"""
Module with basic views for use by inheriting actions
"""
from django.contrib import messages
from django.db.transaction import atomic
from django.shortcuts import redirect, render
from django.views.generic import View

from misago.acl import add_acl
from misago.core.shortcuts import get_object_or_404, paginate, validate_slug
from misago.forums.lists import get_forums_list, get_forum_path
from misago.forums.models import Forum
from misago.forums.permissions import allow_see_forum, allow_browse_forum

from misago.threads.posting import (InterruptChanges, EditorFormset,
                                    START, REPLY, EDIT)
from misago.threads.models import Thread, Post
from misago.threads.permissions import allow_see_thread, allow_start_thread


class ForumMixin(object):
    """
    Mixin for getting forums
    """
    def get_forum(self, request, lock=False, **kwargs):
        forum = self.fetch_forum(request, lock, **kwargs)
        self.check_forum_permissions(request, forum)

        if kwargs.get('forum_slug'):
            validate_slug(forum, kwargs.get('forum_slug'))

        return forum

    def fetch_forum(self, request, lock=False, **kwargs):
        queryset = Forum.objects
        if lock:
            queryset = queryset.select_for_update()

        return get_object_or_404(
            queryset, id=kwargs.get('forum_id'), role='forum')

    def check_forum_permissions(self, request, forum):
        add_acl(request.user, forum)
        allow_see_forum(request.user, forum)
        allow_browse_forum(request.user, forum)


class ThreadMixin(object):
    """
    Mixin for getting thread
    """
    def get_thread(self, request, lock=False, **kwargs):
        thread = self.fetch_thread(request, lock, **kwargs)
        self.check_thread_permissions(request, thread)

        if kwargs.get('thread_slug'):
            validate_slug(thread, kwargs.get('thread_slug'))

        return thread

    def fetch_thread(self, request, lock=False, **kwargs):
        queryset = Thread.objects
        if lock:
            queryset = queryset.select_for_update()

        return get_object_or_404(queryset, id=kwargs.get('thread_id'))

    def check_thread_permissions(self, request, thread):
        add_acl(request.user, thread)
        allow_see_thread(request.user, thread)


class ViewBase(ForumMixin, View):
    templates_dir = ''
    template = ''

    def final_template(self):
        return '%s/%s' % (self.templates_dir, self.template)

    def process_context(self, request, context):
        """
        Simple hook for extending and manipulating template context.
        """
        return context

    def render(self, request, context=None, template=None):
        context = self.process_context(request, context or {})
        template = template or self.final_template()
        return render(request, template, context)


class ForumView(ViewBase):
    """
    Basic view for threads lists
    """
    template = 'list.html'

    def get_threads(self, request, forum, **kwargs):
        return forum.thread_set

    def dispatch(self, request, *args, **kwargs):
        forum = self.get_forum(request, **kwargs)
        forum.subforums = get_forums_list(request.user, forum)
        threads = self.get_threads(request, forum, **kwargs)

        return self.render(request, {
            'forum': forum,
            'path': get_forum_path(forum),
        })


class ThreadView(ViewBase):
    """
    Basic view for threads
    """
    def fetch_thread(self, request, **kwargs):
        pass

    def dispatch(self, request, *args, **kwargs):
        thread = self.fetch_thread(request, **kwargs)


class PostView(ViewBase):
    """
    Basic view for posts
    """
    def fetch_post(self, request, **kwargs):
        pass

    def dispatch(self, request, *args, **kwargs):
        post = self.fetch_post(request, **kwargs)


class EditorView(ViewBase):
    """
    Basic view for starting/replying/editing
    """
    template = 'editor.html'

    def find_mode(self, request, *args, **kwargs):
        """
        First step: guess from request what kind of view we are
        """
        is_post = request.method == 'POST'

        if 'forum_id' in kwargs:
            mode = START
            user = request.user

            forum = self.get_forum(request, lock=is_post, **kwargs)
            thread = Thread(forum=forum, starter=user, last_poster=user)
            post = Post(forum=forum, thread=thread, poster=user)
            quote = Post(0)
        elif 'thread_id' in kwargs:
            thread = self.get_thread(request, lock=is_post, **kwargs)
            forum = thread.forum

        return mode, forum, thread, post, quote

    def allow_mode(self, user, mode, forum, thread, post, quote):
        """
        Second step: check start/reply/edit permissions
        """
        if mode == START:
            self.allow_start(user, forum)
        if mode == REPLY:
            self.allow_reply(user, forum, thread, quote)
        if mode == EDIT:
            self.allow_edit(user, forum, thread, post)

    def allow_start(self, user, forum):
        allow_start_thread(user, forum)

    def allow_reply(self, user, forum, thread, quote):
        raise NotImplementedError()

    def allow_edit(self, user, forum, thread, post):
        raise NotImplementedError()

    def dispatch(self, request, *args, **kwargs):
        if request.method == 'POST':
            with atomic():
                return self.real_dispatch(request, *args, **kwargs)
        else:
            return self.real_dispatch(request, *args, **kwargs)

    def real_dispatch(self, request, *args, **kwargs):
        mode_context = self.find_mode(request, *args, **kwargs)
        self.allow_mode(request.user, *mode_context)

        mode, forum, thread, post, quote = mode_context
        formset = EditorFormset(request=request,
                                mode=mode,
                                user=request.user,
                                forum=forum,
                                thread=thread,
                                post=post,
                                quote=quote)

        if request.method == 'POST':
            if 'submit' in request.POST and formset.is_valid():
                try:
                    formset.save()
                    return redirect('misago:index')
                except InterruptChanges as e:
                    messages.error(request, e.message)
            else:
                formset.update()

        return self.render(request, {
            'mode': mode,
            'formset': formset,
            'forms': formset.get_forms_list(),
            'main_forms': formset.get_main_forms(),
            'supporting_forms': formset.get_supporting_forms(),
            'forum': forum,
            'path': get_forum_path(forum),
            'thread': thread,
            'post': post,
            'quote': quote
        })