#!/usr/bin/env python3

import asyncio
import http.cookies
import json
import os
import pathlib
import time
from datetime import datetime

import aiohttp

from .fc2 import FC2LiveStream, FC2WebSocket
from .ffmpeg import FFMpeg
from .hls import HLSDownloader
from .util import Logger, sanitize_filename


class FC2LiveDL:
    # Constants
    STREAM_QUALITY = {
        "150Kbps": 10,
        "400Kbps": 20,
        "1.2Mbps": 30,
        "2Mbps": 40,
        "3Mbps": 50,
        "sound": 90,
    }
    STREAM_LATENCY = {
        "low": 0,
        "high": 1,
        "mid": 2,
    }
    DEFAULT_PARAMS = {
        "quality": "3Mbps",
        "latency": "mid",
        "threads": 1,
        "outtmpl": "%(date)s %(title)s (%(channel_name)s).%(ext)s",
        "write_chat": False,
        "write_info_json": False,
        "write_thumbnail": False,
        "wait_for_live": False,
        "wait_for_quality_timeout": 15,
        "wait_poll_interval": 5,
        "cookies_file": None,
        "remux": True,
        "keep_intermediates": False,
        "extract_audio": False,
        "trust_env_proxy": False,
        # Debug params
        "dump_websocket": False,
    }

    def __init__(self, params={}):
        self._logger = Logger("fc2")
        self._session = None
        self._background_tasks = []

        self.params = json.loads(json.dumps(self.DEFAULT_PARAMS))
        self.params.update(params)
        # Validate outtmpl
        self._format_outtmpl()

        # Parse cookies
        self._cookie_jar = aiohttp.CookieJar()
        cookies_file = self.params["cookies_file"]
        if cookies_file is not None:
            self._logger.info("Loading cookies from", cookies_file)
            cookies = self._parse_cookies_file(cookies_file)
            self._cookie_jar.update_cookies(cookies)

    async def __aenter__(self):
        self._session = aiohttp.ClientSession(
            cookie_jar=self._cookie_jar,
            trust_env=self.params["trust_env_proxy"],
        )
        self._loop = asyncio.get_running_loop()
        return self

    async def __aexit__(self, *err):
        self._logger.trace("exit", err)
        await self._session.close()
        self._session = None

    async def download(self, channel_id):
        self._logger = Logger("fc2 " + channel_id)
        tasks = []
        fname_stream = None
        try:
            live = FC2LiveStream(self._session, channel_id)

            self._logger.info("Fetching stream info")

            is_online = await live.is_online()
            if not is_online:
                if not self.params["wait_for_live"]:
                    raise FC2LiveStream.NotOnlineException()
                await live.wait_for_online(self.params["wait_poll_interval"])

            meta = await live.get_meta(refetch=False)

            fname_info = self._prepare_file(meta, "info.json")
            fname_thumb = self._prepare_file(meta, "png")
            fname_stream = self._prepare_file(meta, "ts")
            fname_chat = self._prepare_file(meta, "fc2chat.json")
            fname_muxed = self._prepare_file(
                meta, "m4a" if self.params["quality"] == "sound" else "mp4"
            )
            fname_audio = self._prepare_file(meta, "m4a")
            fname_websocket = (
                self._prepare_file(meta, "ws")
                if self.params["dump_websocket"]
                else None
            )

            if self.params["write_info_json"]:
                self._logger.info("Writing info json to", fname_info)
                with open(fname_info, "w") as f:
                    f.write(json.dumps(meta))

            if self.params["write_thumbnail"]:
                self._logger.info("Writing thumbnail to", fname_thumb)
                thumb_url = meta["channel_data"]["image"]
                async with self._session.get(thumb_url) as resp:
                    with open(fname_thumb, "wb") as f:
                        async for data in resp.content.iter_chunked(1024):
                            f.write(data)

            ws_url = await live.get_websocket_url()
            self._logger.info("Found websocket url")
            async with FC2WebSocket(
                self._session, ws_url, output_file=fname_websocket
            ) as ws:
                started = time.time()
                mode = self._get_mode()
                got_mode = None
                hls_url = None

                # Wait for the selected quality to be available
                while (
                    time.time() - started < self.params["wait_for_quality_timeout"]
                    and got_mode != mode
                ):
                    hls_info = await ws.get_hls_information()
                    hls_url, got_mode = self._get_hls_url(hls_info, mode)

