#!/usr/bin/env python3
"""converts DXT5 dds files to DXT1 without generation loss."""

import sys
import os
import os.path
import argparse
import dds

parser = argparse.ArgumentParser(
    description=__doc__)
parser.add_argument('files', type=str, nargs='*',
    help = "input dds files. Paths are read from stdin if none are given")

args = parser.parse_args()

if len(args.files) < 1 and not sys.stdin.isatty():
    args.files = sys.stdin.read().splitlines()

for argv in args.files:
    path = os.path.abspath(argv)

    # read DDS file
    with open(path, 'rb') as file:
        ddsfile = dds.DDSFile(file)

    # check its actually dxt5
    if ddsfile.four_cc != 'DXT5':
        print(f'[{argv}] file is not DXT5, aborting.')
        continue
    print(f'[{argv}] converting to DXT1')

    # make modifications
    ddsfile.four_cc = 'DXT1'
    ddsfile.textures = [tex.to_dxt1() for tex in ddsfile.textures]
    ddsfile.linear_size //= 2

    # write DDS file
    with open(path, 'wb') as file:
        ddsfile.write(file)