#!/usr/bin/env python3
"""Assemble ordered scanner pages; OpenCV is optional, PDF creation is not."""
import argparse
import json
from pathlib import Path

from PIL import Image


def create_document(inputs, output, resolution, use_postprocess=False, profile="document", strict=False):
    if not inputs:
        raise ValueError("Keine Seiten vorhanden")
    output = Path(output)
    file_format = {".pdf": "PDF", ".png": "PNG", ".tiff": "TIFF"}.get(output.suffix.lower())
    if not file_format:
        raise ValueError("Unbekanntes Ausgabeformat")
    if file_format != "PDF" and len(inputs) != 1:
        raise ValueError("Mehrseitige Scans benötigen PDF als Ausgabeformat")

    warnings = []
    processor = None
    if use_postprocess:
        try:
            from opencv_postprocess import postprocess
            processor = postprocess
        except ImportError:
            if strict:
                raise
            warnings.append("OpenCV fehlt; alle Seiten wurden ohne Bildkorrektur übernommen.")

    partial = output.with_name(output.name + ".partial")
    try:
        for index, input_path in enumerate(inputs):
            input_path = Path(input_path)
            image_path = input_path
            corrected = input_path.with_name(input_path.stem + ".corrected.png")
            if processor:
                try:
                    processor(input_path, corrected, profile)
                    image_path = corrected
                except Exception:
                    if strict:
                        raise
                    warnings.append(f"Seite {index + 1}: Bildkorrektur fehlgeschlagen; Rohscan übernommen.")

            # Only one decoded page is kept in memory, even for large duplex stacks.
            with Image.open(image_path) as image:
                with image.convert("RGB") as rgb:
                    if file_format == "PDF":
                        rgb.save(partial, "PDF", resolution=resolution, quality=90, append=index > 0)
                    else:
                        rgb.save(partial, file_format, dpi=(resolution, resolution))
            corrected.unlink(missing_ok=True)
        partial.replace(output)
    finally:
        partial.unlink(missing_ok=True)

    return {"pageCount": len(inputs), "warnings": warnings}


def main():
    parser = argparse.ArgumentParser(description="Scan-Seiten zu einer Datei zusammenführen")
    parser.add_argument("--inputs", nargs="+", required=True)
    parser.add_argument("--output", required=True)
    parser.add_argument("--resolution", type=float, required=True)
    parser.add_argument("--profile", choices=["document", "receipt", "raw"], default="document")
    parser.add_argument("--postprocess", action="store_true")
    parser.add_argument("--strict", action="store_true")
    args = parser.parse_args()
    print(json.dumps(create_document(args.inputs, args.output, args.resolution, args.postprocess, args.profile, args.strict)))


if __name__ == "__main__":
    main()