#    Society Self-Service
#    Copyright © 2018-2019  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
from ssmain.email import Emailer

import functools
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)
		
		group = None
		
		if request.user.groups.filter(name='Treasury').exists() and state == models.BudgetState.AWAIT_REVIEW:
			group = budgets_action
		elif request.user.groups.filter(name='Secretary').exists() and state == models.BudgetState.ENDORSED:
			group = budgets_action
		else:
			if request.user in revision.contributors.all():
				if state in [models.BudgetState.DRAFT, models.BudgetState.RESUBMIT]:
					group = budgets_action
				elif state in [models.BudgetState.AWAIT_REVIEW, models.BudgetState.ENDORSED]:
					group = budgets_open
				else:
					group = budgets_closed
			else:
				if request.user in revision.contributors.all() or request.user.groups.filter(name='Treasury').exists() or request.user.groups.filter(name='Secretary').exists():
					if state == models.BudgetState.APPROVED:
						group = budgets_closed
					else:
						group = budgets_open
		
		if group is not None:
			group.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]
	
	if request.user not in revision.contributors.all():
		if not request.user.groups.filter(name='Treasury').exists():
			raise PermissionDenied
	
	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
	})

@login_required
def budget_print(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]
	
	if request.user not in revision.contributors.all():
		if not request.user.groups.filter(name='Treasury').exists():
			raise PermissionDenied
	
	return render(request, 'sstreasury/budget_print.html', {
		'revision': revision,
		'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.action = models.BudgetAction.CREATE.value
			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
		})

def uses_budget(viewfunc):
	@functools.wraps(viewfunc)
	def func(request, id):
		budget = models.Budget.objects.get(id=id)
		revision = budget.budgetrevision_set.reverse()[0]
		return viewfunc(request, budget, revision)
	return func

def budget_viewable(viewfunc):
	@functools.wraps(viewfunc)
	def func(request, budget, revision):
		if request.user not in revision.contributors.all():
			if not request.user.groups.filter(name='Treasury').exists():
				raise PermissionDenied
		
		return viewfunc(request, budget, revision)
	return func

def budget_editable(viewfunc):
	@functools.wraps(viewfunc)
	def func(request, budget, revision):
		if revision.state == models.BudgetState.APPROVED.value:
			raise PermissionDenied
		
		if revision.state != models.BudgetState.DRAFT.value and revision.state != models.BudgetState.RESUBMIT.value:
			if not request.user.groups.filter(name='Treasury').exists():
				raise PermissionDenied
		
		if request.user not in revision.contributors.all():
			if not request.user.groups.filter(name='Treasury').exists():
				raise PermissionDenied
		
		return viewfunc(request, budget, revision)
	return func

@login_required
@uses_budget
@budget_editable
def budget_edit(request, budget, revision):
	if request.method == 'POST':
		if request.POST['submit'] == 'Delete':
			budget.delete()
			return redirect(reverse('budget_list'))
		
		with transaction.atomic():
			revision = models.BudgetRevision()
			revision.author = request.user
			revision.time = timezone.now()
			revision.action = models.BudgetAction.EDIT.value
			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:
		return render(request, 'sstreasury/budget_edit.html', {
			'revision': revision,
			'contributors': '\n'.join(revision.contributors.all().values_list('email', flat=True))
		})

@login_required
@uses_budget
@budget_editable
def budget_action(request, budget, revision):
	actions = request.POST['action'].split(',')
	
	if 'Comment' in actions and request.POST.get('comment', None):
		with transaction.atomic():
			comment = models.BudgetComment()
			comment.budget = budget
			comment.author = request.user
			comment.time = timezone.now()
			comment.content = request.POST['comment']
			comment.save()
			
			emailer = Emailer()
			for user in User.objects.filter(groups__name='Treasury'):
				if user != request.user:
					emailer.send_mail([user.email], 'New comment on budget: {}'.format(revision.name), 'sstreasury/email/commented.md', {'revision': revision, 'comment': comment})
			for user in revision.contributors.all():
				if user != request.user:
					emailer.send_mail([user.email], 'New comment on budget: {}'.format(revision.name), 'sstreasury/email/commented.md', {'revision': revision, 'comment': comment})
	
	if 'Submit' in actions:
		if revision.state != models.BudgetState.DRAFT.value and revision.state != models.BudgetState.RESUBMIT.value:
			raise PermissionDenied
		
