import uuid
from datetime import datetime

from sqlalchemy import String, Boolean, Float, ForeignKey, Index, func, Text
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(
        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"),
    )