import enum
import uuid
from datetime import datetime

from sqlalchemy import DateTime, Enum, ForeignKey, Integer, String, Text
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.database import Base


def _uuid() -> str:
    return str(uuid.uuid4())


def _now() -> datetime:
    return datetime.utcnow()


class DocumentStatus(str, enum.Enum):
    pending = "pending"
    processing = "processing"
    completed = "completed"
    failed = "failed"


class KnowledgeBase(Base):
    __tablename__ = "knowledge_bases"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=_uuid)
    tenant_id: Mapped[str] = mapped_column(
        String(36), ForeignKey("tenants.id"), nullable=False, index=True
    )
    name: Mapped[str] = mapped_column(String(200), nullable=False)
    description: Mapped[str | None] = mapped_column(Text, nullable=True)
    embedding_model: Mapped[str] = mapped_column(String(100), default="text-embedding-3-small")
    created_at: Mapped[datetime] = mapped_column(DateTime, default=_now)
    updated_at: Mapped[datetime] = mapped_column(DateTime, default=_now, onupdate=_now)

    documents: Mapped[list["Document"]] = relationship(
        back_populates="knowledge_base", cascade="all, delete-orphan", lazy="selectin"
    )
    tenant = relationship("Tenant", lazy="selectin")


class Document(Base):
    __tablename__ = "documents"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=_uuid)
    knowledge_base_id: Mapped[str] = mapped_column(
        String(36), ForeignKey("knowledge_bases.id"), nullable=False, index=True
    )
    filename: Mapped[str] = mapped_column(String(500), nullable=False)
    file_type: Mapped[str] = mapped_column(String(20), nullable=False)
    file_size: Mapped[int] = mapped_column(Integer, default=0)
    chunk_count: Mapped[int] = mapped_column(Integer, default=0)
    status: Mapped[DocumentStatus] = mapped_column(
        Enum(DocumentStatus), default=DocumentStatus.pending
    )
    error_message: Mapped[str | None] = mapped_column(Text, nullable=True)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=_now)
    updated_at: Mapped[datetime] = mapped_column(DateTime, default=_now, onupdate=_now)

    knowledge_base: Mapped["KnowledgeBase"] = relationship(back_populates="documents")