#!/usr/bin/env python3
"""Generate flat-array C wrappers for all ts functions.

Each wrapper takes flat input/output arrays instead of pointer-of-pointers,
eliminating ctypes pointer marshaling overhead.
"""

import argparse
import importlib.util
import os
import sys

_spec = importlib.util.spec_from_file_location(
    "ts_parser",
    os.path.join(os.path.dirname(os.path.abspath(__file__)), "ts_parser.py"),
)
if _spec and _spec.loader:
    _ts_parser = importlib.util.module_from_spec(_spec)
    _spec.loader.exec_module(_ts_parser)
    parse_all = _ts_parser.parse_all
else:
    print("Error: could not load ts_parser", file=sys.stderr)
    sys.exit(1)

ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
OUT = os.path.join(ROOT, "lib", "ts_flat_generated.c")


def generate_wrappers(funcs, dry_run=False):
    """Generate flat-array C wrapper functions."""
    if dry_run:
        print(f"[dry-run] Would generate {len(funcs)} flat wrappers -> {OUT}")
        return

    with open(OUT, "w", encoding="utf-8") as f:
        f.write("/* Auto-generated flat-array wrappers. Do not edit. */\n\n")
        f.write("#include <string.h>\n")
        f.write('#include "ts.h"\n\n')

        for fm in funcs:
            safe_x_n = max(fm.x_n, 1)
            safe_y_n = max(fm.y_n, 1)

            f.write(f"/* {fm.name}: x_n={fm.x_n}, y_n={fm.y_n}, c_n={fm.c_n} */\n")
            f.write(f"int ts_{fm.name}_flat(\n")

            for i in range(fm.y_n):
                f.write(f"    fp_t *y{i},\n")

            for i in range(fm.x_n):
                f.write(f"    fp_t const *x{i},\n")

            f.write(f"    uint_t n,\n")
            f.write(f"    ts_constant_t const *params\n")
            f.write(f")\n{{\n")

            f.write(f"    fp_t * const _y[{safe_y_n}] = {{")
            f.write(", ".join(f"y{i}" for i in range(fm.y_n)))
            f.write("};\n")

            f.write(f"    fp_t const * const _x[{safe_x_n}] = {{")
            f.write(", ".join(f"x{i}" for i in range(fm.x_n)))
            f.write("};\n")

            for i in range(fm.y_n):
                f.write(f"    memset(y{i}, 0, n * sizeof(fp_t));\n")

            f.write(
                f"    return ts_{fm.name}(_y, {fm.y_n}, _x, {fm.x_n}, n, params);\n"
            )
            f.write("}\n\n")


def main():
    parser = argparse.ArgumentParser(description="Generate flat-array C wrappers")
    parser.add_argument(
        "--dry-run",
        action="store_true",
        help="Print what would be generated without writing",
    )
    args = parser.parse_args()

    funcs = parse_all(detect_x_access=True)

    if not funcs:
        print("Warning: no ts_parameter declarations found.", file=sys.stderr)
        sys.exit(1)

    generate_wrappers(funcs, dry_run=args.dry_run)

    if not args.dry_run:
        print(f"Generated {len(funcs)} flat wrappers -> {OUT}")


if __name__ == "__main__":
    main()