#    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

# HELPER DECORATORS

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 not revision.can_view(request.user):
			raise PermissionDenied
		return viewfunc(request, budget, revision)
	return func

def budget_editable(viewfunc):
	@functools.wraps(viewfunc)
	def func(request, budget, revision):
		if not revision.can_edit(request.user):
			raise PermissionDenied
		return viewfunc(request, budget, revision)
	return func

def uses_claim(viewfunc):
	@functools.wraps(viewfunc)
	def func(request, id):
		claim = models.ReimbursementClaim.objects.get(id=id)
		return viewfunc(request, claim)
	return func

def claim_viewable(viewfunc):
	@functools.wraps(viewfunc)
	def func(request, claim):
		if not claim.can_view(request.user):
			raise PermissionDenied
		return viewfunc(request, claim)
	return func

def claim_editable(viewfunc):
	@functools.wraps(viewfunc)
	def func(request, claim):
		if not claim.can_edit(request.user):
			raise PermissionDenied
		return viewfunc(request, claim)
	return func

# HELPER FUNCTIONS

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.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

def claim_from_form(claim, form):
	claim.purpose = form['purpose']
	claim.date = form['date'] if form['date'] else None
	claim.budget_id = form['budget_id']
	
	claim.comments = form['comments']
	claim.state = models.ClaimState.DRAFT.value
	claim.items = json.loads(form['items'])
	
	claim.save()
	
	return claim

# INDEX VIEW

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

# BUDGET VIEWS

@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
		elif request.user.groups.filter(name='Committee').exists() and state == models.BudgetState.ENDORSED:
			group = budgets_action
		elif request.user == revision.author or 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
		elif 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
@uses_budget
def budget_view(request, budget, revision):
	if 'revision' in request.GET:
		revision = budget.budgetrevision_set.get(id=int(request.GET['revision']))
	
	if not revision.can_view(request.user):
		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
@uses_budget
def budget_print(request, budget, revision):
	if 'revision' in request.GET:
		revision = budget.budgetrevision_set.get(id=int(request.GET['revision']))
	
	if not revision.can_view(request.user):
		raise PermissionDenied
	
	return render(request, 'sstreasury/budget_print.html', {
		'revision': revision,
		'is_latest': 'revision' not in request.GET
	})

@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.state = models.BudgetState.DRAFT.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
		})

@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/budget_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/budget_commented.md', {'revision': revision, 'comment': comment})
	
	if 'Submit' in actions:
		if not revision.can_submit(request.user):
			raise PermissionDenied
		
		with transaction.atomic():
			revision.update_state(request.user, models.BudgetState.AWAIT_REVIEW)
			
			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/budget_submitted_treasurer.md', {'revision': revision})
			for user in revision.contributors.all():
				emailer.send_mail([user.email], 'Budget submitted: {}'.format(revision.name), 'sstreasury/email/budget_submitted_drafter.md', {'revision': revision})
	
	if 'Withdraw' in actions:
		if not revision.can_withdraw(user):
			raise PermissionDenied
		
		with transaction.atomic():
			revision.update_state(request.user, models.BudgetState.DRAFT)
	
	if 'Endorse' in actions:
		if not revision.can_endorse(user):
			raise PermissionDenied
		
		with transaction.atomic():
			revision.update_state(request.user, models.BudgetState.ENDORSED)
			
			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/budget_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/budget_endorsed_drafter.md', {'revision': revision})
	
	if 'Return' in actions:
		if not revision.can_return(user):
			raise PermissionDenied
		
		with transaction.atomic():
			revision.update_state(request.user, models.BudgetState.RESUBMIT)
			
			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/budget_returned.md', {'revision': revision})
	
	if 'Approve' in actions:
		if not revision.can_approve(user):
			return PermissionDenied
		
		with transaction.atomic():
			revision.update_state(request.user, models.BudgetState.APPROVED)
			
			emailer = Emailer()
			for user in revision.contributors.all():
				emailer.send_mail([user.email], 'Budget approved: {}'.format(revision.name), 'sstreasury/email/budget_approved.md', {'revision': revision})
	
	if 'CmteReturn' in actions:
		if not revision.can_cmtereturn(user):
			return PermissionDenied
		
		with transaction.atomic():
			revision.update_state(request.user, models.BudgetState.RESUBMIT)
			
			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/budget_returned_committee.md', {'revision': revision})
	
	return redirect(reverse('budget_view', kwargs={'id': budget.id}))

@login_required
def claim_list(request):
	claims_action = []
	claims_open = []
	claims_closed = []
	
	for claim in models.ReimbursementClaim.objects.all():
		state = models.ClaimState(claim.state)
		
		group = None
		
		if request.user.groups.filter(name='Treasury').exists() and state in [models.ClaimState.AWAIT_REVIEW, models.ClaimState.APPROVED]:
			group = claims_action
		elif request.user == claim.author:
			if state in [models.ClaimState.DRAFT, models.ClaimState.RESUBMIT]:
				group = claims_action
			elif state in [models.ClaimState.AWAIT_REVIEW, models.ClaimState.APPROVED]:
				group = claims_open
			else:
				group = claims_closed
		elif request.user.groups.filter(name='Treasury').exists():
			if state == models.ClaimState.APPROVED:
				group = claims_closed
			else:
				group = claims_open
		
		if group is not None:
			group.append(claim)
	
	return render(request, 'sstreasury/claim_list.html', {
		'claims_action': claims_action,
		'claims_open': claims_open,
		'claims_closed': claims_closed
	})

