# GNU GPLv3, see LICENSE

import random
from unittest import TestCase

from shamira import _shareByte
from shamira import *


class TestShamira(TestCase):
	_urandom=os.urandom

	@classmethod
	def setUpClass(cls):
		random.seed(17)
		os.urandom=lambda n: bytes(random.randint(0,255) for i in range(n))

	@classmethod
	def tearDownClass(cls):
		os.urandom=cls._urandom

	def test_shareByte(self):
		with self.assertRaises(AssertionError): # too few shares
			_shareByte(b"a",5,4)
		with self.assertRaises(AssertionError): # too many shares
			_shareByte(b"a",5,255)
		with self.assertRaises(ValueError): # not castable to int
			_shareByte("x",2,3)

		vals=_shareByte(ord(b"a"),2,3)
		points=list(zip(range(1,256), vals))
		self.assertEqual(gf256.getConstantCoef(*points), ord(b"a"))
		self.assertEqual(gf256.getConstantCoef(*points[:2]), ord(b"a"))
		self.assertNotEqual(gf256.getConstantCoef(*points[:1]), ord(b"a")) # underdetermined => random

	def testGenerateReconstructRaw(self):
		for (k,n) in [(2,3), (254,254)]:
			shares=generateRaw(b"abcd",k,n)
			random.shuffle(shares)
			self.assertEqual(reconstructRaw(*shares[:k]), b"abcd")
			self.assertNotEqual(reconstructRaw(*shares[:k-1]), b"abcd")

	def testGenerateReconstruct(self):
		for encoding in ["hex","b32","b64"]:
			for secret in [b"abcd","abcde","ěščřžý"]:
				for (k,n) in [(2,3), (254,254)]:
					raw=isinstance(secret,bytes)
					with self.subTest(enc=encoding,r=raw,sec=secret,k=k,n=n):
						shares=generate(secret,k,n,encoding)
						random.shuffle(shares)
						self.assertEqual(reconstruct(*shares[:k],encoding=encoding,raw=raw), secret)
						self.assertEqual(reconstruct(*shares[:k],raw=raw), secret)
						s=secret if raw else secret.encode("utf-8")
						self.assertNotEqual(reconstruct(*shares[:k-1],encoding=encoding,raw=True), s)
		shares=generate(b"\xfeaa",2,3)
		with self.assertRaises(UnicodeDecodeError):
			reconstruct(*shares)

	def testEncode(self):
		share=(2,b"\x00\x01\x02")
		for (encoding,encodedStr) in [("hex",'000102'),("b32",'AAAQE==='),("b64",'AAEC')]:
			with self.subTest(enc=encoding):
				self.assertEqual(encode(share,encoding), "2."+encodedStr)

	def testDecode(self):
		with self.assertRaises(ValueError):
			decode("AAA")
			decode("1.")
			decode(".AAA")
			decode("1AAA")
			decode("1.0001020f","hex")
			decode("1.000102030","hex")
			decode("1.AAAQEAY")
			decode("1.AAAQEAy=")
			decode("1.AAECAw=","b64")
			decode("1.AAECA?==","b64")
			decode("256.00010203","hex")
		self.assertEqual(decode("1.00010203","hex"), (1,b"\x00\x01\x02\x03"))
		self.assertEqual(decode("2.AAAQEAY=","b32"), (2,b"\x00\x01\x02\x03"))
		self.assertEqual(decode("3.AAECAw==","b64"), (3,b"\x00\x01\x02\x03"))


	def testDetectEncoding(self):
		for shares in [
			["1.00010f"], # bad case
			["1.000102030"], # bad char count
			["1.AAAQEAY"], # no padding
			["1.AAAQe==="], # bad case
			["1.AAECA?=="], # bad char
			["1.AAECAw="], # bad padding
			["1.000102","2.AAAQEAY="], # mixed encoding
			["1.000102","2.AAECAw=="],
			["1.AAECAw==","2.AAAQE==="],
			[".00010203"], # no index
			["00010203"] # no index
		]:
			with self.subTest(shares=shares):
				with self.assertRaises(ValueError):
					detectEncoding(shares)
		self.assertEqual(detectEncoding(["10.00010203"]), "hex")
		self.assertEqual(detectEncoding(["2.AAAQEAY="]), "b32")
		self.assertEqual(detectEncoding(["3.AAECAw=="]), "b64")
		self.assertEqual(detectEncoding(["3.AAECAwQF","1.00010203"]), "b64")