{-# LANGUAGE AllowAmbiguousTypes #-}
{-# LANGUAGE ApplicativeDo #-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE TypeApplications #-}

module Main (main) where

import Control.Exception (throwIO)
import Control.Monad
import Data.Bool (bool)
import Data.Functor.Identity (Identity (..))
import Data.List (intercalate, sort)
import Data.Maybe (fromMaybe, mapMaybe)
import qualified Data.Text.IO as TIO
import Data.Version (showVersion)
import Development.GitRev
import Options.Applicative
import Ormolu
import Ormolu.Config
import Ormolu.Diff.Text (diffText, printTextDiff)
import Ormolu.Parser (manualExts)
import Ormolu.Terminal
import Ormolu.Utils (showOutputable)
import Ormolu.Utils.Extensions (getCabalExtensionDynOptions)
import Ormolu.Utils.IO
import Paths_fourmolu (version)
import System.Directory (getCurrentDirectory)
import System.Exit (ExitCode (..), exitWith)
import qualified System.FilePath as FP
import System.IO (hPutStrLn, stderr)

-- | Entry point of the program.
main :: IO ()
main = do
  opts@Opts {..} <- execParser optsParserInfo

  cfg <- case optInputFiles of
    [] -> mkConfigFromCWD opts
    ["-"] -> mkConfigFromCWD opts
    file : _ -> mkConfig file opts
  let formatOne' = formatOne optCabalDefaultExtensions optMode cfg

  exitCode <- case optInputFiles of
    [] -> formatOne' Nothing
    ["-"] -> formatOne' Nothing
    [x] -> formatOne' (Just x)
    xs -> do
      let selectFailure = \case
            ExitSuccess -> Nothing
            ExitFailure n -> Just n
      errorCodes <-
        mapMaybe selectFailure <$> mapM (formatOne' . Just) (sort xs)
      return $
        if null errorCodes
          then ExitSuccess
          else
            ExitFailure $
              if all (== 100) errorCodes
                then 100
                else 102
  exitWith exitCode

-- | Format a single input.
formatOne ::
  -- | Whether to respect default-extensions from .cabal files
  CabalDefaultExtensionsOpts ->
  -- | Mode of operation
  Mode ->
  -- | Configuration
  Config RegionIndices ->
  -- | File to format or stdin as 'Nothing'
  Maybe FilePath ->
  IO ExitCode
formatOne CabalDefaultExtensionsOpts {..} mode config mpath =
  withPrettyOrmoluExceptions (cfgColorMode config) $
    case FP.normalise <$> mpath of
      Nothing -> do
        extraDynOptions <-
          if optUseCabalDefaultExtensions
            then case optStdinInputFile of
              Just stdinInputFile ->
                getCabalExtensionDynOptions stdinInputFile
              Nothing -> throwIO OrmoluMissingStdinInputFile
            else pure []
        r <- ormoluStdin (configPlus extraDynOptions)
        case mode of
          Stdout -> do
            TIO.putStr r
            return ExitSuccess
          _ -> do
            hPutStrLn
              stderr
              "This feature is not supported when input comes from stdin."
            -- 101 is different from all the other exit codes we already use.
            return (ExitFailure 101)
      Just inputFile -> do
        extraDynOptions <-
          if optUseCabalDefaultExtensions
            then getCabalExtensionDynOptions inputFile
            else pure []
        originalInput <- readFileUtf8 inputFile
        formattedInput <- ormoluFile (configPlus extraDynOptions) inputFile
        case mode of
          Stdout -> do
            TIO.putStr formattedInput
            return ExitSuccess
          InPlace -> do
            -- Only write when the contents have changed, in order to avoid
            -- updating the modified timestamp if the file was already correctly
            -- formatted.
            when (formattedInput /= originalInput) $
              writeFileUtf8 inputFile formattedInput
            return ExitSuccess
          Check ->
            case diffText originalInput formattedInput inputFile of
              Nothing -> return ExitSuccess
              Just diff -> do
                runTerm (printTextDiff diff) (cfgColorMode config) stderr
                -- 100 is different to all the other exit code that are emitted
                -- either from an 'OrmoluException' or from 'error' and
                -- 'notImplemented'.
                return (ExitFailure 100)
  where
    configPlus dynOpts = config {cfgDynOptions = cfgDynOptions config ++ dynOpts}

----------------------------------------------------------------------------
-- Command line options parsing

data Opts = Opts
  { -- | Mode of operation
    optMode :: !Mode,
    -- | Ormolu 'Config'
    optConfig :: !(Config RegionIndices),
    -- | Options for respecting default-extensions from .cabal files
    optCabalDefaultExtensions :: CabalDefaultExtensionsOpts,
    -- | Fourmolu-specific options
    optPrinterOpts :: !PrinterOptsPartial,
    -- | Haskell source files to format or stdin (when the list is empty)
    optInputFiles :: ![FilePath]
  }

-- | Mode of operation.
data Mode
  = -- | Output formatted source code to stdout
    Stdout
  | -- | Overwrite original file
    InPlace
  | -- | Exit with non-zero status code if
    -- source is not already formatted
    Check
  deriving (Eq, Show, Bounded, Enum)

