from __future__ import annotations

from datetime import datetime
from typing import Any

from sqlalchemy import CheckConstraint, DateTime, Index, Integer, JSON, String, Text
from sqlalchemy.dialects.postgresql import JSONB
from sqlalchemy.orm import Mapped, mapped_column

from app.models.base import Base, TimestampMixin


JsonType = JSON().with_variant(JSONB, "postgresql")


class ModelPricingRule(Base, TimestampMixin):
    __tablename__ = "model_pricing_rules"
    __table_args__ = (
        Index(
            "uq_model_pricing_rules_provider_model_version",
            "provider",
            "model_name",
            "version_code",
            unique=True,
        ),
        Index(
            "ix_model_pricing_rules_resolve",
            "provider",
            "model_name",
            "publish_status",
            "effective_from",
            "effective_to",
        ),
        Index("ix_model_pricing_rules_category_status", "model_category", "publish_status"),
        CheckConstraint(
            "effective_to IS NULL OR effective_to >= effective_from",
            name="ck_model_pricing_rules_effective_range",
        ),
    )

    id: Mapped[str] = mapped_column(String(32), primary_key=True)
    provider: Mapped[str] = mapped_column(String(32), nullable=False, index=True)
    model_name: Mapped[str] = mapped_column(String(128), nullable=False, index=True)
    model_category: Mapped[str] = mapped_column(String(16), nullable=False, index=True)
    billing_mode: Mapped[str] = mapped_column(String(48), nullable=False, index=True)
    calculator_version: Mapped[str] = mapped_column(String(64), nullable=False, index=True)
    version_code: Mapped[str] = mapped_column(String(64), nullable=False)

    effective_from: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, index=True)
    effective_to: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True, index=True)
    publish_status: Mapped[str] = mapped_column(String(16), nullable=False, default="draft", index=True)

    currency: Mapped[str] = mapped_column(String(8), nullable=False, default="CNY")
    rule_schema_version: Mapped[int] = mapped_column(Integer, nullable=False, default=1)
    # 规则 JSON 统一使用“构建新 dict 后整体赋值”，禁止嵌套原地修改。
    rule_json: Mapped[dict[str, Any]] = mapped_column(JsonType, nullable=False, default=dict)
    rule_content_hash: Mapped[str] = mapped_column(String(64), nullable=False, index=True)

    source_url: Mapped[str | None] = mapped_column(Text, nullable=True)
    source_updated_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    remark: Mapped[str | None] = mapped_column(Text, nullable=True)
    created_by: Mapped[str | None] = mapped_column(String(32), nullable=True)
    updated_by: Mapped[str | None] = mapped_column(String(32), nullable=True)