from __future__ import annotations

from datetime import UTC, datetime
from enum import StrEnum
from typing import Annotated

from annotated_types import MinLen
from pydantic import BaseModel, Field
from pydantic_extra_types.country import CountryAlpha2
from ulid import ULID

from .ref import AccountRef


class ChannelType(StrEnum):
    """渠道类型"""

    PAYMENT_CARD = "PAYMENT_CARD"
    E_WALLET = "E_WALLET"
    CASH = "CASH"


class PaymentInstrumentType(StrEnum):
    """支付工具类型"""

    CREDIT = "CREDIT"
    DEBIT = "DEBIT"

    # 暂无实现的必要
    # PREPAID = "PREPAID"
    # BNPL = "BNPL"
    # CONSUMER_LOAN = "CONSUMER_LOAN"


class BaseChannel(BaseModel):
    """基础渠道模型"""

    id: ULID = Field(default_factory=ULID)
    ref_accounts: Annotated[list[AccountRef], "关联的账户引用列表", MinLen(1)]
    created_at: Annotated[datetime, "创建时间", Field(default_factory=lambda: datetime.now(UTC))]
    updated_at: Annotated[datetime, "更新时间", Field(default_factory=lambda: datetime.now(UTC))]
    deleted_at: Annotated[datetime | None, "软删除时间（None=未删除）", Field(default=None)]


class PaymentCardChannel(BaseChannel):
    """支付卡渠道"""

    channel_type = ChannelType.PAYMENT_CARD
    region: Annotated[CountryAlpha2, "发卡地/清算区域"]
    issuer_name: Annotated[str, "发卡方名称", MinLen(1)]
    card_type: Annotated[PaymentInstrumentType, "卡类型"]
    card_suffix: Annotated[str, "卡号末尾部分，可为后4/5位或完整卡号", MinLen(1)]
    card_brand: Annotated[
        str | None,
        "卡组织: UnionPay/Visa/Mastercard/JCB/AMEX/Octopus。通常可由完整卡号自动推断",
        Field(default=None),
    ]


class EWalletChannel(BaseChannel):
    """电子钱包渠道"""

    channel_type = ChannelType.E_WALLET
    region: Annotated[CountryAlpha2, "钱包所属区域"]
    platform: Annotated[
        str,
        "平台名: Alipay/WeChatPay/PayMe/AlipayHK/MPay/Octopus/AlipayMO",
        MinLen(1),
    ]
    platform_account_id: Annotated[str | None, "平台账户ID/手机号掩码", Field(default=None)]

    sub_channel: Annotated[
        str | None, "子渠道: 余额/花呗/信用卡快捷/八达通App等", Field(default=None)
    ]
    sub_channel_type: Annotated[PaymentInstrumentType, "子渠道类型"]


class CashChannel(BaseChannel):
    """现金渠道"""

    channel_type = ChannelType.CASH


class TransferChannel(BaseChannel):
    """转账渠道"""

    channel_type = ChannelType.TRANSFER


type Channel = Annotated[
    PaymentCardChannel | EWalletChannel | CashChannel,
    Field(discriminator="channel_type"),
]