from __future__ import annotations

import hashlib
import os
import re
from pathlib import Path

IMAGE_EXTENSIONS = {".jpg", ".jpeg", ".png", ".gif", ".webp", ".bmp", ".svg"}
VIDEO_EXTENSIONS = {".mp4", ".mov", ".avi", ".mkv", ".webm", ".flv", ".wmv"}
ALLOWED_EXTENSIONS = IMAGE_EXTENSIONS | VIDEO_EXTENSIONS | {".pdf", ".txt", ".json", ".zip", ".rar"}

_DEFAULT_MAX_FILE_BYTES = 50 * 1024 * 1024


class FileService:
    def __init__(self, storage_dir: str | Path, max_file_bytes: int = _DEFAULT_MAX_FILE_BYTES):
        self.storage_dir = Path(storage_dir)
        self.storage_dir.mkdir(parents=True, exist_ok=True)
        self.max_file_bytes = max_file_bytes

    def classify(self, filename: str) -> str:
        ext = os.path.splitext(filename)[1].lower()
        if ext in IMAGE_EXTENSIONS:
            return "image"
        if ext in VIDEO_EXTENSIONS:
            return "video"
        return "file"

    def generate_safe_name(self, original_name: str) -> str:
        name = self._sanitize_filename(original_name)
        h = hashlib.sha256(name.encode()).hexdigest()[:12]
        ext = os.path.splitext(original_name)[1].lower()
        return f"{h}_{name}"

    async def save_upload(self, content: bytes, safe_name: str) -> Path:
        dest = self.storage_dir / safe_name
        dest.write_bytes(content)
        return dest

    @staticmethod
    def _sanitize_filename(filename: str) -> str:
        return re.sub(r"[^\w.\-]", "_", filename)