#   pdf-segmented: Generate PDFs using separate compression for foreground and background
#   Copyright (C) 2025  Lee Yingtong Li
#
#   This program is free software: you can redistribute it and/or modify
#   it under the terms of the GNU Affero General Public License as published by
#   the Free Software Foundation, either version 3 of the License, or
#   (at your option) any later version.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU Affero General Public License for more details.
#
#   You should have received a copy of the GNU Affero General Public License
#   along with this program.  If not, see <https://www.gnu.org/licenses/>.

from . import CompressedLayer
from ..util import assert_has_jbig2

from PIL import Image

from dataclasses import dataclass
import os
import subprocess
import tempfile

@dataclass
class JBIG2Layer(CompressedLayer):
	data: bytes

def jbig2_compress_layer(layer: Image, tempdir: str) -> JBIG2Layer:
	assert_has_jbig2('JBIG2 compression requires jbig2enc')
	
	# Save image to PNG temporarily
	_, png_file = tempfile.mkstemp(suffix='.png', dir=tempdir)
	
	try:
		layer.save(png_file, format='png')
		
		# Compress using JBIG2
		# Passing "-s" uses lossly JBIG2 encoding, so we do not pass this option
		jbig2_proc = subprocess.run(['jbig2', '-p', '-v', png_file], cwd=tempdir, check=True, capture_output=True)
		jbig2_data = jbig2_proc.stdout
	finally:
		# Clean up
		os.unlink(png_file)
	
	return JBIG2Layer(data=jbig2_data)