from datetime import datetime
import random
import string
import logging
from django.db import models
from django.contrib.auth.models import User
from django.utils.translation import ugettext as _
from askbot.models.post import Post
from askbot.models.base import BaseQuerySetManager
from askbot.conf import settings as askbot_settings
from askbot import mail

class ReplyAddressManager(BaseQuerySetManager):
    """A manager for the :class:`ReplyAddress` model"""

    def get_unused(self, address, allowed_from_email):
        return self.get(
            address = address,
            allowed_from_email = allowed_from_email,
            used_at__isnull = True
        )
    
    def create_new(self, **kwargs):
        """creates a new reply address"""
        kwargs['allowed_from_email'] = kwargs['user'].email
        reply_address = ReplyAddress(**kwargs)
        while True:
            reply_address.address = ''.join(random.choice(string.letters +
                string.digits) for i in xrange(random.randint(12, 25))).lower()
            if self.filter(address = reply_address.address).count() == 0:
                break
        reply_address.save()
        return reply_address
			

REPLY_ACTION_CHOICES = (
    ('post_answer', 'Post an answer'),
    ('post_comment', 'Post a comment'),
    ('replace_content', 'Edit post'),
    ('append_content', 'Append to post'),
    ('auto_answer_or_comment', 'Answer or comment, depending on the size of post'),
    ('validate_email', 'Validate email and record signature'),
)
class ReplyAddress(models.Model):
    """Stores a reply address for the post
    and the user"""
    address = models.CharField(max_length = 25, unique = True)
    post = models.ForeignKey(
                            Post,
                            null = True,#reply not necessarily to posts
                            related_name = 'reply_addresses'
                        )#the emailed post
    reply_action = models.CharField(
                        max_length = 32,
                        choices = REPLY_ACTION_CHOICES,
                        default = 'auto_answer_or_comment'
                    )
    response_post = models.ForeignKey(
                            Post,
                            null = True,
                            related_name = 'edit_addresses'
                        )
    user = models.ForeignKey(User)
    allowed_from_email = models.EmailField(max_length = 150)
    used_at = models.DateTimeField(null = True, default = None)

    objects = ReplyAddressManager()


    class Meta:
        app_label = 'askbot'
        db_table = 'askbot_replyaddress'

    @property
    def was_used(self):
        """True if was used"""
        return self.used_at != None

    def as_email_address(self, prefix = 'reply-'):
        """returns email address, prefix is added
        in front of the code"""
        return '%s%s@%s' % (
                        prefix,
                        self.address,
                        askbot_settings.REPLY_BY_EMAIL_HOSTNAME
                    )

    def edit_post(
        self, body_text, title = None, edit_response = False
    ):
        """edits the created post upon repeated response
        to the same address"""
        if self.was_used or edit_response:
            reply_action = 'append_content'
        else:
            reply_action = self.reply_action

        if edit_response:
            post = self.response_post
        else:
            post = self.post

        if reply_action == 'append_content':
            body_text = post.text + '\n\n' + body_text
            revision_comment = _('added content by email')
        else:
            assert(reply_action == 'replace_content')
            revision_comment = _('edited by email')

        if post.post_type == 'question':
            assert(post is self.post)
            self.user.edit_question(
                question = post,
                body_text = body_text,
                title = title,
                revision_comment = revision_comment,
                by_email = True
            )
        else:
            self.user.edit_post(
                post = post,
                body_text = body_text,
                revision_comment = revision_comment,
                by_email = True
            )
        self.post.thread.invalidate_cached_data()

    def create_reply(self, body_text):
        """creates a reply to the post which was emailed
        to the user
        """
        result = None
        if self.post.post_type == 'answer':
            result = self.user.post_comment(
                                        self.post,
                                        body_text,
                                        by_email = True
                                    )
        elif self.post.post_type == 'question':
            if self.reply_action == 'auto_answer_or_comment':
                wordcount = len(body_text)/6#todo: this is a simplistic hack
                if wordcount > askbot_settings.MIN_WORDS_FOR_ANSWER_BY_EMAIL:
                    reply_action = 'post_answer'
                else:
                    reply_action = 'post_comment'
            else:
                reply_action = self.reply_action

            if reply_action == 'post_answer':
                result = self.user.post_answer(
                                            self.post,
                                            body_text,
                                            by_email = True
                                        )
            elif reply_action == 'post_comment':
                result = self.user.post_comment(
                                            self.post,
                                            body_text,
                                            by_email = True
                                        )
            else:
                logging.critical(
                    'Unexpected reply action: "%s", post by email failed' % reply_action
                )
                return None#todo: there may be a better action to take here...
        elif self.post.post_type == 'comment':
            result = self.user.post_comment(
                                    self.post.parent,
                                    body_text,
                                    by_email = True
                                )
        result.thread.invalidate_cached_data()
        self.response_post = result
        self.used_at = datetime.now()
        self.save()
        return result
