import argparse
import datetime
import json
import os
import re
import sys

INT32_MAX = 2 ** 31 - 1

def guess_build_top():
    if 'ANDROID_BUILD_TOP' in os.environ:
        return os.environ['ANDROID_BUILD_TOP']
    cwd = os.getcwd()
    parts = cwd.split('/out/soong/')
    return parts[0]


def get_build_number():
    top = guess_build_top()
    with open(f'{top}/out/soong/build_number.txt', 'r') as file:
        soong_build_number = file.read().strip()
        return soong_build_number


def get_build_id():
    top = guess_build_top()
    with open(f'{top}/build/core/build_id.mk', 'r') as file:
        for line in file:
            if line.startswith('BUILD_ID='):
                _, rc = line.strip().split('=', 1)
                return rc


def hdr(args):
    output = f'''\
#ifndef {args.guard}
#define {args.guard}

#define WV_ANDROID_BUILD_ID "{get_build_id()}"

#endif  // {args.guard}'''
    print(output)


def safe_int(str_value):
    """Converts a build number to an integer, capped at INT32_MAX.

    INT32_MAX is the max supported by Android Build.

    Args:
        str_value: The build number to convert.

    Returns:
        The integer representation of build number, capped at INT32_MAX;
        0 on error.
    """
    try:
        v = int(str_value)
        return min(INT32_MAX, v)
    except ValueError:
        return 0


def apex_manifest(args):
    rc = get_build_id()
    v = get_build_number()

    if v.startswith('eng.'):
        # local build
        #
        # set large version so local builds can overwrite other build types
        v = INT32_MAX
    elif re.match(r'P\d+$', v):
        # presubmit build
        #
        # numeric value of presubmit builds are typically higher than
        # postsubmit builds, so presubmit builds can overwrite postsubmit
        # builds during test
        v = safe_int(v[1:])
    elif rc in ('MASTER', 'MAIN'):
        # postsubmit dev branch
        #
        # set APEX version to 1 (preserve udc behavior)
        v = 1
    elif re.match(r'\d+$', v):
        # postsubmit release branch
        #
        # set APEX version to ab build number
        v = safe_int(v)
    else:
        raise RuntimeError('Unsupported Widevine APEX build env')

    out = dict(name=args.name, version=v, requireNativeLibs=['liboemcrypto'])
    print(json.dumps(out))


if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Widevine Android genrule utility')
    parser.set_defaults(func=lambda _: parser.print_help())
    subparsers = parser.add_subparsers(help='Available subcommands')

    hdr_description = 'Generate build id C++ header (stdout)'
    parser_hdr = subparsers.add_parser('build_id_header', help=hdr_description)
    parser_hdr.add_argument('--guard', type=str,
                            default='WVCDM_WV_ANDROID_BUILD_ID_H_',
                            help='Include guard')
    parser_hdr.set_defaults(func=hdr)

    apex_description = 'Generate APEX manifest json (stdout)'
    parser_apex = subparsers.add_parser('apex_manifest', help=apex_description)
    parser_apex.add_argument('--name', help='apex name',
                             default='com.google.android.widevine')
    parser_apex.set_defaults(func=apex_manifest)

    # Parse the arguments and call the appropriate function
    args = parser.parse_args()
    args.func(args)