# EXI is specified in w3.org/TR/exi
# For decoding and encoding, different decoders are availabe:
#  1.  https://github.com/FlUxIuS/V2Gdecoder
#      https://github.com/FlUxIuS/V2Gdecoder/releases
#      Install java from https://www.java.com/de/download/manual.jsp
#
#      C:\>java -version
#      java version "1.8.0_351"
#      Java(TM) SE Runtime Environment (build 1.8.0_351-b10)
#      Java HotSpot(TM) Client VM (build 25.351-b10, mixed mode, sharing)
#      C:\>
#
#      java -jar V2Gdecoder.jar -e -s 8000dbab9371d3234b71d1b981899189d191818991d26b9b3a232b30020000040040
#      ERROR:  'Premature EOS found while reading data.'
#      <?xml version="1.0" encoding="UTF-8"?><ns4:supportedAppProtocolReq xmlns:ns4="urn:iso:15118:2:2010:AppProtocol" 
#      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ns3="http://www.w3.org/2001/XMLSchema">
#      <AppProtocol>
#      <ProtocolNamespace>urn:din:70121:2012:MsgDef</ProtocolNamespace>
#      <VersionNumberMajor>2</VersionNumberMajor>
#      <VersionNumberMinor>0</VersionNumberMinor>
#      <SchemaID>1</SchemaID>
#      <Priority>1</Priority>
#      </AppProtocol>
#      </ns4:supportedAppProtocolReq>
#
#  2. OpenV2G from https://github.com/Martin-P/OpenV2G
#      Pro: The schema-specific files are already included as generated C-code, this
#         makes it very fast.
#      Contra: Is only a demo, does not provide an interface which could be used for decoding/encoding.
#      Work in progress: Fork in https://github.com/uhi22/OpenV2Gx, to add a command line interface (and maybe a socket interface).
#
#
#
#
#
#
#

from helpers import showAsHex, twoCharHex
import subprocess
import sys
import time
import json

# Example data:
#   (1) From the Ioniq:
#     In wireshark: Copy as hex stream
#     01fe8001000000228000dbab9371d3234b71d1b981899189d191818991d26b9b3a232b30020000040040
#     remove the 8 bytes V2GTP header
#     8000dbab9371d3234b71d1b981899189d191818991d26b9b3a232b30020000040040
exiHexDemoSupportedApplicationProtocolRequestIoniq="8000dbab9371d3234b71d1b981899189d191818991d26b9b3a232b30020000040040"
# Command line:
# ./OpenV2G.exe DH8000dbab9371d3234b71d1b981899189d191818991d26b9b3a232b30020000040040


#   (2) From OpenV2G main_example.appHandshake()
#     8000ebab9371d34b9b79d189a98989c1d191d191818981d26b9b3a232b30010000040001b75726e3a64696e3a37303132313a323031323a4d73674465660020000100880
exiHexDemoSupportedApplicationProtocolRequest2="8000ebab9371d34b9b79d189a98989c1d191d191818981d26b9b3a232b30010000040001b75726e3a64696e3a37303132313a323031323a4d73674465660020000100880"
# Command line:
# ./OpenV2G.exe DH8000ebab9371d34b9b79d189a98989c1d191d191818981d26b9b3a232b30010000040001b75726e3a64696e3a37303132313a323031323a4d73674465660020000100880

#   (3) SupportedApplicationProtocolResponse
#    80400040
# Command line:
# ./OpenV2G.exe DH80400040


# Configuration of the exi converter tool
pathToOpenV2GExe = "..\\OpenV2Gx\\Release\\OpenV2G.exe";

# Functions
def exiHexToByteArray(hexString):
    # input: a string with the two-byte-hex representation
    # output: a byte array with the same data.
    # If the convertion fails, we return an empty byte array. 
    hexlen=len(hexString)
    if ((hexlen % 2)!=0):
        print("exiHexToByteArray: unplausible length of " + hexString)
        return bytearray(0)
    exiframe = bytearray(int(hexlen/2)) # two characters in the input string are one byte in the exiframe
    for i in range(0, int(hexlen/2)):
        x = hexString[2*i: 2*i+2]        
        #print("valuestring = " + x)
        try:
            v = int(x, 16)
            #print("value " + hex(v))
            exiframe[i] = v
        except:
            print("exiHexToByteArray: unplausible data " + x)
            return bytearray(0)
    return exiframe

def exiByteArrayToHex(b):
    # input: Byte array
    # output: a string with the two-byte-hex representation of the byte array
    s = ""
    for i in range(0, len(b)):
        s = s + twoCharHex(b[i])
    return s

