{- yt-dlp (and deprecated youtube-dl) integration for git-annex
 -
 - Copyright 2017-2024 Joey Hess <id@joeyh.name>
 -
 - Licensed under the GNU AGPL version 3 or higher.
 -}

{-# LANGUAGE DeriveGeneric #-}

module Annex.YoutubeDl (
	youtubeDl,
	youtubeDlTo,
	youtubeDlSupported,
	youtubeDlCheck,
	youtubeDlFileName,
	youtubeDlFileNameHtmlOnly,
	youtubeDlCommand,
	youtubePlaylist,
	YoutubePlaylistItem(..),
) where

import Annex.Common
import qualified Annex
import Annex.Content
import Annex.Url
import Utility.DiskFree
import Utility.HtmlDetect
import Utility.Process.Transcript
import Utility.Metered
import Utility.Tmp
import Messages.Progress
import Logs.Transfer

import Network.URI
import Control.Concurrent.Async
import Text.Read
import Data.Either
import qualified Data.Aeson as Aeson
import GHC.Generics
import qualified Data.ByteString as B
import qualified Data.ByteString.Char8 as B8

-- youtube-dl can follow redirects to anywhere, including potentially
-- localhost or a private address. So, it's only allowed to download
-- content if the user has allowed access to all addresses.
youtubeDlAllowed :: Annex Bool
youtubeDlAllowed = ipAddressesUnlimited

youtubeDlNotAllowedMessage :: String
youtubeDlNotAllowedMessage = unwords
	[ "This url is supported by yt-dlp, but"
	, "yt-dlp could potentially access any address, and the"
	, "configuration of annex.security.allowed-ip-addresses"
	, "does not allow that. Not using yt-dlp (or youtube-dl)."
	]

-- Runs youtube-dl in a work directory, to download a single media file
-- from the url. Returns the path to the media file in the work directory.
--
-- Displays a progress meter as youtube-dl downloads.
--
-- If no file is downloaded, or the program is not installed,
-- returns Right Nothing.
--
-- youtube-dl can write to multiple files, either temporary files, or
-- multiple videos found at the url, and git-annex needs only one file.
-- So we need to find the destination file, and make sure there is not
-- more than one. With yt-dlp use --print-to-file to make it record the 
-- file(s) it downloads. With youtube-dl, the best that can be done is
-- to require that the work directory end up with only 1 file in it.
-- (This can fail, but youtube-dl is deprecated, and they closed my
-- issue requesting something like --print-to-file; 
-- <https://github.com/rg3/youtube-dl/issues/14864>)
youtubeDl :: URLString -> FilePath -> MeterUpdate -> Annex (Either String (Maybe FilePath))
youtubeDl url workdir p = ifM ipAddressesUnlimited
	( withUrlOptions $ youtubeDl' url workdir p
	, return $ Left youtubeDlNotAllowedMessage
	)

