###
# Copyright (c) 2002-2004, Jeremiah Fincher
# Copyright (c) 2008-2010, James McCoy
# Copyright (c) 2014, Valentin Lorentz
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
#   * Redistributions of source code must retain the above copyright notice,
#     this list of conditions, and the following disclaimer.
#   * Redistributions in binary form must reproduce the above copyright notice,
#     this list of conditions, and the following disclaimer in the
#     documentation and/or other materials provided with the distribution.
#   * Neither the name of the author of this software nor the name of
#     contributors to this software may be used to endorse or promote products
#     derived from this software without specific prior written consent.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
###

import re
import os
import sys
import json
import time
import types
import string
import socket
import threading
import feedparser

import supybot.conf as conf
import supybot.utils as utils
import supybot.world as world
from supybot.commands import *
import supybot.utils.minisix as minisix
import supybot.ircmsgs as ircmsgs
import supybot.ircutils as ircutils
import supybot.registry as registry
import supybot.callbacks as callbacks
from supybot.i18n import PluginInternationalization, internationalizeDocstring
_ = PluginInternationalization('RSS')

def get_feedName(irc, msg, args, state):
    if ircutils.isChannel(args[0]):
        state.errorInvalid('feed name', args[0], 'must not be channel names.')
    if not registry.isValidRegistryName(args[0]):
        state.errorInvalid('feed name', args[0],
                           'Feed names must not include spaces.')
    state.args.append(callbacks.canonicalName(args.pop(0)))
addConverter('feedName', get_feedName)

announced_headlines_filename = \
        conf.supybot.directories.data.dirize('RSS_announced.flat')

def only_one_at_once(f):
    lock = [False]
    def newf(*args, **kwargs):
        if lock[0]:
            return
        lock[0] = True
        try:
            f(*args, **kwargs)
        finally:
            lock[0] = False
    return newf

class InvalidFeedUrl(ValueError):
    pass

class Feed:
    __slots__ = ('url', 'name', 'data', 'last_update', 'entries',
            'etag', 'modified', 'initial',
            'lock', 'announced_entries')
    def __init__(self, name, url, initial,
            plugin_is_loading=False, announced=None):
        assert name, name
        if not url:
            if not utils.web.httpUrlRe.match(name):
                raise InvalidFeedUrl(name)
            url = name
        self.name = name
        self.url = url
        self.initial = initial
        self.data = None
        # We don't want to fetch feeds right after the plugin is
        # loaded (the bot could be starting, and thus already busy)
        self.last_update = time.time() if plugin_is_loading else 0
        self.entries = []
        self.etag = None
        self.modified = None
        self.lock = threading.Lock()
        self.announced_entries = announced or \
                utils.structures.TruncatableSet()

    def __repr__(self):
        return 'Feed(%r, %r, %b, <bool>, %r)' % \
                (self.name, self.url, self.initial, self.announced_entries)

    def get_command(self, plugin):
        docstring = format(_("""[<number of headlines>]

        Reports the titles for %s at the RSS feed %u.  If
        <number of headlines> is given, returns only that many headlines.
        RSS feeds are only looked up every supybot.plugins.RSS.waitPeriod
        seconds, which defaults to 1800 (30 minutes) since that's what most
        websites prefer."""), self.name, self.url)
        def f(self2, irc, msg, args):
            args.insert(0, self.name)
            self2.rss(irc, msg, args)
        f = utils.python.changeFunctionName(f, self.name, docstring)
        f = types.MethodType(f, plugin)
        return f

_sort_parameters = {
        'oldestFirst':   (('published_parsed', 'updated_parsed'), False),
        'newestFirst':   (('published_parsed', 'updated_parsed'), True),
        'outdatedFirst': (('updated_parsed', 'published_parsed'), False),
        'updatedFirst':  (('updated_parsed', 'published_parsed'), True),
        }
def _sort_arguments(order):
    (fields, reverse) = _sort_parameters[order]
    def key(entry):
        for field in fields:
            if field in entry:
                return entry[field]
        raise KeyError('No date field in entry.')
    return (key, reverse)

def sort_feed_items(items, order):
    """Return feed items, sorted according to sortFeedItems."""
    if order == 'asInFeed':
        return items
    (key, reverse) = _sort_arguments(order)
    try:
        sitems = sorted(items, key=key, reverse=reverse)
    except KeyError:
        # feedparser normalizes required timestamp fields in ATOM and RSS
        # to the "published"/"updated" fields. Feeds missing it are unsortable by date.
        return items
    return sitems

def load_announces_db(fd):
    return dict((name, utils.structures.TruncatableSet(entries))
                for (name, entries) in json.load(fd).items())
def save_announces_db(db, fd):
    json.dump(dict((name, list(entries)) for (name, entries) in db), fd)


