from sqlalchemy import func

from app import db
from app.models import Folder, 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_user_photo_count(user_id):
    return Photo.query.filter_by(user_id=user_id).count()


def get_user_folder_count(user_id):
    return Folder.query.filter_by(owner_id=user_id).count()


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 _limit_reached(current, limit):
    return limit > 0 and current >= limit


def check_folder_limit(user):
    group = get_user_group(user)
    if not group or group.max_folders == 0:
        return True, ""

    count = get_user_folder_count(user.id)
    if _limit_reached(count, group.max_folders):
        return False, (
            f"Достигнут лимит папок группы «{group.name}»: "
            f"{count} / {group.max_folders}"
        )
    return True, ""


def check_photo_count_limit(user, additional_count=1):
    group = get_user_group(user)
    if not group or group.max_photos == 0:
        return True, ""

    count = get_user_photo_count(user.id)
    if count + additional_count > group.max_photos:
        return False, (
            f"Достигнут лимит фото группы «{group.name}»: "
            f"{count} / {group.max_photos}"
        )
    return True, ""


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:
        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)
    photo_count = get_user_photo_count(user.id)
    folder_count = get_user_folder_count(user.id)
    quota_bytes = get_group_quota_bytes(group)

    photos_unlimited = not group or group.max_photos == 0
    folders_unlimited = not group or group.max_folders == 0

    if quota_bytes is None:
        return {
            "group": group,
            "used": used,
            "quota_bytes": None,
            "percent": 0,
            "unlimited": True,
            "photo_count": photo_count,
            "photo_limit": group.max_photos if group else 0,
            "photos_unlimited": photos_unlimited,
            "photos_percent": 0,
            "folder_count": folder_count,
            "folder_limit": group.max_folders if group else 0,
            "folders_unlimited": folders_unlimited,
            "folders_percent": 0,
        }

    percent = min(100, int(used / quota_bytes * 100)) if quota_bytes else 0
    photos_percent = (
        min(100, int(photo_count / group.max_photos * 100))
        if group and group.max_photos
        else 0
    )
    folders_percent = (
        min(100, int(folder_count / group.max_folders * 100))
        if group and group.max_folders
        else 0
    )

    return {
        "group": group,
        "used": used,
        "quota_bytes": quota_bytes,
        "percent": percent,
        "unlimited": False,
        "photo_count": photo_count,
        "photo_limit": group.max_photos if group else 0,
        "photos_unlimited": photos_unlimited,
        "photos_percent": photos_percent,
        "folder_count": folder_count,
        "folder_limit": group.max_folders if group else 0,
        "folders_unlimited": folders_unlimited,
        "folders_percent": folders_percent,
    }