import os
import re
import json
import html
import base64
import requests
import hmac, hashlib
import requests_cache
import dateutil.parser
from xml.etree import ElementTree
from configparser import ConfigParser
from datetime import datetime, timezone
from urllib.parse import parse_qs, urlparse

cf = ConfigParser()
config_filename = os.environ.get('YT_CONFIG', '/etc/yt/config.ini')
cf.read(config_filename)
if not 'global' in cf: # todo: full config check
    raise Exception("Configuration file not found or empty")

# Note: currently expiring after 10 minutes. googlevideo-urls are valid for 5h59m, but this makes reddit very stale and premiere videos won't start.  TODO: exipre when video is livestream/premiere/etc
requests_cache.install_cache(backend='memory', expire_after=10*60, allowable_codes=(200,))

# Note: this should only be required for the 'memory' backed cache.
# TODO: only run for long-running processes, i.e. the frontend
from threading import Timer
def purge_cache(sec):
    requests_cache.remove_expired_responses()
    t = Timer(sec, purge_cache, args=(sec,))
    t.setDaemon(True)
    t.start()
purge_cache(10*60)

# for debugging purposes, monkey patch requests session to store each requests-request in a flask-request's g object (url and response). we can then use a flask error_handler to include the request data in the error log.
# since we also call config from outside the flask appcontext, it is wrapped in a try-catch block.
from flask import g
import requests
from requests import Session as OriginalSession
class _NSASession(OriginalSession):
    def request(self, method, url, params=None, data=None, **kwargs):
        response = super(_NSASession, self).request(
            method, url, params, data, **kwargs
            )
        try:
            if 'api_requests' not in g:
                g.api_requests = []
            g.api_requests.append((url, params, response.text))
        except RuntimeError: pass # not within flask (e.g. utils.py)
        return response
requests.Session = requests.sessions.Session = _NSASession

def fetch_xml(feed_type, feed_id):
    # TODO: handle requests.exceptions.ConnectionError
    r = requests.get("https://www.youtube.com/feeds/videos.xml", {
        feed_type: feed_id,
    })
    if not r.ok:
        return None

    return r.text

def parse_xml(xmldata):
    ns = {
        'atom':"http://www.w3.org/2005/Atom",
        'yt': "http://www.youtube.com/xml/schemas/2015",
        'media':"http://search.yahoo.com/mrss/",
        'at': "http://purl.org/atompub/tombstones/1.0",
    }

    feed = ElementTree.fromstring(xmldata)

    if feed.find('at:deleted-entry',ns):
        (_,_,vid) = feed.find('at:deleted-entry',ns).get('ref').rpartition(':')
        return None, None, [{'deleted': True, 'video_id': vid}]

    title = feed.find('atom:title',ns).text
    author = feed.find('atom:author/atom:name',ns).text \
        if feed.find('atom:author',ns) else None
    videos = []
    for entry in feed.findall('atom:entry',ns):
        videos.append({
            'video_id': entry.find('yt:videoId',ns).text,
            'title': entry.find('atom:title',ns).text,
            'published': entry.find('atom:published',ns).text,
            'channel_id': entry.find('yt:channelId',ns).text,
            'author': entry.find('atom:author',ns).find('atom:name',ns).text,
            # extra fields for pull_subs/webhook:
            'updated': entry.find('atom:updated',ns).text,
        })

    return title, author, videos

def update_channel(db, xmldata, from_webhook=False):
    if not xmldata: return False

    # Note: websub does not return global author, hence taking from first video
    _, _, videos = parse_xml(xmldata)

    c = db.cursor()
    from flask import current_app # XXX: remove
    for i, video in enumerate(videos):
        if video.get('deleted'):
            current_app.logger.info(f"ignoring deleted video {video['video_id']}") # XXX: remove
            # TODO: enable once we enforce hmac validation:
            #c.execute("DELETE FROM videos WHERE id = ?", (video['video_id'],))
            break

