from datetime import datetime, timezone
from sqlalchemy import (
    Column,
    Integer,
    String,
    Text,
    ForeignKey,
    DateTime,
    UniqueConstraint,
)
from sqlalchemy.dialects.postgresql import JSONB
from sqlalchemy.orm import relationship
from .database import Base


class User(Base):
    __tablename__ = "users"

    id = Column(Integer, primary_key=True, index=True)
    username = Column(String(64), unique=True, nullable=False, index=True)
    email = Column(String(255), unique=True, nullable=False, index=True)
    password_hash = Column(String(255), nullable=False)
    created_at = Column(DateTime(timezone=True), default=lambda: datetime.now(timezone.utc), nullable=False)

    # Relationships
    pdfs = relationship("PDF", back_populates="owner", cascade="all, delete-orphan")
    annotations = relationship("Annotation", back_populates="owner", cascade="all, delete-orphan")


class PDF(Base):
    __tablename__ = "pdfs"

    id = Column(Integer, primary_key=True, index=True)
    user_id = Column(Integer, ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True)
    title = Column(String(255), nullable=False)
    file_path = Column(Text, nullable=False)       # path inside Docker volume
    total_pages = Column(Integer, nullable=True)   # populated after upload processing
    created_at = Column(DateTime(timezone=True), default=lambda: datetime.now(timezone.utc), nullable=False)

    # Relationships
    owner = relationship("User", back_populates="pdfs")
    annotations = relationship("Annotation", back_populates="pdf", cascade="all, delete-orphan")


class Annotation(Base):
    __tablename__ = "annotations"
    __table_args__ = (
        # One annotation record per (pdf, user, page) — upsert target
        UniqueConstraint("pdf_id", "user_id", "page_number", name="uq_annotation_pdf_user_page"),
    )

    id = Column(Integer, primary_key=True, index=True)
    pdf_id = Column(Integer, ForeignKey("pdfs.id", ondelete="CASCADE"), nullable=False, index=True)
    user_id = Column(Integer, ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True)
    page_number = Column(Integer, nullable=False)   # 1-based
    canvas_data = Column(JSONB, nullable=False, default=dict)  # Fabric.js JSON state
    updated_at = Column(
        DateTime(timezone=True),
        default=lambda: datetime.now(timezone.utc),
        onupdate=lambda: datetime.now(timezone.utc),
        nullable=False,
    )

    # Relationships
    pdf = relationship("PDF", back_populates="annotations")
    owner = relationship("User", back_populates="annotations")