import hashlib
import json
import string
import time
from datetime import datetime
import re

from django.core import serializers
from django.core.urlresolvers import reverse
from django.http import HttpResponseRedirect
from django.http.response import HttpResponse
from django.template import RequestContext
from django.shortcuts import render, redirect, get_object_or_404
from django.utils import timezone
from django.db import transaction
from django.views.decorators.cache import cache_page
from django.views.i18n import javascript_catalog

from boards import forms
import boards
from boards import utils
from boards.forms import ThreadForm, PostForm, SettingsForm, PlainErrorList, \
    ThreadCaptchaForm, PostCaptchaForm, LoginForm, ModeratorSettingsForm
from boards.models import Post, Tag, Ban, User
from boards.models.post import SETTING_MODERATE, REGEX_REPLY
from boards.models.user import RANK_USER
from boards import authors
from boards.utils import get_client_ip
import neboard


BAN_REASON_SPAM = 'Autoban: spam bot'


def index(request, page=0):
    context = _init_default_context(request)

    if utils.need_include_captcha(request):
        threadFormClass = ThreadCaptchaForm
        kwargs = {'request': request}
    else:
        threadFormClass = ThreadForm
        kwargs = {}

    if request.method == 'POST':
        form = threadFormClass(request.POST, request.FILES,
                               error_class=PlainErrorList, **kwargs)
        form.session = request.session

        if form.is_valid():
            return _new_post(request, form)
        if form.need_to_ban:
            # Ban user because he is suspected to be a bot
            _ban_current_user(request)
    else:
        form = threadFormClass(error_class=PlainErrorList, **kwargs)

    threads = []
    for thread_to_show in Post.objects.get_threads(page=int(page)):
        threads.append(_get_template_thread(thread_to_show))

    # TODO Make this generic for tag and threads list pages
    context['threads'] = None if len(threads) == 0 else threads
    context['form'] = form

    page_count = Post.objects.get_thread_page_count()
    context['pages'] = range(page_count)
    page = int(page)
    if page < page_count - 1:
        context['next_page'] = str(page + 1)
    if page > 0:
        context['prev_page'] = str(page - 1)

    return render(request, 'boards/posting_general.html',
                  context)


@transaction.atomic
def _new_post(request, form, opening_post=None):
    """Add a new post (in thread or as a reply)."""

    ip = get_client_ip(request)
    is_banned = Ban.objects.filter(ip=ip).exists()

    if is_banned:
        return redirect(you_are_banned)

    data = form.cleaned_data

    title = data['title']
    text = data['text']

    text = _remove_invalid_links(text)

    if 'image' in data.keys():
        image = data['image']
    else:
        image = None

    tags = []

    if not opening_post:
        tag_strings = data['tags']

        if tag_strings:
            tag_strings = tag_strings.split(' ')
            for tag_name in tag_strings:
                tag_name = string.lower(tag_name.strip())
                if len(tag_name) > 0:
                    tag, created = Tag.objects.get_or_create(name=tag_name)
                    tags.append(tag)
        post_thread = None
    else:
        post_thread = opening_post.thread_new

    post = Post.objects.create_post(title=title, text=text, ip=ip,
                                    thread=post_thread, image=image,
                                    tags=tags, user=_get_user(request))

    thread_to_show = (opening_post.id if opening_post else post.id)

    if opening_post:
        return redirect(reverse(thread, kwargs={'post_id': thread_to_show}) +
                        '#' + str(post.id))
    else:
        return redirect(thread, post_id=thread_to_show)


def tag(request, tag_name, page=0):
    """
    Get all tag threads. Threads are split in pages, so some page is
    requested. Default page is 0.
    """

    tag = get_object_or_404(Tag, name=tag_name)
    threads = []
    for thread_to_show in Post.objects.get_threads(page=int(page), tag=tag):
        threads.append(_get_template_thread(thread_to_show))

    if request.method == 'POST':
        form = ThreadForm(request.POST, request.FILES,
                          error_class=PlainErrorList)
        form.session = request.session

        if form.is_valid():
            return _new_post(request, form)
        if form.need_to_ban:
            # Ban user because he is suspected to be a bot
            _ban_current_user(request)
    else:
        form = forms.ThreadForm(initial={'tags': tag_name},
                                error_class=PlainErrorList)

    context = _init_default_context(request)
    context['threads'] = None if len(threads) == 0 else threads
    context['tag'] = tag

    page_count = Post.objects.get_thread_page_count(tag=tag)
    context['pages'] = range(page_count)
    page = int(page)
    if page < page_count - 1:
        context['next_page'] = str(page + 1)
    if page > 0:
        context['prev_page'] = str(page - 1)

    context['form'] = form

    return render(request, 'boards/posting_general.html',
                  context)


def thread(request, post_id):
    """Get all thread posts"""

    if utils.need_include_captcha(request):
        postFormClass = PostCaptchaForm
        kwargs = {'request': request}
    else:
        postFormClass = PostForm
        kwargs = {}

    if request.method == 'POST':
        form = postFormClass(request.POST, request.FILES,
                             error_class=PlainErrorList, **kwargs)
        form.session = request.session

