-- -*-haskell-*-
--  Vision (for the Voice): an XMMS2 client.
--
--  Author:  Oleg Belozeorov
--  Created: 21 Jun. 2010
--
--  Copyright (C) 2010 Oleg Belozeorov
--
--  This program is free software; you can redistribute it and/or
--  modify it under the terms of the GNU General Public License as
--  published by the Free Software Foundation; either version 3 of
--  the License, or (at your option) any later version.
--
--  This program is distributed in the hope that it will be useful,
--  but WITHOUT ANY WARRANTY; without even the implied warranty of
--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
--  General Public License for more details.
--

{-# OPTIONS_GHC -fno-warn-incomplete-patterns #-}

module Playlist.Index
  ( initIndex
  , getInfo
  , addToIndex
  ) where

import Control.Applicative
import Control.Concurrent.MVar
import Data.IntMap (IntMap)
import qualified Data.IntMap as IntMap

import Graphics.UI.Gtk hiding (add)

import Medialib hiding (getInfo)
import Context
import Handler
import Playlist.Model
import Playlist.Format


data IndexEntry
  = IENone
  | IERetrieving
  | IEReady Stamp MediaInfo TrackInfo

data Index
  = Index { iTable :: MVar (IntMap (IndexEntry, [TreeRowReference])) }

index = iTable context


initIndex = do
  context <- initContext
  let ?context = context

  onMediaInfo . add . ever $ handleInfo
  onFormatsChanged . add . ever . const $ handleFormats

  return ?context


initContext = do
  table <- newMVar IntMap.empty
  return $ augmentContext
    Index { iTable = table }

handleInfo (id, stamp, info) = do
  let id' = fromIntegral id
  modifyMVar_ index $ \ix ->
    case IntMap.lookup id' ix of
      Just (entry, list) -> updateIndex ix id' stamp info entry list
      Nothing            -> return ix

handleFormats =
  modifyMVar_ index $ \ix ->
    IntMap.fromList <$> mapM update (IntMap.toList ix)
  where update (i, (IEReady s m _, l)) = do
          t <- makeTrackInfo m
          mapM_ touch l
          return (i, (IEReady s m t, l))
        update other =
          return other

updateIndex ix id stamp info old list =
  if upd
  then do
    ti <- makeTrackInfo info
    mapM_ touch list
    return $ IntMap.insert id (IEReady stamp info ti, list) ix
  else
    return ix
  where upd = case old of
          IEReady oldStamp _ _ -> stamp /= oldStamp
          _                    -> True

touch ref = do
  path <- treeRowReferenceGetPath ref
  case path of
    [n] -> touchPlaylist n
    _   -> return ()

getInfo id force = do
  let id' = fromIntegral id
  modifyMVar index $ \ix ->
    case IntMap.lookup id' ix of
      Just (IEReady _ _ info, _) ->
        return (ix, Just info)
      Just (IENone, list) | force -> do
        requestInfo id
        return (IntMap.insert id'(IERetrieving, list) ix, Nothing)
      _ ->
        return (ix, Nothing)

addToIndex id n =
  modifyMVar_ index $ \ix -> do
    Just ref <- treeRowReferenceNew playlistStore [n]
    return $ IntMap.insertWith iw (fromIntegral id) (IENone, [ref]) ix
  where iw (_, [new]) (entry, old) = (entry, new : old)