youtubeDl' :: URLString -> FilePath -> MeterUpdate -> UrlOptions -> Annex (Either String (Maybe FilePath))
youtubeDl' url workdir p uo
	| supportedScheme uo url = do
		cmd <- youtubeDlCommand
		ifM (liftIO $ inSearchPath cmd)
			( runcmd cmd >>= \case
				Right True -> downloadedfiles cmd >>= \case
					(f:[]) -> return (Right (Just f))
					[] -> return (nofiles cmd)
					fs -> return (toomanyfiles cmd fs)
				Right False -> workdirfiles >>= \case
					[] -> return (Right Nothing)
					_ -> return (Left $ cmd ++ " download is incomplete. Run the command again to resume.")
				Left msg -> return (Left msg)
			, return (Right Nothing)
			)
	| otherwise = return (Right Nothing)
  where
	nofiles cmd = Left $ cmd ++ " did not put any media in its work directory, perhaps it's been configured to store files somewhere else?"
	toomanyfiles cmd fs = Left $ cmd ++ " downloaded multiple media files; git-annex is only able to deal with one per url: " ++ show fs
	downloadedfiles cmd
		| isytdlp cmd = liftIO $ 
			(nub . lines <$> readFile filelistfile)
				`catchIO` (pure . const [])
		| otherwise = workdirfiles
	workdirfiles = liftIO $ filter (/= filelistfile) 
		<$> (filterM (doesFileExist) =<< dirContents workdir)
	filelistfile = workdir </> filelistfilebase
	filelistfilebase = "git-annex-file-list-file"
	isytdlp cmd = cmd == "yt-dlp"
	runcmd cmd = youtubeDlMaxSize workdir >>= \case
		Left msg -> return (Left msg)
		Right maxsize -> do
			opts <- youtubeDlOpts (dlopts cmd ++ maxsize)
			oh <- mkOutputHandlerQuiet
			-- The size is unknown to start. Once youtube-dl
			-- outputs some progress, the meter will be updated
			-- with the size, which is why it's important the
			-- meter is passed into commandMeter'
			let unknownsize = Nothing :: Maybe FileSize
			ok <- metered (Just p) unknownsize Nothing $ \meter meterupdate ->
				liftIO $ commandMeter'
					(if isytdlp cmd then parseYtdlpProgress else parseYoutubeDlProgress)
					oh (Just meter) meterupdate cmd opts
					(\pr -> pr { cwd = Just workdir })
			return (Right ok)
	dlopts cmd = 
		[ Param url
		-- To make it only download one file when given a
		-- page with a video and a playlist, download only the video.
		, Param "--no-playlist"
		-- And when given a page with only a playlist, download only
		-- the first video on the playlist. (Assumes the video is
		-- somewhat stable, but this is the only way to prevent
		-- it from downloading the whole playlist.)
		, Param "--playlist-items", Param "0"
		] ++
			if isytdlp cmd
				then
					-- Avoid warnings, which go to
					-- stderr and may mess up
					-- git-annex's display.
					[ Param "--no-warnings"
					, Param "--progress-template"
					, Param progressTemplate
					, Param "--print-to-file"
					, Param "after_move:filepath"
					, Param filelistfilebase
					]
				else []

-- To honor annex.diskreserve, ask youtube-dl to not download too
-- large a media file. Factors in other downloads that are in progress,
-- and any files in the workdir that it may have partially downloaded
-- before.
youtubeDlMaxSize :: FilePath -> Annex (Either String [CommandParam])
youtubeDlMaxSize workdir = ifM (Annex.getRead Annex.force)
	( return $ Right []
	, liftIO (getDiskFree workdir) >>= \case
		Just have -> do
			inprogress <- sizeOfDownloadsInProgress (const True)
			partial <- liftIO $ sum 
				<$> (mapM (getFileSize . toRawFilePath) =<< dirContents workdir)
			reserve <- annexDiskReserve <$> Annex.getGitConfig
			let maxsize = have - reserve - inprogress + partial
			if maxsize > 0
				then return $ Right
					[ Param "--max-filesize"
					, Param (show maxsize)
					]
				else return $ Left $
					needMoreDiskSpace $
						negate maxsize + 1024
		Nothing -> return $ Right []
	)

-- Download a media file to a destination, 
youtubeDlTo :: Key -> URLString -> FilePath -> MeterUpdate -> Annex Bool
youtubeDlTo key url dest p = do
	res <- withTmpWorkDir key $ \workdir ->
		youtubeDl url (fromRawFilePath workdir) p >>= \case
			Right (Just mediafile) -> do
				liftIO $ moveFile (toRawFilePath mediafile) (toRawFilePath dest)
				return (Just True)
			Right Nothing -> return (Just False)
			Left msg -> do
				warning (UnquotedString msg)
				return Nothing
	return (fromMaybe False res)

-- youtube-dl supports downloading urls that are not html pages,
-- but we don't want to use it for such urls, since they can be downloaded
-- without it. So, this first downloads part of the content and checks 
-- if it's a html page; only then is youtube-dl used.
htmlOnly :: URLString -> a -> Annex a -> Annex a
htmlOnly url fallback a = withUrlOptions $ \uo -> 
	liftIO (downloadPartial url uo htmlPrefixLength) >>= \case
		Just bs | isHtmlBs bs -> a
		_ -> return fallback

-- Check if youtube-dl supports downloading content from an url.
youtubeDlSupported :: URLString -> Annex Bool
youtubeDlSupported url = either (const False) id
	<$> withUrlOptions (youtubeDlCheck' url)

