from __future__ import annotations

from datetime import datetime
from decimal import Decimal

from sqlalchemy import Boolean, CheckConstraint, DateTime, Index, JSON, Numeric, String
from sqlalchemy.orm import Mapped, mapped_column

from app.enums.credit_balance import CreditLevel
from app.enums.credit_product import CreditProductType
from app.models.base import Base, TimestampMixin


class CreditProduct(Base, TimestampMixin):
    __tablename__ = "credit_products"
    __table_args__ = (
        Index("uq_credit_products_code", "product_code", unique=True),
        Index("ix_credit_products_public", "product_type", "is_active", "sort_order"),
        CheckConstraint("price >= 0", name="ck_credit_products_price_nonnegative"),
        CheckConstraint("first_purchase_price IS NULL OR first_purchase_price >= 0", name="ck_credit_products_first_price_nonnegative"),
        CheckConstraint("regular_price IS NULL OR regular_price >= 0", name="ck_credit_products_regular_price_nonnegative"),
        CheckConstraint("activity_price IS NULL OR activity_price >= 0", name="ck_credit_products_activity_price_nonnegative"),
        CheckConstraint("monthly_grant_credits IS NULL OR monthly_grant_credits > 0", name="ck_credit_products_monthly_grant_positive"),
        CheckConstraint("grant_credits IS NULL OR grant_credits > 0", name="ck_credit_products_grant_positive"),
        CheckConstraint(
            "(product_type = 'subscription' AND tier_code IS NOT NULL AND tier_rank IS NOT NULL "
            "AND billing_cycle IS NOT NULL AND monthly_grant_credits IS NOT NULL "
            "AND first_purchase_price IS NOT NULL AND regular_price IS NOT NULL "
            "AND grant_credits IS NULL AND validity_months IS NULL) "
            "OR (product_type = 'credit_addon' AND grant_credits IS NOT NULL "
            "AND validity_months = 1 AND tier_code IS NULL AND tier_rank IS NULL "
            "AND billing_cycle IS NULL AND monthly_grant_credits IS NULL "
            "AND first_purchase_price IS NULL AND regular_price IS NULL "
            "AND activity_price IS NULL AND activity_start_at IS NULL AND activity_end_at IS NULL)",
            name="ck_credit_products_type_required_fields",
        ),
        CheckConstraint(
            "(activity_price IS NULL AND activity_start_at IS NULL AND activity_end_at IS NULL) "
            "OR (activity_price IS NOT NULL AND activity_start_at IS NOT NULL "
            "AND activity_end_at IS NOT NULL AND activity_end_at > activity_start_at)",
            name="ck_credit_products_activity_window",
        ),
    )

    id: Mapped[str] = mapped_column(String(32), primary_key=True)
    product_code: Mapped[str] = mapped_column(String(64), nullable=False)
    product_type: Mapped[str] = mapped_column(String(24), nullable=False, index=True)
    name: Mapped[str] = mapped_column(String(96), nullable=False)
    description: Mapped[str | None] = mapped_column(String(512), nullable=True)
    features_json: Mapped[list | None] = mapped_column(JSON, nullable=True)

    # 订阅套餐字段
    tier_code: Mapped[str | None] = mapped_column(String(32), nullable=True)
    tier_rank: Mapped[int | None] = mapped_column(nullable=True)
    billing_cycle: Mapped[str | None] = mapped_column(String(24), nullable=True)
    monthly_grant_credits: Mapped[Decimal | None] = mapped_column(Numeric(20, 2), nullable=True)
    first_purchase_price: Mapped[Decimal | None] = mapped_column(Numeric(20, 2), nullable=True)
    regular_price: Mapped[Decimal | None] = mapped_column(Numeric(20, 2), nullable=True)
    activity_price: Mapped[Decimal | None] = mapped_column(Numeric(20, 2), nullable=True)
    activity_start_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    activity_end_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    renewal_enabled: Mapped[bool] = mapped_column(
        Boolean, nullable=False, default=True, server_default="true"
    )

    # 积分增值包字段；当前固定一个自然月有效。
    grant_credits: Mapped[Decimal | None] = mapped_column(Numeric(20, 2), nullable=True)
    validity_months: Mapped[int | None] = mapped_column(nullable=True)

    price: Mapped[Decimal] = mapped_column(Numeric(20, 2), nullable=False, default=Decimal("0.00"), server_default="0")
    credit_level: Mapped[str] = mapped_column(
        String(32), nullable=False, default=CreditLevel.GENERAL.value, server_default=CreditLevel.GENERAL.value
    )
    currency: Mapped[str] = mapped_column(String(8), nullable=False, default="CNY", server_default="CNY")
    is_active: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True, server_default="true")
    sort_order: Mapped[int] = mapped_column(nullable=False, default=0, server_default="0")

    @property
    def is_subscription(self) -> bool:
        return self.product_type == CreditProductType.SUBSCRIPTION.value

    @property
    def is_credit_addon(self) -> bool:
        return self.product_type == CreditProductType.CREDIT_ADDON.value