        now = datetime.now(timezone.utc)
        timestamp, published = None, None
        # The 'published' timestamp sent in websub POSTs are often wrong (e.g.:
        # video gets uploaded as unlisted on day A and set to public on day B;
        # the webhook is sent on day B, but 'published' says A. The video
        # therefore looks like it's just an update to an older video). If
        # that's the case, we fetch get_video_info and double-check.
        # We only need to do this to not-yet-in-the-database videos.
        c.execute("SELECT 1 from videos where id = ?", (video['video_id'],))
        new_video = len(c.fetchall()) < 1
        if from_webhook and new_video:
            _, meta, _, _ = get_video_info(video['video_id'])
            if meta:
                meta = prepare_metadata(meta)
                published = dateutil.parser.parse(meta['published'])
                current_app.logger.info(f"new video {video['video_id']}, uploaded {published}") # XXX: remove
                # if published within the last week, assume it's new
                if (now - published).days < 7:
                    timestamp = now
                else:#, it's just an update to an older video.
                    timestamp = published
        # if we update from an rss-pull, we can rely on the embedded published
        # dates (and don't have to fire off a whole bunch of requests)
        else:
            updated = dateutil.parser.parse(video['updated'])
            published = dateutil.parser.parse(video['published'])
            if (updated - published).seconds < 60 and (now - published).days < 7:
                timestamp = now
            else:#, it's just an update to an older video.
                timestamp = published


        c.execute("""
            INSERT OR IGNORE INTO videos (id, channel_id, title, published, crawled)
                           VALUES (?, ?, ?, datetime(?), datetime(?))
        """, (
            video['video_id'],
            video['channel_id'],
            video['title'],
            video['published'],
            timestamp
        ))

        if i == 0: # only required once per feed
            c.execute("""
                INSERT OR REPLACE INTO channels (id, name)
                                VALUES (?, ?)
            """, (video['channel_id'], video['author']))
    db.commit()

    return True

def get_video_info(video_id, sts=0, algo=""):
    """
    returns: best-quality muxed video stream, player_response, error-type/mesage
    error types: player, malformed, livestream, geolocked, exhausted
    """
    player_error = None # for 'exhausted'
    for el in ['embedded', 'detailpage']:#sometimes, only one or the other works
        r = requests.get("https://www.youtube.com/get_video_info", {
            "video_id": video_id,
            "eurl": f"https://youtube.googleapis.com/v/{video_id}",
            "el": el,
            "sts": sts,
            "hl": "en_US",
        })
        params = parse_qs(r.text)
        if 'errorcode' in params: # status=fail
            return None, None, 'malformed', params['reason'][0]

        metadata = json.loads(params.get('player_response')[0])
        playabilityStatus = metadata['playabilityStatus']['status']
        if playabilityStatus != "OK":
            playabilityReason = metadata['playabilityStatus'].get('reason',
                    '//'.join(metadata['playabilityStatus'].get('messages',[])))
            player_error = f"{playabilityStatus}: {playabilityReason}"
            if playabilityStatus == "UNPLAYABLE":
                continue  # try again with next el value (or fail as exhausted)
            # without videoDetails, there's only the error message
            maybe_metadata = metadata if 'videoDetails' in metadata else None
            return None, maybe_metadata, 'player', player_error
        if metadata['videoDetails']['isLiveContent'] and \
                (metadata['videoDetails'].get('isLive', False) or \
                metadata['videoDetails'].get('isPostLiveDvr', False)):
            return None, metadata, 'livestream', None

        if not 'formats' in metadata['streamingData']:
            continue # no urls

        formats = metadata['streamingData']['formats']
        for (i,v) in enumerate(formats):
            if not ('cipher' in v or 'signatureCipher' in v): continue
            cipher = parse_qs(v.get('cipher') or v.get('signatureCipher'))
            formats[i]['url'] = unscramble(cipher, algo)

        # todo: check if we have urls or try again
        url = sorted(formats, key=lambda k: k['height'], reverse=True)[0]['url']

        if 'gcr' in parse_qs(url):
            return None, metadata, 'geolocked', None

        return url, metadata, None, None
    else:
        return None, metadata, 'exhausted', player_error

def unscramble(cipher, algo):  # test video id: UxxajLWwzqY
    signature = list(cipher['s'][0])
    for c in algo.split():
        op, ix = re.match(r"([rsw])(\d+)?", c).groups()
        ix = int(ix) % len(signature) if ix else 0
        if not op: continue
        if op == 'r': signature = list(reversed(signature))
        if op == 's': signature = signature[ix:]
        if op == 'w': signature[0], signature[ix] = signature[ix], signature[0]
    sp = cipher.get('sp', ['signature'])[0]
    sig = cipher.get('sig', [''.join(signature)])[0]
    return f"{cipher['url'][0]}&{sp}={sig}"

def prepare_metadata(metadata):
    meta1 = metadata['videoDetails']
    meta2 = metadata['microformat']['playerMicroformatRenderer']
    cards = metadata['cards']['cardCollectionRenderer']['cards'] \
        if 'cards' in metadata else []
    endsc = metadata['endscreen']['endscreenRenderer']['elements'] \
        if 'endscreen' in metadata else []

