from datetime import datetime

from sqlalchemy import DateTime, ForeignKey, Integer, String, Text, UniqueConstraint, func
from sqlalchemy.orm import Mapped, mapped_column, relationship
from pgvector.sqlalchemy import Vector

from app.config import get_settings

from app.database import Base

settings = get_settings()


class User(Base):
    __tablename__ = "users"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    email: Mapped[str] = mapped_column(String(255), unique=True, nullable=False, index=True)
    password_hash: Mapped[str] = mapped_column(String(255), nullable=False)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), nullable=False)

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


class Document(Base):
    __tablename__ = "documents"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    filename: Mapped[str] = mapped_column(String(512), nullable=False)
    file_hash: Mapped[str] = mapped_column(String(64), unique=True, nullable=False, index=True)
    file_path: Mapped[str] = mapped_column(String(1024), nullable=False)
    page_count: Mapped[int] = mapped_column(Integer, default=0, nullable=False)
    summary: Mapped[str] = mapped_column(Text, default="", nullable=False)
    extracted_preview: Mapped[str] = mapped_column(Text, default="", nullable=False)
    processing_status: Mapped[str] = mapped_column(String(32), default="completed", nullable=False)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), nullable=False)

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


class UserDocument(Base):
    __tablename__ = "user_documents"
    __table_args__ = (UniqueConstraint("user_id", "document_id", name="uq_user_document"),)

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    user_id: Mapped[int] = mapped_column(ForeignKey("users.id"), nullable=False, index=True)
    document_id: Mapped[int] = mapped_column(ForeignKey("documents.id"), nullable=False, index=True)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), nullable=False)

    user: Mapped["User"] = relationship(back_populates="documents")
    document: Mapped["Document"] = relationship(back_populates="users")


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

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    document_id: Mapped[int] = mapped_column(ForeignKey("documents.id"), nullable=False, index=True)
    file_hash: Mapped[str] = mapped_column(String(64), nullable=False, index=True)
    filename: Mapped[str] = mapped_column(String(512), nullable=False)
    chunk_index: Mapped[int] = mapped_column(Integer, nullable=False)
    page_number: Mapped[int | None] = mapped_column(Integer, nullable=True, index=True)
    content: Mapped[str] = mapped_column(Text, nullable=False)
    embedding: Mapped[list[float]] = mapped_column(Vector(settings.embedding_dimensions), nullable=False)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), nullable=False)

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