'use strict';

require('dotenv').config({ path: __dirname + '/../.env' });

const { spawn } = require('child_process');
const http = require('http');
const path = require('path');

if (process.env.GOOGLE_CLIENT_ID && process.env.GOOGLE_CLIENT_ID !== 'your-google-client-id-here') {
  console.log('[test] OAuth enabled — skipping E2E (requires browser flow).');
  process.exit(0);
}

const HUB_PORT = 3000;
const TOTAL_TIMEOUT_MS = 15000;
const POLL_INTERVAL_MS = 200;

let hubProc = null;
let backendProc = null;
let sseReq = null;
let exitCalled = false;

function cleanup() {
  if (sseReq) { try { sseReq.destroy(); } catch (_) {} sseReq = null; }
  if (backendProc) { try { backendProc.kill(); } catch (_) {} backendProc = null; }
  if (hubProc) { try { hubProc.kill(); } catch (_) {} hubProc = null; }
}

function die(msg, code = 1) {
  if (exitCalled) return;
  exitCalled = true;
  console.error('[e2e] FAIL:', msg);
  cleanup();
  process.exit(code);
}

function pass(msg) {
  if (exitCalled) return;
  exitCalled = true;
  console.log('[e2e] PASS:', msg);
  cleanup();
  process.exit(0);
}

const globalTimer = setTimeout(() => die('Total timeout exceeded (15s)'), TOTAL_TIMEOUT_MS);
globalTimer.unref();

function httpGet(url) {
  return new Promise((resolve, reject) => {
    http.get(url, (res) => {
      let body = '';
      res.on('data', (d) => { body += d; });
      res.on('end', () => {
        try { resolve({ status: res.statusCode, body: JSON.parse(body) }); }
        catch (e) { resolve({ status: res.statusCode, body }); }
      });
    }).on('error', reject);
  });
}

function httpPost(url, payload) {
  return new Promise((resolve, reject) => {
    const data = JSON.stringify(payload);
    const opts = {
      method: 'POST',
      headers: { 'Content-Type': 'application/json', 'Content-Length': Buffer.byteLength(data) },
    };
    const u = new URL(url);
    opts.hostname = u.hostname;
    opts.port = u.port;
    opts.path = u.pathname + u.search;

    const req = http.request(opts, (res) => {
      let body = '';
      res.on('data', (d) => { body += d; });
      res.on('end', () => {
        try { resolve({ status: res.statusCode, body: JSON.parse(body) }); }
        catch (e) { resolve({ status: res.statusCode, body }); }
      });
    });
    req.on('error', reject);
    req.write(data);
    req.end();
  });
}

function poll(fn, label, timeoutMs = 8000) {
  return new Promise((resolve, reject) => {
    const deadline = Date.now() + timeoutMs;
    function attempt() {
      if (Date.now() > deadline) return reject(new Error('Timeout waiting for: ' + label));
      fn().then((ok) => {
        if (ok) resolve();
        else setTimeout(attempt, POLL_INTERVAL_MS);
      }).catch(() => setTimeout(attempt, POLL_INTERVAL_MS));
    }
    attempt();
  });
}

function spawnProc(name, cmd, args, env) {
  const proc = spawn(cmd, args, {
    env: { ...process.env, ...env },
    stdio: ['ignore', 'pipe', 'pipe'],
  });
  proc.stdout.on('data', (d) => process.stdout.write(`[${name}] ${d}`));
  proc.stderr.on('data', (d) => process.stderr.write(`[${name}] ${d}`));
  proc.on('exit', (code) => {
    if (!exitCalled && code !== null && code !== 0) {
      die(`${name} exited with code ${code}`);
    }
  });
  return proc;
}

// Open SSE connection and return a stream of parsed events {event, data}
function openSSE(url) {
  return new Promise((resolve, reject) => {
    const u = new URL(url);
    const options = { hostname: u.hostname, port: u.port, path: u.pathname + u.search, headers: { Accept: 'text/event-stream' } };

    const req = http.get(options, (res) => {
      if (res.statusCode !== 200) {
        return reject(new Error('SSE connect failed: ' + res.statusCode));
      }

      const listeners = [];
      let buffer = '';

      res.on('data', (chunk) => {
        buffer += chunk.toString();
        const parts = buffer.split('\n\n');
        buffer = parts.pop(); // keep incomplete last chunk
        for (const part of parts) {
          if (!part.trim()) continue;
          let event = 'message';
          let data = '';
          for (const line of part.split('\n')) {
            if (line.startsWith('event: ')) event = line.slice(7).trim();
            else if (line.startsWith('data: ')) data = line.slice(6).trim();
          }
          for (const fn of listeners) fn({ event, data });
        }
      });

      res.on('error', (err) => { if (!exitCalled) die('SSE stream error: ' + err.message); });
      res.on('end', () => { if (!exitCalled) die('SSE stream ended unexpectedly'); });

