from django.contrib.auth.decorators import login_required
from django.shortcuts import render, redirect, get_object_or_404
from django.core.exceptions import PermissionDenied
from django.contrib import messages
from django.urls import reverse
from django.http import HttpResponse
from django.views.decorators.csrf import csrf_exempt
from django.views.decorators.http import require_POST
from django.utils import timezone
from django.db.models import Count, Q

from .models import TaskList, Task
from .forms import TaskForm, CommentForm
from .decorators import allowed_tasklist_required


@login_required
def tasklist_list(request):
    lists = TaskList.objects.all()
    if not request.user.is_superuser:
        lists = lists.filter(group__in=request.user.groups.all())
    lists = lists.order_by('name')
    lists = lists.annotate(own_uncompleted_task_count=Count('task', filter=Q(task__completed_date__isnull=True, task__assigned_to=request.user)))
    return render(request, 'todo/tasklist_list.html', {
        'lists': lists,
        'task_count': Task.objects.filter(completed_date__isnull=True, task_list__in=lists).count(),
        'list_count': lists.count(),
    })


@allowed_tasklist_required
def tasklist_detail(request, tasklist, completed=False):
    task_list = tasklist.task_set.filter(completed_date__isnull=not completed)
    return render(request, 'todo/tasklist_detail.html', {
        'tasklist': tasklist,
        'task_list': task_list,
        'completed': completed,
    })


@allowed_tasklist_required
def tasklist_reorder(request, tasklist):
    newtasklist = request.POST.getlist("tasktable[]")
    if newtasklist:
        # Re-prioritize each task in list
        i = 1
        for pk in newtasklist:
            try:
                task = Task.objects.get(task_list=tasklist, pk=pk)
                task.priority = i
                task.save()
                i += 1
            except Task.DoesNotExist:
                # Can occur if task is deleted behind the scenes during re-ordering.
                # Not easy to remove it from the UI without page refresh, but prevent crash.
                pass
    # All views must return an httpresponse of some kind ... without this we get
    # error 500s in the log even though things look peachy in the browser.
    return HttpResponse(status=201)


@allowed_tasklist_required
def task_form(request, tasklist, task_id=None):
    if task_id:
        task = get_object_or_404(Task, task_list=tasklist, pk=task_id)
        redirect_url = reverse('todo:show-task', kwargs={'tasklist_slug': tasklist.slug, 'task_id': task.pk})
    else:
        task = None
        redirect_url = reverse('todo:show-tasklist', kwargs={'tasklist_slug': tasklist.slug})
    form = TaskForm(request.POST or None, tasklist=tasklist, instance=task)
    if request.method == 'POST' and form.is_valid():
        if task:
            form.save()
            messages.success(request, 'Tâche mise à jour avec succès.')
        else:
            task = form.save(commit=False)
            task.task_list = tasklist
            task.created_by = request.user
            task.save()
            messages.success(request, 'Tâche créée avec succès.')
        return redirect(redirect_url)
    return render(request, 'todo/task_form.html', {
        'tasklist': tasklist,
        'task': task,
        'form': form,
        'cancel_url': redirect_url,
    })


@allowed_tasklist_required
def task_detail(request, tasklist, task_id):
    task = get_object_or_404(Task, task_list=tasklist, pk=task_id)
    form = CommentForm(request.POST or None)
    if request.method == 'POST' and form.is_valid():
        comment = form.save(commit=False)
        comment.task = task
        comment.author = request.user
        comment.save()
        messages.success(request, 'Commentaire ajouté avec succès.')
        return redirect(reverse('todo:show-task', kwargs={'tasklist_slug': tasklist.slug, 'task_id': task_id}))
    return render(request, 'todo/task_detail.html', {
        'tasklist': tasklist,
        'task': task,
        'form': form,
    })


@allowed_tasklist_required
def task_toggle_done(request, tasklist, task_id):
    task = get_object_or_404(Task, task_list=tasklist, pk=task_id)
    if task.completed_date:
        task.completed_date = None
        messages.success(request, "La tâche « {} » a été marquée en cours.".format(task.title))
    else:
        task.completed_date = timezone.now()
        messages.success(request, "La tâche « {} » a été marquée complétée.".format(task.title))
    task.save()
    return redirect(reverse('todo:show-task', kwargs={'tasklist_slug': tasklist.slug, 'task_id': task_id}))


@allowed_tasklist_required
def task_edit(request, tasklist, task_id):
    task = get_object_or_404(Task, task_list=tasklist, pk=task_id)
    form = CommentForm(request.POST)
    if form.is_valid():
        comment = form.save(commit=False)
        comment.save()
        messages.success(request, "La tâche « {} » a été marquée complétée.".format(task.title))
    return redirect(reverse('todo:show-task', kwargs={'tasklist_slug': tasklist.slug, 'task_id': task_id}))


# TODO: are you sure?
@require_POST
@allowed_tasklist_required
def task_delete(request, tasklist, task_id):
    task = get_object_or_404(Task, task_list=tasklist, pk=task_id)
    task.delete()
    messages.success(request, "La tâche « {} » a été supprimée.".format(task.title))
    return redirect(reverse('todo:show-tasklist', kwargs={'tasklist_slug': tasklist.slug}))