# -*- coding: utf-8 -*-
import datetime
import json
import logging
import random
import select
import threading
import time

import flectra
from flectra import api, fields, models, SUPERUSER_ID
from flectra.tools.misc import DEFAULT_SERVER_DATETIME_FORMAT

_logger = logging.getLogger(__name__)

# longpolling timeout connection
TIMEOUT = 50

#----------------------------------------------------------
# Bus
#----------------------------------------------------------
def json_dump(v):
    return json.dumps(v, separators=(',', ':'))

def hashable(key):
    if isinstance(key, list):
        key = tuple(key)
    return key


class ImBus(models.Model):

    _name = 'bus.bus'

    create_date = fields.Datetime('Create date')
    channel = fields.Char('Channel')
    message = fields.Char('Message')

    @api.model
    def gc(self):
        timeout_ago = datetime.datetime.utcnow()-datetime.timedelta(seconds=TIMEOUT*2)
        domain = [('create_date', '<', timeout_ago.strftime(DEFAULT_SERVER_DATETIME_FORMAT))]
        return self.sudo().search(domain).unlink()

    @api.model
    def sendmany(self, notifications):
        channels = set()
        for channel, message in notifications:
            channels.add(channel)
            values = {
                "channel": json_dump(channel),
                "message": json_dump(message)
            }
            self.sudo().create(values)
            if random.random() < 0.01:
                self.gc()
        if channels:
            # We have to wait until the notifications are commited in database.
            # When calling `NOTIFY imbus`, some concurrent threads will be
            # awakened and will fetch the notification in the bus table. If the
            # transaction is not commited yet, there will be nothing to fetch,
            # and the longpolling will return no notification.
            def notify():
                with flectra.sql_db.db_connect('postgres').cursor() as cr:
                    cr.execute("notify imbus, %s", (json_dump(list(channels)),))
            self._cr.after('commit', notify)

    @api.model
    def sendone(self, channel, message):
        self.sendmany([[channel, message]])

    @api.model
    def poll(self, channels, last=0, options=None, force_status=False):
        if options is None:
            options = {}
        # first poll return the notification in the 'buffer'
        if last == 0:
            timeout_ago = datetime.datetime.utcnow()-datetime.timedelta(seconds=TIMEOUT)
            domain = [('create_date', '>', timeout_ago.strftime(DEFAULT_SERVER_DATETIME_FORMAT))]
        else:  # else returns the unread notifications
            domain = [('id', '>', last)]
        channels = [json_dump(c) for c in channels]
        domain.append(('channel', 'in', channels))
        notifications = self.sudo().search_read(domain)
        # list of notification to return
        result = []
        for notif in notifications:
            result.append({
                'id': notif['id'],
                'channel': json.loads(notif['channel']),
                'message': json.loads(notif['message']),
            })

        if result or force_status:
            partner_ids = options.get('bus_presence_partner_ids')
            if partner_ids:
                partners = self.env['res.partner'].browse(partner_ids)
                result += [{
                    'id': -1,
                    'channel': (self._cr.dbname, 'bus.presence'),
                    'message': {'id': r.id, 'im_status': r.im_status}} for r in partners]
        return result


#----------------------------------------------------------
# Dispatcher
#----------------------------------------------------------
class ImDispatch(object):
    def __init__(self):
        self.channels = {}
        self.started = False

    def poll(self, dbname, channels, last, options=None, timeout=TIMEOUT):
        if options is None:
            options = {}
        # Dont hang ctrl-c for a poll request, we need to bypass private
        # attribute access because we dont know before starting the thread that
        # it will handle a longpolling request
        if not flectra.evented:
            current = threading.current_thread()
            current._Thread__daemonic = True # PY2
            current._daemonic = True         # PY3
            # rename the thread to avoid tests waiting for a longpolling
            current.setName("flectra.longpolling.request.%s" % current.ident)

        registry = flectra.registry(dbname)

        # immediatly returns if past notifications exist
        with registry.cursor() as cr:
            env = api.Environment(cr, SUPERUSER_ID, {})
            notifications = env['bus.bus'].poll(channels, last, options)

        # immediatly returns in peek mode
        if options.get('peek'):
            return dict(notifications=notifications, channels=channels)

        # or wait for future ones
        if not notifications:
            if not self.started:
                # Lazy start of events listener
                self.start()

            event = self.Event()
            for channel in channels:
                self.channels.setdefault(hashable(channel), []).append(event)
            try:
                event.wait(timeout=timeout)
                with registry.cursor() as cr:
                    env = api.Environment(cr, SUPERUSER_ID, {})
                    notifications = env['bus.bus'].poll(channels, last, options, force_status=True)
            except Exception:
                # timeout
                pass
        return notifications

    def loop(self):
        """ Dispatch postgres notifications to the relevant polling threads/greenlets """
        _logger.info("Bus.loop listen imbus on db postgres")
        with flectra.sql_db.db_connect('postgres').cursor() as cr:
            conn = cr._cnx
            cr.execute("listen imbus")
            cr.commit();
            while True:
                if select.select([conn], [], [], TIMEOUT) == ([], [], []):
                    pass
                else:
                    conn.poll()
                    channels = []
                    while conn.notifies:
                        channels.extend(json.loads(conn.notifies.pop().payload))
                    # dispatch to local threads/greenlets
                    events = set()
                    for channel in channels:
                        events.update(self.channels.pop(hashable(channel), []))
                    for event in events:
                        event.set()

    def run(self):
        while True:
            try:
                self.loop()
            except Exception as e:
                _logger.exception("Bus.loop error, sleep and retry")
                time.sleep(TIMEOUT)

    def start(self):
        if flectra.evented:
            # gevent mode
            import gevent
            self.Event = gevent.event.Event
            gevent.spawn(self.run)
        else:
            # threaded mode
            self.Event = threading.Event
            t = threading.Thread(name="%s.Bus" % __name__, target=self.run)
            t.daemon = True
            t.start()
        self.started = True
        return self

dispatch = None
if not flectra.multi_process or flectra.evented:
    # We only use the event dispatcher in threaded and gevent mode
    dispatch = ImDispatch()