line_info.segments != [] do
            # Multi-color: render each segment
            scale = if line_info.length > 0, do: available_width / line_info.length, else: 1

            line_info.segments
            |> Enum.map(fn seg ->
              seg_x = base_x + trunc(seg.start * scale)
              seg_width = max(1, trunc(seg.length * scale))

              %{
                x: seg_x,
                width: seg_width,
                color: seg.color,
                y: index,
                line_number: actual_line,
                highlighted: highlighted
              }
            end)
          else
            # Single color fallback
            width =
              if line_info.length == 0 do
                2
              else
                max(2, trunc(line_info.length / max_length * available_width))
              end

            [
              %{
                x: base_x,
                width: width,
                color: line_info.color,
                y: index,
                line_number: actual_line,
                highlighted: highlighted
              }
            ]
          end

        %{y: index, line_number: actual_line, highlighted: highlighted, segments: segments}
      end)

    assigns =
      assigns
      |> assign(:height, height)
      |> assign(:rendered_lines, rendered_lines)

    ~H"""
    <svg
      width={@width}
      height={@height}
      viewBox={"0 0 #{@width} #{@height}"}
      class={"block mt-1 #{if @clickable, do: "cursor-pointer", else: ""}"}
    >
      <%= for line <- @rendered_lines do %>
        <%= for segment <- line.segments do %>
          <rect
            x={segment.x}
            y={segment.y}
            width={segment.width}
            height="1"
            fill={segment.color}
            opacity={if segment.highlighted, do: "1", else: "0.8"}
            phx-click={if @clickable, do: "highlight_line"}
            phx-value-line={if @clickable, do: segment.line_number}
            phx-value-path={if @clickable, do: @file_path}
          />
        <% end %>
      <% end %>
      <%= if @highlighted_line do %>
        <rect
          x="0"
          y={highlight_y(@rendered_lines, @highlighted_line)}
          width={@width}
          height="3"
          fill="none"
          stroke="#000"
          stroke-width="1"
          pointer-events="none"
        />
      <% end %>
    </svg>
    """
  end

  defp highlight_y(rendered_lines, highlighted_line) do
    case Enum.find(rendered_lines, &(&1.line_number == highlighted_line)) do
      nil -> 0
      line -> max(0, line.y - 1)
    end
  end

  defp sample_line_mapping(line_count, max_count) do
    step = line_count / max_count

    0..(max_count - 1)
    |> Enum.map(fn i -> trunc(i * step) end)
  end

  # Sample lines evenly when we have more lines than pixels available
  defp sample_lines(lines, max_count) do
    line_count = length(lines)
    step = line_count / max_count

    0..(max_count - 1)
    |> Enum.map(fn i ->
      index = trunc(i * step)
      Enum.at(lines, index)
    end)
  end

  @doc """
  Renders a color legend for microprint visualizations.

  Shows each syntax type with its corresponding color.
  """
  def microprint_legend(assigns) do
    assigns = assign(assigns, :legend, Microprint.color_legend())

    ~H"""
    <div class="flex flex-wrap gap-3 text-xs">
      <%= for {label, color} <- @legend do %>
        <div class="flex items-center gap-1">
          <span
            class="w-3 h-3 inline-block rounded-sm"
            style={"background: #{color};"}
          >
          </span>
          <span class="text-base-content/60">{label}</span>
        </div>
      <% end %>
    </div>
    """
  end

  @doc """
  Renders source code with line numbers and optional highlighting.

  ## Attributes

  * `:content` - The source code content as a string
  * `:highlighted_line` - Line number to highlight (0-indexed, optional)
  * `:language` - Language for syntax highlighting (e.g., "elixir", "javascript", "typescript", "markdown")
  """
  attr :content, :string, required: true
  attr :highlighted_line, :integer, default: nil
  attr :language, :string, default: nil

  def source_viewer(assigns) do
    ~H"""
    <div
      id="source-viewer"
      class="source-viewer mt-2 max-h-96 overflow-auto rounded font-mono text-xs"
      phx-hook="SourceViewer"
      data-highlighted-line={@highlighted_line}
      data-language={@language}
      style="background: var(--sv-bg); color: var(--sv-text);"
    >
      <pre id="source-viewer-pre" phx-update="ignore" class="m-0 p-2"><code class={"language-#{@language || "plaintext"}"}><%= @content %></code></pre>
    </div>
    """
  end
end