    # the actual video streams have exact information:
    try:
        sd = metadata['streamingData']
        some_stream = (sd.get('adaptiveFormats',[]) + sd.get('formats',[]))[0]
        aspect_ratio = some_stream['width'] / some_stream['height']
    # if that's unavailable (e.g. on livestreams), fall back to
    # thumbnails (only either 4:3 or 16:9).
    except:
        some_img = meta2['thumbnail']['thumbnails'][0]
        aspect_ratio = some_img['width'] / some_img['height']

    subtitles = sorted([
        {'url':cc['baseUrl'],
         'code':cc['languageCode'],
         'autogenerated':cc.get('kind')=="asr", 
         'name':cc['name']['simpleText']}
        for cc in metadata.get('captions',{})
            .get('playerCaptionsTracklistRenderer',{})
            .get('captionTracks',[])
    ], key=lambda cc: cc['autogenerated'])

    def clean_url(url):
        # externals URLs are redirected through youtube.com/redirect, but we
        # may encounter internal URLs, too
        return parse_qs(urlparse(url).query).get('q',[url])[0]
    # Remove left-/rightmost word from string:
    delL = lambda s: s.partition(' ')[2]
    delR = lambda s: s.rpartition(' ')[0]
    # Thousands seperator aware int():
    intT = lambda s: int(s.replace(',', ''))

    def parse_infocard(card):
        card = card['cardRenderer']
        ctype = list(card['content'].keys())[0]
        content = card['content'][ctype]
        if ctype == "pollRenderer":
            ctype = "POLL"
            content = {
                'question': content['question']['simpleText'],
                'answers': [(a['text']['simpleText'],a['numVotes']) \
                    for a in content['choices']],
            }
        elif ctype == "videoInfoCardContentRenderer":
            ctype = "VIDEO"
            # if the card references a live stream, it has no length, but a "LIVE NOW" badge.
            # TODO: this is ugly; cleanup.
            is_live = content.get('badge',{}).get('liveBadgeRenderer',{})
            length = is_live.get('label',{}).get('simpleText') or content['lengthString']['simpleText']  # '23:03'
            content = {
                'video_id': content['action']['watchEndpoint']['videoId'],
                'title': content['videoTitle']['simpleText'],
                'author': delL(content['channelName']['simpleText']),
                'length': length,
                'views': intT(delR(content['viewCountText']['simpleText'])),
            }
        elif ctype == "playlistInfoCardContentRenderer":
            ctype = "PLAYLIST"
            content = {
                'playlist_id': content['action']['watchEndpoint']['playlistId'],
                'video_id': content['action']['watchEndpoint']['videoId'],
                'title': content['playlistTitle']['simpleText'],
                'author': delL(content['channelName']['simpleText']),
                'n_videos': intT(content['playlistVideoCount']['simpleText']),
            }
        elif ctype == "simpleCardContentRenderer" and 'urlEndpoint' in content['command']:
            ctype = "WEBSITE"
            content = {
                'url': clean_url(content['command']['urlEndpoint']['url']),
                'domain': content['displayDomain']['simpleText'],
                'title': content['title']['simpleText'],
                # XXX: no thumbnails for infocards
            }
        elif ctype == "collaboratorInfoCardContentRenderer":
            ctype = "CHANNEL"
            content = {
                'channel_id': content['endpoint']['browseEndpoint']['browseId'],
                'title': content['channelName']['simpleText'],
                'icons': mkthumbs(content['channelAvatar']['thumbnails']),
                'subscribers': content.get('subscriberCountText',{}).get('simpleText',''), # "545K subscribers"
            }
        else:
            import pprint
            content = {'error': f"{ctype} is not implemented; <pre>{pprint.pformat(card)}</pre>"}

