"""
Views for the messages application.

"""
import datetime
import json

from django.contrib.auth.decorators import login_required
from django.contrib.auth.models import User
from django.contrib import messages as django_messages
from django.core.paginator import Paginator, EmptyPage, InvalidPage
from django.core.urlresolvers import reverse
from django.http import HttpResponse
from django.http import HttpResponseForbidden
from django.http import HttpResponseNotAllowed
from django.shortcuts import get_object_or_404
from django.shortcuts import render

from messages.models import Message, Options
from messages.forms import OptionsForm, ComposeForm
from messages.utils import reply_subject
from messages import MSG_BOX_LIMIT
from core.functions import quote_message


MSGS_PER_PAGE = 20      # message pagination value

# This must match the jQuery UI tab control
TAB_INDICES = {
    'inbox': 0,
    'compose': 1,
    'outbox': 2,
    'trash': 3,
    'options': 4,
}


def _get_page(request):
    try:
        n = int(request.GET.get('page', '1'))
    except ValueError:
        n = 1
    return n


def _quota_check(box_name, count, request):
    """
    Checks the message box count against MSG_BOX_LIMIT.
    Emits a message to the user if the quota is exceeded.

    Returns the percent used as an integer between 0-100.

    """
    if count >= MSG_BOX_LIMIT:
        django_messages.warning(request,
            "Your %s is full. Please delete some messages." % box_name)

    return 100 * count / MSG_BOX_LIMIT


@login_required
def index(request, tab=None):
    """
    This function displays the base tabbed private messages view.

    """
    tab_index = TAB_INDICES[tab] if tab else 0
    return render(request, 'messages/tabbed_base.html', {
        'tab': tab_index,
        'unread_count': Message.objects.unread_count(request.user),
        })


@login_required
def compose_to(request, receiver):
    """
    This function displays the base tabbed private messages view,
    and configures it to display the compose PM tab for the given
    receiver.

    """
    user = get_object_or_404(User, username=receiver)
    tab_index = TAB_INDICES['compose']
    return render(request, 'messages/tabbed_base.html', {
        'tab': tab_index,
        'receiver': receiver,
        'unread_count': Message.objects.unread_count(request.user),
        })


def inbox(request):
    """
    Returns the inbox for the user.

    """
    if not request.user.is_authenticated():
        return HttpResponseForbidden()

    msg_list = Message.objects.inbox(request.user)
    msg_count = msg_list.count()
    pct_used = _quota_check('inbox', msg_count, request)

    paginator = Paginator(msg_list, MSGS_PER_PAGE)
    try:
        msgs = paginator.page(_get_page(request))
    except (EmptyPage, InvalidPage):
        msgs = paginator.page(paginator.num_pages)

    return render(request, 'messages/inbox_tab.html', {
        'msgs': msgs,
        'url': reverse('messages-inbox'),
        'pct_used': pct_used,
        })


def outbox(request):
    """
    Returns the outbox for the user.

    """
    if not request.user.is_authenticated():
        return HttpResponseForbidden()

    msg_list = Message.objects.outbox(request.user)
    msg_count = msg_list.count()
    pct_used = _quota_check('outbox', msg_count, request)

    paginator = Paginator(msg_list, MSGS_PER_PAGE)
    try:
        msgs = paginator.page(_get_page(request))
    except (EmptyPage, InvalidPage):
        msgs = paginator.page(paginator.num_pages)

    return render(request, 'messages/outbox_tab.html', {
        'msgs': msgs,
        'url': reverse('messages-outbox'),
        'pct_used': pct_used,
        })


def trash(request):
    """
    Returns the trash for the user.

    """
    if not request.user.is_authenticated():
        return HttpResponseForbidden()

    msg_list = Message.objects.trash(request.user)
    paginator = Paginator(msg_list, MSGS_PER_PAGE)
    try:
        msgs = paginator.page(_get_page(request))
    except (EmptyPage, InvalidPage):
        msgs = paginator.page(paginator.num_pages)

    return render(request, 'messages/trash_tab.html', {
        'msgs': msgs,
        'url': reverse('messages-trash'),
        })


def message(request):
    """
    This view function retrieves a message and returns it as a JSON object.

