import enum
import uuid
from datetime import datetime

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

from app.db.base_class import Base


class DocumentScopeType(str, enum.Enum):
    GLOBAL = "GLOBAL"
    SITE = "SITE"
    DERIVED = "DERIVED"


class DocumentStatus(str, enum.Enum):
    DRAFT = "DRAFT"
    ACTIVE = "ACTIVE"
    ARCHIVED = "ARCHIVED"


class Document(Base):
    __tablename__ = "documents"
    __table_args__ = (UniqueConstraint("trial_id", "doc_no", name="uq_documents_trial_doc_no"),)

    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
    trial_id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), ForeignKey("studies.id"), nullable=False)
    site_id: Mapped[uuid.UUID | None] = mapped_column(UUID(as_uuid=True), ForeignKey("sites.id"), nullable=True)
    doc_no: Mapped[str] = mapped_column(String(50), nullable=False)
    doc_type: Mapped[str] = mapped_column(String(50), nullable=False)
    title: Mapped[str] = mapped_column(String(200), nullable=False)
    scope_type: Mapped[DocumentScopeType] = mapped_column(
        Enum(DocumentScopeType, name="document_scope_type"),
        nullable=False,
        server_default=DocumentScopeType.GLOBAL.value,
    )
    owner_id: Mapped[uuid.UUID | None] = mapped_column(UUID(as_uuid=True), ForeignKey("users.id"), nullable=True)
    status: Mapped[DocumentStatus] = mapped_column(
        Enum(DocumentStatus, name="document_status"),
        nullable=False,
        server_default=DocumentStatus.ACTIVE.value,
    )
    current_effective_version_id: Mapped[uuid.UUID | None] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("document_versions.id"),
        nullable=True,
    )
    description: Mapped[str | None] = mapped_column(Text, 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(),
    )

    versions = relationship(
        "DocumentVersion",
        back_populates="document",
        cascade="all, delete-orphan",
        foreign_keys="DocumentVersion.document_id",
    )
    current_effective_version = relationship(
        "DocumentVersion",
        foreign_keys=[current_effective_version_id],
        post_update=True,
    )