        opening_post = get_object_or_404(Post, id=post_id)
        if form.is_valid():
            return _new_post(request, form, opening_post)
        if form.need_to_ban:
            # Ban user because he is suspected to be a bot
            _ban_current_user(request)
    else:
        form = postFormClass(error_class=PlainErrorList, **kwargs)

    thread_to_show = get_object_or_404(Post, id=post_id).thread_new

    context = _init_default_context(request)

    posts = thread_to_show.get_replies()
    context['form'] = form
    context['bumpable'] = thread_to_show.can_bump()
    if context['bumpable']:
        context['posts_left'] = neboard.settings.MAX_POSTS_PER_THREAD - posts\
            .count()
        context['bumplimit_progress'] = str(
            float(context['posts_left']) /
            neboard.settings.MAX_POSTS_PER_THREAD * 100)
    context["last_update"] = _datetime_to_epoch(thread_to_show.last_edit_time)
    context["thread"] = thread_to_show

    return render(request, 'boards/thread.html', context)


def login(request):
    """Log in with user id"""

    context = _init_default_context(request)

    if request.method == 'POST':
        form = LoginForm(request.POST, request.FILES,
                         error_class=PlainErrorList)
        form.session = request.session

        if form.is_valid():
            user = User.objects.get(user_id=form.cleaned_data['user_id'])
            request.session['user_id'] = user.id
            return redirect(index)

    else:
        form = LoginForm()

    context['form'] = form

    return render(request, 'boards/login.html', context)


def settings(request):
    """User's settings"""

    context = _init_default_context(request)
    user = _get_user(request)
    is_moderator = user.is_moderator()

    if request.method == 'POST':
        with transaction.atomic():
            if is_moderator:
                form = ModeratorSettingsForm(request.POST,
                                             error_class=PlainErrorList)
            else:
                form = SettingsForm(request.POST, error_class=PlainErrorList)

            if form.is_valid():
                selected_theme = form.cleaned_data['theme']

                user.save_setting('theme', selected_theme)

                if is_moderator:
                    moderate = form.cleaned_data['moderate']
                    user.save_setting(SETTING_MODERATE, moderate)

            return redirect(settings)
    else:
        selected_theme = _get_theme(request)

        if is_moderator:
            form = ModeratorSettingsForm(initial={'theme': selected_theme,
                                         'moderate': context['moderator']},
                                         error_class=PlainErrorList)
        else:
            form = SettingsForm(initial={'theme': selected_theme},
                                error_class=PlainErrorList)

    context['form'] = form

    return render(request, 'boards/settings.html', context)


def all_tags(request):
    """All tags list"""

    context = _init_default_context(request)
    context['all_tags'] = Tag.objects.get_not_empty_tags()

    return render(request, 'boards/tags.html', context)


def jump_to_post(request, post_id):
    """Determine thread in which the requested post is and open it's page"""

    post = get_object_or_404(Post, id=post_id)

    if not post.thread:
        return redirect(thread, post_id=post.id)
    else:
        return redirect(reverse(thread, kwargs={'post_id': post.thread.id})
                        + '#' + str(post.id))


def authors(request):
    """Show authors list"""

    context = _init_default_context(request)
    context['authors'] = boards.authors.authors

    return render(request, 'boards/authors.html', context)


@transaction.atomic
def delete(request, post_id):
    """Delete post"""

    user = _get_user(request)
    post = get_object_or_404(Post, id=post_id)

    if user.is_moderator():
        # TODO Show confirmation page before deletion
        Post.objects.delete_post(post)

    if not post.thread:
        return _redirect_to_next(request)
    else:
        return redirect(thread, post_id=post.thread.id)


@transaction.atomic
def ban(request, post_id):
    """Ban user"""

    user = _get_user(request)
    post = get_object_or_404(Post, id=post_id)

    if user.is_moderator():
        # TODO Show confirmation page before ban
        ban, created = Ban.objects.get_or_create(ip=post.poster_ip)
        if created:
            ban.reason = 'Banned for post ' + str(post_id)
            ban.save()

    return _redirect_to_next(request)


def you_are_banned(request):
    """Show the page that notifies that user is banned"""

    context = _init_default_context(request)

    ban = get_object_or_404(Ban, ip=utils.get_client_ip(request))
    context['ban_reason'] = ban.reason
    return render(request, 'boards/staticpages/banned.html', context)


def page_404(request):
    """Show page 404 (not found error)"""

    context = _init_default_context(request)
    return render(request, 'boards/404.html', context)


@transaction.atomic
def tag_subscribe(request, tag_name):
    """Add tag to favorites"""

    user = _get_user(request)
    tag = get_object_or_404(Tag, name=tag_name)

    if not tag in user.fav_tags.all():
        user.add_tag(tag)

    return _redirect_to_next(request)