                    # Log a warning if the requested mode is not available
                    if got_mode != mode:
                        self._logger.warn(
                            "Requested quality",
                            self._format_mode(mode),
                            "is not available, waiting ({}/{}s)".format(
                                round(time.time() - started),
                                self.params["wait_for_quality_timeout"],
                            ),
                        )
                        await asyncio.sleep(1)

                if got_mode != mode:
                    self._logger.warn(
                        "Timeout reached, falling back to next best quality",
                        self._format_mode(got_mode),
                    )

                self._logger.info("Received HLS info")

                coros = []

                coros.append(ws.wait_disconnection())

                self._logger.info("Writing stream to", fname_stream)
                coros.append(self._download_stream(hls_url, fname_stream))

                if self.params["write_chat"]:
                    self._logger.info("Writing chat to", fname_chat)
                    coros.append(self._download_chat(ws, fname_chat))

                tasks = [asyncio.create_task(coro) for coro in coros]

                self._logger.debug("Starting", len(tasks), "tasks")
                _exited, _pending = await asyncio.wait(
                    tasks, return_when=asyncio.FIRST_COMPLETED
                )
                self._logger.debug("Tasks exited")

                while len(_pending) > 0:
                    pending_task = _pending.pop()
                    self._logger.debug("Cancelling pending task", pending_task)
                    pending_task.cancel()

                exited = _exited.pop()
                self._logger.debug("Exited task was", exited)
                if exited.exception() is not None:
                    raise exited.exception()
        except asyncio.CancelledError:
            self._logger.error("Interrupted by user")
        except FC2WebSocket.ServerDisconnection as ex:
            self._logger.error(ex)
        except FC2WebSocket.StreamEnded:
            self._logger.info("Stream ended")
        finally:
            self._logger.debug("Cancelling tasks")
            for task in tasks:
                if not task.done():
                    self._logger.debug("Cancelling", task)
                    task.cancel()
                    await task

        if (
            fname_stream is not None
            and self.params["remux"]
            and os.path.isfile(fname_stream)
        ):
            self._logger.info("Remuxing stream to", fname_muxed)
            await self._remux_stream(fname_stream, fname_muxed)
            self._logger.debug("Finished remuxing stream", fname_muxed)

            if self.params["extract_audio"]:
                self._logger.info("Extracting audio to", fname_audio)
                await self._remux_stream(fname_stream, fname_audio, extra_flags=["-vn"])
                self._logger.debug("Finished remuxing stream", fname_muxed)

            if not self.params["keep_intermediates"] and os.path.isfile(fname_muxed):
                self._logger.info("Removing intermediate files")
                os.remove(fname_stream)
            else:
                self._logger.debug("Not removing intermediates")
        else:
            self._logger.debug("Not remuxing stream")

        self._logger.info("Done")

    async def _download_stream(self, hls_url, fname):
        def sizeof_fmt(num, suffix="B"):
            for unit in ["", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei", "Zi"]:
                if abs(num) < 1024.0:
                    return f"{num:3.1f}{unit}{suffix}"
                num /= 1024.0
            return f"{num:.1f}Yi{suffix}"

        try:
            async with HLSDownloader(
                self._session, hls_url, self.params["threads"]
            ) as hls:
                with open(fname, "wb") as out:
                    n_frags = 0
                    total_size = 0
                    async for frag in hls.read():
                        n_frags += 1
                        total_size += len(frag)
                        out.write(frag)
                        self._logger.info(
                            "Downloaded",
                            n_frags,
                            "fragments,",
                            sizeof_fmt(total_size),
                            inline=True,
                        )
        except asyncio.CancelledError:
            self._logger.debug("_download_stream cancelled")
        except Exception as ex:
            self._logger.error(ex)

    async def _remux_stream(self, ifname, ofname, *, extra_flags=[]):
        mux_flags = [
            "-y",
            "-hide_banner",
            "-loglevel",
            "fatal",
            "-stats",
            "-i",
            ifname,
            *extra_flags,
            "-c",
            "copy",
            "-movflags",
            "faststart",
            ofname,
        ]
        async with FFMpeg(mux_flags) as mux:
            self._logger.info("Remuxing stream", inline=True)
            while await mux.print_status():
                pass

