#!/usr/bin/env python3

# Copyright 2022 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import argparse
import contextlib
import os
import subprocess
import sys

# Set up path to be able to import action_helpers.
sys.path.append(
    os.path.join(
        os.path.dirname(os.path.abspath(__file__)),
        os.pardir,
        os.pardir,
        os.pardir,
        'build',
    )
)
import action_helpers

from filter_clang_args import filter_clang_args


def PrependVersionLine(filepath):
    # Prepending a version line accomplishes two goals:
    # * P1: Incrementing the version forces reindexing of the generated code
    #   by Chromium Code Search (e.g. needed to verify the fix from
    #   https://crbug.com/466084840)
    # * P2: It leaves a breadcrumb about `//build/rust` to help readers of
    #   the generated code figure out where/how to control how Chromium
    #   invokes `bindgen`.
    VERSION = "2025-12-22"
    with open(filepath, 'r', encoding='utf-8') as f:
        original_content = f.read()
    with open(filepath, 'w', encoding='utf-8') as f:
        tool_description = f"`//build/rust/gni_impl/run_bindgen.py` v{VERSION}"
        f.write(f"/* @generated by {tool_description} */\n")
        f.write(original_content)


def main():
    parser = argparse.ArgumentParser("run_bindgen.py")
    (
        parser.add_argument(
            "--bindgen-exe", help="Path to bindgen", required=True
        ),
    )
    (
        parser.add_argument(
            "--rustfmt-exe", help="Path to rustfmt", required=True
        ),
    )
    parser.add_argument(
        "--header", help="C header file to generate bindings for", required=True
    )
    parser.add_argument(
        "--depfile", help="depfile to output with header dependencies"
    )
    parser.add_argument("--output", help="output .rs bindings", required=True)
    parser.add_argument(
        "--wrap-static-fns",
        help="output source file for `static` and `static inline` functions",
    )
    parser.add_argument(
        "--ld-library-path",
        help="LD_LIBRARY_PATH (or DYLD_LIBRARY_PATH on Mac) to set",
    )
    parser.add_argument(
        "--libclang-path", help="Path to the libclang shared libray."
    )
    parser.add_argument("-I", "--include", help="include path", action="append")
    parser.add_argument(
        "--bindgen-flags", help="flags to pass to bindgen", nargs="*"
    )
    parser.add_argument(
        "clangargs",
        metavar="CLANGARGS",
        help="arguments to pass to libclang (see "
        "https://docs.rs/bindgen/latest/bindgen/struct.Builder.html#method.clang_args)",
        nargs="*",
    )
    args = parser.parse_args()

    # Abort if `TARGET` exists in the environment. Cargo sets `TARGET` when
    # running build scripts and bindgen will try to be helpful by using that value
    # if it's set. In practice we've seen a case where someone had the value set
    # in their build environment with no intention of it reaching bindgen, leading
    # to a hard-to-debug build error.
    if 'TARGET' in os.environ:
        sys.exit(
            'ERROR: saw TARGET in environment, remove to avoid bindgen failures'
        )

    with contextlib.ExitStack() as stack:
        # Args passed to the actual bindgen cli
        genargs = []
        genargs.append('--no-layout-tests')
        if args.bindgen_flags is not None:
            for flag in args.bindgen_flags:
                genargs.append("--" + flag)

        # TODO(danakj): We need to point bindgen to
        # //third_party/rust-toolchain/bin/rustfmt.
        genargs.append('--no-rustfmt-bindings')
        genargs += ['--rust-target', 'nightly']

        if args.depfile:
            depfile = stack.enter_context(
                action_helpers.atomic_output(args.depfile)
            )
            genargs.append('--depfile')
            genargs.append(depfile.name)
        # Ideally we would use action_helpers.atomic_output for the output file, but
        # this would put the wrong name in the depfile.
        genargs.append('--output')
        genargs.append(args.output)

        # The GN rules know what path to find the system headers in, and we want to
        # use the headers we specify, instead of non-hermetic headers from elsewhere
        # in the system.
        genargs.append('--no-include-path-detection')

        if args.wrap_static_fns:
            wrap_static_fns = stack.enter_context(
                action_helpers.atomic_output(args.wrap_static_fns)
            )
            genargs.append('--experimental')
            genargs.append('--wrap-static-fns')
            genargs.append('--wrap-static-fns-path')
            genargs.append(wrap_static_fns.name)
        genargs.append(args.header)
        genargs.append('--')
        genargs.extend(filter_clang_args(args.clangargs))
        env = os.environ
        if args.ld_library_path:
            if sys.platform == 'darwin':
                env["DYLD_LIBRARY_PATH"] = args.ld_library_path
            else:
                env["LD_LIBRARY_PATH"] = args.ld_library_path
        if args.libclang_path:
            env["LIBCLANG_PATH"] = args.libclang_path
        try:
            subprocess.check_call([args.bindgen_exe, *genargs], env=env)

            fmtargs = [
                args.output,
                "--config=normalize_doc_attributes=true",
            ]
            subprocess.check_call([args.rustfmt_exe, *fmtargs])

            PrependVersionLine(args.output)
        except:
            # Make sure we don't emit anything if bindgen failed. The other files use
            # action_helpers for this.
            try:
                os.remove(args.output)
            except FileNotFoundError:
                pass
            raise


if __name__ == '__main__':
    main()