#!/usr/bin/env python3
"""Generate compile_commands.json (repo root) from a dry run of the makefiles.

Used by VS Code IntelliSense (C/C++ extension) and clangd.
Usage: python3 gcc/gen_compile_commands.py
"""
import json
import os
import re
import shlex
import subprocess

ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), ".."))
MAKEFILES = ["gcc/makefile_boot", "gcc/makefile_appli"]
COMPILERS = ("arm-none-eabi-gcc", "arm-none-eabi-g++")


def dry_run(makefile):
    # -B forces every compile command to be printed, -n executes nothing
    out = subprocess.run(
        ["make", "-r", "-B", "-n", "-f", makefile, "build_executable"],
        cwd=ROOT, capture_output=True, text=True,
    ).stdout
    return re.sub(r"\\\n\s*", " ", out).splitlines()


def main():
    entries = []
    seen = set()
    for makefile in MAKEFILES:
        for line in dry_run(makefile):
            line = line.strip()
            if not line.startswith(COMPILERS) or " -c " not in f" {line} ":
                continue
            args = shlex.split(line)
            source = next((a for a in args if a.endswith((".c", ".cpp", ".s"))), None)
            if not source or source in seen:
                continue
            seen.add(source)
            entries.append({
                "directory": ROOT,
                "arguments": args,
                "file": os.path.join(ROOT, source),
            })
    path = os.path.join(ROOT, "compile_commands.json")
    with open(path, "w") as f:
        json.dump(entries, f, indent=1)
    print(f"{len(entries)} entries written to {path}")


if __name__ == "__main__":
    main()