def addV2GTPHeader(exidata):
    #print("type is " + str(type(exidata)))
    if (str(type(exidata)) == "<class 'str'>"):
        #print("changing type to bytearray")
        exidata = exiHexToByteArray(exidata)
    #print("type is " + str(type(exidata)))
    # takes the bytearray with exidata, and adds a header to it, according to the Vehicle-to-Grid-Transport-Protocol
    exiLen = len(exidata)
    header = bytearray(8) # V2GTP header has 8 bytes
                          # 1 byte protocol version
                          # 1 byte protocol version inverted
                          # 2 bytes payload type
                          # 4 byte payload length
    header[0] = 0x01 # version
    header[1] = 0xfe # version inverted
    header[2] = 0x80 # payload type. 0x8001 means "EXI data"
    header[3] = 0x01 # 
    header[4] = (exiLen >> 24) & 0xff # length 4 byte.
    header[5] = (exiLen >> 16) & 0xff
    header[6] = (exiLen >> 8) & 0xff
    header[7] = exiLen & 0xff
    return header + exidata

def removeV2GTPHeader(v2gtpData):
    #removeV2GTPHeader
    return v2gtpData[8:]

def exiDecode(exiHex, prefix="DH"):
    # input: exi data. Either hexstring, or bytearray or bytes
    #        prefix to select the schema
    # if the input is a byte array, we convert it into hex string. If it is already a hex string, we take it as it is.
    #print("type is " + str(type(exiHex)))
    if (str(type(exiHex)) == "<class 'bytearray'>"):
        #print("changing type to hex string")
        exiHex = exiByteArrayToHex(exiHex)
    if (str(type(exiHex)) == "<class 'bytes'>"):
        #print("changing type to hex string")
        exiHex = exiByteArrayToHex(exiHex)
    #print("type is " + str(type(exiHex)))
    param1 = prefix + exiHex # DH for decode handshake
    print("exiDecode: trying to decode " + exiHex + " with schema " + prefix)
    result = subprocess.run(
        [pathToOpenV2GExe, param1], capture_output=True, text=True)
    #print("stdout:", result.stdout)
    if (len(result.stderr)>0):
        print("exiDecode ERROR. stderr:" + result.stderr)
    strConverterResult = result.stdout
    return strConverterResult
    
def exiEncode(strMessageName, params=""):
    # todo: handle the schema, the message name and the parameters
    # param1 = "Eh" # Eh for encode handshake, SupportedApplicationProtocolResponse
    # param1 = "EDa" # EDa for Encode, Din, SessionSetupResponse
    param1 = strMessageName
    result = subprocess.run([pathToOpenV2GExe, param1], capture_output=True, text=True)    
    if (len(result.stderr)>0):
        strConverterResult = "exiEncode ERROR. stderr:" + result.stderr
        print(strConverterResult)
    else:
        print("exiEncode stdout:", result.stdout)
        # Now we have an encoder result in json form, something like:
        # {
        # "info": "",
        # "error": "",
        # "result": "8004440400"
        # }
        try:
            y = json.loads(result.stdout)
            strConverterResult = y["result"]
            print("strConverterResult is " + str(strConverterResult))
        except:
            strConverterResult = "exiEncode failed to convert json to dict."
            print(strConverterResult)
    return strConverterResult    
    

def testByteArrayConversion(s):
    print("Testing conversion of " + s)
    x = exiHexToByteArray(s)
    newHexString = exiByteArrayToHex(x)
    print("exi as hex=" + newHexString)
    exiWithHeader = addV2GTPHeader(x)
    exiWithHeaderString = exiByteArrayToHex(exiWithHeader)
    print("with V2GTP header=" + exiWithHeaderString)


if __name__ == "__main__":
    print("Testing exiConnector...")
    testByteArrayConversion("123456")
    testByteArrayConversion("1234567")
    testByteArrayConversion("ABCDEF")
    testByteArrayConversion("00112233445566778899AABBCCDDEEFF")
    testByteArrayConversion("TRASH!")
        
    print("Testing exiDecode with exiHexDemoSupportedApplicationProtocolRequestIoniq")
    print(exiDecode(exiHexDemoSupportedApplicationProtocolRequestIoniq))
    print("Testing exiDecode with exiHexDemoSupportedApplicationProtocolRequest2")
    strConverterResult = exiDecode(exiHexDemoSupportedApplicationProtocolRequest2)
    print(strConverterResult)

    strConverterResult = exiDecode(exiHexToByteArray(exiHexDemoSupportedApplicationProtocolRequest2))
    print(strConverterResult)
    
    if (strConverterResult.find("ProtocolNamespace=urn:din")>0):
        print("Detected DIN")
        
    param1 = "ED1" # ED for encode DIN, session setup response
    result = subprocess.run([pathToOpenV2GExe, param1], capture_output=True, text=True)    
    print("stdout:", result.stdout)
    print("stderr:", result.stderr)