{- SPDX-FileCopyrightText: 2018-2019 Serokell <https://serokell.io>
 -
 - SPDX-License-Identifier: MPL-2.0
 -}

{-# LANGUAGE ApplicativeDo #-}

module Xrefcheck.CLI
    ( VerifyMode (..)
    , shouldCheckLocal
    , shouldCheckExternal
    , Command (..)
    , Options (..)
    , TraversalOptions (..)
    , addTraversalOptions
    , defaultConfigPaths
    , getCommand
    ) where

import qualified Data.List as L
import Data.Version (showVersion)
import Options.Applicative (Parser, ReadM, command, eitherReader, execParser, flag', footerDoc, fullDesc,
                            help, helper, hsubparser, info, infoOption, long, metavar, option, progDesc,
                            short, strOption, switch, value)
import Options.Applicative.Help.Pretty (Doc, displayS, fill, fillSep, indent, renderPretty, text)

import Paths_xrefcheck (version)
import Xrefcheck.Config
import Xrefcheck.Core

modeReadM :: ReadM VerifyMode
modeReadM = eitherReader $ \s ->
    case find ((== s) . fst) modes of
        Just (_, mode) -> Right mode
        Nothing -> Left . mconcat $ intersperse "\n"
            [ "Unknown mode " <> show s <> "."
            , "Allowed values: " <> mconcat (intersperse ", " $ map (show . fst) modes)
            ]
  where
    modes =
        [ ("local-only", LocalOnlyMode)
        , ("external-only", ExternalOnlyMode)
        , ("full", FullMode)
        ]

data Command
  = DefaultCommand Options
  | DumpConfig FilePath

data Options = Options
    { oConfigPath       :: Maybe FilePath
    , oRoot             :: FilePath
    , oMode             :: VerifyMode
    , oVerbose          :: Bool
    , oShowProgressBar  :: Maybe Bool
    , oTraversalOptions :: TraversalOptions
    }

data TraversalOptions = TraversalOptions
    { toIgnored :: [FilePath]
    }

addTraversalOptions :: TraversalConfig -> TraversalOptions -> TraversalConfig
addTraversalOptions TraversalConfig{..} (TraversalOptions ignored) =
  TraversalConfig
  { tcIgnored = tcIgnored ++ ignored
  , ..
  }

-- | Where to try to seek configuration if specific path is not set.
defaultConfigPaths :: [FilePath]
defaultConfigPaths = ["./xrefcheck.yaml", "./.xrefcheck.yaml"]

optionsParser :: Parser Options
optionsParser = do
    oConfigPath <- optional . strOption $
        short 'c' <>
        long "config" <>
        metavar "FILEPATH" <>
        help ("Path to configuration file. \
             \If not specified, tries to read config from one of " <>
             (mconcat . intersperse ", " $ map show defaultConfigPaths) <> ". \
             \If none of these files exist, default configuration is used."
             )
    oRoot <- strOption $
        short 'r' <>
        long "root" <>
        metavar "DIRECTORY" <>
        help "Path to repository root." <>
        value "."
    oMode <- option modeReadM $
        short 'm' <>
        long "mode" <>
        metavar "KEYWORD" <>
        value FullMode <>
        help "Which parts of verification to invoke. \
             \You can enable only verification of repository-local references, \
             \only verification of external references or both. \
             \Default mode: full."
    oVerbose <- switch $
        short 'v' <>
        long "verbose" <>
        help "Report repository scan and verification details."
    oShowProgressBar <- asum
        [ flag' (Just True) $
            long "progress" <>
            help "Display progress bar during verification. \
                 \This is enabled by default unless `CI` env var is set to true."
        , flag' (Just False) $
            long "no-progress" <>
            help "Do not display progress bar during verification."
        , pure Nothing
        ]
    oTraversalOptions <- traversalOptionsParser
    return Options{..}

traversalOptionsParser :: Parser TraversalOptions
traversalOptionsParser = do
    toIgnored <- many . strOption $
        long "ignored" <>
        metavar "FILEPATH" <>
        help "Files and folders which we pretend do not exist."
    return TraversalOptions{..}

dumpConfigOptions :: Parser FilePath
dumpConfigOptions = hsubparser $
  command "dump-config" $
    info parser $
    progDesc "Dump default configuration into a file."
  where
    parser = strOption $
      short 'o' <>
      long "output" <>
      metavar "FILEPATH" <>
      value ".xrefcheck.yaml" <>
      help "Name of created config file."

totalParser :: Parser Command
totalParser = asum
  [ DefaultCommand <$> optionsParser
  , DumpConfig <$> dumpConfigOptions
  ]

versionOption :: Parser (a -> a)
versionOption = infoOption ("xrefcheck-" <> showVersion version) $
    long "version" <>
    help "Show version."

getCommand :: IO Command
getCommand = do
    execParser $
        info (helper <*> versionOption <*> totalParser) $
        fullDesc <>
        progDesc "Cross-references verifier for markdown documentation in \
                 \Git repositories." <>
        (footerDoc $ pure ignoreModesMsg)

ignoreModesMsg :: Doc
ignoreModesMsg = text $ header <> body
    where
        header = "To ignore a link in your markdown, \
                 \include \"<!-- xrefcheck: ignore <mode> -->\"\n\
                 \comment with one of these modes:\n"
        body = displayS (renderPretty pageParam pageWidth doc) ""

        pageWidth = 80
        pageParam = 1

        doc = fillSep $ map formatDesc modeDescr

        modeDescr =
            [ ("  \"link\"",      L.words $ "Ignore the link right after the comment.")
            , ("  \"paragraph\"", L.words $ "Ignore the whole paragraph after the comment.")
            , ("  \"file\"",      L.words $ "This mode can only be used at the top of markdown \
                                            \or right after comments at the top.")
            ]

        modeIndent = length ("\"paragraph\"" :: String) + 2
        descrIndent = 27 - modeIndent

        formatDesc (mode, descr) =
            (fill modeIndent $ text mode) <>
            (indent descrIndent $ fillSep $ map text descr)