#!/usr/bin/env python3


"""
Script that download videos that are linked as an article
in a RSS feed.
The common use case would be a feed from an RSS aggregator
with the unread items (non-video links are ignored).
"""

import enum
import functools
import logging
import os
import pickle
import random
import re
import subprocess
import sys
import time
import typing
import urllib.parse
import urllib.request
import urllib.error
from xml.dom import minidom

import coloredlogs
import configargparse
import yt_dlp

log = logging.getLogger(__name__)

# TODO Lockfile, or a way to parallel watch and download
# TODO Save ytdl infos and view info separately

def configure_logging(args: configargparse.Namespace) -> None:
    # Configure logging
    if args.verbosity:
        coloredlogs.install(
            level=args.verbosity,
        )
    else:
        coloredlogs.install(
            fmt="%(message)s",
            logger=log,
        )


class SaveInfoPP(yt_dlp.postprocessor.common.PostProcessor):
    """
    yt_dlp.process_ie_result() doesn't return a completely updated info dict,
    notably the extension is still the one before it realizes the files cannot
    be merged. So we use this PostProcessor to catch the info dict in its final
    form and save it.
    """

    def __init__(self, rvelement: "RVElement") -> None:
        self.rvelement = rvelement
        super().__init__()

    def run(self, info: dict) -> tuple[list, dict]:
        self.rvelement.ytdl_infos = info
        return [], info

def parse_duration(string: str) -> int:
    DURATION_MULTIPLIERS = {"s": 1, "m": 60, "h": 3600, "": 1}

    mult_index = string[-1].lower()
    if mult_index.isdigit():
        mult_index = ""
    else:
        string = string[:-1]
    try:
        multiplier = DURATION_MULTIPLIERS[mult_index]
    except IndexError:
        raise ValueError(f"Unknown duration multiplier: {mult_index}")

    return int(string) * multiplier


def compare_duration(compstr: str) -> typing.Callable[[int], bool]:
    DURATION_COMPARATORS = {
        "<": int.__lt__,
        "-": int.__lt__,
        ">": int.__gt__,
        "+": int.__gt__,
        "=": int.__eq__,
        "": int.__le__,
    }

    comp_index = compstr[0]
    if comp_index.isdigit():
        comp_index = ""
    else:
        compstr = compstr[1:]
    try:
        comparator = DURATION_COMPARATORS[comp_index]
    except IndexError:
        raise ValueError(f"Unknown duration comparator: {comp_index}")

    duration = parse_duration(compstr)

    return lambda d: comparator(d, duration)

def format_duration(duration: int) -> str:
    return time.strftime("%H:%M:%S", time.gmtime(duration))


class RVElement:
    parent: "RVDatabase"
    item: minidom.Element
    was_downloaded: bool
    watched: bool

    def __init__(self, parent: "RVDatabase", item: minidom.Element) -> None:
        self.parent = parent
        self.item = item
        self.was_downloaded = False
        self.watched = False

    def get_tag_data(self, tag_name: str) -> str:
        nodes = self.item.getElementsByTagName(tag_name)
        if len(nodes) != 1:
            raise KeyError(f"Exepected 1 tag `{tag_name}`, got {len(nodes)}.")
        children = nodes[0].childNodes
        if len(children) != 1:
            raise KeyError(
                f"Exepected 1 children for tag `{tag_name}`, got {len(children)}."
            )
        return children[0].data

    @property
    def title(self) -> str:
        return self.get_tag_data("title")

    @property
    def link(self) -> str:
        return self.get_tag_data("link")

    @property
    def creator(self) -> typing.Optional[str]:
        try:
            return self.get_tag_data("dc:creator")
        except KeyError:
            return None

    @property
    def description(self) -> str:
        # TODO Testing
        return self.get_tag_data("description")

    @property
    def date(self) -> str:
        # TODO datetime format
        return self.get_tag_data("pubDate")

    @property
    def guid(self) -> int:
        return int(self.get_tag_data("guid"))

    @property
    def is_researched(self) -> bool:
        return "ytdl_infos" in self.__dict__

    def salvage_cache(self, cache: "RVElement") -> None:
        if not self.parent.args.research and cache.is_researched:
            self.__dict__["ytdl_infos"] = cache.__dict__["ytdl_infos"]
            log.debug(f"From cache: {self}")
        # if cache.was_downloaded:
        #     self.was_downloaded = True
        if cache.watched:
            self.watched = True

    def __str__(self) -> str:
        str = f"{self.guid}: {self.creator if self.creator else '?'} – {self.title}"
        if self.is_researched:
            if self.is_video:
                str += f" ({format_duration(self.duration)})"
            else:
                str += " (N/A)"
        else:
            str += " (?)"
        str += f" – {self.link}"
        return str

