from __future__ import annotations

import enum
import uuid
from datetime import datetime

from sqlalchemy import (
    DateTime,
    Enum,
    ForeignKey,
    func,
)
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.database.database import Base


class WorkflowStatus(str, enum.Enum):
    PENDING = "PENDING"
    RUNNING = "RUNNING"
    WAITING_FOR_REVIEW = "WAITING_FOR_REVIEW"
    COMPLETED = "COMPLETED"
    FAILED = "FAILED"
    CANCELLED = "CANCELLED"


class WorkflowRun(Base):
    """
    Represents one execution of the document intelligence workflow.
    """

    __tablename__ = "workflow_runs"

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        primary_key=True,
        default=uuid.uuid4,
    )

    workspace_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("workspaces.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )

    document_version_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("document_versions.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )

    status: Mapped[WorkflowStatus] = mapped_column(
        Enum(WorkflowStatus, name="workflow_status"),
        nullable=False,
        default=WorkflowStatus.PENDING,
        server_default=WorkflowStatus.PENDING.value,
        index=True,
    )

    started_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        nullable=False,
        server_default=func.now(),
    )

    completed_at: Mapped[datetime | None] = mapped_column(
        DateTime(timezone=True),
        nullable=True,
    )

    # ------------------------------------------------------------------
    # Relationships
    # ------------------------------------------------------------------

    workspace: Mapped["Workspace"] = relationship(
        back_populates="workflow_runs",
    )

    document_version: Mapped["DocumentVersion"] = relationship(
        back_populates="workflow_runs",
    )

    checkpoints: Mapped[list["WorkflowCheckpoint"]] = relationship(
        back_populates="workflow_run",
        cascade="all, delete-orphan",
    )

    def __repr__(self) -> str:
        return (
            f"<WorkflowRun("
            f"id={self.id}, "
            f"status='{self.status.value}')>"
        )