'''
Manage talks scheduling in a semantic way
'''

from __future__ import print_function
import os
import io
from functools import wraps
import logging
import re
import datetime
import shutil
import time
from copy import copy

import markdown
from docutils import nodes
from docutils.parsers.rst import directives, Directive

from pelican import signals, generators
import jinja2


TALKS_PATH = 'talks'
TALK_ATTACHMENT_PATH = 'res'
TALK_ICS = 'schedule.ics'
GRID_STEP = 15


def memoize(function):
    '''decorators to cache'''
    memo = {}

    @wraps(function)
    def wrapper(*args):
        if args in memo:
            return memo[args]
        else:
            rv = function(*args)
            memo[args] = rv
            return rv
    return wrapper


@memoize
def get_talk_names():
    return [name for name in os.listdir(TALKS_PATH)
            if not name.startswith('_') and
            get_talk_data(name) is not None
            ]


def all_talks():
    return [get_talk_data(tn) for tn in get_talk_names()]


def unique_attr(iterable, attr):
    return {x[attr] for x in iterable
            if attr in x}


@memoize
def get_global_data():
    fname = os.path.join(TALKS_PATH, 'meta.yaml')
    if not os.path.isfile(fname):
        return None
    with io.open(fname, encoding='utf8') as buf:
        try:
            data = yaml.load(buf)
        except Exception:
            logging.exception("Syntax error reading %s; skipping", fname)
            return None
    if data is None:
        return None
    if 'startdate' not in data:
        logging.error("Missing startdate in global data")
        data['startdate'] = datetime.datetime.now()
    return data


@memoize
def get_talk_data(talkname):
    fname = os.path.join(TALKS_PATH, talkname, 'meta.yaml')
    if not os.path.isfile(fname):
        return None
    with io.open(fname, encoding='utf8') as buf:
        try:
            data = yaml.load(buf)
        except Exception as exc:
            logging.exception("Syntax error reading %s; skipping", fname)
            return None
    if data is None:
        return None
    if 'title' not in data:
        logging.warn("Talk <{}> has no `title` field".format(talkname))
        data['title'] = talkname
    if 'text' not in data:
        logging.warn("Talk <{}> has no `text` field".format(talkname))
        data['text'] = ''
    if 'duration' not in data:
        logging.info("Talk <{}> has no `duration` field (50min used)"
                     .format(talkname))
        data['duration'] = 50
    data['duration'] = int(data['duration'])
    if data['duration'] < GRID_STEP:
        logging.info("Talk <{}> lasts only {} minutes; changing to {}"
                     .format(talkname, data['duration'], GRID_STEP))
        data['duration'] = GRID_STEP
    if 'links' not in data or not data['links']:
        data['links'] = []
    if 'contacts' not in data or not data['contacts']:
        data['contacts'] = []
    if 'needs' not in data or not data['needs']:
        data['needs'] = []
    if 'room' not in data:
        logging.warn("Talk <{}> has no `room` field".format(talkname))
    if 'time' not in data or 'day' not in data:
        logging.warn("Talk <{}> has no `time` or `day`".format(talkname))
    if 'day' in data:
        data['day'] = get_global_data()['startdate'] + datetime.timedelta(days=data['day'])
    if 'time' in data and 'day' in data:
        timeparts = re.findall(r'\d+', str(data['time']))
        if 4 > len(timeparts) > 0:
            timeparts = [int(p) for p in timeparts]
            data['time'] = datetime.datetime.combine(data['day'],
                                                     datetime.time(*timeparts))
        else:
            logging.error("Talk <{}> has malformed `time`".format(talkname))
    data['id'] = talkname
    resdir = os.path.join(TALKS_PATH, talkname, TALK_ATTACHMENT_PATH)
    if os.path.isdir(resdir) and os.listdir(resdir):
        data['resources'] = resdir
    return data


jinja_env = jinja2.Environment(
    loader=jinja2.FileSystemLoader(os.path.join(TALKS_PATH, '_templates')),
    autoescape=True,
)
jinja_env.filters['markdown'] = lambda text: \
        jinja2.Markup(markdown.Markdown(extensions=['meta']).
                      convert(text))


class TalkListDirective(Directive):
    required_arguments = 0
    optional_arguments = 0
    final_argument_whitespace = True
    has_content = True

    def run(self):
        tmpl = jinja_env.get_template('talk.html')
        return [
            nodes.raw('', tmpl.render(**get_talk_data(n)),
                      format='html')
            for n in get_talk_names()
        ]


class TalkDirective(Directive):
    required_arguments = 1
    optional_arguments = 0
    final_argument_whitespace = True
    has_content = True

    def run(self):
        tmpl = jinja_env.get_template('talk.html')
        data = get_talk_data(self.arguments[0])
        if data is None:
            return []
        return [
            nodes.raw('', tmpl.render(**data),
                      format='html')
        ]


