import uuid
from datetime import datetime
from typing import TYPE_CHECKING

from sqlalchemy import CheckConstraint, DateTime, ForeignKey, Index, String, text
from sqlalchemy.dialects.postgresql import JSONB, UUID
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.core.db import Base
from app.models.mixins import TimestampMixin, UUIDPrimaryKeyMixin

if TYPE_CHECKING:
    from app.models.user import User

RULE_TYPES = (
    "possible_duplicate_customer",
    "missing_required_field",
    "odometer_regression",
    "booking_overlap",
    "vehicle_status_conflict",
)
SEVERITIES = ("low", "medium", "high")
ISSUE_STATUSES = ("open", "deferred", "resolved", "rejected")


class DataQualityIssue(UUIDPrimaryKeyMixin, TimestampMixin, Base):
    __tablename__ = "data_quality_issues"
    __table_args__ = (
        CheckConstraint(
            "rule_type IN ('possible_duplicate_customer','missing_required_field',"
            "'odometer_regression','booking_overlap','vehicle_status_conflict')",
            name="ck_data_quality_rule_type",
        ),
        CheckConstraint("severity IN ('low','medium','high')", name="ck_data_quality_severity"),
        CheckConstraint(
            "status IN ('open','deferred','resolved','rejected')",
            name="ck_data_quality_status",
        ),
        Index("ix_data_quality_work_queue", "status", "due_at", "severity"),
        Index(
            "uq_data_quality_one_open_condition",
            "rule_type",
            "entity_type",
            "entity_id",
            unique=True,
            postgresql_where=text("status = 'open'"),
        ),
    )

    public_ref: Mapped[str] = mapped_column(String(20), unique=True, nullable=False)
    rule_type: Mapped[str] = mapped_column(String(40), nullable=False)
    entity_type: Mapped[str] = mapped_column(String(30), nullable=False)
    entity_id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), nullable=False)
    severity: Mapped[str] = mapped_column(String(10), nullable=False)
    status: Mapped[str] = mapped_column(String(20), nullable=False, default="open")
    evidence_json: Mapped[dict] = mapped_column(JSONB, nullable=False, default=dict)
    proposed_action_json: Mapped[dict] = mapped_column(JSONB, nullable=False, default=dict)
    detected_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
    due_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), index=True)
    assigned_to_user_id: Mapped[uuid.UUID | None] = mapped_column(
        UUID(as_uuid=True), ForeignKey("users.id", ondelete="SET NULL"), index=True
    )
    assigned_to_user: Mapped["User | None"] = relationship(lazy="selectin")
    resolved_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
    resolved_by: Mapped[str | None] = mapped_column(String(120))