"""
Scratchpad tools for Inara.

A lightweight, persistent notepad stored at inara/SCRATCH.md.
Nothing here is ever distilled or archived — it is intentionally transient.
Good for: working notes mid-task, half-formed ideas, things too long for
a chat response but not worth saving to memory or a journal entry.

Operations:
  scratch_read    — return the full contents (or a message if empty)
  scratch_write   — replace the entire scratchpad
  scratch_append  — add a new timestamped section at the bottom
  scratch_clear   — erase everything
"""

import asyncio
from datetime import datetime, timezone
from pathlib import Path

from persona import persona_path


def _scratch_path() -> Path:
    return persona_path() / "SCRATCH.md"


def _now_label() -> str:
    return datetime.now(timezone.utc).strftime("%Y-%m-%d %H:%M UTC")


# ---------------------------------------------------------------------------
# Sync implementations
# ---------------------------------------------------------------------------

def _scratch_read() -> str:
    p = _scratch_path()
    if not p.exists() or not p.read_text().strip():
        return "Scratchpad is empty."
    return p.read_text()


def _scratch_write(content: str) -> str:
    _scratch_path().write_text(content.rstrip() + "\n")
    return "Scratchpad updated."


def _scratch_append(content: str, heading: str | None = None) -> str:
    p = _scratch_path()
    existing = p.read_text() if p.exists() else ""
    label = heading or _now_label()
    section = f"\n## {label}\n\n{content.strip()}\n"
    p.write_text(existing.rstrip() + "\n" + section)
    return f"Appended section: {label}"


def _scratch_clear() -> str:
    p = _scratch_path()
    p.write_text("")
    return "Scratchpad cleared."


# ---------------------------------------------------------------------------
# Async wrappers
# ---------------------------------------------------------------------------

async def scratch_read() -> str:
    return await asyncio.to_thread(_scratch_read)


async def scratch_write(content: str) -> str:
    return await asyncio.to_thread(_scratch_write, content)


async def scratch_append(content: str, heading: str | None = None) -> str:
    return await asyncio.to_thread(_scratch_append, content, heading)


async def scratch_clear() -> str:
    return await asyncio.to_thread(_scratch_clear)