import uuid
from datetime import datetime
from sqlalchemy import String, Integer, Float, Text, DateTime, ForeignKey, JSON, func
from sqlalchemy.orm import Mapped, mapped_column, relationship
from app.core.database import Base


def gen_uuid():
    return str(uuid.uuid4())


class Book(Base):
    __tablename__ = "books"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=gen_uuid)
    filename: Mapped[str] = mapped_column(String(500), nullable=False)
    title: Mapped[str | None] = mapped_column(String(500))
    author: Mapped[str | None] = mapped_column(String(500))
    language: Mapped[str] = mapped_column(String(20), default="zh")
    file_path: Mapped[str] = mapped_column(String(1000), nullable=False)
    file_hash: Mapped[str | None] = mapped_column(String(64), unique=True)
    char_count: Mapped[int] = mapped_column(Integer, default=0)
    status: Mapped[str] = mapped_column(String(20), default="uploaded")
    created_at: Mapped[datetime] = mapped_column(DateTime, server_default=func.now())

    chapters: Mapped[list["Chapter"]] = relationship(back_populates="book", cascade="all, delete-orphan")


class Chapter(Base):
    __tablename__ = "chapters"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=gen_uuid)
    book_id: Mapped[str] = mapped_column(String(36), ForeignKey("books.id", ondelete="CASCADE"))
    order_idx: Mapped[int] = mapped_column(Integer, default=0)
    title: Mapped[str | None] = mapped_column(String(500))
    level: Mapped[int] = mapped_column(Integer, default=1)
    heading_path: Mapped[str | None] = mapped_column(Text)
    cfi_start: Mapped[str | None] = mapped_column(String(500))
    cfi_end: Mapped[str | None] = mapped_column(String(500))
    char_count: Mapped[int] = mapped_column(Integer, default=0)

    book: Mapped["Book"] = relationship(back_populates="chapters")
    segments: Mapped[list["Segment"]] = relationship(back_populates="chapter", cascade="all, delete-orphan")


class Segment(Base):
    __tablename__ = "segments"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=gen_uuid)
    chapter_id: Mapped[str] = mapped_column(String(36), ForeignKey("chapters.id", ondelete="CASCADE"))
    book_id: Mapped[str] = mapped_column(String(36), ForeignKey("books.id", ondelete="CASCADE"))
    order_idx: Mapped[int] = mapped_column(Integer, default=0)
    text: Mapped[str] = mapped_column(Text, nullable=False)
    char_count: Mapped[int] = mapped_column(Integer, default=0)
    cfi: Mapped[str | None] = mapped_column(String(500))
    page_estimate: Mapped[float | None] = mapped_column(Float)
    metadata_: Mapped[str | None] = mapped_column("metadata", Text)
    embedding: Mapped[str | None] = mapped_column(Text)  # JSON 浮点数组（向量检索用）；NULL = 尚未生成向量

    chapter: Mapped["Chapter"] = relationship(back_populates="segments")