    async def _download_chat(self, ws, fname):
        with open(fname, "w") as f:
            while True:
                comment = await ws.comments.get()
                f.write(json.dumps(comment))
                f.write("\n")

    def _get_hls_url(self, hls_info, mode):
        p_merged = self._merge_playlists(hls_info)
        p_sorted = self._sort_playlists(p_merged)
        playlist = self._get_playlist_or_best(p_sorted, mode)
        return playlist["url"], playlist["mode"]

    def _get_playlist_or_best(self, sorted_playlists, mode):
        playlist = None

        if len(sorted_playlists) == 0:
            raise FC2WebSocket.EmptyPlaylistException()

        # Find the playlist with matching (quality, latency) mode
        for p in sorted_playlists:
            if p["mode"] == mode:
                playlist = p

        # If no playlist matches, ignore the quality and find the best
        # one matching the latency
        if playlist is None:
            for p in sorted_playlists:
                _, p_latency = self._format_mode(p["mode"])
                _, r_latency = self._format_mode(mode)
                if p_latency == r_latency:
                    playlist = p
                    break

        # If no playlist matches, return the first one
        if playlist is None:
            playlist = sorted_playlists[0]

        return playlist

    def _sort_playlists(self, merged_playlists):
        def key_map(playlist):
            mode = playlist["mode"]
            if mode >= 90:
                return mode - 90
            return mode

        return sorted(merged_playlists, reverse=True, key=key_map)

    def _merge_playlists(self, hls_info):
        playlists = []
        for name in ["playlists", "playlists_high_latency", "playlists_middle_latency"]:
            if name in hls_info:
                playlists.extend(hls_info[name])
        return playlists

    def _get_mode(self):
        mode = 0
        mode += self.STREAM_QUALITY[self.params["quality"]]
        mode += self.STREAM_LATENCY[self.params["latency"]]
        return mode

    def _format_mode(self, mode):
        def dict_search(haystack, needle):
            return list(haystack.keys())[list(haystack.values()).index(needle)]

        latency = dict_search(self.STREAM_LATENCY, mode % 10)
        quality = dict_search(self.STREAM_QUALITY, mode // 10 * 10)
        return quality, latency

    def _prepare_file(self, meta=None, ext=""):
        def get_unique_name(meta, ext):
            n = 0
            while True:
                extn = ext if n == 0 else "{}.{}".format(n, ext)
                fname = self._format_outtmpl(meta, {"ext": extn})
                n += 1
                if not os.path.exists(fname):
                    return fname

        fname = get_unique_name(meta, ext)
        fpath = pathlib.Path(fname)
        fpath.parent.mkdir(parents=True, exist_ok=True)
        return fname

    def _format_outtmpl(self, meta=None, overrides={}):
        finfo = {
            "channel_id": "",
            "channel_name": "",
            "date": datetime.now().strftime("%F"),
            "time": datetime.now().strftime("%H%M%S"),
            "title": "",
            "ext": "",
        }

        if meta is not None:
            finfo["channel_id"] = sanitize_filename(meta["channel_data"]["channelid"])
            finfo["channel_name"] = sanitize_filename(meta["profile_data"]["name"])
            finfo["title"] = sanitize_filename(meta["channel_data"]["title"])

        for key in self.params:
            if key.startswith("_"):
                finfo[key] = self.params[key]

        finfo.update(overrides)

        formatted = self.params["outtmpl"] % finfo
        if formatted.startswith("-"):
            formatted = "_" + formatted

        return formatted

    def _parse_cookies_file(self, cookies_file):
        cookies = http.cookies.SimpleCookie()
        with open(cookies_file, "r") as cf:
            for line in cf:
                try:
                    domain, _flag, path, secure, _expiration, name, value = [
                        t.strip() for t in line.split("\t")
                    ]
                    cookies[name] = value
                    cookies[name]["domain"] = domain.replace("#HttpOnly_", "")
                    cookies[name]["path"] = path
                    cookies[name]["secure"] = secure
                    cookies[name]["httponly"] = domain.startswith("#HttpOnly_")
                except Exception as ex:
                    self._logger.trace(line, repr(ex), str(ex))
        return cookies