-- Check if youtube-dl can find media in an url.
--
-- While this does not download anything, it checks youtubeDlAllowed
-- for symmetry with youtubeDl; the check should not succeed if the
-- download won't succeed.
youtubeDlCheck :: URLString -> Annex (Either String Bool)
youtubeDlCheck url = ifM youtubeDlAllowed
	( withUrlOptions $ youtubeDlCheck' url
	, return $ Left youtubeDlNotAllowedMessage
	)

youtubeDlCheck' :: URLString -> UrlOptions -> Annex (Either String Bool)
youtubeDlCheck' url uo
	| supportedScheme uo url = catchMsgIO $ htmlOnly url False $ do
		opts <- youtubeDlOpts [ Param url, Param "--simulate" ]
		cmd <- youtubeDlCommand
		liftIO $ snd <$> processTranscript cmd (toCommand opts) Nothing
	| otherwise = return (Right False)

-- Ask youtube-dl for the filename of media in an url.
--
-- (This is not always identical to the filename it uses when downloading.)
youtubeDlFileName :: URLString -> Annex (Either String FilePath)
youtubeDlFileName url = withUrlOptions go
  where
	go uo
		| supportedScheme uo url = flip catchIO (pure . Left . show) $
			htmlOnly url nomedia (youtubeDlFileNameHtmlOnly' url uo)
		| otherwise = return nomedia
	nomedia = Left "no media in url"

-- Does not check if the url contains htmlOnly; use when that's already
-- been verified.
youtubeDlFileNameHtmlOnly :: URLString -> Annex (Either String FilePath)
youtubeDlFileNameHtmlOnly = withUrlOptions . youtubeDlFileNameHtmlOnly'

youtubeDlFileNameHtmlOnly' :: URLString -> UrlOptions -> Annex (Either String FilePath)
youtubeDlFileNameHtmlOnly' url uo
	| supportedScheme uo url = flip catchIO (pure . Left . show) go
	| otherwise = return nomedia
  where
	go = do
		-- Sometimes youtube-dl will fail with an ugly backtrace
		-- (eg, http://bugs.debian.org/874321)
		-- so catch stderr as well as stdout to avoid the user
		-- seeing it. --no-warnings avoids warning messages that
		-- are output to stdout.
		opts <- youtubeDlOpts
			[ Param url
			, Param "--get-filename"
			, Param "--no-warnings"
			, Param "--no-playlist"
			]
		cmd <- youtubeDlCommand
		let p = (proc cmd (toCommand opts))
			{ std_out = CreatePipe
			, std_err = CreatePipe
			}
		liftIO $ withCreateProcess p waitproc
	
	waitproc Nothing (Just o) (Just e) pid = do
		errt <- async $ discardstderr pid e
		output <- hGetContentsStrict o
		ok <- liftIO $ checkSuccessProcess pid
		wait errt
		return $ case (ok, lines output) of
			(True, (f:_)) | not (null f) -> Right f
			_ -> nomedia
	waitproc _ _ _ _ = error "internal"

	discardstderr pid e = hGetLineUntilExitOrEOF pid e >>= \case
		Nothing -> return ()
		Just _ -> discardstderr pid e

	nomedia = Left "no media in url"

youtubeDlOpts :: [CommandParam] -> Annex [CommandParam]
youtubeDlOpts addopts = do
	opts <- map Param . annexYoutubeDlOptions <$> Annex.getGitConfig
	return (opts ++ addopts)

youtubeDlCommand :: Annex String
youtubeDlCommand = annexYoutubeDlCommand <$> Annex.getGitConfig >>= \case
	Just c -> pure c
	Nothing -> ifM (liftIO $ inSearchPath "yt-dlp")
		( return "yt-dlp"
		, return "youtube-dl"
		)

supportedScheme :: UrlOptions -> URLString -> Bool
supportedScheme uo url = case parseURIRelaxed url of
	Nothing -> False
	Just u -> case uriScheme u of
		-- avoid ugly message from youtube-dl about not supporting file:
		"file:" -> False
		-- ftp indexes may look like html pages, and there's no point
		-- involving youtube-dl in a ftp download
		"ftp:" -> False
		_ -> allowedScheme uo u

progressTemplate :: String
progressTemplate = "ANNEX %(progress.downloaded_bytes)i %(progress.total_bytes_estimate)i %(progress.total_bytes)i ANNEX"