-- | Configuration for how to account for default-extension
-- from .cabal files
data CabalDefaultExtensionsOpts = CabalDefaultExtensionsOpts
  { -- | Account for default-extensions from .cabal files
    optUseCabalDefaultExtensions :: Bool,
    -- | Optional path to a file which will be used to
    -- find a .cabal file when using input from stdin
    optStdinInputFile :: Maybe FilePath
  }
  deriving (Show)

optsParserInfo :: ParserInfo Opts
optsParserInfo =
  info (helper <*> ver <*> exts <*> optsParser) . mconcat $
    [fullDesc]
  where
    ver :: Parser (a -> a)
    ver =
      infoOption verStr . mconcat $
        [ long "version",
          short 'v',
          help "Print version of the program"
        ]
    verStr =
      intercalate
        "\n"
        [ unwords
            [ "fourmolu",
              showVersion version,
              $gitBranch,
              $gitHash
            ],
          "using ghc-lib-parser " ++ VERSION_ghc_lib_parser
        ]
    exts :: Parser (a -> a)
    exts =
      infoOption displayExts . mconcat $
        [ long "manual-exts",
          help "Display extensions that need to be enabled manually"
        ]
    displayExts = unlines $ sort (showOutputable <$> manualExts)

optsParser :: Parser Opts
optsParser =
  Opts
    <$> ( (fmap (bool Stdout InPlace) . switch . mconcat)
            [ short 'i',
              help "A shortcut for --mode inplace"
            ]
            <|> (option parseBoundedEnum . mconcat)
              [ long "mode",
                short 'm',
                metavar "MODE",
                value Stdout,
                help "Mode of operation: 'stdout' (the default), 'inplace', or 'check'"
              ]
        )
    <*> configParser
    <*> cabalDefaultExtensionsParser
    <*> printerOptsParser
    <*> (many . strArgument . mconcat)
      [ metavar "FILE",
        help "Haskell source files to format or stdin (the default)"
      ]

cabalDefaultExtensionsParser :: Parser CabalDefaultExtensionsOpts
cabalDefaultExtensionsParser =
  CabalDefaultExtensionsOpts
    <$> (switch . mconcat)
      [ short 'e',
        long "cabal-default-extensions",
        help "Account for default-extensions from .cabal files"
      ]
    <*> (optional . strOption . mconcat)
      [ long "stdin-input-file",
        help "Path which will be used to find the .cabal file when using input from stdin"
      ]

configParser :: Parser (Config RegionIndices)
configParser =
  Config
    <$> (fmap (fmap DynOption) . many . strOption . mconcat)
      [ long "ghc-opt",
        short 'o',
        metavar "OPT",
        help "GHC options to enable (e.g. language extensions)"
      ]
    <*> (switch . mconcat)
      [ long "unsafe",
        short 'u',
        help "Do formatting faster but without automatic detection of defects"
      ]
    <*> (switch . mconcat)
      [ long "debug",
        short 'd',
        help "Output information useful for debugging"
      ]
    <*> (switch . mconcat)
      [ long "check-idempotence",
        short 'c',
        help "Fail if formatting is not idempotent"
      ]
    <*> (option parseBoundedEnum . mconcat)
      [ long "color",
        metavar "WHEN",
        value Auto,
        help "Colorize the output; WHEN can be 'never', 'always', or 'auto' (the default)"
      ]
    <*> ( RegionIndices
            <$> (optional . option auto . mconcat)
              [ long "start-line",
                metavar "START",
                help "Start line of the region to format (starts from 1)"
              ]
            <*> (optional . option auto . mconcat)
              [ long "end-line",
                metavar "END",
                help "End line of the region to format (inclusive)"
              ]
        )
    <*> pure defaultPrinterOpts

printerOptsParser :: Parser PrinterOptsPartial
printerOptsParser = do
  poIndentation <-
    (optional . option auto . mconcat)
      [ long "indentation",
        metavar "WIDTH",
        help $
          "Number of spaces per indentation step"
            <> showDefaultValue poIndentation
      ]
  poCommaStyle <-
    (optional . option parseBoundedEnum . mconcat)
      [ long "comma-style",
        metavar "STYLE",
        help $
          "How to place commas in multi-line lists, records etc: "
            <> showAllValues @CommaStyle
            <> showDefaultValue poCommaStyle
      ]
  poIndentWheres <-
    (optional . option parseBoundedEnum . mconcat)
      [ long "indent-wheres",
        metavar "BOOL",
        help $
          "Whether to indent 'where' bindings past the preceding body"
            <> " (rather than half-indenting the 'where' keyword)"
            <> showDefaultValue poIndentWheres
      ]
  poRecordBraceSpace <-
    (optional . option parseBoundedEnum . mconcat)
      [ long "record-brace-space",
        metavar "BOOL",
        help $
          "Whether to leave a space before an opening record brace"
            <> showDefaultValue poRecordBraceSpace
      ]
  poDiffFriendlyImportExport <-
    (optional . option parseBoundedEnum . mconcat)
      [ long "diff-friendly-import-export",
        metavar "BOOL",
        help $
          "Whether to make use of extra commas in import/export lists"
            <> " (as opposed to Ormolu's style)"
            <> showDefaultValue poDiffFriendlyImportExport
      ]
  poRespectful <-
    (optional . option parseBoundedEnum . mconcat)
      [ long "respectful",
        metavar "BOOL",
        help $
          "Give the programmer more choice on where to insert blank lines"
            <> showDefaultValue poRespectful
      ]
  poHaddockStyle <-
    (optional . option parseBoundedEnum . mconcat)
      [ long "haddock-style",
        metavar "STYLE",
        help $
          "How to print Haddock comments: "
            <> showAllValues @HaddockPrintStyle
            <> showDefaultValue poHaddockStyle
      ]
  poNewlinesBetweenDecls <-
    (optional . option auto . mconcat)
      [ long "newlines-between-decls",
        metavar "HEIGHT",
        help $
          "Number of spaces between top-level declarations"
            <> showDefaultValue poNewlinesBetweenDecls
      ]
  pure PrinterOpts {..}

