bazel/private/zephyr_transition.bzl

# Copyright 2026 The Pigweed Authors
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License. You may obtain a copy of
# the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations under
# the License.
"""Incoming transition for Zephyr applications."""

load("@zephyr-bazel//:naming.bzl", "get_zc_repo_name")
load("@zephyr_index//:index.bzl", "PACKAGE_TO_BOARDS", "REPO_NAME_TO_CANONICAL")

def resolve_board_id(platform_label, pkg, pkg_boards, package_to_boards):
    """Resolves the Zephyr board ID from the platform label and context discovery index.

    Args:
        platform_label: The user requested platform label.
        pkg: The resolved package path.
        pkg_boards: Boards mapped to that package.
        package_to_boards: The global boards configuration index dict.

    Returns:
        The resolved board_id or None.
    """
    board_id = None

    # Construct candidates list: (candidate_pkg, candidate_boards)
    # First candidate is the current package
    candidates = [(pkg, pkg_boards)]

    # Add sub-packages as fallback candidates
    prefix = pkg + "/"
    for sub_pkg, sub_pkg_boards in package_to_boards.items():
        if sub_pkg.startswith(prefix):
            candidates.append((sub_pkg, sub_pkg_boards))

    # Run resolution rules on candidates
    for cand_pkg, cand_boards in candidates:
        # Default Shortcut
        if not board_id and platform_label.name == "default" and len(cand_boards) == 1:
            board_id = cand_boards[0]

        # Explicit Match (with default SoC resolution for HWM v2)
        if not board_id and platform_label.name in cand_boards:
            prefix_b = platform_label.name + "/"
            qualified_variants = [b for b in cand_boards if b.startswith(prefix_b)]
            if qualified_variants:
                # Resolve to the first qualified variant (default SoC)
                board_id = qualified_variants[0]
            else:
                board_id = platform_label.name

        # SoC/Variant Match (e.g. :nrf52833 for board nrf52833dk)
        if not board_id and cand_boards:
            for b in cand_boards:
                if b.endswith("/" + platform_label.name):
                    board_id = b
                    break
                # Handle board/soc/variant where board == soc, simplified to board_variant (e.g. qemu_malta_be)
                parts = b.split("/")
                if len(parts) == 3 and parts[0] == parts[1]:
                    short_name = parts[0] + "_" + parts[2]
                    if short_name == platform_label.name:
                        board_id = b
                        break

            # Fallback: if exactly one BASE board exists, assume it's board/soc
            if not board_id:
                base_boards = [b for b in cand_boards if "/" not in b]
                if len(base_boards) == 1:
                    board_id = base_boards[0] + "/" + platform_label.name

        if board_id:
            break
    return board_id

def _zephyr_transition_impl(settings, attr):
    platforms = settings["//command_line_option:platforms"]
    if not platforms:
        return {}

    platform_label = platforms[0]

    # If already transitioned, do nothing.
    # Check both the old zc_ pattern and the new canonical Bzlmod pattern.
    if platform_label.workspace_name and ("zc_" in platform_label.workspace_name or "+zephyr_setup+" in platform_label.workspace_name):
        return {}

    # Resolve package path as used in PACKAGE_TO_BOARDS
    pkg = str(platform_label).split(":")[0]
    if pkg.startswith("//"):
        pkg = "@@" + pkg

    if not pkg.endswith("//"):
        pkg = pkg.rstrip("/")
    pkg_boards = PACKAGE_TO_BOARDS.get(pkg, None)

    if pkg_boards == None:
        # This platform is not in a package that contains Zephyr boards.
        # Bypass the transition and let Bazel handle it.
        return {}

    board_id = resolve_board_id(platform_label, pkg, pkg_boards, PACKAGE_TO_BOARDS)

    if not board_id:
        fail("Unknown Zephyr board: %s. Valid boards in %s: %s" % (platform_label, pkg, pkg_boards))

    repo_name = get_zc_repo_name(attr.app_label, board_id)
    canonical_repo = REPO_NAME_TO_CANONICAL.get(repo_name)
    if not canonical_repo:
        fail("""
Board combination '%s' for app '%s' was filtered out by heuristics.
To fix this, you can either:
  1. Add a .conf or .overlay file for this board under the 'boards/' directory of the app.
  2. Add the board to the 'manual_boards' attribute of 'zephyr_setup.env' in MODULE.bazel
""" % (board_id, attr.app_label))

    return {"//command_line_option:platforms": ["%s//:platform" % canonical_repo]}

zephyr_transition = transition(
    implementation = _zephyr_transition_impl,
    inputs = ["//command_line_option:platforms"],
    outputs = ["//command_line_option:platforms"],
)