from __future__ import annotations

import uuid
from datetime import datetime

from sqlalchemy import BigInteger, Boolean, DateTime, ForeignKey, Index, Integer, Text, func
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy.orm import Mapped, mapped_column

from . import Base
from ..common import iso

class Note(Base):
    __tablename__ = "notes"
    __table_args__ = (
        # Covers the board queries: a user's notes filtered by trash/archive state,
        # pinned first.
        Index("ix_notes_owner_board", "owner_id", "deleted_at", "archived", "pinned"),
    )

    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
    owner_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True), ForeignKey("users.id", ondelete="CASCADE"), nullable=False
    )
    # The note's NAME: its first non-empty body line, else its first checklist item
    # (see notes.derive_display_title). There is no title field to prefer — a note is
    # a body plus optional items, and this is simply the first thing written in it.
    # Persisted so search results and export filenames have something to say, and so
    # the full-text vector can weight it above the rest of the body.
    display_title: Mapped[str] = mapped_column(Text(), nullable=False, server_default="")
    body: Mapped[str] = mapped_column(Text(), nullable=False, server_default="")
    # Manual drag order (higher = earlier); 0 until the user reorders.
    position: Mapped[int] = mapped_column(Integer(), nullable=False, server_default="0")
    pinned: Mapped[bool] = mapped_column(Boolean(), nullable=False, server_default=func.false())
    archived: Mapped[bool] = mapped_column(Boolean(), nullable=False, server_default=func.false())
    # Soft delete: non-null => in Trash. Restore sets it back to null.
    deleted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    # Optional reminder time (surfaced in the Reminders view + foreground delivery).
    remind_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    # Optional recurrence for the reminder: daily | weekly | monthly | yearly (else null).
    # On "complete", a recurring reminder advances remind_at to its next occurrence.
    recurrence: Mapped[str | None] = mapped_column(Text(), nullable=True)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, server_default=func.now())
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(), onupdate=func.now()
    )
    # Sync (M8): a monotonic per-row revision drawn from sync_revision_seq and assigned
    # by a DB trigger on every insert/update — the delta cursor native clients pull
    # against. Nullable in the ORM because the trigger populates it server-side.
    sync_revision: Mapped[int | None] = mapped_column(BigInteger(), nullable=True)
    # Hard-delete tombstone: non-null => permanently deleted (content cleared), kept so
    # offline clients learn the row is gone. Distinct from deleted_at (= recoverable trash).
    purged_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)

    def serialize(self) -> dict:
        return {
            "id": str(self.id),
            "display_title": self.display_title,
            "body": self.body,
            "position": self.position,
            "pinned": self.pinned,
            "archived": self.archived,
            "trashed": self.deleted_at is not None,
            # WHEN it was trashed, not just that it was: clients count the retention
            # window from here to show how long a note has left before it's purged.
            "deleted_at": iso(self.deleted_at),
            "remind_at": iso(self.remind_at),
            "recurrence": self.recurrence,
            "created_at": iso(self.created_at),
            "updated_at": iso(self.updated_at),
        }