const express = require('express');
const { spawn } = require('child_process');
const Database = require('better-sqlite3');
const { v4: uuidv4 } = require('uuid');
const path = require('path');
const fs = require('fs');
const os = require('os');

const app = express();
app.use(express.json());
app.use(express.static(path.join(__dirname, '../frontend')));

// Init SQLite
const DB_PATH = process.env.DB_PATH || '/data/history.db';
fs.mkdirSync(path.dirname(DB_PATH), { recursive: true });
const db = new Database(DB_PATH);

db.exec(`
  CREATE TABLE IF NOT EXISTS tests (
    id TEXT PRIMARY KEY,
    url TEXT NOT NULL,
    vus INTEGER NOT NULL,
    duration INTEGER NOT NULL,
    rps_limit INTEGER,
    http_method TEXT NOT NULL DEFAULT 'GET',
    request_body TEXT,
    headers TEXT,
    cache_mode TEXT NOT NULL DEFAULT 'normal',
    gzip INTEGER NOT NULL DEFAULT 1,
    device TEXT NOT NULL DEFAULT 'desktop',
    status TEXT NOT NULL DEFAULT 'pending',
    created_at INTEGER NOT NULL,
    finished_at INTEGER,
    summary TEXT,
    output TEXT
  )
`);

// Non-destructive migration for existing DBs
try { db.exec(`ALTER TABLE tests ADD COLUMN cache_mode TEXT NOT NULL DEFAULT 'normal'`); } catch {}
try { db.exec(`ALTER TABLE tests ADD COLUMN gzip INTEGER NOT NULL DEFAULT 1`); } catch {}
try { db.exec(`ALTER TABLE tests ADD COLUMN device TEXT NOT NULL DEFAULT 'desktop'`); } catch {}

// Stream active test outputs (testId -> {process, clients})
const activeTests = {};

const USER_AGENTS = {
  desktop: 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36',
  mobile:  'Mozilla/5.0 (iPhone; CPU iPhone OS 17_4 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.4 Mobile/15E148 Safari/604.1',
};

// Generate a k6 script from test params
function generateScript(params) {
  const { url, vus, duration, rpsLimit, httpMethod, requestBody, headers, cacheMode, gzip, device } = params;

  // Build the merged headers object
  const userHeaders = (() => {
    try { return JSON.parse(headers || '{}'); } catch { return {}; }
  })();

  // User-Agent
  userHeaders['User-Agent'] = USER_AGENTS[device] || USER_AGENTS.desktop;

  // Cache control headers
  if (cacheMode === 'no-cache' || cacheMode === 'bust') {
    userHeaders['Cache-Control'] = 'no-cache, no-store';
    userHeaders['Pragma'] = 'no-cache';
  }

  // Encoding header
  if (gzip === false || gzip === 0) {
    userHeaders['Accept-Encoding'] = 'identity';
  }
  // When gzip=true, omit the header entirely so k6 sends its default (gzip, deflate, br)

  const headersJs = Object.entries(userHeaders)
    .map(([k, v]) => `    '${k.replace(/'/g, "\\'")}': '${v.replace(/'/g, "\\'")}',`)
    .join('\n');

  // For cache-bust mode, append a random query param per iteration
  const targetUrl = cacheMode === 'bust'
    ? `\`${url}${url.includes('?') ? '&' : '?'}_cb=\${Date.now()}-\${Math.random().toString(36).slice(2)}\``
    : `'${url}'`;

  const bodyLine = (httpMethod !== 'GET' && httpMethod !== 'HEAD' && requestBody)
    ? `const body = \`${requestBody.replace(/`/g, '\\`')}\`;`
    : 'const body = null;';

  const rpsOption = rpsLimit && rpsLimit > 0
    ? `  rps: ${rpsLimit},`
    : '';

  return `import http from 'k6/http';
import { check, sleep } from 'k6';
import { Trend, Rate, Counter } from 'k6/metrics';

const reqDuration = new Trend('req_duration');
const errorRate = new Rate('error_rate');
const requestCount = new Counter('request_count');

export const options = {
  vus: ${vus},
  duration: '${duration}s',
${rpsOption}
  thresholds: {
    http_req_duration: ['p(95)<5000'],
    error_rate: ['rate<0.1'],
  },
};