class RSS(callbacks.Plugin):
    """This plugin is useful both for announcing updates to RSS feeds in a
    channel, and for retrieving the headlines of RSS feeds via command.  Use
    the "add" command to add feeds to this plugin, and use the "announce"
    command to determine what feeds should be announced in a given channel."""
    threaded = True
    def __init__(self, irc):
        self.__parent = super(RSS, self)
        self.__parent.__init__(irc)
        # Scheme: {name: url}
        self.feed_names = callbacks.CanonicalNameDict()
        # Scheme: {url: feed}
        self.feeds = {}
        if os.path.isfile(announced_headlines_filename):
            with open(announced_headlines_filename) as fd:
                announced = load_announces_db(fd)
        else:
            announced = {}
        for name in self.registryValue('feeds'):
            self.assert_feed_does_not_exist(name)
            self.register_feed_config(name)
            try:
                url = self.registryValue(registry.join(['feeds', name]))
            except registry.NonExistentRegistryEntry:
                self.log.warning('%s is not a registered feed, removing.',name)
                continue
            try:
                self.register_feed(name, url, True, True, announced.get(name, []))
            except InvalidFeedUrl:
                self.log.error('%s is not a valid feed, removing.', name)
                continue
        world.flushers.append(self._flush)

    def die(self):
        self._flush()
        world.flushers.remove(self._flush)
        self.__parent.die()

    def _flush(self):
        l = [(f.name, f.announced_entries) for f in self.feeds.values()]
        with utils.file.AtomicFile(announced_headlines_filename, 'w',
                                   backupDir='/dev/null') as fd:
            save_announces_db(l, fd)


    ##################
    # Feed registering

    def assert_feed_does_not_exist(self, name, url=None):
        if self.isCommandMethod(name):
            s = format(_('I already have a command in this plugin named %s.'),
                    name)
            raise callbacks.Error(s)
        if url:
            feed = self.feeds.get(url)
            if feed and feed.name != feed.url:
                s = format(_('I already have a feed with that URL named %s.'),
                        feed.name)
                raise callbacks.Error(s)

    def register_feed_config(self, name, url=''):
        self.registryValue('feeds').add(name)
        group = self.registryValue('feeds', value=False)
        conf.registerGlobalValue(group, name, registry.String(url, ''))
        feed_group = conf.registerGroup(group, name)
        conf.registerChannelValue(feed_group, 'format',
                registry.String('', _("""Feed-specific format. Defaults to
                supybot.plugins.RSS.format if empty.""")))
        conf.registerChannelValue(feed_group, 'announceFormat',
                registry.String('', _("""Feed-specific announce format.
                Defaults to supybot.plugins.RSS.announceFormat if empty.""")))
        conf.registerGlobalValue(feed_group, 'waitPeriod',
                registry.NonNegativeInteger(0, _("""If set to a non-zero
                value, overrides supybot.plugins.RSS.waitPeriod for this
                particular feed.""")))

    def register_feed(self, name, url, initial,
            plugin_is_loading, announced=[]):
        self.feed_names[name] = url
        self.feeds[url] = Feed(name, url, initial,
                plugin_is_loading, announced)

    def remove_feed(self, feed):
        del self.feed_names[feed.name]
        del self.feeds[feed.url]
        conf.supybot.plugins.RSS.feeds().remove(feed.name)
        conf.supybot.plugins.RSS.feeds.unregister(feed.name)

    ##################
    # Methods handling

    def isCommandMethod(self, name):
        if not self.__parent.isCommandMethod(name):
            return bool(self.get_feed(name))
        else:
            return True

    def listCommands(self):
        return self.__parent.listCommands(self.feed_names.keys())

    def getCommandMethod(self, command):
        try:
            return self.__parent.getCommandMethod(command)
        except AttributeError:
            return self.get_feed(command[0]).get_command(self)

    def __call__(self, irc, msg):
        self.__parent.__call__(irc, msg)
        threading.Thread(target=self.update_feeds).start()


    ##################
    # Status accessors

    def get_feed(self, name):
        return self.feeds.get(self.feed_names.get(name, name), None)

    def is_expired(self, feed):
        assert feed
        period = self.registryValue('waitPeriod')
        if feed.name != feed.url: # Named feed
            specific_period = self.registryValue('feeds.%s.waitPeriod' % feed.name)
            if specific_period:
                period = specific_period
        event_horizon = time.time() - period
        return feed.last_update < event_horizon

    ###############
    # Feed fetching

    def update_feed(self, feed):
        with feed.lock:
            d = feedparser.parse(feed.url, etag=feed.etag,
                    modified=feed.modified)
            if 'status' not in d or d.status != 304: # Not modified
                if 'etag' in d:
                    feed.etag = d.etag
                if 'modified' in d:
                    feed.modified = d.modified
                feed.data = d.feed
                feed.entries = d.entries
                feed.last_update = time.time()
            (initial, feed.initial) = (feed.initial, False)
        self.announce_feed(feed, initial)

    def update_feed_in_thread(self, feed):
        feed.last_update = time.time()
        t = world.SupyThread(target=self.update_feed,
                             name=format('Fetching feed %u', feed.url),
                             args=(feed,))
        t.setDaemon(True)
        t.start()

    def update_feed_if_needed(self, feed):
        if self.is_expired(feed):
            self.update_feed(feed)

