#!/usr/bin/env python3
#
# Copyright (c) 2017 Intel Corporation
# Copyright (c) 2025 Siemens AG
#
# SPDX-License-Identifier: Apache-2.0


"""Convert a file to a list of hex characters

The list of hex characters can then be included to a source file. Optionally,
the output can be compressed.

"""

import argparse
import codecs
import gzip
import io


def parse_args():
    global args

    parser = argparse.ArgumentParser(
        description=__doc__,
        formatter_class=argparse.RawDescriptionHelpFormatter,
        allow_abbrev=False,
    )

    parser.add_argument("-f", "--file", required=True, help="Input file")
    parser.add_argument(
        "-o", "--offset", type=lambda x: int(x, 0), default=0, help="Byte offset in the input file"
    )
    parser.add_argument(
        "-l",
        "--length",
        type=lambda x: int(x, 0),
        default=-1,
        help="""Length in bytes to read from the input file.
                Defaults to reading till the end of the input file.""",
    )
    parser.add_argument(
        "-m",
        "--format",
        default="list",
        help="Output format: 'list' (default) or 'literal' (string literal)",
    )
    parser.add_argument(
        "-g", "--gzip", action="store_true", help="Compress the file using gzip before output"
    )
    parser.add_argument(
        "-t",
        "--gzip-mtime",
        type=int,
        default=0,
        nargs='?',
        const=None,
        help="""mtime seconds in the gzip header.
                Defaults to zero to keep builds deterministic. For
                current date and time (= "now") use this option
                without any value.""",
    )
    args = parser.parse_args()


def get_nice_string(list_or_iterator):
    # Convert into comma separated list form.
    s = ", ".join("0x" + str(x) for x in list_or_iterator)

    # Format the list to eight values per line.
    return "\n".join(s[i : i + 47] for i in range(0, len(s), 48))


def make_hex(chunk):
    hexdata = codecs.encode(chunk, 'hex').decode("utf-8")
    hexlist = map(''.join, zip(*[iter(hexdata)] * 2, strict=False))
    print(get_nice_string(hexlist) + ',')


def make_string_literal(chunk):
    hexdata = codecs.encode(chunk, 'hex').decode("utf-8")
    hexlist = map(''.join, zip(*[iter(hexdata)] * 2, strict=False))
    print(''.join("\\x" + str(x) for x in hexlist), end='')


def chunker(source, remaining=-1):
    while chunk_raw := source.read(1024):
        if chunk_raw == b"":
            break
        if remaining == -1:
            yield chunk_raw
        elif remaining < len(chunk_raw):
            yield chunk_raw[:remaining]
        else:
            yield chunk_raw
            remaining -= len(chunk_raw)


def main():
    parse_args()

    if args.gzip:
        with io.BytesIO() as content:
            with open(args.file, 'rb') as fg:
                fg.seek(args.offset)
                with gzip.GzipFile(
                    fileobj=content, mode='w', mtime=args.gzip_mtime, compresslevel=9
                ) as gz_obj:
                    gz_obj.write(fg.read(args.length))

            content.seek(0)
            if args.format == "literal":
                print('"', end='')
                for chunk in chunker(content):
                    make_string_literal(chunk)
                print('"', end='')
            else:
                for chunk in chunker(content):
                    make_hex(chunk)
    else:
        with open(args.file, "rb") as fp:
            fp.seek(args.offset)

            if args.format == "literal":
                print('"', end='')
                for chunk in chunker(fp, args.length):
                    make_string_literal(chunk)
                print('"', end='')
            else:
                for chunk in chunker(fp, args.length):
                    make_hex(chunk)


if __name__ == "__main__":
    main()