        return {'type': ctype, 'content': content}

    def mkthumbs(thumbs):
        return {e['height']: e['url'] for e in thumbs}
    def parse_endcard(card):
        card = card.get('endscreenElementRenderer', card) #only sometimes nested
        ctype = card['style']
        if ctype == "CHANNEL":
            content = {
                'channel_id': card['endpoint']['browseEndpoint']['browseId'],
                'title': card['title']['simpleText'],
                'icons': mkthumbs(card['image']['thumbnails']),
            }
        elif ctype == "VIDEO":
            content = {
                'video_id': card['endpoint']['watchEndpoint']['videoId'], # XXX: KeyError 'endpoint' exception (no idea which youtube video this was on)
                'title': card['title']['simpleText'],
                'length': card['videoDuration']['simpleText'],  # '12:21'
                'views': delR(card['metadata']['simpleText']),
                # XXX: no channel name
            }
        elif ctype == "PLAYLIST":
            content = {
                'playlist_id': card['endpoint']['watchEndpoint']['playlistId'],
                'video_id': card['endpoint']['watchEndpoint']['videoId'],
                'title': card['title']['simpleText'],
                'author': delL(card['metadata']['simpleText']),
                'n_videos': intT(delR(card['playlistLength']['simpleText'])),
            }
        elif ctype == "WEBSITE" or ctype == "CREATOR_MERCHANDISE":
            ctype = "WEBSITE"
            url = clean_url(card['endpoint']['urlEndpoint']['url'])
            content = {
                'url': url,
                'domain': urlparse(url).netloc,
                'title': card['title']['simpleText'],
                'icons': mkthumbs(card['image']['thumbnails']),
            }
        else:
            import pprint
            content = {'error': f"{ctype} is not implemented; <pre>{pprint.pformat(card)}</pre>"}
        
        return {'type': ctype, 'content': content}

    infocards = [parse_infocard(card) for card in cards]
    endcards = [parse_endcard(card) for card in endsc]
    # combine cards to weed out duplicates. for videos and playlists prefer
    # infocards, for channels and websites prefer endcards, as those have more
    # information than the other.
    # if the card type is not in ident, we use the whole card for comparison
    # (otherwise they'd all replace each other)
    ident = { # ctype -> ident
        'VIDEO': 'video_id',
        'PLAYLIST': 'playlist_id',
        'CHANNEL': 'channel_id',
        'WEBSITE': 'url',
        'POLL': 'question',
    }
    getident = lambda c: c['content'].get(ident.get(c['type']), c)
    mkexclude = lambda cards, types: [getident(c) for c in cards if c['type'] in types]
    exclude = lambda cards, without: [c for c in cards if getident(c) not in without]

    allcards = exclude(infocards, mkexclude(endcards,  ['CHANNEL','WEBSITE'])) + \
               exclude(endcards,  mkexclude(infocards, ['VIDEO','PLAYLIST']))

    all_countries = """AD AE AF AG AI AL AM AO AQ AR AS AT AU AW AX AZ BA BB BD
        BE BF BG BH BI BJ BL BM BN BO BQ BR BS BT BV BW BY BZ CA CC CD CF CG CH
        CI CK CL CM CN CO CR CU CV CW CX CY CZ DE DJ DK DM DO DZ EC EE EG EH ER
        ES ET FI FJ FK FM FO FR GA GB GD GE GF GG GH GI GL GM GN GP GQ GR GS GT
        GU GW GY HK HM HN HR HT HU ID IE IL IM IN IO IQ IR IS IT JE JM JO JP KE
        KG KH KI KM KN KP KR KW KY KZ LA LB LC LI LK LR LS LT LU LV LY MA MC MD
        ME MF MG MH MK ML MM MN MO MP MQ MR MS MT MU MV MW MX MY MZ NA NC NE NF
        NG NI NL NO NP NR NU NZ OM PA PE PF PG PH PK PL PM PN PR PS PT PW PY QA
        RE RO RS RU RW SA SB SC SD SE SG SH SI SJ SK SL SM SN SO SR SS ST SV SX
        SY SZ TC TD TF TG TH TJ TK TL TM TN TO TR TT TV TW TZ UA UG UM US UY UZ
        VA VC VE VG VI VN VU WF WS YE YT ZA ZM ZW""".split()
    whitelisted = sorted(meta2.get('availableCountries',[]))
    blacklisted = sorted(set(all_countries) - set(whitelisted))

    published_at = f"{meta2['publishDate']}T00:00:00Z" # yyyy-mm-dd
    # 'premiere' videos (and livestreams?) have a ISO8601 date available:
    if 'liveBroadcastDetails' in meta2 and 'startTimestamp' in meta2['liveBroadcastDetails']: # TODO: tighten up
        published_at = meta2['liveBroadcastDetails']['startTimestamp']