${bodyLine}

export default function () {
  const params = {
    headers: {
${headersJs}
    },
    timeout: '30s',
  };

  const res = http.${httpMethod.toLowerCase()}(${targetUrl}${httpMethod !== 'GET' && httpMethod !== 'HEAD' ? ', body' : ''}, params);

  const ok = check(res, {
    'status is 2xx': (r) => r.status >= 200 && r.status < 300,
    'response time < 5s': (r) => r.timings.duration < 5000,
  });

  reqDuration.add(res.timings.duration);
  errorRate.add(!ok);
  requestCount.add(1);

  sleep(0.1);
}
`;
}

// POST /api/tests — start a new test
app.post('/api/tests', (req, res) => {
  const {
    url,
    vus = 10,
    duration = 30,
    rpsLimit = 0,
    httpMethod = 'GET',
    requestBody = '',
    headers = '{}',
    cacheMode = 'normal',
    gzip = true,
    device = 'desktop',
  } = req.body;

  if (!url || !url.startsWith('http')) {
    return res.status(400).json({ error: 'Valid URL required (must start with http/https)' });
  }

  const id = uuidv4();
  const createdAt = Date.now();

  db.prepare(`
    INSERT INTO tests (id, url, vus, duration, rps_limit, http_method, request_body, headers, cache_mode, gzip, device, status, created_at)
    VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 'running', ?)
  `).run(id, url, vus, duration, rpsLimit || null, httpMethod, requestBody, headers, cacheMode, gzip ? 1 : 0, device, createdAt);

  const script = generateScript({ url, vus, duration, rpsLimit, httpMethod, requestBody, headers, cacheMode, gzip, device });
  const tmpScript = path.join(os.tmpdir(), `k6-script-${id}.js`);
  fs.writeFileSync(tmpScript, script);

  let outputBuffer = '';
  const clients = new Set();
  activeTests[id] = { clients };

  // Live metric aggregation state
  const live = {
    durations: [],       // http_req_duration values (ms)
    p90durations: [],    // sampled for percentile calc
    totalReqs: 0,
    failedReqs: 0,
    checksTotal: 0,
    checksPassed: 0,
    startTime: Date.now(),
    lastBroadcast: 0,
  };

  const k6 = spawn('k6', [
    'run',
    '--out', 'json=-',
    '--summary-trend-stats', 'avg,min,med,max,p(90),p(95),p(99)',
    tmpScript,
  ]);

  const broadcast = (data) => {
    outputBuffer += data;
    for (const client of clients) {
      client.write(`data: ${JSON.stringify({ chunk: data })}\n\n`);
    }
  };

  const broadcastMetrics = () => {
    const m = computeLiveMetrics(live);
    for (const client of clients) {
      client.write(`data: ${JSON.stringify({ metrics: m })}\n\n`);
    }
  };

  // stdout = JSON metric data points + final summary text (non-JSON lines)
  let jsonBuf = '';
  k6.stdout.on('data', (chunk) => {
    jsonBuf += chunk.toString();
    const lines = jsonBuf.split('\n');
    jsonBuf = lines.pop(); // keep incomplete last line
    for (const line of lines) {
      if (!line.trim()) { broadcast('\n'); continue; }
      try {
        const obj = JSON.parse(line);
        if (obj.type === 'Point') ingestPoint(obj, live);
        // throttle metric broadcasts to once per second
        const now = Date.now();
        if (now - live.lastBroadcast >= 1000) {
          live.lastBroadcast = now;
          broadcastMetrics();
        }
      } catch {
        // Not JSON — it's the human-readable summary; forward to log
        broadcast(line + '\n');
      }
    }
  });

  // stderr = progress bars + warnings
  k6.stderr.on('data', (data) => broadcast(data.toString()));

  k6.on('close', (code) => {
    fs.unlink(tmpScript, () => {});

    const summary = parseSummary(outputBuffer);
    // Merge live computed metrics into summary for persistence
    summary.live = computeLiveMetrics(live);

    const finishedAt = Date.now();
    const status = code === 0 ? 'completed' : 'failed';

    db.prepare(`
      UPDATE tests SET status=?, finished_at=?, summary=?, output=? WHERE id=?
    `).run(status, finishedAt, JSON.stringify(summary), outputBuffer, id);

    for (const client of clients) {
      client.write(`data: ${JSON.stringify({ done: true, status, summary })}\n\n`);
      client.end();
    }
    delete activeTests[id];
  });

  res.json({ id });
});

// GET /api/tests/:id/stream — SSE stream of live output
app.get('/api/tests/:id/stream', (req, res) => {
  const { id } = req.params;

  res.setHeader('Content-Type', 'text/event-stream');
  res.setHeader('Cache-Control', 'no-cache');
  res.setHeader('Connection', 'keep-alive');
  res.flushHeaders();

  const test = db.prepare('SELECT * FROM tests WHERE id=?').get(id);
  if (!test) {
    res.write(`data: ${JSON.stringify({ error: 'Test not found' })}\n\n`);
    return res.end();
  }

  // If already finished, send stored output and done
  if (test.status !== 'running') {
    if (test.output) res.write(`data: ${JSON.stringify({ chunk: test.output })}\n\n`);
    res.write(`data: ${JSON.stringify({ done: true, status: test.status, summary: JSON.parse(test.summary || 'null') })}\n\n`);
    return res.end();
  }

