"""
Service layer data transfer objects.

These dataclasses represent the data returned by service functions,
providing explicit types instead of raw dicts or ORM objects.
"""
from dataclasses import dataclass
from datetime import datetime


@dataclass(frozen=True)
class AssetData:
    """Plain data extracted from an Asset ORM object."""
    hash: str
    size_bytes: int | None
    mime_type: str | None


@dataclass(frozen=True)
class AssetInfoData:
    """Plain data extracted from an AssetInfo ORM object."""
    id: str
    name: str
    user_metadata: dict | None
    preview_id: str | None
    created_at: datetime
    updated_at: datetime
    last_access_time: datetime | None


@dataclass(frozen=True)
class AssetDetailResult:
    """Result from get_asset_detail and similar operations."""
    info: AssetInfoData
    asset: AssetData | None
    tags: list[str]


@dataclass(frozen=True)
class RegisterAssetResult:
    """Result from register_existing_asset."""
    info: AssetInfoData
    asset: AssetData
    tags: list[str]
    created: bool


def extract_info_data(info) -> AssetInfoData:
    """Extract plain data from an AssetInfo ORM object."""
    return AssetInfoData(
        id=info.id,
        name=info.name,
        user_metadata=info.user_metadata,
        preview_id=info.preview_id,
        created_at=info.created_at,
        updated_at=info.updated_at,
        last_access_time=info.last_access_time,
    )


def extract_asset_data(asset) -> AssetData | None:
    """Extract plain data from an Asset ORM object."""
    if asset is None:
        return None
    return AssetData(
        hash=asset.hash,
        size_bytes=asset.size_bytes,
        mime_type=asset.mime_type,
    )