# Copyright 2012 The ChromiumOS Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Script for calculating compatible binhosts.

Generates a file that sets the specified board's binhosts to include all of the
other compatible boards in this buildroot.
"""

import collections
import glob
import os
import sys

from chromite.lib import commandline
from chromite.lib import portage_util


def FindCandidateBoards():
    """Find candidate local boards to grab prebuilts from."""
    portageq_prefix = "/usr/local/bin/portageq-"
    for path in sorted(glob.glob("%s*" % portageq_prefix)):
        # Strip off the portageq prefix, leaving only the board.
        yield path.replace(portageq_prefix, "")


def SummarizeCompatibility(board):
    """Returns a string that will be the same for compatible boards."""
    result = portage_util.PortageqEnvvars(["ARCH", "CFLAGS"], board=board)
    return "%s %s" % (result["ARCH"], result["CFLAGS"])


def GenerateBinhostLine(build_root, compatible_boards):
    """Generate a binhost line pulling binaries from the specified boards."""
    # TODO(davidjames): Prioritize binhosts with more matching use flags.
    local_binhosts = " ".join(
        [
            "file://localhost" + os.path.join(build_root, x, "packages")
            for x in sorted(compatible_boards)
        ]
    )
    return "LOCAL_BINHOST='%s'" % local_binhosts


def GetParser():
    """Return a command line parser."""
    parser = commandline.ArgumentParser(description=__doc__)
    parser.add_argument(
        "--build_root",
        default="/build",
        help="Location of boards (normally %(default)s)",
    )
    parser.add_argument("--board", required=True, help="Board name")
    return parser


def main(argv) -> None:
    parser = GetParser()
    flags = parser.parse_args(argv)

    by_compatibility = collections.defaultdict(set)
    compatible_boards = None
    for other_board in FindCandidateBoards():
        compat_id = SummarizeCompatibility(other_board)
        if other_board == flags.board:
            compatible_boards = by_compatibility[compat_id]
        else:
            by_compatibility[compat_id].add(other_board)

    if compatible_boards is None:
        print("Missing portageq wrapper for %s" % flags.board, file=sys.stderr)
        sys.exit(1)

    print("# Generated by cros_generate_local_binhosts.")
    print(GenerateBinhostLine(flags.build_root, compatible_boards))