#!/usr/bin/env python3

import asyncio
import http.cookies
import json
import os
import pathlib
import time
from datetime import datetime

import aiohttp

from .fc2 import FC2LiveStream, FC2WebSocket
from .ffmpeg import FFMpeg
from .hls import HLSDownloader
from .util import Logger, sanitize_filename


class FC2LiveDL:
    # Constants
    STREAM_QUALITY = {
        "150Kbps": 10,
        "400Kbps": 20,
        "1.2Mbps": 30,
        "2Mbps": 40,
        "3Mbps": 50,
        "sound": 90,
    }
    STREAM_LATENCY = {
        "low": 0,
        "high": 1,
        "mid": 2,
    }
    DEFAULT_PARAMS = {
        "quality": "3Mbps",
        "latency": "mid",
        "threads": 1,
        "outtmpl": "%(date)s %(title)s (%(channel_name)s).%(ext)s",
        "write_chat": False,
        "write_info_json": False,
        "write_thumbnail": False,
        "wait_for_live": False,
        "wait_for_quality_timeout": 15,
        "wait_poll_interval": 5,
        "cookies_file": None,
        "remux": True,
        "keep_intermediates": False,
        "extract_audio": False,
        "trust_env_proxy": False,
        # Debug params
        "dump_websocket": False,
    }

    def __init__(self, params={}):
        self._logger = Logger("fc2")
        self._session = None
        self._background_tasks = []

        self.params = json.loads(json.dumps(self.DEFAULT_PARAMS))
        self.params.update(params)
        # Validate outtmpl
        self._format_outtmpl()

        # Parse cookies
        self._cookie_jar = aiohttp.CookieJar()
        cookies_file = self.params["cookies_file"]
        if cookies_file is not None:
            self._logger.info("Loading cookies from", cookies_file)
            cookies = self._parse_cookies_file(cookies_file)
            self._cookie_jar.update_cookies(cookies)

    async def __aenter__(self):
        self._session = aiohttp.ClientSession(
            cookie_jar=self._cookie_jar,
            trust_env=self.params["trust_env_proxy"],
        )
        self._loop = asyncio.get_running_loop()
        return self

    async def __aexit__(self, *err):
        self._logger.trace("exit", err)
        await self._session.close()
        self._session = None

    async def download(self, channel_id):
        self._logger = Logger("fc2 " + channel_id)
        tasks = []
        fname_stream = None
        try:
            live = FC2LiveStream(self._session, channel_id)

            self._logger.info("Fetching stream info")

            is_online = await live.is_online()
            if not is_online:
                if not self.params["wait_for_live"]:
                    raise FC2LiveStream.NotOnlineException()
                await live.wait_for_online(self.params["wait_poll_interval"])

            meta = await live.get_meta(refetch=False)

            fname_info = self._prepare_file(meta, "info.json")
            fname_thumb = self._prepare_file(meta, "png")
            fname_stream = self._prepare_file(meta, "ts")
            fname_chat = self._prepare_file(meta, "fc2chat.json")
            fname_muxed = self._prepare_file(
                meta, "m4a" if self.params["quality"] == "sound" else "mp4"
            )
            fname_audio = self._prepare_file(meta, "m4a")
            fname_websocket = (
                self._prepare_file(meta, "ws")
                if self.params["dump_websocket"]
                else None
            )

            if self.params["write_info_json"]:
                self._logger.info("Writing info json to", fname_info)
                with open(fname_info, "w") as f:
                    f.write(json.dumps(meta))

            if self.params["write_thumbnail"]:
                self._logger.info("Writing thumbnail to", fname_thumb)
                thumb_url = meta["channel_data"]["image"]
                async with self._session.get(thumb_url) as resp:
                    with open(fname_thumb, "wb") as f:
                        async for data in resp.content.iter_chunked(1024):
                            f.write(data)

            ws_url = await live.get_websocket_url()
            self._logger.info("Found websocket url")
            async with FC2WebSocket(
                self._session, ws_url, output_file=fname_websocket
            ) as ws:
                started = time.time()
                mode = self._get_mode()
                got_mode = None
                hls_url = None

                # Wait for the selected quality to be available
                while (
                    time.time() - started < self.params["wait_for_quality_timeout"]
                    and got_mode != mode
                ):
                    hls_info = await ws.get_hls_information()
                    hls_url, got_mode = self._get_hls_url(hls_info, mode)

