#!/usr/bin/python3
#
# Copyright (C) 2019 Richard Hughes <richard@hughsie.com>
#
# SPDX-License-Identifier: LGPL-2.1+

import sys
import uuid
import argparse
import ctypes

CAPSULE_FLAGS_PERSIST_ACROSS_RESET = 0x00010000
CAPSULE_FLAGS_POPULATE_SYSTEM_TABLE = 0x00020000
CAPSULE_FLAGS_INITIATE_RESET = 0x00040000


def add_header(infile, outfile, gd, fl=None):
    # parse GUID from command line
    try:
        guid = uuid.UUID(gd)
    except ValueError as e:
        print(e)
        return 1
    import struct

    try:
        with open(infile, "rb") as f:
            bin_data = f.read()
    except FileNotFoundError as e:
        print(e)
        return 1

    # check if already has header
    hdrsz = struct.calcsize("<16sIII")
    if len(bin_data) >= hdrsz:
        hdr = struct.unpack("<16sIII", bin_data[:hdrsz])
        imgsz = hdr[3]
        if imgsz == len(bin_data):
            print("Replacing existing CAPSULE_HEADER of:")
            guid_mixed = uuid.UUID(bytes_le=hdr[0])
            hdrsz_old = hdr[1]
            flags = hdr[2]
            print(f"GUID:      {guid_mixed}")
            print(f"HdrSz:     0x{hdrsz_old:04x}")
            print(f"Flags:     0x{flags:04x}")
            print(f"PayloadSz: 0x{imgsz:04x}")
            bin_data = bin_data[hdrsz_old:]

    # set header flags
    flags = (
        CAPSULE_FLAGS_PERSIST_ACROSS_RESET
        | CAPSULE_FLAGS_INITIATE_RESET
        | CAPSULE_FLAGS_POPULATE_SYSTEM_TABLE
    )
    if fl:
        flags = int(fl, 16)

    # build update capsule header
    hdrsz = 4096
    imgsz = hdrsz + len(bin_data)
    hdr = ctypes.create_string_buffer(hdrsz)
    struct.pack_into("<16sIII", hdr, 0, guid.bytes_le, hdrsz, flags, imgsz)
    with open(outfile, "wb") as f:
        f.write(hdr)
        f.write(bin_data)
    print(f"Wrote capsule {outfile}")
    print(f"GUID:      {guid}")
    print(f"HdrSz:     0x{hdrsz:04x}")
    print(f"Flags:     0x{flags:04x}")
    print(f"PayloadSz: 0x{imgsz:04x}")
    return 0


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Add capsule header on firmware")
    parser.add_argument("--guid", help="GUID of the device", required=True)
    parser.add_argument("--bin", help="Path to the .bin file", required=True)
    parser.add_argument("--cap", help="Output capsule file path", required=True)
    parser.add_argument("--flags", help="Flags, e.g. 0x40000", default=None)
    args = parser.parse_args()

    sys.exit(add_header(args.bin, args.cap, args.guid, args.flags))