from __future__ import annotations

import enum
from datetime import datetime, timezone
from uuid import uuid4

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

from src.session import Base


def utcnow() -> datetime:
    return datetime.now(timezone.utc)


class SourceKind(str, enum.Enum):
    WEBSITE = "website"


class SourceStatus(str, enum.Enum):
    COMPLETED = "completed"


class Source(Base):
    __tablename__ = "sources"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid4()))
    kind: Mapped[SourceKind] = mapped_column(String(32))
    status: Mapped[SourceStatus] = mapped_column(String(32), index=True)
    title: Mapped[str] = mapped_column(String(500))
    source_url: Mapped[str | None] = mapped_column(String(2048), nullable=True)
    extra_json: Mapped[dict] = mapped_column(JSON, default=dict)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=utcnow)
    updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=utcnow, onupdate=utcnow)

    documents: Mapped[list["Document"]] = relationship(back_populates="source", cascade="all, delete-orphan")


class Document(Base):
    __tablename__ = "documents"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid4()))
    source_id: Mapped[str] = mapped_column(ForeignKey("sources.id", ondelete="CASCADE"), index=True)
    title: Mapped[str] = mapped_column(String(500))
    content: Mapped[str] = mapped_column(Text)
    language: Mapped[str] = mapped_column(String(8), default="en")
    content_sha256: Mapped[str] = mapped_column(String(64), index=True)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=utcnow)

    source: Mapped[Source] = relationship(back_populates="documents")
    chunks: Mapped[list["DocumentChunk"]] = relationship(back_populates="document", cascade="all, delete-orphan")


class DocumentChunk(Base):
    __tablename__ = "document_chunks"
    __table_args__ = (UniqueConstraint("document_id", "chunk_index", name="uq_document_chunk_idx"),)

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid4()))
    document_id: Mapped[str] = mapped_column(ForeignKey("documents.id", ondelete="CASCADE"), index=True)
    chunk_index: Mapped[int] = mapped_column(Integer)
    content: Mapped[str] = mapped_column(Text)
    token_estimate: Mapped[int] = mapped_column(Integer)
    embedding: Mapped[list[float]] = mapped_column(JSON)
    extra_json: Mapped[dict] = mapped_column(JSON, default=dict)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=utcnow)

    document: Mapped[Document] = relationship(back_populates="chunks")