from sqlalchemy import func

from app import db
from app.models import Photo, User, UserGroup


def get_default_group():
    return UserGroup.query.filter_by(is_default=True).first()


def get_user_group(user):
    if user.group_id and user.group:
        return user.group
    return get_default_group()


def get_user_storage_used(user_id):
    result = db.session.query(func.coalesce(func.sum(Photo.file_size), 0)).filter(
        Photo.user_id == user_id
    ).scalar()
    return int(result or 0)


def get_group_quota_bytes(group):
    if not group or group.disk_quota_mb == 0:
        return None
    return group.disk_quota_mb * 1024 * 1024


def check_upload_quota(user, new_file_size):
    group = get_user_group(user)
    quota_bytes = get_group_quota_bytes(group)
    if quota_bytes is None:
        return True, ""

    used = get_user_storage_used(user.id)
    if used + new_file_size > quota_bytes:
        from app.models import Photo as _Photo

        used_human = _Photo(file_size=used).size_human if used else "0 Б"
        quota_human = f"{group.disk_quota_mb} МБ"
        return False, f"Превышена квота группы «{group.name}»: {used_human} / {quota_human}"
    return True, ""


def quota_status(user):
    group = get_user_group(user)
    used = get_user_storage_used(user.id)
    quota_bytes = get_group_quota_bytes(group)
    if quota_bytes is None:
        return {
            "group": group,
            "used": used,
            "quota_bytes": None,
            "percent": 0,
            "unlimited": True,
        }
    percent = min(100, int(used / quota_bytes * 100)) if quota_bytes else 0
    return {
        "group": group,
        "used": used,
        "quota_bytes": quota_bytes,
        "percent": percent,
        "unlimited": False,
    }