generate_diff.py

# Copyright 2025 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.

import argparse
import pathlib
import io
import sys
from typing import List


def get_bazel_files(root_dir: pathlib.Path) -> List[pathlib.Path]:
    """Finds files matching "BUILD.bazel" or "*.bzl" under the given directory.

    Args:
        root_dir: The root directory to search in.

    Returns:
        A list of pathlib.Path objects representing the matching files.
    """
    return [
        path
        for path in root_dir.rglob("*")
        if path.match("BUILD.bazel") or path.match("*.bzl")
    ]

def get_py_files(root_dir: pathlib.Path) -> List[pathlib.Path]:
    """Finds files matching "*.py" under the given directory.

    Args:
        root_dir: The root directory to search in.

    Returns:
        A list of pathlib.Path objects representing the matching files.
    """
    return [
        path
        for path in root_dir.rglob("*")
        if path.match("*.py")
    ]

def get_cc_files(root_dir: pathlib.Path) -> List[pathlib.Path]:
    """Finds C/C++ and linker files under the given directory.

    Args:
        root_dir: The root directory to search in.

    Returns:
        A list of pathlib.Path objects representing the matching files.
    """
    patterns = (
        "Kconfig*",
        "*.c",
        "*.cc",
        "*.dts",
        "*.dtsi",
        "*.h",
        "*.ld",
        "*.S",
        "*.yml",
    )
    return [
        path
        for path in root_dir.rglob("*")
        if any(path.match(p) for p in patterns)
    ]

def print_file_info(
        file_path: pathlib.Path,
        root_dir: pathlib.Path,
        writer: io.TextIOWrapper,
):
    """Prints the relative path, line count, and prefixed content of a file.

    Args:
        file_path: The path to the file.
        root_dir: The root directory to calculate the relative path from.
        writer: Where to write the output
    """
    relative_path = file_path.relative_to(root_dir)
    with open(file_path, "r", encoding="utf-8") as file:
        content = file.readlines()
        line_count = len(content)
        writer.write("\n")
        writer.write("--- /dev/null\n")
        writer.write(f"+++ b/{relative_path}\n")
        writer.write(f"@@ -0,0 +1,{line_count} @@\n")
        for line in content:
            writer.write(f"+{line.rstrip()}\n")

def print_all(root_dir: pathlib.Path, writer: io.TextIOWrapper):
    """Iterate through all BUILD.bazel and *.bzl files and write them to writer

    Args:
        root_dir: The root directory to calculate the relative path from.
        writer: Where to write the output
    """
    file_paths = get_bazel_files(root_dir=root_dir)
    file_paths += get_py_files(root_dir=root_dir)
    file_paths += get_cc_files(root_dir=root_dir)
    for file_path in file_paths:
        print_file_info(file_path=file_path, root_dir=root_dir, writer=writer)

def append_custom_patches(
    root_dir: pathlib.Path,
    custom_patches_dir_name: str,
    writer: io.TextIOWrapper,
):
    custom_patches_dir = root_dir / custom_patches_dir_name
    if custom_patches_dir.exists():
        for path in custom_patches_dir.glob("*.patch"):
            with open(path, "r", encoding="utf-8") as f:
                writer.write(f.read())

def main() -> None:
    """Finds all BUILD.bazel files and *.bzl files and generates a diff"""
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "--root-dir",
        type=pathlib.Path,
        nargs="+",
    )
    parser.add_argument(
        "-o",
        dest="output",
        type=pathlib.Path,
    )
    parser.add_argument(
        "--custom-patches-dir",
        type=str,
        default="custom_patches",
        help="Directory name for custom patches, relative to root-dir",
    )
    args = parser.parse_args()
    if args.output:
        args.output.parent.mkdir(parents=True, exist_ok=True)
        with open(args.output, mode="w", encoding="utf-8") as o:
            for root_dir in args.root_dir:
                print_all(root_dir=root_dir, writer=o)
                append_custom_patches(
                    root_dir=root_dir,
                    custom_patches_dir_name=args.custom_patches_dir,
                    writer=o,
                )
    else:
        writer = io.TextIOWrapper(sys.stdout.buffer, encoding="utf-8")
        for root_dir in args.root_dir:
            print_all(root_dir=root_dir, writer=writer)
            append_custom_patches(
                root_dir=root_dir,
                custom_patches_dir_name=args.custom_patches_dir,
                writer=writer,
            )
        writer.flush()

if __name__ == "__main__":
    main()