"""Document model — uploaded PDFs with soft-delete support."""

import uuid
from datetime import datetime, timezone

from sqlalchemy import Index, Integer, Text
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.db import Base


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


def _now_iso() -> str:
    return datetime.now(timezone.utc).isoformat()


class Document(Base):
    """
    A single uploaded PDF document.

    Supports soft deletion via `deleted_at` — when set, the document
    is in the trash and can be restored or permanently purged.
    """

    __tablename__ = "documents"

    id: Mapped[str] = mapped_column(Text, primary_key=True, default=_uuid)
    title: Mapped[str] = mapped_column(Text, nullable=False)
    original_filename: Mapped[str] = mapped_column(Text, nullable=False)
    file_path: Mapped[str] = mapped_column(Text, nullable=False)
    thumbnail_path: Mapped[str | None] = mapped_column(Text, nullable=True, default=None)
    size_bytes: Mapped[int] = mapped_column(Integer, nullable=False)
    page_count: Mapped[int] = mapped_column(Integer, nullable=False)
    created_at: Mapped[str] = mapped_column(Text, default=_now_iso)
    updated_at: Mapped[str] = mapped_column(Text, default=_now_iso, onupdate=_now_iso)
    deleted_at: Mapped[str | None] = mapped_column(Text, nullable=True, default=None)

    @property
    def in_trash(self) -> bool:
        return self.deleted_at is not None

    @property
    def filename(self) -> str:
        return self.original_filename

    @property
    def mime_type(self) -> str:
        return "application/pdf"

    # Relationships
    annotation_state: Mapped["AnnotationState"] = relationship(
        "AnnotationState",
        back_populates="document",
        uselist=False,
        cascade="all, delete-orphan",
    )
    versions: Mapped[list["Version"]] = relationship(
        "Version",
        back_populates="document",
        cascade="all, delete-orphan",
        order_by="Version.created_at.desc()",
    )

    __table_args__ = (
        Index("ix_documents_updated_at", "updated_at"),
        Index("ix_documents_deleted_at", "deleted_at"),
    )