#   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 .compression import CompressionOptions, compress_pages
from .input.xcf import xcf_get_pages
from .output.djvu import djvu_write_pages
from .output.pdf import pdf_write_pages
from .segmentation import segment_pages

import os
import sys
import tempfile
from typing import Optional

def convert_file(
	input_file: str,
	output_file: str,
	input_format: Optional[str] = None,
	output_format: Optional[str] = None,
	fg_compression: Optional[str] = None,
	bg_compression: Optional[str] = None,
	options: CompressionOptions = CompressionOptions()
) -> None:
	# Create temporary directory
	tempdir = tempfile.mkdtemp('pdf-segmented')
	
	try:
		# Impute arguments
		if input_format is None:
			if input_file.endswith('.xcf'):
				input_format = 'xcf'
			else:
				print('Warning: Unknown input file extension, assuming XCF', file=sys.stderr)
		
		if output_format is None:
			if output_file.endswith('.pdf'):
				output_format = 'pdf'
			elif output_file.endswith('.djvu'):
				output_format = 'djvu'
			else:
				print('Error: Unknown output file extension (try --output-format)', file=sys.stderr)
				sys.exit(1)
		
		if fg_compression is None:
			if output_format == 'pdf':
				fg_compression = 'jbig2'
			elif output_format == 'djvu':
				fg_compression = 'jb2'
			else:
				raise NotImplementedError()
		
		if bg_compression is None:
			if output_format == 'pdf':
				bg_compression = 'jpeg'
			elif output_format == 'djvu':
				bg_compression = 'iw44'
			else:
				raise NotImplementedError()
		
		# Validate format compatibility
		if output_format == 'pdf':
			if bg_compression not in ('jp2', 'jpeg', 'png'):
				print('Error: Unsupported --bg-compression for PDF format (supported: jp2, jpeg, png)')
				sys.exit(1)
			if fg_compression not in ('jbig2', 'png'):
				print('Error: Unsupported --fg-compression for PDF format (supported: jp2, jpeg, png)')
				sys.exit(1)
		
		if output_format == 'djvu':
			if bg_compression != 'iw44':
				print('Error: Unsupported --bg-compression for DjVu format (supported: iw44)')
				sys.exit(1)
			if fg_compression != 'jb2':
				print('Error: Unsupported --fg-compression for DjVu format (supported: jb2)')
				sys.exit(1)
		
		# Get input pages
		if input_format == 'xcf':
			input_pages = xcf_get_pages(input_file)
		else:
			raise NotImplementedError()
		
		# Segment foreground and background
		segmented_pages = segment_pages(input_pages)
		
		# Compress layers
		compressed_pages = compress_pages(
			input_pages=input_pages,
			segmented_pages=segmented_pages,
			fg_compression=fg_compression,
			bg_compression=bg_compression,
			options=options,
			tempdir=tempdir
		)
		
		# Convert to output format
		if output_format == 'pdf':
			pdf_write_pages(
				input_pages=input_pages,
				compressed_pages=compressed_pages,
				output_file=output_file
			)
		elif output_format == 'djvu':
			djvu_write_pages(
				input_pages=input_pages,
				compressed_pages=compressed_pages,
				output_file=output_file,
				tempdir=tempdir
			)
		else:
			raise NotImplementedError()
	finally:
		# Clean up
		if os.path.exists(tempdir):
			os.rmdir(tempdir)