from dataclasses import dataclass, field
from typing import List, Optional


@dataclass
class MerchantCategoryMail:
    """Domain entity representing a mail entry linked to one or more merchant
    categories.

    category_ids is the parsed form of the DB's comma-separated
    merchant_category_list column (e.g. "1,3,7" → [1, 3, 7]).
    """

    id: int
    email: str
    category_ids: List[int] = field(default_factory=list)
    created_by: Optional[int] = None
    updated_by: Optional[int] = None


@dataclass
class MerchantCategoryMailSummary:
    """Slim view used when listing all entries (id + email only)."""

    id: int
    email: str