import argon2, os

from .misc import time_function_pprint


class PasswordHasher:
	'''
	Argon2 password hasher and validator

	Attributes:
		config (dict): The settings used for the hasher

	Methods:
		get_config(key): Get the value of a config options
		set_config(key, value): Set a config option
		hash(password): hash a password and return the digest as a hex string
		verify(hash, password): verify a password and the password hash match
		iteration_test(string, passes, iterations): Time the hashing functionality
	'''

	aliases = {
		'iterations': 'time_cost',
		'memory': 'memory_cost',
		'threads': 'parallelism'
	}


	def __init__(self, iterations=16, memory=100, threads=os.cpu_count(), type=argon2.Type.ID):
		if not argon2:
			raise ValueError('password hashing disabled')

		self.config = {
			'time_cost': iterations,
			'memory_cost': memory * 1024,
			'parallelism': threads,
			'encoding': 'utf-8',
			'type': type,
		}

		self.hasher = argon2.PasswordHasher(**self.config)


	def get_config(self, key):
		key = self.aliases.get(key, key)

		value = self.config[key]
		return value / 1024 if key == 'memory_cost' else value


	def set_config(self, key, value):
		key = self.aliases.get(key, key)
		self.config[key] = value * 1024 if key == 'memory_cost' else value
		self.hasher = argon2.PasswordHasher(**self.config)


	def hash(self, password: str):
		return self.hasher.hash(password)


	def verify(self, passhash: str, password: str):
		try:
			return self.hasher.verify(passhash, password)

		except argon2.exceptions.VerifyMismatchError:
			return False


	def iteration_test(self, string='hecking heck', passes=3, iterations=[8,16,24,32,40,48,56,64]):
		original_iter = self.get_config('iterations')

		for iteration in iterations:
			self.set_config('iterations', iteration)
			print('\nTesting hash iterations:', iteration)

			time_function_pprint(self.verify, self.hash(string), string, passes=passes)

		self.set_config('iterations', original_iter)