		with transaction.atomic():
			revision.copy()
			revision.author = request.user
			revision.time = timezone.now()
			revision.state = models.BudgetState.AWAIT_REVIEW.value
			revision.action = models.BudgetAction.UPDATE_STATE.value
			revision.save()
			
			emailer = Emailer()
			for user in User.objects.filter(groups__name='Treasury'):
				emailer.send_mail([user.email], 'Action required: Budget submitted: {}'.format(revision.name), 'sstreasury/email/submitted_treasurer.md', {'revision': revision})
			for user in revision.contributors.all():
				emailer.send_mail([user.email], 'Budget submitted: {}'.format(revision.name), 'sstreasury/email/submitted_drafter.md', {'revision': revision})
	
	if 'Withdraw' in actions:
		if revision.state == models.BudgetState.DRAFT.value or revision.state == models.BudgetState.RESUBMIT.value or revision.state == models.BudgetState.APPROVED.value:
			raise PermissionDenied
		
		revision.copy()
		revision.author = request.user
		revision.time = timezone.now()
		revision.state = models.BudgetState.DRAFT.value
		revision.action = models.BudgetAction.UPDATE_STATE.value
		revision.save()
	
	if 'Endorse' in actions:
		if revision.state != models.BudgetState.AWAIT_REVIEW.value:
			raise PermissionDenied
		if not request.user.groups.filter(name='Treasury').exists():
			raise PermissionDenied
		
		with transaction.atomic():
			revision.copy()
			revision.author = request.user
			revision.time = timezone.now()
			revision.state = models.BudgetState.ENDORSED.value
			revision.action = models.BudgetAction.UPDATE_STATE.value
			revision.save()
			
			emailer = Emailer()
			for user in User.objects.filter(groups__name='Secretary'):
				emailer.send_mail([user.email], 'Action required: Budget endorsed: {}'.format(revision.name), 'sstreasury/email/endorsed_secretary.md', {'revision': revision})
			for user in revision.contributors.all():
				emailer.send_mail([user.email], 'Budget endorsed, awaiting committee approval: {}'.format(revision.name), 'sstreasury/email/endorsed.md', {'revision': revision})
	
	if 'Return' in actions:
		if revision.state != models.BudgetState.AWAIT_REVIEW.value:
			raise PermissionDenied
		if not request.user.groups.filter(name='Treasury').exists():
			raise PermissionDenied
		
		with transaction.atomic():
			revision.copy()
			revision.author = request.user
			revision.time = timezone.now()
			revision.state = models.BudgetState.RESUBMIT.value
			revision.action = models.BudgetAction.UPDATE_STATE.value
			revision.save()
			
			emailer = Emailer()
			for user in revision.contributors.all():
				emailer.send_mail([user.email], 'Action required: Budget returned for re-drafting: {}'.format(revision.name), 'sstreasury/email/returned.md', {'revision': revision})
	
	if 'Approve' in actions:
		if revision.state == models.BudgetState.APPROVED.value:
			raise PermissionDenied
		if not request.user.groups.filter(name='Secretary').exists():
			raise PermissionDenied
		
		with transaction.atomic():
			revision.copy()
			revision.author = request.user
			revision.time = timezone.now()
			revision.state = models.BudgetState.APPROVED.value
			revision.action = models.BudgetAction.UPDATE_STATE.value
			revision.save()
			
			emailer = Emailer()
			for user in revision.contributors.all():
				emailer.send_mail([user.email], 'Budget approved: {}'.format(revision.name), 'sstreasury/email/approved.md', {'revision': revision})
	
	if 'CmteReturn' in actions:
		if revision.state == models.BudgetState.APPROVED.value:
			raise PermissionDenied
		if not request.user.groups.filter(name='Secretary').exists():
			raise PermissionDenied
		
		with transaction.atomic():
			revision.copy()
			revision.author = request.user
			revision.time = timezone.now()
			revision.state = models.BudgetState.RESUBMIT.value
			revision.action = models.BudgetAction.UPDATE_STATE.value
			revision.save()
			
			emailer = Emailer()
			for user in revision.contributors.all():
				emailer.send_mail([user.email], 'Action required: Budget returned for re-drafting: {}'.format(revision.name), 'sstreasury/email/returned_committee.md', {'revision': revision})
	
	return redirect(reverse('budget_view', kwargs={'id': budget.id}))