{-
 - Copyright 2011-2013 Per Magnus Therning
 -
 - Licensed under the Apache License, Version 2.0 (the "License");
 - you may not use this file except in compliance with the License.
 - You may obtain a copy of the License at
 -
 -     http://www.apache.org/licenses/LICENSE-2.0
 -
 - Unless required by applicable law or agreed to in writing, software
 - distributed under the License is distributed on an "AS IS" BASIS,
 - WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 - See the License for the specific language governing permissions and
 - limitations under the License.
 -}

module Updates where

import PkgDB
import Util.Misc

import Codec.Archive.Tar as Tar
import Codec.Compression.GZip as GZip
import Control.Arrow
import Control.Monad
import Control.Monad.Reader
import Data.Maybe
import Distribution.Text
import Distribution.Version
import System.FilePath

updates :: Command ()
updates = do
    db <- cfgGet dbFile >>= liftIO . readDb
    aD <- cfgGet appDir
    aCS <- cfgGet $ idxStyle .optsCmd
    entries <- liftIO $ liftM (Tar.read . GZip.decompress) (readIndexFile aD)
    let nonBasePkgs = filter (not . isBasePkg) db
    let pkgsNVers = map (pkgName &&& pkgVersion) nonBasePkgs
    let availPkgs = catMaybes $ eMap extractPkgVer entries
    let outdated = filter
            (\ (p, v) -> maybe False (> v) (latestVer p availPkgs))
            pkgsNVers
    let printer = if aCS
            then printOutdatedIdx
            else printOutdated
    liftIO $ mapM_ (`printer` availPkgs) outdated

type PkgVer = (String, Version)

extractPkgVer :: Entry -> Maybe PkgVer
extractPkgVer e = let
        ep = entryPath e
        isCabal = '/' `elem` ep
        (pkg:ver':_) = map dropTrailingPathSeparator $ splitPath ep
        ver = simpleParse ver'
    in if isCabal && isJust ver
        then Just (pkg, fromJust ver)
        else Nothing

latestVer p pvs = let
        vs = map snd $ filter ((== p) . fst) pvs
    in if null vs
        then Nothing
        else Just $ maximum vs

eMap _ Done = []
eMap f (Next e es) = f e:eMap f es
eMap _ (Fail _) = error "Failure to read index"

printOutdated (p, v) avail = let
        l = fromJust $ latestVer p avail
    in
        putStrLn $ p ++ ": " ++ display v ++ " (" ++ display l ++ ")"

printOutdatedIdx (p, _) avail = let
        l = fromJust $ latestVer p avail
    in
        putStrLn $ p ++ "," ++ display l