    @only_one_at_once
    def update_feeds(self):
        announced_feeds = set()
        for irc in world.ircs:
            for channel in irc.state.channels:
                announced_feeds |= self.registryValue('announce', channel)
        for name in announced_feeds:
            feed = self.get_feed(name)
            if not feed:
                self.log.warning('Feed %s is announced but does not exist.',
                        name)
                continue
            self.update_feed_if_needed(feed)

    def get_new_entries(self, feed):
        # http://validator.w3.org/feed/docs/rss2.html#hrelementsOfLtitemgt
        get_id = lambda entry: entry.id if hasattr(entry, 'id') else (
                entry.title if hasattr(entry, 'title') else entry.description)

        with feed.lock:
            entries = feed.entries
            new_entries = [entry for entry in entries
                    if get_id(entry) not in feed.announced_entries]
            if not new_entries:
                return []
            feed.announced_entries |= set(get_id(entry) for entry in new_entries)
            # We keep a little more because we don't want to re-announce
            # oldest entries if one of the newest gets removed.
            feed.announced_entries.truncate(10*len(entries))
        return new_entries

    def announce_feed(self, feed, initial):
        new_entries = self.get_new_entries(feed)

        order = self.registryValue('sortFeedItems')
        new_entries = sort_feed_items(new_entries, order)
        for irc in world.ircs:
            for channel in irc.state.channels:
                if feed.name not in self.registryValue('announce', channel):
                    continue
                if initial:
                    n = self.registryValue('initialAnnounceHeadlines', channel)
                    if n:
                        announced_entries = new_entries[-n:]
                    else:
                        announced_entries = []
                else:
                    announced_entries = new_entries
                for entry in announced_entries:
                    self.announce_entry(irc, channel, feed, entry)


    #################
    # Entry rendering

    def should_send_entry(self, channel, entry):
        whitelist = self.registryValue('keywordWhitelist', channel)
        blacklist = self.registryValue('keywordBlacklist', channel)
        if whitelist:
            if all(kw not in entry.title and kw not in entry.description
                   for kw in whitelist):
                return False
        if blacklist:
            if any(kw in entry.title or kw in entry.description
                   for kw in blacklist):
                return False
        return True

    _normalize_entry = utils.str.multipleReplacer(
            {'\r': ' ', '\n': ' ', '\x00': ''})
    def format_entry(self, channel, feed, entry, is_announce):
        key_name = 'announceFormat' if is_announce else 'format'
        if feed.name in self.registryValue('feeds'):
            specific_key_name = registry.join(['feeds', feed.name, key_name])
            template = self.registryValue(specific_key_name, channel) or \
                    self.registryValue(key_name, channel)
        else:
            template = self.registryValue(key_name, channel)
        date = entry.get('published_parsed')
        date = utils.str.timestamp(date)
        s = string.Template(template).safe_substitute(
                feed_name=feed.name,
                date=date,
                **entry)
        return self._normalize_entry(s)

    def announce_entry(self, irc, channel, feed, entry):
        if self.should_send_entry(channel, entry):
            s = self.format_entry(channel, feed, entry, True)
            if self.registryValue('notice', channel):
                m = ircmsgs.notice(channel, s)
            else:
                m = ircmsgs.privmsg(channel, s)
            irc.queueMsg(m)


    ##########
    # Commands

    @internationalizeDocstring
    def add(self, irc, msg, args, name, url):
        """<name> <url>

        Adds a command to this plugin that will look up the RSS feed at the
        given URL.
        """
        self.assert_feed_does_not_exist(name, url)
        self.register_feed_config(name, url)
        self.register_feed(name, url, True, False)
        irc.replySuccess()
    add = wrap(add, ['feedName', 'url'])

    @internationalizeDocstring
    def remove(self, irc, msg, args, name):
        """<name>

        Removes the command for looking up RSS feeds at <name> from
        this plugin.
        """
        feed = self.get_feed(name)
        if not feed:
            irc.error(_('That\'s not a valid RSS feed command name.'))
            return
        self.remove_feed(feed)
        irc.replySuccess()
    remove = wrap(remove, ['feedName'])

    class announce(callbacks.Commands):
        @internationalizeDocstring
        def list(self, irc, msg, args, channel):
            """[<channel>]

            Returns the list of feeds announced in <channel>.  <channel> is
            only necessary if the message isn't sent in the channel itself.
            """
            announce = conf.supybot.plugins.RSS.announce
            feeds = format('%L', list(announce.get(channel)()))
            irc.reply(feeds or _('I am currently not announcing any feeds.'))
        list = wrap(list, ['channel',])

        @internationalizeDocstring
        def add(self, irc, msg, args, channel, feeds):
            """[<channel>] <name|url> [<name|url> ...]

            Adds the list of feeds to the current list of announced feeds in