import datetime
import os
import re
from django.db import models
from django.db.models.signals import post_save
from django.dispatch import receiver

from seaserv import get_group_members

from shortcuts import get_first_object_or_none
from notifications.models import UserNotification
from profile.models import Profile

class GroupMessage(models.Model):
    group_id = models.IntegerField(db_index=True)
    from_email = models.EmailField()
    message = models.CharField(max_length=500)
    timestamp = models.DateTimeField(default=datetime.datetime.now)

class MessageReply(models.Model):
    reply_to = models.ForeignKey(GroupMessage)
    from_email = models.EmailField()
    message = models.CharField(max_length=150)
    timestamp = models.DateTimeField(default=datetime.datetime.now)

@receiver(post_save, sender=MessageReply)
def msgreply_save_handler(sender, instance, **kwargs):
    """
    Handl sending notification to '@<user>' when reply messages.
    """
    from_email = instance.from_email
    reply_msg =  instance.message
    group_msg =  instance.reply_to
    to_user = ''
    
    at_pattern = re.compile(r'(\s|^)(@\w+)', flags=re.U)
    m = re.match(at_pattern, reply_msg)
    if m:
        nickname_or_emailprefix = m.group()[1:]
        p = get_first_object_or_none(\
            Profile.objects.filter(nickname=nickname_or_emailprefix))
        if p:
            to_user = p.user
        else:
            # Match email prefix in group members.
            group_members = get_group_members(group_msg.group_id)
            for m in group_members:
                if m.user_name.startswith(nickname_or_emailprefix):
                    to_user = m.user_name
                    break
                
        if to_user and to_user != from_email:
            # Send notification to the user if user replies someone else'
            # message.
            try:
                UserNotification.objects.get(to_user=to_user,
                                             msg_type='grpmsg_reply',
                                             detail=group_msg.id)
            except UserNotification.DoesNotExist:
                n = UserNotification(to_user=to_user,
                                     msg_type='grpmsg_reply',
                                     detail=group_msg.id)
                n.save()