                    # Log a warning if the requested mode is not available
                    if got_mode != mode:
                        self._logger.warn(
                            "Requested quality",
                            self._format_mode(mode),
                            "is not available, waiting ({}/{}s)".format(
                                round(time.time() - started),
                                self.params["wait_for_quality_timeout"],
                            ),
                        )
                        await asyncio.sleep(1)

                if got_mode != mode:
                    self._logger.warn(
                        "Timeout reached, falling back to next best quality",
                        self._format_mode(got_mode),
                    )

                self._logger.info("Received HLS info")

                coros = []

                coros.append(ws.wait_disconnection())

                self._logger.info("Writing stream to", fname_stream)
                coros.append(self._download_stream(hls_url, fname_stream))

                if self.params["write_chat"]:
                    self._logger.info("Writing chat to", fname_chat)
                    coros.append(self._download_chat(ws, fname_chat))

                tasks = [asyncio.create_task(coro) for coro in coros]

                self._logger.debug("Starting", len(tasks), "tasks")
                _exited, _pending = await asyncio.wait(
                    tasks, return_when=asyncio.FIRST_COMPLETED
                )
                self._logger.debug("Tasks exited")

                while len(_pending) > 0:
                    pending_task = _pending.pop()
                    self._logger.debug("Cancelling pending task", pending_task)
                    pending_task.cancel()

                exited = _exited.pop()
                self._logger.debug("Exited task was", exited)
                if exited.exception() is not None:
                    raise exited.exception()
        except asyncio.CancelledError:
            self._logger.error("Interrupted by user")
        except FC2WebSocket.ServerDisconnection as ex:
            self._logger.error(ex)
        except FC2WebSocket.StreamEnded:
            self._logger.info("Stream ended")
        finally:
            self._logger.debug("Cancelling tasks")
            for task in tasks:
                if not task.done():
                    self._logger.debug("Cancelling", task)
                    task.cancel()
                    await task

        if (
            fname_stream is not None
            and self.params["remux"]
            and os.path.isfile(fname_stream)
        ):
            self._logger.info("Remuxing stream to", fname_muxed)
            await self._remux_stream(fname_stream, fname_muxed)
            self._logger.debug("Finished remuxing stream", fname_muxed)

            if self.params["extract_audio"]:
                self._logger.info("Extracting audio to", fname_audio)
                await self._remux_stream(fname_stream, fname_audio, extra_flags=["-vn"])
                self._logger.debug("Finished remuxing stream", fname_muxed)

            if not self.params["keep_intermediates"] and os.path.isfile(fname_muxed):
                self._logger.info("Removing intermediate files")
                os.remove(fname_stream)
            else:
                self._logger.debug("Not removing intermediates")
        else:
            self._logger.debug("Not remuxing stream")

        self._logger.info("Done")

    async def _download_stream(self, hls_url, fname):
        def sizeof_fmt(num, suffix="B"):
            for unit in ["", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei", "Zi"]:
                if abs(num) < 1024.0:
                    return f"{num:3.1f}{unit}{suffix}"
                num /= 1024.0
            return f"{num:.1f}Yi{suffix}"

        try:
            async with HLSDownloader(
                self._session, hls_url, self.params["threads"]
            ) as hls:
                with open(fname, "wb") as out:
                    n_frags = 0
                    total_size = 0
                    async for frag in hls.read():
                        n_frags += 1
                        total_size += len(frag)
                        out.write(frag)
                        self._logger.info(
                            "Downloaded",
                            n_frags,
                            "fragments,",
                            sizeof_fmt(total_size),
                            inline=True,
                        )
        except asyncio.CancelledError:
            self._logger.debug("_download_stream cancelled")
        except Exception as ex:
            self._logger.error(ex)

    async def _remux_stream(self, ifname, ofname, *, extra_flags=[]):
        mux_flags = [
            "-y",
            "-hide_banner",
            "-loglevel",
            "fatal",
            "-stats",
            "-i",
            ifname,
            *extra_flags,
            "-c",
            "copy",
            "-movflags",
            "faststart",
            ofname,
        ]
        async with FFMpeg(mux_flags) as mux:
            self._logger.info("Remuxing stream", inline=True)
            while await mux.print_status():
                pass

    async def _download_chat(self, ws, fname):
        with open(fname, "w") as f:
            while True:
                comment = await ws.comments.get()
                f.write(json.dumps(comment))
                f.write("\n")

    def _get_hls_url(self, hls_info, mode):
        p_merged = self._merge_playlists(hls_info)
        p_sorted = self._sort_playlists(p_merged)
        playlist = self._get_playlist_or_best(p_sorted, mode)
        return playlist["url"], playlist["mode"]

    def _get_playlist_or_best(self, sorted_playlists, mode):
        playlist = None

        if len(sorted_playlists) == 0:
            raise FC2WebSocket.EmptyPlaylistException()

