#   Eos - Verifiable elections
#   Copyright © 2017  RunasSudo (Yingtong Li)
#
#   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 <http://www.gnu.org/licenses/>.

from eos.core.tests import *

from eos.core.bigint import *
from eos.core.hashing import *
from eos.psr.bitstream import *
from eos.psr.crypto import *
from eos.psr.election import *
from eos.psr.mixnet import *
from eos.psr.workflow import *

class EGTestCase(EosTestCase):
	def test_eg(self):
		pt = DEFAULT_GROUP.random_element()
		sk = EGPrivateKey.generate()
		ct = sk.public_key.encrypt(pt)
		m = sk.decrypt(ct)
		self.assertEqualJSON(pt, m)

class SEGTestCase(EosTestCase):
	def test_eg(self):
		pt = DEFAULT_GROUP.random_element()
		sk = SEGPrivateKey.generate()
		ct = sk.public_key.encrypt(pt)
		self.assertTrue(ct.is_signature_valid())
		m = sk.decrypt(ct)
		self.assertEqualJSON(pt, m)
		
		ct2, _ = ct.reencrypt()
		m2 = sk.decrypt(ct2)
		self.assertEqualJSON(pt, m2)

class BitStreamTestCase(EosTestCase):
	def test_bitstream(self):
		bs = BitStream(BigInt('100101011011', 2))
		self.assertEqual(bs.read(4), 0b1001)
		self.assertEqual(bs.read(4), 0b0101)
		self.assertEqual(bs.read(4), 0b1011)
		bs = BitStream()
		bs.write(BigInt('100101011011', 2))
		bs.seek(0)
		self.assertEqual(bs.read(4), 0b1001)
		self.assertEqual(bs.read(4), 0b0101)
		self.assertEqual(bs.read(4), 0b1011)
		bs.seek(4)
		bs.write(BigInt('11', 2))
		bs.seek(0)
		self.assertEqual(bs.read(4), 0b1001)
		self.assertEqual(bs.read(4), 0b1101)
		self.assertEqual(bs.read(4), 0b0110)
		self.assertEqual(bs.read(2), 0b11)
	
	def test_bitstream_map(self):
		bs = BitStream(BigInt('100101011011', 2))
		result = bs.map(lambda x: x, 4)
		expect = [0b1001, 0b0101, 0b1011]
		for i in range(len(expect)):
			self.assertEqual(result[i], expect[i])
	
	def test_strings(self):
		bs = BitStream()
		bs.write_string('Hello World!')
		bs.seek(0)
		self.assertEqual(bs.read(32), len('Hello World!'))
		bs.seek(0)
		self.assertEqual(bs.read_string(), 'Hello World!')

class BlockEGTestCase(EosTestCase):
	@classmethod
	def setUpClass(cls):
		class Person(TopLevelObject):
			name = StringField()
			address = StringField(default=None)
			def say_hi(self):
				return 'Hello! My name is ' + self.name
		
		cls.Person = Person
		
		#cls.test_group = CyclicGroup(p=BigInt('11'), g=BigInt('2'))
		cls.test_group = CyclicGroup(p=BigInt('283'), g=BigInt('60'))
		cls.sk = EGPrivateKey.generate(cls.test_group)
	
	def test_basic(self):
		pt = BigInt('11010010011111010100101', 2)
		ct = BitStream(pt).multiple_of(self.test_group.p.nbits() - 1).map(self.sk.public_key.encrypt, self.test_group.p.nbits() - 1)
		for i in range(len(ct)):
			self.assertTrue(ct[i].gamma < self.test_group.p)
			self.assertTrue(ct[i].delta < self.test_group.p)
		m = BitStream.unmap(ct, self.sk.decrypt, self.test_group.p.nbits() - 1).read()
		self.assertEqualJSON(pt, m)
	
	def test_object(self):
		obj = self.Person(name='John Smith')
		
		ct = BlockEncryptedAnswer.encrypt(self.sk.public_key, obj)
		m = ct.decrypt(self.sk)
		
		self.assertEqualJSON(obj, m)

class MixnetTestCase(EosTestCase):
	@py_only
	def test_mixnet(self):
		# Generate key
		sk = SEGPrivateKey.generate()
		
