import uuid
from datetime import datetime

from sqlalchemy import String, Boolean, Float, ForeignKey, Index, func, Text, DateTime
from sqlalchemy import Uuid, JSON
from sqlalchemy.dialects.postgresql import JSONB
from sqlalchemy.orm import Mapped, mapped_column, relationship
from sqlalchemy.types import TypeDecorator

from app.database import Base


class JSONType(TypeDecorator):
    """A JSON type that uses JSONB on PostgreSQL and JSON on other databases."""
    impl = JSON
    cache_ok = True

    def load_dialect_impl(self, dialect):
        if dialect.name == "postgresql":
            return dialect.type_descriptor(JSONB())
        return dialect.type_descriptor(JSON())


class Alert(Base):
    """告警记录表"""
    __tablename__ = "alerts"

    id: Mapped[uuid.UUID] = mapped_column(
        Uuid(as_uuid=True),
        primary_key=True,
        default=uuid.uuid4,
    )
    brand_id: Mapped[uuid.UUID] = mapped_column(
        Uuid(as_uuid=True),
        ForeignKey("brands.id", ondelete="CASCADE"),
        nullable=False,
    )
    user_id: Mapped[uuid.UUID] = mapped_column(
        Uuid(as_uuid=True),
        nullable=False,
        index=True,
    )
    alert_type: Mapped[str] = mapped_column(
        String(50), nullable=False,
        comment="告警类型: score_drop / score_rise / negative_sentiment / competitor_overtake / new_platform_mention",
    )
    severity: Mapped[str] = mapped_column(
        String(20), nullable=False,
        comment="严重程度: critical / warning / info",
    )
    title: Mapped[str] = mapped_column(String(200), nullable=False)
    message: Mapped[str] = mapped_column(Text, nullable=False)
    data: Mapped[dict | None] = mapped_column(
        JSONType, nullable=True,
        comment="告警相关数据（JSON）",
    )
    is_read: Mapped[bool] = mapped_column(
        Boolean, default=False, nullable=False,
    )
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )

    brand: Mapped["Brand"] = relationship("Brand")  # noqa: F821

    __table_args__ = (
        Index("idx_alerts_user_id", "user_id"),
        Index("idx_alerts_brand_id", "brand_id"),
        Index("idx_alerts_alert_type", "alert_type"),
        Index("idx_alerts_is_read", "is_read"),
        Index("idx_alerts_created_at", "created_at"),
        Index("idx_alerts_user_read", "user_id", "is_read"),
    )