import uuid
from datetime import datetime, timedelta, timezone

from sqlalchemy import Boolean, DateTime, ForeignKey, Index, String, Uuid, func
from sqlalchemy.orm import Mapped, mapped_column

from app.database import Base, JSONType

VALID_FREQUENCIES = {"hourly", "daily", "weekly"}

FREQUENCY_DELTAS = {
    "hourly": timedelta(hours=1),
    "daily": timedelta(days=1),
    "weekly": timedelta(weeks=1),
}


class DetectionTask(Base):
    __tablename__ = "detection_tasks"

    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,
    )
    name: Mapped[str] = mapped_column(String(200), nullable=False)
    frequency: Mapped[str] = mapped_column(String(20), nullable=False)
    engines: Mapped[list] = mapped_column(JSONType, default=list, nullable=False)
    queries: Mapped[list] = mapped_column(JSONType, default=list, nullable=False)
    competitor_names: Mapped[list | None] = mapped_column(JSONType, nullable=True)
    is_active: Mapped[bool] = mapped_column(Boolean, default=True, nullable=False)
    last_run_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    next_run_at: Mapped[datetime | None] = mapped_column(
        DateTime(timezone=True), nullable=True, default=lambda: datetime.now(timezone.utc)
    )
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        onupdate=func.now(),
        nullable=False,
    )

    __table_args__ = (
        Index("idx_detection_tasks_brand_id", "brand_id"),
        Index("idx_detection_tasks_user_id", "user_id"),
        Index("idx_detection_tasks_is_active", "is_active"),
    )

    def compute_next_run_at(self) -> datetime:
        delta = FREQUENCY_DELTAS.get(self.frequency, timedelta(days=1))
        base = self.last_run_at or datetime.now(timezone.utc)
        return base + delta