		# Generate plaintexts
		pts = []
		for i in range(4):
			pts.append(sk.public_key.group.random_element())
		
		# Encrypt plaintexts
		answers = []
		for i in range(len(pts)):
			bs = BitStream(pts[i])
			bs.multiple_of(sk.public_key.group.p.nbits() - 1)
			ct = bs.map(sk.public_key.encrypt, sk.public_key.group.p.nbits() - 1)
			answers.append(BlockEncryptedAnswer(blocks=ct))
		
		def do_mixnet(mix_order):
			# Set up mixnet
			mixnet = RPCMixnet(mix_order)
			
			# Mix answers
			shuffled_answers, commitments = mixnet.shuffle(answers)
			
			# Decrypt shuffle
			msgs = []
			for i in range(len(shuffled_answers)):
				bs = BitStream.unmap(shuffled_answers[i].blocks, sk.decrypt, sk.public_key.group.p.nbits() - 1)
				m = bs.read()
				msgs.append(m)
			
			# Check decryption
			self.assertEqual(set(int(x) for x in pts), set(int(x) for x in msgs))
			
			# Check commitments
			def verify_shuffle(idx_left, idx_right, reencs):
				claimed_blocks = shuffled_answers[idx_right].blocks
				for j in range(len(answers[idx_left].blocks)):
					reencrypted_block, _ = answers[idx_left].blocks[j].reencrypt(reencs[j])
					self.assertEqual(claimed_blocks[j].gamma, reencrypted_block.gamma)
					self.assertEqual(claimed_blocks[j].delta, reencrypted_block.delta)
			
			for i in range(len(pts)):
				perm, reencs, rand = mixnet.challenge(i)
				val_obj = MixChallengeResponse(index=perm, reenc=reencs, rand=rand)
				self.assertEqual(commitments[i], SHA256().update_text(EosObject.to_json(val_obj.serialise())).hash_as_bigint())
				
				if mixnet.is_left:
					verify_shuffle(i, perm, reencs)
				else:
					verify_shuffle(perm, i, reencs)
		
		# NB: This isn't doing it in sequence, it's just testing a left mixnet and a right mixnet respectively
		do_mixnet(0)
		do_mixnet(1)

class ElectionTestCase(EosTestCase):
	@classmethod
	def setUpClass(cls):
		client.drop_database('test')
	
	def do_task_assert(self, election, task, next_task):
		self.assertEqual(election.workflow.get_task(task).status, WorkflowTask.Status.READY)
		if next_task is not None:
			self.assertEqual(election.workflow.get_task(next_task).status, WorkflowTask.Status.NOT_READY)
		election.workflow.get_task(task).enter()
		self.assertEqual(election.workflow.get_task(task).status, WorkflowTask.Status.EXITED)
		if next_task is not None:
			self.assertEqual(election.workflow.get_task(next_task).status, WorkflowTask.Status.READY)
	
	@py_only
	def test_run_election(self):
		# Set up election
		election = PSRElection()
		election.workflow = PSRWorkflow()
		
		# Set election details
		election.name = 'Test Election'
		
		for i in range(3):
			voter = Voter()
			election.voters.append(voter)
		
		for i in range(3):
			mixing_trustee = MixingTrustee()
			election.mixing_trustees.append(mixing_trustee)
		
		election.sk = EGPrivateKey.generate()
		
		question = ApprovalQuestion(prompt='President', choices=['John Smith', 'Joe Bloggs', 'John Q. Public'])
		election.questions.append(question)
		
		question = ApprovalQuestion(prompt='Chairman', choices=['John Doe', 'Andrew Citizen'])
		election.questions.append(question)
		
		election.save()
		