{- The progressTemplate makes output look like "ANNEX 10 100 NA ANNEX" or
 - "ANNEX 10 NA 100 ANNEX" depending on whether the total bytes are estimated
 - or known. That makes parsing much easier (and less fragile) than parsing
 - the usual progress output.
 -}
parseYtdlpProgress :: ProgressParser
parseYtdlpProgress = go [] . reverse . progresschunks
  where
	delim = '\r'

	progresschunks = splitc delim

	go remainder [] = (Nothing, Nothing, remainder)
	go remainder (x:xs) = case splitc ' ' x of
			("ANNEX":downloaded_bytes_s:total_bytes_estimate_s:total_bytes_s:"ANNEX":[]) ->
				case (readMaybe downloaded_bytes_s, readMaybe total_bytes_estimate_s, readMaybe total_bytes_s) of
					(Just downloaded_bytes, Nothing, Just total_bytes) ->
						( Just (BytesProcessed downloaded_bytes)
						, Just (TotalSize total_bytes)
						, remainder
						)
					(Just downloaded_bytes, Just total_bytes_estimate, _) ->
						( Just (BytesProcessed downloaded_bytes)
						, Just (TotalSize total_bytes_estimate)
						, remainder
						)
					_ -> go (remainder++x) xs
			_ -> go (remainder++x) xs

{- youtube-dl is deprecated, parsing its progress was attempted before but
 - was buggy and is no longer done. -}
parseYoutubeDlProgress :: ProgressParser
parseYoutubeDlProgress _ = (Nothing, Nothing, "")

{- List the items that yt-dlp can download from an url.
 - 
 - Note that this does not check youtubeDlAllowed because it does not
 - download content.
 -}
youtubePlaylist :: URLString -> Annex (Either String [YoutubePlaylistItem])
youtubePlaylist url = do
	cmd <- youtubeDlCommand
	if cmd == "yt-dlp"
		then liftIO $ youtubePlaylist' url cmd
		else return $ Left $ "Scraping needs yt-dlp, but git-annex has been configured to use " ++ cmd

youtubePlaylist' :: URLString -> String -> IO (Either String [YoutubePlaylistItem])
youtubePlaylist' url cmd = withTmpFile "yt-dlp" $ \tmpfile h -> do
	hClose h
	(outerr, ok) <- processTranscript cmd
		[ "--simulate"
		, "--flat-playlist"
		-- Skip live videos in progress
		, "--match-filter", "!is_live"
		, "--print-to-file"
		-- Write json with selected fields.
		, "%(.{" ++ intercalate "," youtubePlaylistItemFields ++ "})j"
		, tmpfile
		, url
		]
		Nothing
	if ok
		then flip catchIO (pure . Left . show) $ do
			v <- map Aeson.eitherDecodeStrict . B8.lines
				<$> B.readFile tmpfile
			return $ case partitionEithers v of
				((parserr:_), _) -> 
					Left $ "yt-dlp json parse errror: " ++ parserr
				([], r) -> Right r
		else return $ Left $ if null outerr
			then "yt-dlp failed"
			else "yt-dlp failed: " ++ outerr

-- There are other fields that yt-dlp can extract, but these are similar to
-- the information from an RSS feed.
youtubePlaylistItemFields :: [String]
youtubePlaylistItemFields =
	[ "playlist_title"
	, "playlist_uploader"
	, "title"
	, "description"
	, "license"
	, "url"
	, "timestamp"
	]

-- Parse JSON generated by yt-dlp for playlist. Note that any field
-- may be omitted when that information is not supported for a given website.
data YoutubePlaylistItem = YoutubePlaylistItem
	{ youtube_playlist_title :: Maybe String
	, youtube_playlist_uploader :: Maybe String
	, youtube_title :: Maybe String
	, youtube_description :: Maybe String
	, youtube_license :: Maybe String
	, youtube_url :: Maybe String
	, youtube_timestamp :: Maybe Integer -- ^ unix timestamp
	} deriving (Generic, Show)

instance Aeson.FromJSON YoutubePlaylistItem
  where
	parseJSON = Aeson.genericParseJSON Aeson.defaultOptions
		{ Aeson.fieldLabelModifier = drop (length "youtube_") }