import os
import uuid
from datetime import datetime, timezone

from werkzeug.utils import secure_filename

from app import db
from app.models import Photo
from app.quota_utils import check_photo_count_limit, check_upload_quota
from app.settings_service import get_settings
from app.storage_service import save_photo_file


def allowed_file(filename, allowed_extensions):
    return "." in filename and filename.rsplit(".", 1)[1].lower() in allowed_extensions


def collect_upload_files(request_files):
    files = request_files.getlist("photos")
    if not files or all(f.filename == "" for f in files):
        single = request_files.get("photo")
        if single and single.filename:
            files = [single]
    return [f for f in files if f and f.filename]


def process_uploads(request_files, user, folder, allowed_extensions):
    settings = get_settings()
    max_bulk = settings.max_bulk_upload or 100
    files = collect_upload_files(request_files)

    if not files:
        return {"uploaded": 0, "errors": ["Файлы не выбраны"], "photos": []}

    if len(files) > max_bulk:
        return {
            "uploaded": 0,
            "errors": [f"Максимум {max_bulk} файлов за раз"],
            "photos": [],
        }

    total_size = 0
    valid_files = []
    errors = []

    for file in files:
        if not allowed_file(file.filename, allowed_extensions):
            errors.append(f"{file.filename}: недопустимый формат")
            continue
        file.seek(0, os.SEEK_END)
        size = file.tell()
        file.seek(0)
        total_size += size
        valid_files.append((file, size))

    if not valid_files:
        return {"uploaded": 0, "errors": errors, "photos": []}

    ok, photo_limit_msg = check_photo_count_limit(user, len(valid_files))
    if not ok:
        return {"uploaded": 0, "errors": [photo_limit_msg], "photos": []}

    ok, quota_msg = check_upload_quota(user, total_size)
    if not ok:
        return {"uploaded": 0, "errors": [quota_msg], "photos": []}

    uploaded_photos = []
    for file, _size in valid_files:
        ext = file.filename.rsplit(".", 1)[1].lower()
        stored_name = f"{uuid.uuid4().hex}.{ext}"
        safe_original = secure_filename(file.filename) or f"photo.{ext}"

        try:
            _path, file_size, storage_backend, sync_errors = save_photo_file(file, stored_name)
            for sync_err in sync_errors:
                errors.append(f"{safe_original}: {sync_err}")

            photo = Photo(
                filename=stored_name,
                original_name=safe_original,
                file_size=file_size,
                mime_type=file.content_type or f"image/{ext}",
                user_id=user.id,
                folder_id=folder.id if folder else None,
                storage_backend=storage_backend,
                created_at=datetime.now(timezone.utc),
            )
            db.session.add(photo)
            uploaded_photos.append(photo)
        except Exception as exc:
            errors.append(f"{safe_original}: {exc}")

    if uploaded_photos:
        db.session.commit()

    return {
        "uploaded": len(uploaded_photos),
        "errors": errors,
        "photos": uploaded_photos,
    }