class TalkGridDirective(Directive):
    '''A complete grid'''
    required_arguments = 0

    optional_arguments = 0
    final_argument_whitespace = True
    has_content = True

    def run(self):
        tmpl = jinja_env.get_template('grid.html')
        output = []
        days = unique_attr(all_talks(), 'day')
        for day in sorted(days):
            talks = {talk['id'] for talk in all_talks()
                     if talk.get('day', None) == day
                     and 'time' in talk
                     and 'room' in talk}
            if not talks:
                continue
            talks = [get_talk_data(t) for t in talks]
            rooms = tuple(sorted(unique_attr(talks, 'room')))
            mintime = min({talk['time'].hour * 60 +
                           talk['time'].minute
                           for talk in talks}) // GRID_STEP * GRID_STEP
            maxtime = max({talk['time'].hour * 60 +
                           talk['time'].minute +
                           talk['duration']
                           for talk in talks})
            times = {}

            for t in range(mintime, maxtime, GRID_STEP):
                times[t] = [None] * len(rooms)
            for talk in sorted(talks, key=lambda x: x['time']):
                talktime = talk['time'].hour * 60 + talk['time'].minute
                position = talktime // GRID_STEP * GRID_STEP  # round
                assert position in times
                roomnum = rooms.index(talk['room'])
                if times[position][roomnum] is not None:
                    logging.error("Talk {} and {} overlap! "
                                  .format(times[position][roomnum]['id'],
                                          talk['id']))
                    continue
                times[position][roomnum] = copy(talk)
                times[position][roomnum]['skip'] = False
                for i in range(1, talk['duration'] // GRID_STEP):
                    times[position + i*GRID_STEP][roomnum] = copy(talk)
                    times[position + i*GRID_STEP][roomnum]['skip'] = True

            render = tmpl.render(times=times,
                                 rooms=rooms,
                                 mintime=mintime, maxtime=maxtime,
                                 timestep=GRID_STEP,
                                 )
            output.append(nodes.raw('', u'<h4>%s</h4>' %
                                    day.strftime('%A %d').decode('utf8').title(),
                                    format='html'))
            output.append(nodes.raw('', render, format='html'))
        return output


def talks_to_ics():
    content = 'BEGIN:VCALENDAR\nVERSION:2.0\nPRODID:pelican\n'
    for t in all_talks():
        content += talk_to_ics(t)
    content += 'END:VCALENDAR\n'
    return content


def talk_to_ics(talk):
    if 'time' not in talk:
        return ''
    start = talk['time']
    end  = start + datetime.timedelta(minutes=talk['duration'])
    content = 'BEGIN:VEVENT\n'
    content += "UID:%s@%d.hackmeeting.org\n" % (talk['id'], talk['day'].year)
    content += "SUMMARY:%s\n" % talk['title']
    content += "DTSTAMP:%s\n" % time.strftime('%Y%m%dT%H%M%SZ',
                                              time.gmtime(float(start.strftime('%s'))))
    content += "DTSTART:%s\n" % time.strftime('%Y%m%dT%H%M%SZ',
                                              time.gmtime(float(
                                                  start.strftime('%s'))))
    content += "DTEND:%s\n" % time.strftime('%Y%m%dT%H%M%SZ',
                                              time.gmtime(float(
                                                  end.strftime('%s'))))
    content += "LOCATION:%s\n" % talk['room']
    content += 'END:VEVENT\n'
    return content


class TalksGenerator(generators.Generator):
    def __init__(self, *args, **kwargs):
        self.talks = []
        super(TalksGenerator, self).__init__(*args, **kwargs)

    def generate_context(self):
        self.talks = {n: get_talk_data(n) for n in get_talk_names()}
        self._update_context(('talks',))

    def generate_output(self, writer=None):
        for talkname in self.talks:
            if 'resources' in self.talks[talkname]:
                outdir = os.path.join(self.output_path, TALKS_PATH, talkname,
                                      TALK_ATTACHMENT_PATH)
                if os.path.isdir(outdir):
                    shutil.rmtree(outdir)
                shutil.copytree(self.talks[talkname]['resources'], outdir)
        with open(os.path.join(self.output_path, TALK_ICS), 'w') as buf:
            buf.write(talks_to_ics())


def add_talks_option_defaults(pelican):
    pelican.settings.setdefault('TALKS_PATH', TALKS_PATH)


def get_generators(gen):
    return TalksGenerator


try:
    import yaml
except ImportError:
    print('ERROR: yaml not found. Talks plugins will be disabled')

    def register():
        pass
else:

    def register():
        signals.get_generators.connect(get_generators)
        signals.initialized.connect(add_talks_option_defaults)
        directives.register_directive('talklist', TalkListDirective)
        directives.register_directive('talk', TalkDirective)
        directives.register_directive('talkgrid', TalkGridDirective)