#    Society Self-Service
#    Copyright © 2018  Yingtong Li (RunasSudo)
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU Affero General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU Affero General Public License for more details.
#
#    You should have received a copy of the GNU Affero General Public License
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.

from django.contrib.auth.decorators import login_required
from django.contrib.auth.models import User
from django.core.exceptions import PermissionDenied
from django.core.validators import validate_email

from django.db import transaction
from django.shortcuts import render, redirect
from django.urls import reverse
from django.utils import timezone
from django.views import generic

from . import models

import itertools
import json

@login_required
def index(request):
	return render(request, 'sstreasury/index.html')

@login_required
def budget_list(request):
	budgets_action = []
	budgets_open = []
	budgets_closed = []
	
	for budget in models.Budget.objects.all():
		revision = budget.budgetrevision_set.reverse()[0]
		state = models.BudgetState(revision.state)
		if state in [models.BudgetState.DRAFT, models.BudgetState.RESUBMIT]:
			budgets_action.append(revision)
		elif state in [models.BudgetState.AWAIT_REVIEW, models.BudgetState.ENDORSED]:
			budgets_open.append(revision)
		else:
			budgets_closed.append(revision)
	
	return render(request, 'sstreasury/budget_list.html', {
		'budgets_action': budgets_action,
		'budgets_open': budgets_open,
		'budgets_closed': budgets_closed
	})

@login_required
def budget_view(request, id):
	budget = models.Budget.objects.get(id=id)
	
	if 'revision' in request.GET:
		revision = budget.budgetrevision_set.get(id=int(request.GET['revision']))
	else:
		revision = budget.budgetrevision_set.reverse()[0]
	
	history = list(itertools.chain(budget.budgetrevision_set.all(), revision.budget.budgetcomment_set.all()))
	history.sort(key=lambda x: x.time, reverse=True)
	
	return render(request, 'sstreasury/budget_view.html', {
		'revision': revision,
		'history': history,
		'is_latest': 'revision' not in request.GET
	})

def revision_from_form(budget, revision, form):
	revision.budget = budget
	
	revision.name = form['name']
	revision.date = form['date'] if form['date'] else None
	
	revision.comments = form['comments']
	revision.state = models.BudgetState.DRAFT.value
	revision.revenue = json.loads(form['revenue'])
	revision.revenue_comments = form['revenue_comments']
	revision.expense = json.loads(form['expense'])
	revision.expense_comments = form['expense_comments']
	revision.expense_no_emergency_fund = True if form.get('expense_no_emergency_fund', False) else False
	
	revision.save()
	
	contributors = form['contributors'].split('\n')
	for contributor in contributors:
		validate_email(contributor.strip())
	for contributor in contributors:
		try:
			user = User.objects.get(email=contributor.strip())
		except User.DoesNotExist:
			user = User.objects.create_user(contributor.strip().split('@')[0], contributor.strip())
		revision.contributors.add(user)
	
	revision.save()
	
	return revision

@login_required
def budget_new(request):
	if request.method == 'POST':
		with transaction.atomic():
			budget = models.Budget()
			budget.save()
			revision = models.BudgetRevision()
			revision.author = request.user
			revision.time = timezone.now()
			revision = revision_from_form(budget, revision, request.POST)
		
		if request.POST['submit'] == 'Save':
			return redirect(reverse('budget_view', kwargs={'id': budget.id}))
		else:
			return redirect(reverse('budget_edit', kwargs={'id': budget.id}))
	else:
		budget = models.Budget()
		revision = models.BudgetRevision()
		revision.budget = budget
		
		return render(request, 'sstreasury/budget_edit.html', {
			'revision': revision,
			'contributors': request.user.email
		})

@login_required
def budget_edit(request, id):
	if request.method == 'POST':
		budget = models.Budget.objects.get(id=id)
		revision = budget.budgetrevision_set.reverse()[0]
		
		if request.user not in revision.contributors.all():
			raise PermissionDenied
		
		with transaction.atomic():
			revision = models.BudgetRevision()
			revision.author = request.user
			revision.time = timezone.now()
			revision = revision_from_form(budget, revision, request.POST)
		
		if request.POST['submit'] == 'Save':
			return redirect(reverse('budget_view', kwargs={'id': budget.id}))
		else:
			return redirect(reverse('budget_edit', kwargs={'id': budget.id}))
	else:
		budget = models.Budget.objects.get(id=id)
		revision = budget.budgetrevision_set.reverse()[0]
		
		return render(request, 'sstreasury/budget_edit.html', {
			'revision': revision,
			'contributors': '\n'.join(revision.contributors.all().values_list('email', flat=True))
		})

@login_required
def budget_action(request, id):
	budget = models.Budget.objects.get(id=id)
	revision = budget.budgetrevision_set.reverse()[0]
	
	if request.user not in revision.contributors.all():
		raise PermissionDenied
	
	if request.POST['action'] == 'Comment':
		comment = models.BudgetComment()
		comment.budget = budget
		comment.author = request.user
		comment.time = timezone.now()
		comment.content = request.POST['comment']
		comment.save()
	
	return redirect(reverse('budget_view', kwargs={'id': budget.id}))