@transaction.atomic
def tag_unsubscribe(request, tag_name):
    """Remove tag from favorites"""

    user = _get_user(request)
    tag = get_object_or_404(Tag, name=tag_name)

    if tag in user.fav_tags.all():
        user.remove_tag(tag)

    return _redirect_to_next(request)


def static_page(request, name):
    """Show a static page that needs only tags list and a CSS"""

    context = _init_default_context(request)
    return render(request, 'boards/staticpages/' + name + '.html', context)


def api_get_post(request, post_id):
    """
    Get the JSON of a post. This can be
    used as and API for external clients.
    """

    post = get_object_or_404(Post, id=post_id)

    json = serializers.serialize("json", [post], fields=(
        "pub_time", "_text_rendered", "title", "text", "image",
        "image_width", "image_height", "replies", "tags"
    ))

    return HttpResponse(content=json)


@transaction.atomic
def api_get_threaddiff(request, thread_id, last_update_time):
    """Get posts that were changed or added since time"""

    thread = get_object_or_404(Post, id=thread_id).thread_new

    filter_time = datetime.fromtimestamp(float(last_update_time) / 1000000,
                                         timezone.get_current_timezone())

    json_data = {
        'added': [],
        'updated': [],
        'last_update': None,
    }
    added_posts = Post.objects.filter(thread_new=thread,
                                      pub_time__gt=filter_time)\
        .order_by('pub_time')
    updated_posts = Post.objects.filter(thread_new=thread,
                                        pub_time__lte=filter_time,
                                        last_edit_time__gt=filter_time)
    for post in added_posts:
        json_data['added'].append(get_post(request, post.id).content.strip())
    for post in updated_posts:
        json_data['updated'].append(get_post(request, post.id).content.strip())
    json_data['last_update'] = _datetime_to_epoch(thread.last_edit_time)

    return HttpResponse(content=json.dumps(json_data))


def get_post(request, post_id):
    """Get the html of a post. Used for popups."""

    post = get_object_or_404(Post, id=post_id)
    thread = post.thread_new

    context = RequestContext(request)
    context["post"] = post
    context["can_bump"] = thread.can_bump()
    if "truncated" in request.GET:
        context["truncated"] = True

    return render(request, 'boards/post.html', context)

@cache_page(86400)
def cached_js_catalog(request, domain='djangojs', packages=None):
    return javascript_catalog(request, domain, packages)


def _get_theme(request, user=None):
    """Get user's CSS theme"""

    if not user:
        user = _get_user(request)
    theme = user.get_setting('theme')
    if not theme:
        theme = neboard.settings.DEFAULT_THEME

    return theme


def _init_default_context(request):
    """Create context with default values that are used in most views"""

    context = RequestContext(request)

    user = _get_user(request)
    context['user'] = user
    context['tags'] = user.get_sorted_fav_tags()
    context['posts_per_day'] = float(Post.objects.get_posts_per_day())

    theme = _get_theme(request, user)
    context['theme'] = theme
    context['theme_css'] = 'css/' + theme + '/base_page.css'

    # This shows the moderator panel
    moderate = user.get_setting(SETTING_MODERATE)
    if moderate == 'True':
        context['moderator'] = user.is_moderator()
    else:
        context['moderator'] = False

    return context


def _get_user(request):
    """
    Get current user from the session. If the user does not exist, create
    a new one.
    """

    session = request.session
    if not 'user_id' in session:
        request.session.save()

        md5 = hashlib.md5()
        md5.update(session.session_key)
        new_id = md5.hexdigest()

        time_now = timezone.now()
        user = User.objects.create(user_id=new_id, rank=RANK_USER,
                                   registration_time=time_now)

        session['user_id'] = user.id
    else:
        user = User.objects.get(id=session['user_id'])

    return user


def _redirect_to_next(request):
    """
    If a 'next' parameter was specified, redirect to the next page. This is
    used when the user is required to return to some page after the current
    view has finished its work.
    """

    if 'next' in request.GET:
        next_page = request.GET['next']
        return HttpResponseRedirect(next_page)
    else:
        return redirect(index)


@transaction.atomic
def _ban_current_user(request):
    """Add current user to the IP ban list"""

    ip = utils.get_client_ip(request)
    ban, created = Ban.objects.get_or_create(ip=ip)
    if created:
        ban.can_read = False
        ban.reason = BAN_REASON_SPAM
    ban.save()


def _remove_invalid_links(text):
    """
    Replace invalid links in posts so that they won't be parsed.
    Invalid links are links to non-existent posts
    """

    for reply_number in re.finditer(REGEX_REPLY, text):
        post_id = reply_number.group(1)
        post = Post.objects.filter(id=post_id)
        if not post.exists():
            text = string.replace(text, '>>' + post_id, post_id)

    return text


def _datetime_to_epoch(datetime):
    return int(time.mktime(timezone.localtime(
        datetime,timezone.get_current_timezone()).timetuple())
               * 1000000 + datetime.microsecond)


def _get_template_thread(thread_to_show):
    """Get template values for thread"""

    last_replies = thread_to_show.get_last_replies()
    skipped_replies_count = thread_to_show.get_replies().count() \
                            - len(last_replies) - 1
    return {
        'thread': thread_to_show,
        'op': thread_to_show.get_replies()[0],
        'bumpable': thread_to_show.can_bump(),
        'last_replies': last_replies,
        'skipped_replies': skipped_replies_count,
        }