import filecmp
import os

g_key_table = None

class hsm_param:
	def __init__(self):
		#you can add parameter required by your HSM here
		self.m_ref_key_path = ""
		self.m_key_id = 0
		self.m_attr1 = 0
		self.m_attr2 = 0
		self.m_padding_dict = {"raw": 0, "pss": 1}
		self.m_padding = 0 #default: raw

def create_key_table():
	global g_key_table
	if None == g_key_table:
		#create key table
		#here is reference design, please customize
		#this part according to your HSM spec.
		script_folder, script_name = os.path.split(os.path.realpath(__file__))
		key_folder = os.path.join(script_folder, "keys")
		key_folder = os.path.join(key_folder, "hsm")
		g_key_table = list()
		#key1 parameter
		key1_param = hsm_param()
		key1_param.m_ref_key_path = os.path.join(key_folder, 'pubk1.pem')
		key1_param.m_key_id = 0
		key1_param.m_attr1 = 1
		key1_param.m_attr2 = 1
		g_key_table.append(key1_param)
		#key2 parameter
		key2_param = hsm_param()
		key2_param.m_ref_key_path = os.path.join(key_folder, 'pubk2.pem')
		key2_param.m_key_id = 1
		key2_param.m_attr1 = 2
		key2_param.m_attr2 = 2
		g_key_table.append(key2_param)
	return

def query_key_table(key):
	global g_key_table
	create_key_table()
	for key_table_entry in g_key_table:
		if filecmp.cmp(key, key_table_entry.m_ref_key_path):
			print "key index: " + hex(key_table_entry.m_key_id)
			return key_table_entry
	print "no valid key entry found in table"
	return None

def hsm_rsa_sign(data, key, padding, sig):
	hsm_param_obj =	None

	#note that key is pubk actually, use it as index for
	#HSM parameters such as key selection
	hsm_param_obj = query_key_table(key)
	if None == hsm_param_obj:
		return -1
	hsm_param_obj.m_padding = hsm_param_obj.m_padding_dict[padding]

	print "========================"
	print "HSM parameter:"
	print "    m_key_id  = " + hex(hsm_param_obj.m_key_id)
	print "    m_padding = " + hex(hsm_param_obj.m_padding)
	print "    m_attr1   = " + hex(hsm_param_obj.m_attr1)
	print "    m_attr2   = " + hex(hsm_param_obj.m_attr2)
	print "========================"

	#place hsm request here -- start
	#create dummy sig for now
	sig_file = open(sig, 'wb')
	for i in range(0, 256):
		sig_file.write(chr(0))
	sig_file.close()
	#place hsm request here -- end
	return 0