    @property
    def downloaded(self) -> bool:
        if not self.is_researched:
            return False
        return os.path.isfile(self.filepath)

    @functools.cached_property
    def ytdl_infos(self) -> typing.Optional[dict]:
        # TODO Sanitize according to documentation
        log.info(f"Researching: {self}")
        try:
            infos = self.parent.ytdl_dry.extract_info(self.link, download=False)
        except KeyboardInterrupt as e:
            raise e
        except yt_dlp.utils.DownloadError as e:
            # TODO Still raise in case of temporary network issue
            log.warning(e)
            infos = None
        # Apparently that thing is transformed from a LazyList
        # somewhere in the normal yt_dlp process
        if (
            infos
            and "thumbnails" in infos
            and isinstance(infos["thumbnails"], yt_dlp.utils.LazyList)
        ):
            infos["thumbnails"] = infos["thumbnails"].exhaust()
        # Save database once it's been computed
        self.__dict__["ytdl_infos"] = infos
        self.parent.save()
        return infos

    @property
    def duration(self) -> int:
        assert self.is_video
        assert self.ytdl_infos
        return self.ytdl_infos["duration"]

    @property
    def is_video(self) -> bool:
        # Duration might be missing in playlists and stuff
        return self.ytdl_infos is not None and "duration" in self.ytdl_infos

    @property
    def filepath(self) -> str:
        assert self.is_video
        return self.parent.ytdl_dry.prepare_filename(self.ytdl_infos)

    @property
    def filename(self) -> str:
        assert self.is_video
        return os.path.splitext(self.filepath)[0]

    def download(self) -> None:
        assert self.is_video
        log.info(f"Downloading: {self}")
        if not self.parent.args.dryrun:
            with yt_dlp.YoutubeDL(self.parent.ytdl_opts) as ydl:
                ydl.add_post_processor(SaveInfoPP(self))
                ydl.process_ie_result(self.ytdl_infos, download=True)
        self.was_downloaded = True
        self.parent.save()

    def preload(self) -> None:
        assert self.is_video
        if self.downloaded:
            log.debug(f"Currently downloaded: {self}")
            return
        if self.was_downloaded:
            log.debug(f"Downloaded previously: {self}")
            return
        self.download()

    def matches_filter(self, args: configargparse.Namespace) -> bool:
        # Inexpensive filters
        if args.seen != "any" and (args.seen == "seen") != self.watched:
            log.debug(f"Not {args.seen}: {self}")
            return False
        if args.title and not re.search(args.title, self.title):
            log.debug(f"Title not matching {args.title}: {self}")
            return False
        if args.guid and not re.search(args.guid, str(self.guid)):
            log.debug(f"Guid not matching {args.guid}: {self}")
            return False
        if args.link and not re.search(args.link, self.link):
            log.debug(f"Link not matching {args.link}: {self}")
            return False
        if args.creator and (
            not self.creator or not re.search(args.creator, self.creator)
        ):
            log.debug(f"Creator not matching {args.creator}: {self}")
            return False

        # Expensive filters
        if not self.is_video:
            log.debug(f"Not a video: {self}")
            return False
        if args.duration and not compare_duration(args.duration)(self.duration):
            log.debug(
                f"Duration {self.duration} not matching {args.duration}: {self}"
            )
            return False

        return True

    def watch(self) -> None:
        if not self.downloaded:
            self.download()

        cmd = ["mpv", self.filepath]
        log.debug(f"Running {cmd}")
        if not self.parent.args.dryrun:
            proc = subprocess.run(cmd)
            proc.check_returncode()

        self.watched = True
        self.parent.save()

    def clean(self) -> None:
        assert self.is_video
        log.info(f"Removing gone video: {self.filename}*")
        for file in os.listdir():
            if file.startswith(self.filename):
                log.debug(f"Removing file: {file}")
                if not self.parent.args.dryrun:
                    os.unlink(file)


class RVDatabase:
    SAVE_FILE = ".cache.p"

    args: configargparse.Namespace
    elements: list[RVElement]

    def __init__(self, args: configargparse.Namespace) -> None:
        self.args = args

    def save(self) -> None:
        log.debug("Saving cache")
        if self.args.dryrun:
            return
        with open(self.SAVE_FILE, "wb") as save_file:
            pickle.dump(self, save_file)