    """
    if not request.user.is_authenticated():
        return HttpResponseForbidden()
    if request.method != 'POST':
        return HttpResponseNotAllowed(['POST'])

    msg_id = request.POST.get('msg_id')
    msg = get_object_or_404(Message.objects.select_related(), pk=msg_id)
    if msg.sender != request.user and msg.receiver != request.user:
        return HttpResponseForbidden()

    if msg.receiver == request.user and msg.read_date is None:
        msg.read_date = datetime.datetime.now()
        msg.save()

    msg_dict = dict(subject=msg.subject,
                    sender=msg.sender.username,
                    receiver=msg.receiver.username,
                    content=msg.html,
                    re_subject=reply_subject(msg.subject),
                    re_content=quote_message(msg.sender.username, msg.message))

    result = json.dumps(msg_dict, ensure_ascii=False)
    return HttpResponse(result, content_type='application/json')


def options(request):
    """
    This view handles the displaying and changing of private message options.

    """
    if not request.user.is_authenticated():
        return HttpResponseForbidden()

    if request.method == "POST":
        options = Options.objects.for_user(request.user)
        form = OptionsForm(request.POST, instance=options, prefix='opts')
        if form.is_valid():
            form.save()
            django_messages.success(request, 'Options saved.')
    else:
        options = Options.objects.for_user(request.user)
        form = OptionsForm(instance=options, prefix='opts')

    return render(request, 'messages/options_tab.html', {
        'form': form,
        })


def compose(request, receiver=None):
    """
    Process or prepare the compose form to create a new private message.

    """
    if not request.user.is_authenticated():
        return HttpResponseForbidden()

    if request.method == "POST":
        compose_form = ComposeForm(request.user, request.POST)

        # Is this a reply to another message?
        parent_msg_id = request.POST.get('reply_to')
        if parent_msg_id:
            parent_msg = get_object_or_404(Message, id=parent_msg_id)
            if (request.user != parent_msg.receiver and
                request.user != parent_msg.sender):
                return HttpResponseForbidden()
        else:
            parent_msg = None

        if compose_form.is_valid():
            compose_form.save(parent_msg=parent_msg)
            django_messages.success(request, 'Message sent.')
            compose_form = ComposeForm(request.user)
    else:
        if receiver is not None:
            form_data = {'receiver': receiver}
            compose_form = ComposeForm(request.user, initial=form_data)
        else:
            compose_form = ComposeForm(request.user)

        _quota_check('outbox', Message.objects.outbox(request.user).count(), request)

    return render(request, 'messages/compose_tab.html', {
        'compose_form': compose_form,
        })


def _only_integers(slist):
    """
    Accepts a list of strings. Returns a list of integers consisting of only
    those elements from the original list that could be converted to integers

    """
    result = []
    for s in slist:
        try:
            n = int(s)
        except ValueError:
            pass
        else:
            result.append(n)
    return result


def _delete_msgs(user, msg_ids):
    """
    Deletes the messages given by the list of msg_ids. For this to succeed, the
    user has to be either the sender or receiver on each message.

    """
    msg_ids = _only_integers(msg_ids)
    msgs = Message.objects.filter(id__in=msg_ids)

    for msg in msgs:
        if msg.sender == user:
            if (msg.receiver_delete_date is not None or
                    msg.read_date is None):
                # Both parties deleted the message or receiver hasn't read it
                # yet, we can delete it now
                msg.delete()
            else:
                # receiver still has it in inbox
                msg.sender_delete_date = datetime.datetime.now()
                msg.save()

        elif msg.receiver == user:
            if msg.sender_delete_date is not None:
                # both parties deleted the message, we can delete it now
                msg.delete()
            else:
                # sender still has it in the outbox
                msg.receiver_delete_date = datetime.datetime.now()
                msg.save()


def _undelete_msgs(user, msg_ids):
    """
    Attempts to "undelete" the messages given by the msg_ids list.
    This will only succeed if the user is either the sender or receiver.

    """
    msg_ids = _only_integers(msg_ids)
    msgs = Message.objects.filter(id__in=msg_ids)
    for msg in msgs:
        if msg.sender == user:
            msg.sender_delete_date = None
            msg.save()
        elif msg.receiver == user:
            msg.receiver_delete_date = None
            msg.save()


def bulk(request):
    """
    This view processes messages in bulk. Arrays of message ids are expected in
    the POST query dict: inbox_ids and outbox_ids will be deleted; trash_ids will
    be undeleted.

    """
    if not request.user.is_authenticated():
        return HttpResponseForbidden()
    if request.method != 'POST':
        return HttpResponseNotAllowed(['POST'])

    delete_ids = []
    if 'inbox_ids' in request.POST:
        delete_ids.extend(request.POST.getlist('inbox_ids'))
    if 'outbox_ids' in request.POST:
        delete_ids.extend(request.POST.getlist('outbox_ids'))

    if len(delete_ids):
        _delete_msgs(request.user, delete_ids)

    if 'trash_ids' in request.POST:
        _undelete_msgs(request.user, request.POST.getlist('trash_ids'))

    return HttpResponse('');