#!/usr/bin/env python3
"""embed_spirv.py — compile GLSL shaders to SPIR-V (glslc) and emit one C header.

Each input shader (*.vert / *.frag) is compiled to SPIR-V and written into the
output header as a `static const uint32_t spv_<name>_<stage>[]` array plus its
byte length, so the Vulkan backend can create shader modules with zero runtime
file dependencies (keeps the self-contained exe). Stage is inferred from the
file extension.

Usage:
  embed_spirv.py --glslc <glslc> --out <header.h> shader1.vert shader2.frag ...
"""
import argparse, os, subprocess, sys, struct, tempfile

STAGE = {".vert": "vert", ".frag": "frag", ".comp": "comp"}

def ident(path):
    base = os.path.basename(path)
    name, ext = os.path.splitext(base)
    return "%s_%s" % (name.replace("-", "_"), STAGE[ext]), STAGE[ext]

def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--glslc", required=True)
    ap.add_argument("--out", required=True)
    ap.add_argument("shaders", nargs="+")
    a = ap.parse_args()

    os.makedirs(os.path.dirname(a.out), exist_ok=True)
    out = ["/* Auto-generated by embed_spirv.py — do not edit. */",
           "#ifndef PSX_VK_SHADERS_SPV_H",
           "#define PSX_VK_SHADERS_SPV_H",
           "#include <stdint.h>", ""]

    # Scratch dir for the intermediate .spv files. It MUST NOT be the shader
    # source dir: every runtime target (psx-runtime, psx-oracle, each game exe)
    # runs this script over the SAME shaders, and under `ninja -j N` two of them
    # overlap. Writing "<shader>.spv" next to the source made them race — one
    # process removed the file the other had just written, and the loser died
    # with FileNotFoundError on a shader it had compiled successfully. Keeping
    # the scratch per-invocation makes concurrent runs independent, and the
    # TemporaryDirectory also stops a crash from leaving .spv litter in the
    # source tree.
    with tempfile.TemporaryDirectory(prefix="psx_spirv_") as scratch:
      for sh in a.shaders:
        name, stage = ident(sh)
        spv = os.path.join(scratch, os.path.basename(sh) + ".spv")
        cmd = [a.glslc, "--target-env=vulkan1.1", "-O", sh, "-o", spv]
        r = subprocess.run(cmd, capture_output=True, text=True)
        if r.returncode != 0:
            sys.stderr.write("glslc failed for %s:\n%s\n" % (sh, r.stderr))
            return 1
        with open(spv, "rb") as f:
            data = f.read()
        os.remove(spv)
        if len(data) % 4 != 0:
            sys.stderr.write("SPIR-V for %s not 4-byte aligned\n" % sh)
            return 1
        words = struct.unpack("<%dI" % (len(data) // 4), data)
        out.append("static const uint32_t spv_%s[] = {" % name)
        line = "  "
        for w in words:
            tok = "0x%08x," % w
            if len(line) + len(tok) > 96:
                out.append(line); line = "  "
            line += tok
        if line.strip():
            out.append(line)
        out.append("};")
        out.append("static const uint32_t spv_%s_size = sizeof(spv_%s);" % (name, name))
        out.append("")

    out.append("#endif")
    with open(a.out, "w") as f:
        f.write("\n".join(out))
    return 0

if __name__ == "__main__":
    sys.exit(main())