@login_required
def claim_new(request):
	if request.method == 'POST':
		with transaction.atomic():
			claim = models.ReimbursementClaim()
			claim.author = request.user
			claim.time = timezone.now()
			claim.state = models.BudgetState.DRAFT.value
			claim = claim_from_form(claim, request.POST)
			
			claim_history = models.ClaimHistory()
			claim_history.claim = claim
			claim_history.author = request.user
			claim_history.state = claim.state
			claim_history.time = timezone.now()
			claim_history.action = models.ClaimAction.CREATE.value
			claim_history.save()
		
		if request.POST['submit'] == 'Save':
			return redirect(reverse('claim_view', kwargs={'id': claim.id}))
		else:
			return redirect(reverse('claim_edit', kwargs={'id': claim.id}))
		pass
	else:
		claim = models.ReimbursementClaim()
		claim.author = request.user
		
		return render(request, 'sstreasury/claim_edit.html', {
			'claim': claim
		})

@login_required
@uses_claim
@claim_viewable
def claim_view(request, claim):
	history = list(itertools.chain(claim.claimhistory_set.all(), claim.claimcomment_set.all()))
	history.sort(key=lambda x: x.time, reverse=True)
	
	return render(request, 'sstreasury/claim_view.html', {
		'claim': claim,
		'history': history
	})

@login_required
@uses_claim
@claim_viewable
def claim_print(request, claim):
	return render(request, 'sstreasury/claim_print.html', {
		'claim': claim
	})

@login_required
@uses_claim
@claim_editable
def claim_edit(request, claim):
	if request.method == 'POST':
		if request.POST['submit'] == 'Delete':
			claim.delete()
			return redirect(reverse('claim_list'))
		
		with transaction.atomic():
			claim = claim_from_form(claim, request.POST)
			
			claim_history = models.ClaimHistory()
			claim_history.claim = claim
			claim_history.author = request.user
			claim_history.state = claim.state
			claim_history.time = timezone.now()
			claim_history.action = models.ClaimAction.EDIT.value
			claim_history.save()
		
		if request.POST['submit'] == 'Save':
			return redirect(reverse('claim_view', kwargs={'id': claim.id}))
		else:
			return redirect(reverse('claim_edit', kwargs={'id': claim.id}))
	else:
		return render(request, 'sstreasury/claim_edit.html', {
			'claim': claim
		})

@login_required
@uses_claim
@claim_editable
def claim_action(request, claim):
	actions = request.POST['action'].split(',')
	
	if 'Comment' in actions and request.POST.get('comment', None):
		with transaction.atomic():
			comment = models.ClaimComment()
			comment.claim = claim
			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 reimbursement claim: {}'.format(claim.purpose), 'sstreasury/email/claim_commented.md', {'claim': claim, 'comment': comment})
			if comment.author != request.user:
				emailer.send_mail([comment.author], 'New comment on reimbursement claim: {}'.format(revision.name), 'sstreasury/email/claim_commented.md', {'claim': claim, 'comment': comment})
	
	if 'Submit' in actions:
		if not claim.can_submit(request.user):
			raise PermissionDenied
		
		with transaction.atomic():
			claim.update_state(request.user, models.ClaimState.AWAIT_REVIEW)
			
			emailer = Emailer()
			for user in User.objects.filter(groups__name='Treasury'):
				emailer.send_mail([user.email], 'Action required: Reimbursement claim submitted: {}'.format(claim.purpose), 'sstreasury/email/claim_submitted_treasurer.md', {'claim': claim})
			emailer.send_mail([claim.author.email], 'Reimbursement claim submitted: {}'.format(claim.purpose), 'sstreasury/email/claim_submitted_drafter.md', {'claim': claim})
	
	if 'Withdraw' in actions:
		if not claim.can_withdraw(request.user):
			raise PermissionDenied
		
		with transaction.atomic():
			claim.update_state(request.user, models.ClaimState.DRAFT)
	
	if 'Approve' in actions:
		if not claim.can_approve(request.user):
			raise PermissionDenied
		
		with transaction.atomic():
			claim.update_state(request.user, models.ClaimState.APPROVED)
			
			emailer = Emailer()
			emailer.send_mail([claim.author.email], 'Claim approved, awaiting payment: {}'.format(claim.purpose), 'sstreasury/email/claim_approved.md', {'claim': claim})
	
	if 'Return' in actions:
		if not claim.can_approve(request.user):
			raise PermissionDenied
		
		with transaction.atomic():
			claim.update_state(request.user, models.ClaimState.RESUBMIT)
			
			emailer = Emailer()
			emailer.send_mail([claim.author.email], 'Action required: Reimbursement claim returned for re-drafting: {}'.format(claim.purpose), 'sstreasury/email/claim_returned.md', {'claim': claim})
	
	return redirect(reverse('claim_view', kwargs={'id': claim.id}))