#!/usr/bin/env python3
"""Compiles lua/lib/*.lua to LUA_32BITS bytecode and generates a C++ source file embedding
the arrays. The runtime's module searcher checks these as a fallback after the SD card, so
a local copy always shadows the packaged one.

Usage:
    tools/embed.py <luac32> <lua_lib_dir> <output.cpp> [--check]
"""

import subprocess
import sys
import pathlib

HEADER = """\
// GENERATED by tools/embed.py — do not edit. Run `make embed` to regenerate.
#include <lua/embedded_modules.h>

namespace esp32lua {

"""

FOOTER = """

}  // namespace esp32lua
"""


def main():
    check = "--check" in sys.argv
    args = [a for a in sys.argv[1:] if a != "--check"]
    if len(args) != 3:
        sys.exit("usage: embed.py <luac32> <lua_lib_dir> <output.cpp> [--check]")

    luac32, lib_dir, out_path = args
    lib_dir = pathlib.Path(lib_dir)
    out_path = pathlib.Path(out_path)

    sources = sorted(lib_dir.glob("*.lua"))
    arrays = []
    rows = []
    for src in sources:
        import tempfile
        with tempfile.NamedTemporaryFile(suffix=".luac", delete=False) as tmp:
            tmp_path = tmp.name
        subprocess.run([luac32, str(src), tmp_path], check=True)
        bytecode = pathlib.Path(tmp_path).read_bytes()
        pathlib.Path(tmp_path).unlink()
        name = src.stem
        comma = ", ".join(f"0x{b:02x}" for b in bytecode)
        arrays.append(f"static const unsigned char {name}[] = {{{comma}}};\n")
        rows.append(f'    {{"{name}", {name}, sizeof({name})}},')

    footer = "const EmbeddedModule embedded_modules[] = {{\n{rows}\n}};\nconst size_t embedded_modules_count = {count};\n"
    generated = HEADER + "".join(arrays) + footer.format(rows="\n".join(rows), count=len(sources)) + FOOTER

    if check:
        existing = out_path.read_text() if out_path.exists() else ""
        if existing != generated:
            sys.exit(f"{out_path} is stale; run `make embed`")
        return

    out_path.write_text(generated)
    print(f"wrote {len(sources)} modules to {out_path}")


if __name__ == "__main__":
    main()