----------------------------------------------------------------------------
-- Helpers

-- | A standard parser of CLI option arguments, applicable to arguments that
-- have a finite (preferably small) number of possible values. (Basically an
-- inverse of 'toCLIArgument'.)
parseBoundedEnum ::
  forall a.
  (Enum a, Bounded a, ToCLIArgument a) =>
  ReadM a
parseBoundedEnum =
  eitherReader
    ( \s ->
        case lookup s argumentToValue of
          Just v -> Right v
          Nothing ->
            Left $
              "unknown value: '"
                <> s
                <> "'\nValid values are: "
                <> showAllValues @a
                <> "."
    )
  where
    argumentToValue = map (\x -> (toCLIArgument x, x)) [minBound ..]

-- | Values that appear as arguments of CLI options and thus have
-- a corresponding textual representation.
class ToCLIArgument a where
  -- | Convert a value to its representation as a CLI option argument.
  toCLIArgument :: a -> String

  -- | Convert a value to its representation as a CLI option argument wrapped
  -- in apostrophes.
  toCLIArgument' :: a -> String
  toCLIArgument' x = "'" <> toCLIArgument x <> "'"

instance ToCLIArgument Bool where
  toCLIArgument True = "true"
  toCLIArgument False = "false"

instance ToCLIArgument CommaStyle where
  toCLIArgument Leading = "leading"
  toCLIArgument Trailing = "trailing"

instance ToCLIArgument Int where
  toCLIArgument = show

instance ToCLIArgument HaddockPrintStyle where
  toCLIArgument HaddockSingleLine = "single-line"
  toCLIArgument HaddockMultiLine = "multi-line"

instance ToCLIArgument Mode where
  toCLIArgument Stdout = "stdout"
  toCLIArgument InPlace = "inplace"
  toCLIArgument Check = "check"

instance ToCLIArgument ColorMode where
  toCLIArgument Never = "never"
  toCLIArgument Always = "always"
  toCLIArgument Auto = "auto"

showAllValues :: forall a. (Enum a, Bounded a, ToCLIArgument a) => String
showAllValues = format (map toCLIArgument' [(minBound :: a) ..])
  where
    format [] = []
    format [x] = x
    format [x1, x2] = x1 <> " or " <> x2
    format (x : xs) = x <> ", " <> format xs

-- | CLI representation of the default value of an option, formatted for
-- inclusion in the help text.
showDefaultValue ::
  ToCLIArgument a =>
  (PrinterOptsTotal -> Identity a) ->
  String
showDefaultValue =
  (" (default " <>)
    . (<> ")")
    . toCLIArgument'
    . runIdentity
    . ($ defaultPrinterOpts)

-- | Build the full config, by adding 'PrinterOpts' from a file, if found.
mkConfig :: FilePath -> Opts -> IO (Config RegionIndices)
mkConfig path Opts {..} = do
  filePrinterOpts <-
    loadConfigFile path >>= \case
      ConfigLoaded f po -> do
        hPutStrLn stderr $ "Loaded config from: " <> f
        printDebug $ show po
        return $ Just po
      ConfigParseError f (_pos, err) -> do
        -- we ignore '_pos' due to the note on 'Data.YAML.Aeson.decode1'
        hPutStrLn stderr $
          unlines
            [ "Failed to load " <> f <> ":",
              "  " <> err
            ]
        exitWith $ ExitFailure 400
      ConfigNotFound searchDirs -> do
        printDebug
          . unlines
          $ ("No " ++ show configFileName ++ " found in any of:") :
          map ("  " ++) searchDirs
        return Nothing
  return $
    optConfig
      { cfgPrinterOpts =
          fillMissingPrinterOpts
            (optPrinterOpts <> fromMaybe mempty filePrinterOpts)
            (cfgPrinterOpts optConfig)
      }
  where
    printDebug = when (cfgDebug optConfig) . hPutStrLn stderr

mkConfigFromCWD :: Opts -> IO (Config RegionIndices)
mkConfigFromCWD opts = do
  cwd <- getCurrentDirectory
  mkConfig cwd opts