{-# LANGUAGE OverloadedStrings #-}

-- | Core types and error definitions for Docster
module Docster.Types
  ( -- * Error Types
    DocsterError(..)

    -- * Output Format
  , OutputFormat(..)

    -- * Domain Types
  , SourceDir(..)
  , OutputDir(..)
  , OutputPath(..)
  , DiagramId(..)
  , DiagramConfig(..)

    -- * Traversal State
  , TraversalState(..)
  , initialTraversalState
  , normalizeHeading

    -- * Path Utilities
  , computeOutputDir
  , ensureOutputDir
  ) where

import Data.Text (Text)
import qualified Data.Text as T
import Data.Char (isAlphaNum, isSpace)
import Data.Map.Strict (Map)
import qualified Data.Map.Strict as Map
import Control.Exception (Exception)
import System.FilePath (takeDirectory, takeBaseName, (</>))
import System.Directory (createDirectoryIfMissing)

-- | Custom error types for comprehensive error handling
data DocsterError 
  = InvalidUsage Text
  | FileError Text
  | PDFGenerationError Text
  | ProcessError Text
  deriving (Show)

instance Exception DocsterError

-- | Output format for document generation
data OutputFormat = PDF | HTML | DOCX
  deriving (Show, Eq)

-- | Type-safe wrapper for source directory paths
newtype SourceDir = SourceDir FilePath
  deriving (Show, Eq)

-- | Type-safe wrapper for output directory paths
newtype OutputDir = OutputDir FilePath
  deriving (Show, Eq)

-- | Type-safe wrapper for output file paths
newtype OutputPath = OutputPath FilePath
  deriving (Show, Eq)

-- | Type-safe wrapper for diagram identifiers
newtype DiagramId = DiagramId Text 
  deriving (Show, Eq)

-- | Configuration for diagram generation
data DiagramConfig = DiagramConfig
  { dcSourceDir :: SourceDir
  , dcOutputDir :: OutputDir
  , dcOutputFormat :: OutputFormat
  } deriving (Show)

-- | Compute output directory from input file path
-- "docs/readme.md" -> "docs/output/readme"
computeOutputDir :: FilePath -> OutputDir
computeOutputDir inputPath =
  let dir = takeDirectory inputPath
      baseName = takeBaseName inputPath
  in OutputDir $ if null dir || dir == "."
                 then "output" </> baseName
                 else dir </> "output" </> baseName

-- | Ensure output directory exists
ensureOutputDir :: OutputDir -> IO ()
ensureOutputDir (OutputDir dir) = createDirectoryIfMissing True dir

-- | State for heading-aware diagram naming during AST traversal
data TraversalState = TraversalState
  { tsCurrentHeading :: Maybe Text    -- ^ Current heading text (normalized)
  , tsHeadingCounters :: Map Text Int -- ^ Counter for diagrams per heading
  , tsDocumentName :: Text            -- ^ Fallback name when no heading
  } deriving (Show, Eq)

-- | Create initial traversal state with document name as fallback
initialTraversalState :: Text -> TraversalState
initialTraversalState docName = TraversalState
  { tsCurrentHeading = Nothing
  , tsHeadingCounters = Map.empty
  , tsDocumentName = docName
  }

-- | Normalize heading text for use as a filename
-- "File Flow Diagram!" -> "file_flow_diagram"
normalizeHeading :: Text -> Text
normalizeHeading = T.intercalate "_"
                 . T.words
                 . T.filter (\c -> isAlphaNum c || isSpace c)
                 . T.toLower