#!/usr/bin/env node
// stdio ⇄ Streamable HTTP relay for MCP clients that only start stdio
// servers (Claude Desktop). Run by the Theseus executable itself in Node
// mode, so nothing else needs installing:
//
//   "command": "C:\\...\\Theseus Navigator.exe",
//   "args": ["<userData>\\extensions\\claude-connector\\stdio-shim.cjs"],
//   "env": { "ELECTRON_RUN_AS_NODE": "1", "THESEUS_MCP_URL": "http://127.0.0.1:47800/mcp", "THESEUS_MCP_TOKEN": "…" }
//
// THESEUS_MCP_URL may be left out: the shim then reads the address Theseus
// wrote to extensions-data/claude-connector/endpoint.json (THESEUS_USER_DATA,
// else %APPDATA%\Theseus).

const fs = require("node:fs");
const path = require("node:path");
const os = require("node:os");
const readline = require("node:readline");

const TOKEN = process.env.THESEUS_MCP_TOKEN || "";
const err = (...a) => process.stderr.write(`[theseus-shim] ${a.join(" ")}\n`);

function endpoint() {
  if (process.env.THESEUS_MCP_URL) return process.env.THESEUS_MCP_URL;
  const ud = process.env.THESEUS_USER_DATA
    || (process.platform === "win32" ? path.join(process.env.APPDATA || path.join(os.homedir(), "AppData", "Roaming"), "Theseus")
      : process.platform === "darwin" ? path.join(os.homedir(), "Library", "Application Support", "Theseus")
        : path.join(process.env.XDG_CONFIG_HOME || path.join(os.homedir(), ".config"), "Theseus"));
  try { return JSON.parse(fs.readFileSync(path.join(ud, "extensions-data", "claude-connector", "endpoint.json"), "utf8")).url; }
  catch { return null; }
}

let sessionId = null;
let stream = null;
const out = (obj) => process.stdout.write(JSON.stringify(obj) + "\n");

function failFor(msg, text) {
  if (msg && msg.id !== undefined && msg.id !== null) out({ jsonrpc: "2.0", id: msg.id, error: { code: -32000, message: text } });
}

async function post(msg) {
  const url = endpoint();
  if (!url) return failFor(msg, "Theseus is not running, or the Claude connector is off (Settings › Extensions)");
  const headers = { "content-type": "application/json", accept: "application/json, text/event-stream", authorization: `Bearer ${TOKEN}` };
  if (sessionId) headers["mcp-session-id"] = sessionId;
  let res;
  try { res = await fetch(url, { method: "POST", headers, body: JSON.stringify(msg) }); }
  catch (e) { return failFor(msg, `Theseus did not answer at ${url} (${e.message})`); }
  const sid = res.headers.get("mcp-session-id");
  if (sid && sid !== sessionId) { sessionId = sid; openStream(url); }
  if (res.status === 202) return;
  const body = await res.text();
  if (!res.ok && !body.startsWith("{")) return failFor(msg, `Theseus refused the request (${res.status}: ${body.trim()})`);
  try {
    const data = JSON.parse(body);
    for (const m of Array.isArray(data) ? data : [data]) out(m);
  } catch { failFor(msg, `unreadable answer from Theseus (${res.status})`); }
}

// Server notifications (tools/list_changed) and the "still connected" signal.
async function openStream(url) {
  if (stream) stream.abort();
  const ctl = new AbortController();
  stream = ctl;
  try {
    const res = await fetch(url, { headers: { accept: "text/event-stream", authorization: `Bearer ${TOKEN}`, "mcp-session-id": sessionId }, signal: ctl.signal });
    if (!res.ok || !res.body) return;
    const reader = res.body.getReader();
    const dec = new TextDecoder();
    let buf = "";
    for (;;) {
      const { value, done } = await reader.read();
      if (done) break;
      buf += dec.decode(value, { stream: true });
      let i;
      while ((i = buf.indexOf("\n\n")) >= 0) {
        const block = buf.slice(0, i);
        buf = buf.slice(i + 2);
        const data = block.split("\n").filter((l) => l.startsWith("data: ")).map((l) => l.slice(6)).join("\n");
        if (data) { try { out(JSON.parse(data)); } catch {} }
      }
    }
  } catch (e) { if (!ctl.signal.aborted) err("event stream closed:", e.message); }
}

if (!TOKEN) err("THESEUS_MCP_TOKEN is not set; copy the command from the Claude connector panel in Theseus");

// Requests are relayed one at a time, in order.
let chain = Promise.resolve();
const rl = readline.createInterface({ input: process.stdin });
rl.on("line", (line) => {
  if (!line.trim()) return;
  let msg;
  try { msg = JSON.parse(line); } catch { return err("ignored a line that is not JSON"); }
  chain = chain.then(() => post(msg)).catch((e) => err(e.message));
});
rl.on("close", async () => {
  await chain;
  if (stream) stream.abort();
  const url = endpoint();
  if (sessionId && url) { try { await fetch(url, { method: "DELETE", headers: { authorization: `Bearer ${TOKEN}`, "mcp-session-id": sessionId } }); } catch {} }
  process.exit(0);
});