from __future__ import annotations

import re
from pathlib import Path
from uuid import uuid4

from PIL import Image, ImageDraw
from pillow_heif import register_heif_opener
from werkzeug.datastructures import FileStorage
from werkzeug.utils import secure_filename

register_heif_opener()


def allowed_file(filename: str, allowed_extensions: set[str]) -> bool:
    return '.' in filename and filename.rsplit('.', 1)[1].lower() in allowed_extensions


def _apply_image_ops(image: Image.Image, rotate: int = 0, crop_box: tuple[int, int, int, int] | None = None, scale_percent: int = 100) -> Image.Image:
    if image.mode not in ('RGB', 'RGBA'):
        image = image.convert('RGB')
    if rotate:
        image = image.rotate(-rotate, expand=True)
    if crop_box:
        x, y, w, h = crop_box
        if w > 0 and h > 0:
            image = image.crop((x, y, x + w, y + h))
    if scale_percent and scale_percent != 100:
        width = max(1, int(image.width * (scale_percent / 100)))
        height = max(1, int(image.height * (scale_percent / 100)))
        image = image.resize((width, height))
    return image


def _pdf_placeholder(preview_path: Path, original_name: str) -> None:
    image = Image.new('RGB', (800, 1100), color='white')
    draw = ImageDraw.Draw(image)
    draw.text((40, 40), f'PDF preview\n{original_name}', fill='black')
    image.save(preview_path, 'WEBP', quality=80)


def save_document(file: FileStorage, upload_dir: Path, preview_dir: Path, rotate: int = 0, crop_box: tuple[int, int, int, int] | None = None, scale_percent: int = 100) -> tuple[str, str]:
    upload_dir.mkdir(parents=True, exist_ok=True)
    preview_dir.mkdir(parents=True, exist_ok=True)

    original_name = secure_filename(file.filename or 'document')
    extension = original_name.rsplit('.', 1)[1].lower() if '.' in original_name else 'bin'
    stem = re.sub(r'[^a-zA-Z0-9_-]+', '-', Path(original_name).stem).strip('-') or 'document'
    unique_name = f'{stem}-{uuid4().hex}.{extension}'
    saved_path = upload_dir / unique_name
    file.save(saved_path)

    preview_name = f'{stem}-{uuid4().hex}.webp'
    preview_path = preview_dir / preview_name
    if extension in {'jpg', 'jpeg', 'png', 'heic'}:
        image = Image.open(saved_path)
        image = _apply_image_ops(image, rotate=rotate, crop_box=crop_box, scale_percent=scale_percent)
        image.save(preview_path, 'WEBP', quality=80)
    elif extension == 'pdf':
        _pdf_placeholder(preview_path, original_name)
    else:
        preview_name = ''
    return unique_name, preview_name