import uuid
from datetime import datetime

from sqlalchemy import DateTime, Float, ForeignKey, Integer, String, Text, func
from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column, relationship


class Base(DeclarativeBase):
    pass


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


class Author(Base):
    __tablename__ = "authors"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=generate_uuid)
    name: Mapped[str] = mapped_column(String(255), nullable=False, unique=True)
    birth_year: Mapped[int | None] = mapped_column(Integer)
    death_year: Mapped[int | None] = mapped_column(Integer)
    bio: Mapped[str | None] = mapped_column(Text)
    era: Mapped[str | None] = mapped_column(String(50))

    books: Mapped[list["Book"]] = relationship(back_populates="author_rel")


class Book(Base):
    __tablename__ = "books"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=generate_uuid)
    title: Mapped[str] = mapped_column(String(500), nullable=False)
    author: Mapped[str] = mapped_column(String(255), nullable=False)
    author_id: Mapped[str | None] = mapped_column(ForeignKey("authors.id"))
    publication_year: Mapped[int | None] = mapped_column(Integer)
    edition: Mapped[str | None] = mapped_column(String(100))
    source_file: Mapped[str | None] = mapped_column(String(500))
    file_hash: Mapped[str | None] = mapped_column(String(64), unique=True)
    ingestion_status: Mapped[str] = mapped_column(String(20), default="pending")
    ingestion_date: Mapped[datetime | None] = mapped_column(DateTime)
    total_chunks: Mapped[int] = mapped_column(Integer, default=0)
    notes: Mapped[str | None] = mapped_column(Text)
    created_at: Mapped[datetime] = mapped_column(DateTime, server_default=func.now())

    author_rel: Mapped[Author | None] = relationship(back_populates="books")
    chunks: Mapped[list["Chunk"]] = relationship(back_populates="book", cascade="all, delete-orphan")


class Topic(Base):
    __tablename__ = "topics"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=generate_uuid)
    name: Mapped[str] = mapped_column(String(100), nullable=False, unique=True)
    description: Mapped[str | None] = mapped_column(Text)


class ChunkTopic(Base):
    __tablename__ = "chunk_topics"

    chunk_id: Mapped[str] = mapped_column(ForeignKey("chunks.id"), primary_key=True)
    topic_id: Mapped[str] = mapped_column(ForeignKey("topics.id"), primary_key=True)


class Chunk(Base):
    __tablename__ = "chunks"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=generate_uuid)
    book_id: Mapped[str] = mapped_column(ForeignKey("books.id"), nullable=False)
    content: Mapped[str] = mapped_column(Text, nullable=False)
    chapter_number: Mapped[int | None] = mapped_column(Integer)
    chapter_title: Mapped[str | None] = mapped_column(String(500))
    page_start: Mapped[int | None] = mapped_column(Integer)
    page_end: Mapped[int | None] = mapped_column(Integer)
    chunk_index: Mapped[int] = mapped_column(Integer, nullable=False)
    content_type: Mapped[str] = mapped_column(String(50), default="text")
    ocr_confidence: Mapped[float | None] = mapped_column(Float)
    extraction_method: Mapped[str] = mapped_column(String(20), default="digital")
    embedding_id: Mapped[str | None] = mapped_column(String(36), unique=True)
    parent_chunk_id: Mapped[str | None] = mapped_column(ForeignKey("chunks.id"))

    book: Mapped[Book] = relationship(back_populates="chunks")
    topics: Mapped[list[Topic]] = relationship(secondary="chunk_topics")


class QueryLog(Base):
    __tablename__ = "query_log"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=generate_uuid)
    query_text: Mapped[str] = mapped_column(Text, nullable=False)
    model_used: Mapped[str] = mapped_column(String(100))
    response_text: Mapped[str | None] = mapped_column(Text)
    source_chunk_ids: Mapped[str | None] = mapped_column(Text)  # JSON array
    timestamp: Mapped[datetime] = mapped_column(DateTime, server_default=func.now())
    feedback: Mapped[int | None] = mapped_column(Integer)