import asyncio
from typing import Callable, Awaitable, Iterable

from yt_dlp import YoutubeDL
from yt_dlp.postprocessor import FFmpegExtractAudioPP

import config
import id3pp


class _CreateYDL:

    @staticmethod
    def youtube() -> YoutubeDL:
        ydl = YoutubeDL({'format': 'ba'})
        ydl.add_post_processor(id3pp.InfoYouTubePP(), when='before_dl')
        ydl.add_post_processor(FFmpegExtractAudioPP(preferredcodec='mp3'), when='post_process')
        return ydl

    @staticmethod
    def yt_proxied() -> YoutubeDL:
        ydl = _CreateYDL.youtube()
        ydl.params['proxy'] = config.get().yt_proxy
        return ydl

    @staticmethod
    def yandex() -> YoutubeDL:
        return YoutubeDL()


create_ydl_fn = {
    'youtube': _CreateYDL.youtube,
    'yt_proxied': _CreateYDL.yt_proxied,
    'yandex': _CreateYDL.yandex,
}

ydl_fn_keys = create_ydl_fn.keys()


class Downloader:

    def __init__(
            self,
            progress_cb: Callable[[str], Awaitable],
            lyrics_cb: Callable[[list[str]], Awaitable]) -> None:

        self.ydls: dict[str, YoutubeDL | None] = {
            'youtube': None,
            'yt_proxied': None,
            'yandex': None,
        }

        self.cur_ydl: YoutubeDL | None = None

        self.progress_cb = progress_cb
        self.lyrics_cb = lyrics_cb

    def choose_ydl(self, site: str) -> None:

        ydl = self.ydls[site]
        cfg = config.get()

        if ydl is None:
            ydl = create_ydl_fn[site]()

            ydl.params['outtmpl']['default'] = cfg.tmpl
            ydl.add_post_processor(id3pp.ID3TagsPP(), when='post_process')

            cookies = cfg.cookies_dir / (site + '.txt')
            if cookies.exists():
                ydl.params['cookiefile'] = str(cookies)

        self.cur_ydl = ydl

    def get_cur_ydl(self) -> YoutubeDL:

        ydl = self.cur_ydl
        if ydl is None:
            raise RuntimeError('ydl object not initialized')
        return ydl

    async def get_playlist_items(self, url: str) -> list[str]:

        return await asyncio.get_event_loop().run_in_executor(
            None,
            Downloader._target_get_playlist_items,
            self.get_cur_ydl(),
            url,
        )

    @staticmethod
    def _target_get_playlist_items(ydl: YoutubeDL, url: str) -> list[str]:

        info = ydl.extract_info(url, download=False, process=True)
        if info is None:
            raise RuntimeError('ydl.extract_info returned None')
        return [
            entry['track'] if 'track' in entry else entry['title']
            for entry in info['entries']
        ]

    async def download(
            self,
            url: str,
            playlist_items: Iterable[int] | None = None) -> int:

        return await asyncio.get_event_loop().run_in_executor(
            None,
            Downloader._target_download,
            self.get_cur_ydl(),
            url,
            playlist_items,
        )

    @staticmethod
    def _target_download(
            ydl: YoutubeDL,
            url: str,
            playlist_items: Iterable[int] | None = None) -> int:

        if playlist_items:
            ydl.params['playlist_items'] = ','.join(str(i) for i in playlist_items)

        ret = ydl.download(url)
        del ydl.params['playlist_items']

        return ret

    def cleanup(self) -> None:

        for ydl in self.ydls.values():
            if ydl is not None:
                ydl.close()