{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes #-}

module Krank.Checkers.Ignore
  ( IgnoreCommand (..),
    filterViolations,
  )
where

import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as ByteString
import qualified Data.HashMap.Strict as HashM
import qualified Data.List as DataL
import Krank.Types
import PyF (fmt)
import qualified Text.Regex.PCRE.Heavy as RE

data IgnoreCommand = IgnoreLine deriving (Show, Eq)

-- | This regex represents a krank ignore marker
ignoreRe :: RE.Regex
ignoreRe = [RE.re|krank:ignore-(line)|]

-- TODO: support more "ignore" (checker specific, all file, next line)

-- | Extract all issues on one line and returns a list of ignore keyword
extractIssuesOnALine :: ByteString -> [(Int, IgnoreCommand)]
extractIssuesOnALine lineContent = Prelude.map f (RE.scan ignoreRe lineContent)
  where
    f (match, [command]) = (colNo, ignoreCommand)
      where
        colNo = 1 + ByteString.length (fst $ ByteString.breakSubstring match lineContent)
        ignoreCommand
          | command == "line" = IgnoreLine
          | otherwise = error [fmt|Impossible case, update the guard with: {ByteString.unpack command}|]
    -- This case seems impossible, the reasons for pattern match issues are:
    --  A number of items different than 1 in the list: there is only 1 matching groups in the regex
    f res = error ("Error: impossible match" <> show res)

-- | Extract all ignore markers correctly localized
-- Note: we use 'ByteString' internally. This way we do not have to
-- care about the possible encoding of the input files.
-- In programming world, we mostly use ascii variants. This gives a
-- few performance improvement compared to initially converting
-- everything to 'Text' and search on it.
extractIgnores ::
  -- | Path of the file
  FilePath ->
  -- | Content of the file
  ByteString ->
  [Localized IgnoreCommand]
extractIgnores filePath toCheck = concat (zipWith extract [1 ..] (ByteString.lines toCheck))
  where
    extract lineNo lineContent = Prelude.map f (extractIssuesOnALine lineContent)
      where
        f (colNo, gitIssue) = Localized (SourcePos filePath lineNo colNo) gitIssue

-- | Takes a list of Violation, some ignore commands and remove all those that are ignored due to an
-- ignore marker
filterViolations ::
  -- | List of Violation to filter
  [Violation] ->
  -- | Path of the file
  FilePath ->
  -- | Content of the file
  ByteString ->
  [Violation]
filterViolations violations filePath content =
  DataL.filter isNotIgnored violations
  where
    ignoreCommands = extractIgnores filePath content
    f hashMap ignoreCommand = HashM.insert (lineNumber . getLocation $ ignoreCommand) (unLocalized ignoreCommand) hashMap
    ignoreIndex = foldl f HashM.empty ignoreCommands
    isIgnored violation = HashM.lookup (lineNumber . location $ violation) ignoreIndex == Just IgnoreLine
    isNotIgnored = not . isIgnored