#!/usr/bin/env python3
"""Checks any number of dds files for common issues"""

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

class Check(enum.Enum):
    """Kinds of check to perform"""
    TRANPARENCY = 1
    FORMAT = 2

parser = argparse.ArgumentParser(description= __doc__)
parser.add_argument('files', type=str, nargs='*', help = "input dds files")

parser.add_argument('--transparency', '-t',
    action='append_const', dest='checks', const=Check.TRANPARENCY,
    help = "Check textures for unnecessary transparency map")
parser.add_argument('--format', '-f',
    action='append_const', dest='checks', const=Check.FORMAT,
    help = "Check texture formats")
parser.add_argument('--all', '-a',
    action='store_const', dest='checks', const=[Check.TRANPARENCY, Check.FORMAT],
    help = "Perform all checks")

parser.add_argument('--formats', nargs='+', default = ['DXT1', 'DXT5'],
    help="Valid texture formats to check against (default: %(default)s)")

parser.add_argument('--convertcmd', type=str, metavar='CMD', default=dds.convertcmd,
    help="name of imagemagick's convert tool (default: %(default)s)")

args = parser.parse_args()

dds.convertcmd = args.convertcmd

def printerror(path, shortpath, message):
    """either prints a message or just the path depending on if stdout is a tty"""
    if sys.stdout.isatty():
        print(f'[{shortpath}]: {message}')
    else:
        sys.stdout.write(path+'\n')

def checkfile(shortpath, checks, formats):
    """check a single dds file for common issues"""
    path = os.path.abspath(shortpath)

    with open(path, 'rb') as file:
        ddsfile = dds.DDSFile()
        ddsfile.read_header(file)
        four_cc = ddsfile.four_cc
        if four_cc == '':
            four_cc = "uncompressed"

    alpha = dds.alpha(path)

    if Check.TRANPARENCY in checks and four_cc == 'DXT5' and alpha > 254:
        printerror(path, shortpath, 'Image is DXT5 but has no alpha channel')

    if Check.FORMAT in checks and four_cc not in formats:
        printerror(path, shortpath, f'Incompatible format: {four_cc}')

for shortpath in args.files:
    checkfile(shortpath, args.checks, args.formats)