#!/usr/bin/env node
// A bundle that keeps and reads state through the runtime (novox/hq ADR 0201), written against the
// protocol with no SDK: on start it watches STATE_NAME and writes every change it is handed to
// STATE_LOG; its tools put, get, delete and list keys of whichever state they name.
import { appendFileSync } from "node:fs";
import { createInterface } from "node:readline";

const say = (m) => process.stdout.write(JSON.stringify({ jsonrpc: "2.0", ...m }) + "\n");
let next = 1;
const waiting = new Map();
const ask = (method, params) => new Promise((resolve, reject) => {
  const id = `keeper-${next++}`;
  waiting.set(id, { resolve, reject });
  say({ id, method, params });
});
const log = (line) => appendFileSync(process.env.STATE_LOG, line + "\n");
const text = (v) => ({ content: [{ type: "text", text: JSON.stringify(v ?? null) }] });
const tool = (name) => ({ name, description: name, inputSchema: { type: "object", properties: {} } });
const TOOLS = ["put", "get", "del", "keys"].map(tool);

createInterface({ input: process.stdin }).on("line", async (line) => {
  const m = JSON.parse(line);
  if (m.method === undefined && waiting.has(m.id)) {
    const w = waiting.get(m.id); waiting.delete(m.id);
    m.error ? w.reject(new Error(m.error.message)) : w.resolve(m.result);
    return;
  }
  const p = m.params ?? {};
  switch (m.method) {
    case "initialize":
      say({ id: m.id, result: { protocolVersion: "2025-03-26", capabilities: { tools: {} }, serverInfo: { name: "keeper", version: "1" } } });
      // Watched once the runtime has the handshake: the current values, then every change.
      ask("mesh/state.watch", { state: process.env.STATE_NAME })
        .then(() => log("current"), (e) => log("watch refused: " + e.message));
      return;
    case "tools/list":
      say({ id: m.id, result: { tools: TOOLS } });
      return;
    case "mesh/state": {
      const c = p.change;
      log(`${c.current ? "was" : "now"} ${c.op} ${c.key}${c.value !== undefined ? " " + JSON.stringify(c.value) : ""}`);
      say({ id: m.id, result: {} });
      return;
    }
    case "tools/call": {
      const a = p.arguments ?? {};
      const verb = { put: "put", get: "get", del: "delete", keys: "keys" }[p.name];
      try {
        say({ id: m.id, result: text(await ask(`mesh/state.${verb}`, { state: a.state, key: a.key, value: a.value })) });
      } catch (e) {
        say({ id: m.id, result: { content: [{ type: "text", text: e.message }], isError: true } });
      }
      return;
    }
    default:
      if (m.id !== undefined) say({ id: m.id, error: { code: -32601, message: "no " + m.method } });
  }
});