    @classmethod
    def load(cls) -> typing.Optional["RVDatabase"]:
        try:
            with open(cls.SAVE_FILE, "rb") as save_file:
                return pickle.load(save_file)
        except (TypeError, AttributeError, EOFError):
            log.warning("Corrupt / outdated cache, it will be rebuilt.")
        except FileNotFoundError:
            pass
        return None

    def salvage_cache(self, cache: "RVDatabase") -> None:
        log.debug(f"Salvaging cache")
        cache_els = dict()
        for cache_el in cache.elements:
            cache_els[cache_el.guid] = cache_el
        for el in self.elements:
            if el.guid in cache_els:
                el.salvage_cache(cache_els[el.guid])

    def clean_cache(self, cache: "RVDatabase") -> None:
        log.debug(f"Cleaning cache")
        self_els = dict()
        for self_el in self.elements:
            self_els[self_el.guid] = self_el
        for el in cache.elements:
            if el.guid not in self_els:
                if el.is_researched and el.is_video:
                    el.clean()

    def import_cache(self, cache: "RVDatabase") -> None:
        log.debug(f"Importing cache")
        self.feed_xml = cache.feed_xml
        self.read_feed()

    @functools.cached_property
    def feed_xml(self) -> minidom.Document:
        log.info("Fetching RSS feed")
        with urllib.request.urlopen(self.args.feed) as request:
            return minidom.parse(request)

    def read_feed(self) -> None:
        self.elements = []
        for item in self.feed_xml.getElementsByTagName("item"):
            element = RVElement(self, item)
            self.elements.insert(0, element)
            log.debug(f"Known: {element}")

    def clean(self) -> None:
        log.debug("Cleaning")
        filenames = set()
        for element in self.elements:
            if element.is_video:
                filenames.add(element.filename)
        for file in os.listdir():
            if file == RVDatabase.SAVE_FILE:
                continue
            if not os.path.isfile(file):
                continue
            for filename in filenames:
                if file.startswith(filename):
                    break
            else:
                log.info(f"Removing unknown file: {file}")
                if not self.args.dryrun:
                    os.unlink(file)

    @property
    def all_researched(self) -> bool:
        for element in self.elements:
            if not element.is_researched:
                return False
        return True

    def attempt_clean(self) -> None:
        if self.all_researched:
            self.clean()

    @property
    def ytdl_opts(self) -> dict:
        return {"format": self.args.format, "allsubtitles": self.args.subtitles}

    @property
    def ytdl_dry_opts(self) -> dict:
        opts = self.ytdl_opts.copy()
        opts.update({"quiet": True})
        return opts

    @property
    def ytdl_dry(self) -> yt_dlp.YoutubeDL:
        return yt_dlp.YoutubeDL(self.ytdl_dry_opts)

    def filter(self, args: configargparse.Namespace) -> typing.Iterable[RVElement]:
        elements: typing.Iterable[RVElement]
        # Inexpensive sort
        if args.order == "new":
            elements = reversed(self.elements)
        elif args.order == "title":
            elements = sorted(self.elements, key=lambda el: el.title)
        elif args.order == "creator":
            elements = sorted(self.elements, key=lambda el: el.creator or "")
        elif args.order == "link":
            elements = sorted(self.elements, key=lambda el: el.link)
        elif args.order == "random":
            elements_random = self.elements.copy()
            random.shuffle(elements_random)
            elements = elements_random
        else:
            elements = self.elements

        # Possibly expensive filtering
        elements = filter(lambda el: el.matches_filter(args), elements)

        # Expensive sort
        if args.order == "short":
            elements = sorted(
                elements, key=lambda el: el.duration if el.is_video else 0
            )
        elif args.order == "long":
            elements = sorted(
                elements, key=lambda el: el.duration if el.is_video else 0, reverse=True
            )

        # Post sorting filtering
        if args.total_duration:
            rem = parse_duration(args.total_duration)
            old_els = list(elements)
            elements = list()
            while rem > 0:
                for el in old_els:
                    if el.duration < rem:
                        elements.append(el)
                        rem -= el.duration
                        old_els.remove(el)
                        break
                else:
                    break

        return elements


def get_args() -> configargparse.Namespace:
    defaultConfigPath = os.path.join(
        os.path.expanduser(os.getenv("XDG_CONFIG_PATH", "~/.config/")), "rssVideos"
    )

    parser = configargparse.ArgParser(
        description="Download videos linked in "
        + "a RSS feed (e.g. an unread feed from "
        + "an RSS aggregator",
        default_config_files=[defaultConfigPath],
    )