        # Find the playlist with matching (quality, latency) mode
        for p in sorted_playlists:
            if p["mode"] == mode:
                playlist = p

        # If no playlist matches, ignore the quality and find the best
        # one matching the latency
        if playlist is None:
            for p in sorted_playlists:
                _, p_latency = self._format_mode(p["mode"])
                _, r_latency = self._format_mode(mode)
                if p_latency == r_latency:
                    playlist = p
                    break

        # If no playlist matches, return the first one
        if playlist is None:
            playlist = sorted_playlists[0]

        return playlist

    def _sort_playlists(self, merged_playlists):
        def key_map(playlist):
            mode = playlist["mode"]
            if mode >= 90:
                return mode - 90
            return mode

        return sorted(merged_playlists, reverse=True, key=key_map)

    def _merge_playlists(self, hls_info):
        playlists = []
        for name in ["playlists", "playlists_high_latency", "playlists_middle_latency"]:
            if name in hls_info:
                playlists.extend(hls_info[name])
        return playlists

    def _get_mode(self):
        mode = 0
        mode += self.STREAM_QUALITY[self.params["quality"]]
        mode += self.STREAM_LATENCY[self.params["latency"]]
        return mode

    def _format_mode(self, mode):
        def dict_search(haystack, needle):
            return list(haystack.keys())[list(haystack.values()).index(needle)]

        latency = dict_search(self.STREAM_LATENCY, mode % 10)
        quality = dict_search(self.STREAM_QUALITY, mode // 10 * 10)
        return quality, latency

    def _prepare_file(self, meta=None, ext=""):
        def get_unique_name(meta, ext):
            n = 0
            while True:
                extn = ext if n == 0 else "{}.{}".format(n, ext)
                fname = self._format_outtmpl(meta, {"ext": extn})
                n += 1
                if not os.path.exists(fname):
                    return fname

        fname = get_unique_name(meta, ext)
        fpath = pathlib.Path(fname)
        fpath.parent.mkdir(parents=True, exist_ok=True)
        return fname

    def _format_outtmpl(self, meta=None, overrides={}):
        finfo = {
            "channel_id": "",
            "channel_name": "",
            "date": datetime.now().strftime("%F"),
            "time": datetime.now().strftime("%H%M%S"),
            "title": "",
            "ext": "",
        }

        if meta is not None:
            finfo["channel_id"] = sanitize_filename(meta["channel_data"]["channelid"])
            finfo["channel_name"] = sanitize_filename(meta["profile_data"]["name"])
            finfo["title"] = sanitize_filename(meta["channel_data"]["title"])

        for key in self.params:
            if key.startswith("_"):
                finfo[key] = self.params[key]

        finfo.update(overrides)

        formatted = self.params["outtmpl"] % finfo
        if formatted.startswith("-"):
            formatted = "_" + formatted

        return formatted

    def _parse_cookies_file(self, cookies_file):
        cookies = http.cookies.SimpleCookie()
        with open(cookies_file, "r") as cf:
            for line in cf:
                try:
                    domain, _flag, path, secure, _expiration, name, value = [
                        t.strip() for t in line.split("\t")
                    ]
                    cookies[name] = value
                    cookies[name]["domain"] = domain.replace("#HttpOnly_", "")
                    cookies[name]["path"] = path
                    cookies[name]["secure"] = secure
                    cookies[name]["httponly"] = domain.startswith("#HttpOnly_")
                except Exception as ex:
                    self._logger.trace(line, repr(ex), str(ex))
        return cookies

#!/usr/bin/env python3 # Constants # Debug params # Validate outtmpl # Parse cookies # Wait for the selected quality to be available # Log a warning if the requested mode is not available # Find the playlist with matching (quality, latency) mode # If no playlist matches, ignore the quality and find the best # one matching the latency # If no playlist matches, return the first one