		# Freeze election
		self.do_task_assert(election, 'eos.base.workflow.TaskConfigureElection', 'eos.base.workflow.TaskOpenVoting')
		
		# Open voting
		self.do_task_assert(election, 'eos.base.workflow.TaskOpenVoting', 'eos.base.workflow.TaskCloseVoting')
		election.save()
		
		# Cast ballots
		VOTES = [[[0], [0]], [[0, 1], [1]], [[2], [0]]]
		
		for i in range(3):
			ballot = Ballot()
			for j in range(2):
				answer = ApprovalAnswer(choices=VOTES[i][j])
				encrypted_answer = BlockEncryptedAnswer.encrypt(election.sk.public_key, answer)
				ballot.encrypted_answers.append(encrypted_answer)
			election.voters[i].ballots.append(ballot)
		
		election.save()
		
		# Close voting
		self.do_task_assert(election, 'eos.base.workflow.TaskCloseVoting', 'eos.psr.workflow.TaskMixVotes')
		election.save()
		
		# Mix votes
		election.workflow.get_task('eos.psr.workflow.TaskMixVotes').enter()
		election.save()
		
		# Do the mix
		for i in range(len(election.questions)):
			for j in range(len(election.mixing_trustees)):
				# Wouldn't happen server-side IRL
				election.mixing_trustees[j].mixnets.append(RPCMixnet(j))
				if j > 0:
					orig_answers = election.mixing_trustees[j - 1].mixed_questions[i]
				else:
					orig_answers = []
					for voter in election.voters:
						for ballot in voter.ballots:
							orig_answers.append(ballot.encrypted_answers[i])
				shuffled_answers, commitments = election.mixing_trustees[j].mixnets[i].shuffle(orig_answers)
				election.mixing_trustees[j].mixed_questions.append(EosList(shuffled_answers))
				election.mixing_trustees[j].commitments.append(EosList(commitments))
		
		election.workflow.get_task('eos.psr.workflow.TaskMixVotes').exit()
		election.save()
		
		# Verify mixes
		election.workflow.get_task('eos.psr.workflow.TaskVerifyMixes').enter()
		election.save()
		
		# Record challenge responses
		for i in range(len(election.questions)):
			for j in range(len(election.mixing_trustees)):
				trustee = election.mixing_trustees[j]
				if j % 2 == 0:
					trustee.challenge.append(trustee.compute_challenge(i).hash_as_bigint())
				else:
					trustee.challenge.append(election.mixing_trustees[j - 1].challenge[i])
				challenge_bs = InfiniteHashBitStream(trustee.challenge[i])
				
				trustee.response.append(EosList())
				
				nbits = BigInt(len(trustee.mixed_questions[i])).nbits()
				for k in range(len(trustee.mixed_questions[i])):
					challenge_bit = challenge_bs.read(1)
					should_reveal = ((j % 2) == (challenge_bit % 2))
					if should_reveal:
						response = trustee.mixnets[i].challenge(k)
						trustee.response[i].append(MixChallengeResponse(
							challenge_index=k,
							response_index=response[0],
							reenc=response[1],
							rand=response[2]
						))
		
		election.workflow.get_task('eos.psr.workflow.TaskVerifyMixes').exit()
		election.save()
		
		# Decrypt votes, for realsies
		self.do_task_assert(election, 'eos.base.workflow.TaskDecryptVotes', 'eos.base.workflow.TaskReleaseResults')
		election.save()
		
		# Check result
		RESULTS = [[[0], [0, 1], [2]], [[0], [1], [0]]]
		for i in range(len(RESULTS)):
			votes1 = RESULTS[i]
			votes2 = [x.choices for x in election.results[i].answers]
			self.assertEqual(sorted(votes1), sorted(votes2))
		
		# Release result
		self.do_task_assert(election, 'eos.base.workflow.TaskReleaseResults', None)
		election.save()