      resolve({ addListener: (fn) => listeners.push(fn) });
    });

    req.on('error', reject);
    sseReq = req;
  });
}

function waitForEvent(sse, eventName, timeoutMs = 8000) {
  return new Promise((resolve, reject) => {
    const timer = setTimeout(() => reject(new Error('Timeout waiting for SSE event: ' + eventName)), timeoutMs);
    sse.addListener(({ event, data }) => {
      if (event === eventName) {
        clearTimeout(timer);
        resolve(data);
      }
    });
  });
}

function waitForSSEResponse(sse, id, timeoutMs = 8000) {
  return new Promise((resolve, reject) => {
    const timer = setTimeout(() => reject(new Error('Timeout waiting for JSON-RPC response id=' + id)), timeoutMs);
    sse.addListener(({ event, data }) => {
      if (event !== 'message') return;
      try {
        const msg = JSON.parse(data);
        if (msg.id === id) {
          clearTimeout(timer);
          resolve(msg);
        }
      } catch (_) {}
    });
  });
}

async function run() {
  // 1. Start hub
  console.log('[e2e] Starting hub...');
  hubProc = spawnProc('hub', 'node', [path.join(__dirname, '../src/index.js')], {});

  // 2. Wait for hub /health
  await poll(async () => {
    const r = await httpGet(`http://localhost:${HUB_PORT}/health`);
    return r.status === 200;
  }, 'hub /health');
  console.log('[e2e] Hub is ready');

  // 3. Start sample-mcp with local hub URL
  console.log('[e2e] Starting sample-mcp...');
  backendProc = spawnProc('sample-mcp', 'node', [path.join(__dirname, '../sample-mcp/index.js')], {
    HUB_URL: `ws://localhost:${HUB_PORT}/ws/register`,
  });

  // 4. Wait for backend to register
  await poll(async () => {
    const r = await httpGet(`http://localhost:${HUB_PORT}/health`);
    return r.status === 200 && r.body.connectedBackends >= 1;
  }, 'backend registration');
  console.log('[e2e] Backend registered');

  // 5. Open SSE connection
  console.log('[e2e] Opening SSE connection...');
  const sse = await openSSE(`http://localhost:${HUB_PORT}/sample-mcp/sse`);
  console.log('[e2e] SSE connected');

  // 6. Wait for 'endpoint' event
  const endpointData = await waitForEvent(sse, 'endpoint');
  console.log('[e2e] Got endpoint:', endpointData);
  const messageUrl = `http://localhost:${HUB_PORT}${endpointData}`;

  // 7. Send initialize
  const initId = 1;
  const initResponseP = waitForSSEResponse(sse, initId);
  await httpPost(messageUrl, {
    jsonrpc: '2.0',
    id: initId,
    method: 'initialize',
    params: {
      protocolVersion: '2024-11-05',
      capabilities: {},
      clientInfo: { name: 'test', version: '1.0.0' },
    },
  });

  const initResponse = await initResponseP;
  console.log('[e2e] initialize response:', JSON.stringify(initResponse));
  if (!initResponse.result || !initResponse.result.protocolVersion) {
    die('initialize response missing protocolVersion');
  }
  if (!initResponse.result.serverInfo) {
    die('initialize response missing serverInfo');
  }
  console.log('[e2e] ✓ initialize OK');

  // 8. Send initialized notification (no response expected)
  await httpPost(messageUrl, {
    jsonrpc: '2.0',
    method: 'notifications/initialized',
  });
  console.log('[e2e] ✓ initialized notification sent');

  // 9. Send tools/list
  const listId = 2;
  const listResponseP = waitForSSEResponse(sse, listId);
  await httpPost(messageUrl, {
    jsonrpc: '2.0',
    id: listId,
    method: 'tools/list',
    params: {},
  });

  const listResponse = await listResponseP;
  console.log('[e2e] tools/list response:', JSON.stringify(listResponse));
  const tools = listResponse.result && listResponse.result.tools;
  if (!tools || !tools.find((t) => t.name === 'echo')) {
    die('tools/list response missing echo tool');
  }
  console.log('[e2e] ✓ tools/list OK');

  // 10. Send tools/call echo
  const callId = 3;
  const callResponseP = waitForSSEResponse(sse, callId);
  await httpPost(messageUrl, {
    jsonrpc: '2.0',
    id: callId,
    method: 'tools/call',
    params: { name: 'echo', arguments: { message: 'hello hub' } },
  });

  const callResponse = await callResponseP;
  console.log('[e2e] tools/call response:', JSON.stringify(callResponse));
  const content = callResponse.result && callResponse.result.content;
  if (!content || !content[0] || !content[0].text.includes('Echo: hello hub')) {
    die('tools/call response missing "Echo: hello hub"');
  }
  console.log('[e2e] ✓ tools/call OK');

  pass('All checks passed');
}

run().catch((err) => die(err.message));