from datetime import datetime
from decimal import Decimal

from sqlalchemy import Boolean, DateTime, ForeignKey, Index, Integer, JSON, Numeric, String, UniqueConstraint, func
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.models.base import Base, TimestampMixin, UUIDMixin


class Experiment(Base, UUIDMixin, TimestampMixin):
    __tablename__ = "experiments"

    experiment_key: Mapped[str] = mapped_column(String(64), nullable=False, unique=True, index=True)
    cookie_name: Mapped[str] = mapped_column(String(96), nullable=False, unique=True)
    name: Mapped[str] = mapped_column(String(120), nullable=False)
    description: Mapped[str | None] = mapped_column(String(512), nullable=True)
    enabled: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True, index=True)
    eligible_routes: Mapped[list[str]] = mapped_column(JSON, nullable=False, default=list)

    variants: Mapped[list["ExperimentVariant"]] = relationship(
        back_populates="experiment",
        cascade="all, delete-orphan",
        passive_deletes=True,
        order_by="ExperimentVariant.variant_key",
    )


class ExperimentVariant(Base, UUIDMixin, TimestampMixin):
    __tablename__ = "experiment_variants"
    __table_args__ = (
        UniqueConstraint("experiment_id", "variant_key", name="uq_experiment_variants_experiment_variant"),
    )

    experiment_id: Mapped[str] = mapped_column(
        ForeignKey("experiments.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    variant_key: Mapped[str] = mapped_column(String(64), nullable=False)
    label: Mapped[str] = mapped_column(String(120), nullable=False)
    allocation: Mapped[int] = mapped_column(Integer, nullable=False)
    is_control: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)

    experiment: Mapped[Experiment] = relationship(back_populates="variants")


class ExperimentEvent(Base, UUIDMixin):
    __tablename__ = "experiment_events"
    __table_args__ = (
        Index("ix_experiment_events_experiment_variant_created_at", "experiment_key", "variant_key", "created_at"),
        Index("ix_experiment_events_session_created_at", "session_id", "created_at"),
    )

    experiment_key: Mapped[str] = mapped_column(String(64), nullable=False, index=True)
    variant_key: Mapped[str] = mapped_column(String(64), nullable=False, index=True)
    session_id: Mapped[str] = mapped_column(String(128), nullable=False, index=True)
    user_id: Mapped[str | None] = mapped_column(String(64), nullable=True, index=True)
    path: Mapped[str] = mapped_column(String(255), nullable=False, index=True)
    event_type: Mapped[str] = mapped_column(String(64), nullable=False, index=True)
    conversion_value: Mapped[Decimal | None] = mapped_column(Numeric(12, 2), nullable=True)
    metadata_: Mapped[dict | None] = mapped_column("metadata", JSON, nullable=True)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        nullable=False,
        index=True,
        default=datetime.utcnow,
        server_default=func.now(),
    )