    return {
        'title': meta1['title'],
        'author': meta1['author'],
        'channel_id': meta1['channelId'],
        'description': meta1['shortDescription'],
        'published': published_at,
        'views': meta1['viewCount'],
        'length': int(meta1['lengthSeconds']),
        'rating': meta1['averageRating'],
        'category': meta2['category'],
        'aspectr': aspect_ratio,
        'unlisted': meta2['isUnlisted'],
        'whitelisted': whitelisted,
        'blacklisted': blacklisted,
        'poster': meta2['thumbnail']['thumbnails'][0]['url'],
        'infocards': infocards,
        'endcards': endcards,
        'all_cards': allcards,
        'subtitles': subtitles,
    }

class RedditException(Exception): pass
def fetch_reddit(subreddits, sorted_by="hot", time=None, *, limit=36,
        count=None, before=None, after=None):
    """
    fetches data from a subreddit (or a multireddit like gif+gifs) and
    filters/sorts results.
    sorted_by values: hot, new, rising, controversial, top
    time values: hour, day, week, month, year, all (for top and controversial)
    """

    if not subreddits:
        return None

    query = {k:v for k,v in {
        'count':count,
        'before':before,
        'after':after,
        'limit':limit, # 1..100 (default 25)
        't': time, # hour,week,month,year,all
    }.items() if v}
    multireddit = '+'.join(subreddits)
    r = requests.get(f"https://old.reddit.com/r/{multireddit}/{sorted_by}.json",
            query, headers={'User-Agent':'Mozilla/5.0'})
    if not r.ok or not 'data' in r.json():
        raise RedditException(r.text)

    return r.json()

def fetch_reddit_post(post_id):
    # Note: /api/info.json?id=t3_h7mjes == /by_id/t3_h7mjes.json
    r = requests.get(f"https://old.reddit.com/by_id/t3_{post_id}.json",
            headers={'User-Agent':'Mozilla/5.0'})
    if not r.ok or not 'data' in r.json():
        raise RedditException(r.text)

    return r.json()

def parse_reddit_videos(data):
    videos = []
    entries = sorted(data['data']['children'],
            key=lambda e: e['data']['score'] > 1,
            reverse=True)
    for entry in entries:
        e = entry['data']
        if e['domain'] not in ['youtube.com', 'youtu.be', 'invidio.us']:
            continue
        try:
            # Note: youtube.com/<video_id> is not valid (404s), but seen in the wild.
            video_id = re.match(r'^https?://(?:www.|m.)?(?:youtube.com/watch\?(?:.*&amp;)?v=|youtu.be/|youtube.com/embed/|youtube.com/)([-_0-9A-Za-z]+)', e['url']).group(1)
        except:
            continue # XXX: should we log that?
        if not video_id: continue
        videos.append({
            'video_id': video_id,
            'title': html.unescape(e['title']), # Note: we unescape and re-escape in the template
            'url': e['permalink'],
            'n_comments': e['num_comments'],
            'n_karma': e['score'],
            'subreddit': e['subreddit'],
            'post_id': e['id'],
        })

    return videos

class NoFallbackException(Exception): pass
def fallback_route(*args, **kwargs): # TODO: worthy as a flask-extension?
    """
    finds the next route that matches the current url rule, and executes it.
    args, kwargs: pass all arguments of the current route
    """
    from flask import current_app, request, g
    from werkzeug.exceptions import NotFound

    # build a list of endpoints that match the current request's url rule:
    matching = [
        rule.endpoint
        for rule in current_app.url_map.iter_rules()
        if rule.rule == request.url_rule.rule
    ]
    current = matching.index(request.endpoint)

    # since we can't change request.endpoint, we always get the original
    # endpoint back. so for repeated fall throughs, we use the g object to
    # increment how often we want to fall through.
    if not '_fallback_next' in g:
        g._fallback_next = 0
    g._fallback_next += 1

    next_ep = current + g._fallback_next

    if next_ep < len(matching):
        return current_app.view_functions[matching[next_ep]](*args, **kwargs)
    else:
        raise NoFallbackException

def websub_url_hmac(key, feed_id, timestamp, nonce):
    """ generate sha1 hmac, as required by websub/pubsubhubbub """
    sig_input = f"{feed_id}:{timestamp}:{nonce}".encode('ascii')
    return hmac.new(key.encode('ascii'), sig_input, hashlib.sha1).hexdigest()

def websub_body_hmac(key, body):
    return hmac.new(key.encode('ascii'), body, hashlib.sha1).hexdigest()

def pp(*args):
    from pprint import pprint
    import sys, codecs
    pprint(args, stream=codecs.getwriter("utf-8")(sys.stderr.buffer))