module Issue.GroupBy
  ( groupByArg,
    groupIssuesBy,
  )
where

import Data.Map (Map)
import Data.Map qualified as M
import Data.Maybe (mapMaybe)
import Data.Text qualified as T
import Issue (Issue (..))
import Issue.Tag (Tag (..))
import Issue.Tag qualified as I
import Options.Applicative qualified as O


-- FIXME Parse group by using @topic syntax

-- TODO Display number of issues within one group
--
-- ```
-- Issue D
-- Issue E
--
-- @topic tags  (2 issues)
-- Issue A
-- Issue B @topic ids
--
-- @topic ids  (2 issues)
-- Issue B @topic tags
-- Issue C
-- ```

-- TODO Add issues marker as internal tags
--
-- The internal makers `TODO`, `FIXME`, etc. should be available via the
-- internal tag @type

-- TODO Add author and editor as internal tags

groupByArg :: O.Parser (Maybe T.Text)
groupByArg =
  O.optional
    ( O.strOption
        ( O.long "group-by"
            <> O.metavar "TAG"
            <> O.help "Group selected issues."
        )
    )

groupIssuesBy :: T.Text -> [Issue] -> Map T.Text [Issue]
groupIssuesBy groupBy issues =
  foldl
    ( \collected issue ->
        foldl
          (flip $ M.alter (Just . maybe [issue] (issue :)))
          collected
          (groupsOfIssue groupBy issue)
    )
    M.empty
    issues
  where
    groupsOfIssue group issue =
      mapMaybe I.tagValue $
        filter (\(Tag key _) -> key == group) (issue.tags ++ issue.internalTags)