import enum
import uuid
from datetime import datetime

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

from app.db.base_class import Base


class WorkflowStatus(str, enum.Enum):
    PENDING = "PENDING"
    APPROVED = "APPROVED"
    REJECTED = "REJECTED"
    CANCELED = "CANCELED"


class VersionWorkflow(Base):
    __tablename__ = "version_workflows"
    __table_args__ = (UniqueConstraint("version_id", name="uq_version_workflow_version"),)

    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
    document_id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), ForeignKey("documents.id"), nullable=False)
    version_id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), ForeignKey("document_versions.id"), nullable=False)
    template_id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), ForeignKey("workflow_templates.id"), nullable=False)
    status: Mapped[WorkflowStatus] = mapped_column(
        Enum(WorkflowStatus, name="workflow_status"),
        nullable=False,
        server_default=WorkflowStatus.PENDING.value,
    )
    current_node: Mapped[int | None] = mapped_column(Integer, nullable=True)
    submitted_by: Mapped[uuid.UUID | None] = mapped_column(UUID(as_uuid=True), ForeignKey("users.id"), nullable=True)
    submitted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    completed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, server_default=func.now())
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        nullable=False,
        server_default=func.now(),
        onupdate=func.now(),
    )

    template = relationship("WorkflowTemplate")
    version = relationship("DocumentVersion", back_populates="workflow_instance")
    document = relationship("Document")
    actions = relationship("WorkflowAction", back_populates="workflow", cascade="all, delete-orphan")