#!/usr/bin/env python

# Copyright (c) 2018-2019, Ulf Magnusson
# SPDX-License-Identifier: ISC

"""
Generates a header file with #defines from the configuration, matching the
format of include/generated/autoconf.h in the Linux kernel.

Optionally, also writes the configuration output as a .config file. See
--config-out.

Optionally, creates/updates a directory structure with one file per symbol that
can be used to implement incremental builds. See the docstring for
Kconfig.sync_deps() in kconfiglib.py.

Before writing a header file or other configuration output, Kconfiglib compares
the old contents of the file against the new contents. If there's no change,
the write is skipped. This avoids updating file metadata like the modification
time, and might save work depending on your build setup.

By default, the configuration is generated from '.config'. A different
configuration file can be passed in the KCONFIG_CONFIG environment variable.
"""
import argparse

import kconfiglib


DEFAULT_HEADER_PATH = "config.h"
DEFAULT_SYNC_DEPS_PATH = "deps/"


def main():
    parser = argparse.ArgumentParser(
        formatter_class=argparse.RawDescriptionHelpFormatter,
        description=__doc__)

    parser.add_argument(
        "--header-path",
        metavar="HEADER_FILE",
        default=DEFAULT_HEADER_PATH,
        help="Path for the generated header file (default: {})"
             .format(DEFAULT_HEADER_PATH))

    parser.add_argument(
        "--sync-deps",
        dest="sync_deps_path",
        metavar="OUTPUT_DIR",
        nargs="?",
        const=DEFAULT_SYNC_DEPS_PATH,
        help="Enable generation of build dependency information for "
             "incremental builds, optionally specifying the output path "
             "(default: {})".format(DEFAULT_SYNC_DEPS_PATH))

    parser.add_argument(
        "--config-out",
        dest="config_path",
        metavar="CONFIG_FILE",
        help="Write the configuration to the specified filename. "
             "This is useful if you include .config files in Makefiles, as "
             "the generated configuration file will be a full .config file "
             "even if .config is outdated. The generated configuration "
             "matches what olddefconfig would produce. If you use "
             "--sync-deps, you can include deps/auto.conf instead. "
             "--config-out is meant for cases where incremental build "
             "information isn't needed.")

    parser.add_argument(
        "kconfig_filename",
        metavar="KCONFIG_FILENAME",
        nargs="?",
        default="Kconfig",
        help="Top-level Kconfig file (default: Kconfig)")

    args = parser.parse_args()


    kconf = kconfiglib.Kconfig(args.kconfig_filename)
    kconf.load_config(verbose=False)

    kconf.write_autoconf(args.header_path)

    if args.sync_deps_path is not None:
        kconf.sync_deps(args.sync_deps_path)

    if args.config_path is not None:
        kconf.write_config(args.config_path, save_old=False)


if __name__ == "__main__":
    main()