{- This file is part of Vervis.
 -
 - Written in 2016 by fr33domlover <fr33domlover@riseup.net>.
 -
 - ♡ Copying is an act of love. Please copy, reuse and share.
 -
 - The author(s) have dedicated all copyright and related and neighboring
 - rights to this software to the public domain worldwide. This software is
 - distributed without any warranty.
 -
 - You should have received a copy of the CC0 Public Domain Dedication along
 - with this software. If not, see
 - <http://creativecommons.org/publicdomain/zero/1.0/>.
 -}

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE DeriveGeneric #-}

module Vervis.Git
    ( subdirs
    , lastChange
    , timeAgo
    --, timesAgo
    )
where

import Control.Monad (join)
import Control.Monad.Fix (MonadFix)
import Control.Monad.IO.Class
import Control.Monad.Trans.RWS (RWST (..))
import Data.CaseInsensitive (CI)
import Data.Foldable (toList)
import Data.Git
import Data.Git.Revision
import Data.Git.Repository
import Data.Hashable (Hashable)
import Data.HashMap.Lazy (HashMap)
import Data.HashSet (HashSet)
import Data.Hourglass
import Data.Maybe (fromMaybe, mapMaybe)
import Data.Text (Text)
import Data.Time.Units
import GHC.Generics
import System.Directory.Tree hiding (name, file, err)
import System.FilePath ((</>))
import System.Hourglass (dateCurrent)

import qualified Control.Monad.Trans.RWS as RWS
import qualified Data.CaseInsensitive as CI
import qualified Data.HashMap.Lazy as M
import qualified Data.Text as T

{-data Server = Server
    { serverName   :: Text
    , serverDir    :: FilePath
    , serverUsers  :: HashMap Int User
    , serverGroups :: HashMap Int Group
    , serverRepos  :: HashMap (Either Int Int) [Repository]
    }-}

-- | Return the subdirs of a given dir
subdirs :: FilePath -> IO [FilePath]
subdirs dir = do
    _base :/ tree <- buildL dir
    return $ case tree of
        Dir _ cs ->
            let dirName (Dir n _) = Just n
                dirName _         = Nothing
            in  mapMaybe dirName cs
        _ -> []

-- | Determine the time of the last commit in a given git branch
lastBranchChange :: Git -> String -> IO GitTime
lastBranchChange git branch = do
    mref <- resolveRevision git $ Revision branch []
    mco <- traverse (getCommitMaybe git) mref
    let mtime = fmap (personTime . commitCommitter) (join mco)
    return $ fromMaybe (error "mtime is Nothing") mtime

-- | Determine the time of the last commit in any branch for a given repo
lastChange :: FilePath -> IO DateTime
lastChange path = withRepo (fromString path) $ \ git -> do
     --TODO add a better intro to json-state, the docs are bad there

    names <- branchList git
    times <- traverse (lastBranchChange git) $ map refNameRaw $ toList names
    let datetimes = map timeConvert times
    return $ maximum datetimes

showPeriod :: Period -> String
showPeriod (Period 0 0 d) = show d ++ " days"
showPeriod (Period 0 m _) = show m ++ " months"
showPeriod (Period y _ _) = show y ++ " years"

showDuration :: Duration -> String
showDuration (Duration (Hours h) (Minutes m) (Seconds s) _) =
    case (h, m, s) of
        (0, 0, 0) -> "now"
        (0, 0, _) -> show s ++ " seconds"
        (0, _, _) -> show m ++ " minutes"
        _         -> show h ++ " hours"

showAgo :: Period -> Duration -> String
showAgo (Period 0 0 0) d = showDuration d
showAgo p              _ = showPeriod p

fromSec :: Seconds -> (Period, Duration)
fromSec sec =
    let d = 3600 * 24
        m = 30 * d
        y = 365 * d
        fs (Seconds n) = fromIntegral n
        (years, yrest) = sec `divMod` Seconds y
        (months, mrest) = yrest `divMod` Seconds m
        (days, drest) = mrest `divMod` Seconds d
    in  (Period (fs years) (fs months) (fs days), fst $ fromSeconds drest)

timeAgo :: DateTime -> IO String
timeAgo dt = do
    now <- dateCurrent
    let sec = timeDiff now dt
        (period, duration) = fromSec sec
    return $ showAgo period duration

{-repoPaths :: Server -> Either Int Int -> [Repository] -> [FilePath]
repoPaths server (Left uid) repos =
    case M.lookup uid $ serverUsers server of
        Nothing   -> error "';..;'"
        Just user ->
            let dir = serverDir server
                ns = T.unpack $ CI.original $ unUsername $ userName user
                prefix = dir </> ns
                repoNames =
                    map (T.unpack . CI.original . unRepoName . repoName) repos
            in  map (prefix </>) repoNames
repoPaths server (Right gid) repos =
    case M.lookup gid $ serverGroups server of
        Nothing    -> error "';..;'"
        Just group ->
            let dir = serverDir server
                ns = T.unpack $ CI.original $ unGroupName $ groupName group
                prefix = dir </> ns
                repoNames =
                    map (T.unpack . CI.original . unRepoName . repoName) repos
            in  map (prefix </>) repoNames-}

{-timesAgo :: Server -> IO [(Text, Text)]
timesAgo server = do
    -- make list of file paths
    let paths = uncurry $ repoPaths server
        nsRepos = map paths $ M.toList $ serverRepos server
        repos = concat nsRepos
    -- run lastChange on each
    times <- traverse lastChange repos
    -- run timeAgo on each result
    agos <- traverse timeAgo times
    -- return
    return $ zip (map T.pack repos) (map T.pack agos)-}