import math
from datetime import datetime
from celery.utils.log import get_task_logger
from django.core.mail import send_mail
from django.utils.html import strip_tags
from django.template.loader import render_to_string

from pingcap_sso.models import User, UserPointStat
from pingcap_sso.celery import app as celery_app
from pingcap_sso.discourse.models import (
    DiscourseTopic, DiscourseTopicCustomField
)
from pingcap_sso.discourse import api as discourse_api
from pingcap_sso.utils.email import get_MX_records_by_email

logger = get_task_logger(__name__)


@celery_app.task
def sync_user_to_discourse(external_id, username, email, name, bio):
    return discourse_api.sync_user_to_discourse(external_id, username, email, name, bio)


WELCOME_NEWBIE_TITLE = '这是来自 TiDB 社区的一封信，请查收!'

def welcome_context(user):
    topic_count = DiscourseTopic.objects.filter(
        deleted_at__isnull=True,
        visible=True,
        archetype='regular'
    ).count()
    solved_count = DiscourseTopicCustomField.objects.filter(
        name='accepted_answer_post_id',
        value__isnull=False,
        topic__deleted_at__isnull=True,
        topic__archetype='regular'
    ).count()
    return {
        'username': user.username,
        'user_count': User.objects.all().count() - 1,
        'tidb_age': (datetime.now() - datetime.strptime('2015-04-08', '%Y-%m-%d')).days,
        'topic_count': topic_count,
        'solved_count': solved_count
    }


@celery_app.task
def send_welcome_email_to_newbie(user_id):
    user = User.objects.get(id=user_id)
    email_verified = user.email_verified
    email = user.email or user.signup_email

    if email and (email_verified or get_MX_records_by_email(email)):
        html_message = render_to_string(
            'pingcap_sso/email/welcome_newbie.html',
            welcome_context(user)
        )
        send_mail(
            WELCOME_NEWBIE_TITLE,
            strip_tags(html_message),
            None,
            [email],
            html_message=html_message
        )
        logger.info('send welcome email to user:{}, email_address:{}'.format(user.id, email))


@celery_app.task
def send_welcome_asktug_message_to_newbie(user_id):
    user = User.objects.get(id=user_id)
    asktug_message = render_to_string(
        'pingcap_sso/asktug_message/welcome_newbie.md',
        welcome_context(user)
    )
    return discourse_api.send_private_message(
        [user.username],
        WELCOME_NEWBIE_TITLE,
        asktug_message
    )


CONTRIBUTOR_BADGE_RULES = [
    {'level': 1, 'badge_id': 131, 'min_exps': 1000, 'max_exps': 4999},
    {'level': 2, 'badge_id': 132, 'min_exps': 5000, 'max_exps': 9999},
    {'level': 3, 'badge_id': 133, 'min_exps': 10000, 'max_exps': 19999},
    {'level': 4, 'badge_id': 134, 'min_exps': 20000, 'max_exps': float('inf')},
]

@celery_app.task
def grant_community_contributor_badges_to_users():
    # grant community contributor badges to users by experience
    # this task can be run repeatedly
    for rule in CONTRIBUTOR_BADGE_RULES:
        badge_id = rule['badge_id']
        min_exps = rule['min_exps']
        point_stats = UserPointStat.objects.using('default').select_related('pingcap_sso.user').all()
        if not math.isinf(min_exps):
            point_stats = point_stats.filter(experience__gte=min_exps)

        usernames = point_stats.values_list('user__username', flat=True)
        step = 200
        for i in range(math.ceil(len(usernames) / step)):
            sliced_usernames = usernames[i * step: (i + 1) * step]
            if sliced_usernames:
                discourse_api.grant_badge_to_users(sliced_usernames, badge_id)