# Copyright (c) 2026 Dominic Masters
#
# This software is released under the MIT License.
# https://opensource.org/licenses/MIT

"""
Writes DMF (Dusk Mesh Format) files.

DMF format:
  Bytes 0-3:  DMF\x00 (magic)
  Bytes 4-7:  uint32_t version = 1 (little-endian)
  Bytes 8-11: uint32_t vertCount (little-endian)
  Bytes 12+:  meshvertex_t vertices[vertCount]
              Each vertex is 20 bytes: uv[2] + pos[3] (5 floats, LE)

Usage:
  python3 -m tools.asset.dmf <output.dmf> <vertices.bin>
  Reads raw vertex bytes from vertices.bin and writes a DMF file.
"""

import struct
import sys
import os

MAGIC = b'DMF\x00'
VERSION = 1
VERTEX_SIZE = 20


def write_dmf(path, vertex_bytes):
    if len(vertex_bytes) % VERTEX_SIZE != 0:
        raise ValueError(
            f"Vertex data size {len(vertex_bytes)} is not a "
            f"multiple of {VERTEX_SIZE}"
        )
    vert_count = len(vertex_bytes) // VERTEX_SIZE
    buf = bytearray()
    buf += MAGIC
    buf += struct.pack('<I', VERSION)
    buf += struct.pack('<I', vert_count)
    buf += vertex_bytes
    with open(path, 'wb') as f:
        f.write(buf)
    print(
        f'Wrote {path}: {vert_count} vertices, {len(buf)} bytes'
    )
    return vert_count


def main():
    args = sys.argv[1:]
    if len(args) != 2:
        print(
            "Usage: python3 -m tools.asset.dmf "
            "<output.dmf> <vertices.bin>"
        )
        sys.exit(1)

    dst = args[0]
    src = args[1]

    with open(src, 'rb') as f:
        vertex_bytes = f.read()

    write_dmf(dst, vertex_bytes)


if __name__ == '__main__':
    main()