    # Runtime settings
    parser.add_argument(
        "-v",
        "--verbosity",
        choices=["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"],
        default=None,
        help="Verbosity of log messages",
    )
    parser.add(
        "-c", "--config", required=False, is_config_file=True, help="Configuration file"
    )
    parser.add(
        "-n",
        "--dryrun",
        help="Only pretend to do actions",
        action="store_const",
        const=True,
        default=False,
    )

    # Input/Output
    parser.add(
        "--feed",
        help="URL of the RSS feed (must be public for now)",
        env_var="RSS_VIDEOS_FEED",
        required=True,
    )
    parser.add(
        "--research",
        help="Fetch video info again",
        action="store_true",
    )
    parser.add(
        "--no-refresh",
        dest="refresh",
        help="Don't fetch feed",
        action="store_false",
    )
    parser.add(
        "--videos",
        help="Directory to store videos",
        env_var="RSS_VIDEOS_VIDEO_DIR",
        required=True,
    )

    # Which videos
    parser.add(
        "--order",
        choices=("old", "new", "title", "creator", "link", "short", "long", "random"),
        default="old",
        help="Sorting mechanism",
    )
    parser.add("--guid", help="Regex to filter guid")
    parser.add("--creator", help="Regex to filter by creator")
    parser.add("--title", help="Regex to filter by title")
    parser.add("--link", help="Regex to filter by link")
    parser.add("--duration", help="Comparative to filter by duration")
    parser.add(
        "--seen",
        choices=("seen", "unseen", "any"),
        default="unseen",
        help="Only include seen/unseen/any videos",
    )
    parser.add(
        "--total-duration",
        help="Use videos that fit under the total given",
    )
    # TODO Envrionment variables
    parser.add(
        "--max-duration",
        help="(Deprecated, use --duration instead)",
        env_var="RSS_VIDEOS_MAX_DURATION",
        type=int,
        default=0,
    )
    # TODO Allow to ask

    # How to download
    parser.add(
        "--format",
        help="Use this format to download videos."
        + " See FORMAT SELECTION in youtube-dl(1)",
        env_var="RSS_VIDEOS_FORMAT",
        default="bestvideo+bestaudio/best",
    )
    parser.add(
        "--subtitles",
        help="Download all subtitles",
        env_var="RSS_VIDEOS_SUBTITLES",
        action="store_true",
    )

    parser.add(
        "action",
        nargs="?",
        choices=(
            "download",
            "list",
            "watch",
            "binge",
            "clean",
            "seen",
            "unseen",
        ),
        default="download",
    )

    args = parser.parse_args()
    args.videos = os.path.realpath(os.path.expanduser(args.videos))
    if not args.duration and args.max_duration:
        args.duration = str(args.max_duration)

    return args


def main() -> None:
    args = get_args()
    configure_logging(args)

    os.makedirs(args.videos, exist_ok=True)
    os.chdir(args.videos)

    database = RVDatabase(args)
    cache = RVDatabase.load()
    feed_fetched = False
    if args.refresh:
        try:
            database.read_feed()
            feed_fetched = True
        except urllib.error.URLError as err:
            if args.action == "download":
                raise RuntimeError("Couldn't fetch feed, refusing to download")
                # This is a quirky failsafe in case of no internet connection,
                # so the script doesn't go noting that no element is a video.
    if not feed_fetched:
        if cache:
            log.warning("Using cached feed.")
            database.import_cache(cache)
        else:
            raise FileNotFoundError("Feed not fetched and no cached feed.")
    if cache:
        database.salvage_cache(cache)
        database.clean_cache(cache)
        database.save()

    log.debug(f"Running action")
    if args.action == "clean":
        database.clean()
    else:
        database.attempt_clean()
        duration = 0
        for element in database.filter(args):
            if args.action == "download":
                element.preload()
            elif args.action == "list":
                print(element)
            elif args.action in ("watch", "binge"):
                element.watch()
                if args.action == "watch":
                    break
            elif args.action == "seen":
                if not element.watched:
                    log.info(f"Maked as seen: {element}")
                    element.watched = True
            elif args.action == "unseen":
                if element.watched:
                    log.info(f"Maked as unseen: {element}")
                    element.watched = False
            else:
                raise NotImplementedError(f"Unimplemented action: {args.action}")
            duration += element.duration if element.is_video else 0
        log.info(f"Total duration: {format_duration(duration)}")
        database.attempt_clean()
    database.save()


if __name__ == "__main__":
    main()