  // Otherwise subscribe to live output
  const active = activeTests[id];
  if (!active) {
    res.write(`data: ${JSON.stringify({ done: true, status: 'completed' })}\n\n`);
    return res.end();
  }

  active.clients.add(res);
  req.on('close', () => active.clients.delete(res));
});

// GET /api/tests — list all tests
app.get('/api/tests', (req, res) => {
  const rows = db.prepare('SELECT id, url, vus, duration, rps_limit, http_method, cache_mode, gzip, device, status, created_at, finished_at, summary FROM tests ORDER BY created_at DESC LIMIT 50').all();
  res.json(rows.map(r => ({ ...r, summary: r.summary ? JSON.parse(r.summary) : null })));
});

// GET /api/tests/:id — single test detail
app.get('/api/tests/:id', (req, res) => {
  const row = db.prepare('SELECT * FROM tests WHERE id=?').get(req.params.id);
  if (!row) return res.status(404).json({ error: 'Not found' });
  res.json({ ...row, summary: row.summary ? JSON.parse(row.summary) : null });
});

// DELETE /api/tests/:id — delete a test from history
app.delete('/api/tests/:id', (req, res) => {
  db.prepare('DELETE FROM tests WHERE id=?').run(req.params.id);
  res.json({ ok: true });
});

// Ingest a single k6 JSON metric point into the live aggregation state
function ingestPoint(obj, live) {
  const { metric, data } = obj;
  if (metric === 'http_req_duration') {
    if (live.durations.length < 50000) live.durations.push(data.value);
  } else if (metric === 'http_reqs') {
    live.totalReqs++;
  } else if (metric === 'http_req_failed') {
    if (data.value === 1) live.failedReqs++;
  } else if (metric === 'checks') {
    live.checksTotal++;
    if (data.value === 1) live.checksPassed++;
  }
}

// Compute snapshot of live metrics for broadcast
function computeLiveMetrics(live) {
  const elapsed = Math.max(1, (Date.now() - live.startTime) / 1000);
  const sorted  = live.durations.length ? [...live.durations].sort((a, b) => a - b) : [];
  const pct     = (p) => sorted.length ? sorted[Math.min(Math.floor(sorted.length * p / 100), sorted.length - 1)] : 0;
  const avg     = sorted.length ? sorted.reduce((a, b) => a + b, 0) / sorted.length : 0;

  const checksRate    = live.checksTotal > 0 ? live.checksPassed / live.checksTotal * 100 : 100;
  const httpOkRate    = live.totalReqs   > 0 ? (1 - live.failedReqs / live.totalReqs) * 100 : 100;
  const httpErrRate   = live.totalReqs   > 0 ? live.failedReqs / live.totalReqs * 100 : 0;

  const p95 = pct(95);
  const score = computeScore({ p95, httpErrRate, checksRate });

  return {
    totalReqs:   live.totalReqs,
    reqPerSec:   +(live.totalReqs / elapsed).toFixed(1),
    failedReqs:  live.failedReqs,
    httpErrRate: +httpErrRate.toFixed(2),
    httpOkRate:  +httpOkRate.toFixed(2),
    checksTotal: live.checksTotal,
    checksPassed:live.checksPassed,
    checksRate:  +checksRate.toFixed(2),
    avg:         +avg.toFixed(1),
    p90:         +pct(90).toFixed(1),
    p95:         +p95.toFixed(1),
    p99:         +pct(99).toFixed(1),
    max:         sorted.length ? +sorted[sorted.length - 1].toFixed(1) : 0,
    score,
  };
}

function computeScore({ p95, httpErrRate, checksRate }) {
  let s = 100;
  const p95s = (p95 || 0) / 1000;
  if      (p95s > 5)   s -= 50;
  else if (p95s > 3)   s -= 30;
  else if (p95s > 2)   s -= 20;
  else if (p95s > 1)   s -= 10;
  else if (p95s > 0.5) s -= 5;
  s -= Math.min(40, (httpErrRate || 0) * 5);
  s -= Math.min(20, (100 - (checksRate || 100)) * 2);
  return Math.max(0, Math.round(s));
}

// Parse k6 terminal output for key metrics
function parseSummary(output) {
  // Strip ANSI colour codes before matching
  const plain = output.replace(/\x1b\[[0-9;]*m/g, '');
  const summary = {};

  const patterns = {
    http_reqs:         /http_reqs[\s.]+(\d+)\s+([\d.]+\/s)/,
    http_req_duration: /http_req_duration[\s.]+avg=([\d.µms]+)\s+min=([\d.µms]+)\s+med=([\d.µms]+)\s+max=([\d.µms]+)\s+p\(90\)=([\d.µms]+)\s+p\(95\)=([\d.µms]+)\s+p\(99\)=([\d.µms]+)/,
    http_req_failed:   /http_req_failed[\s.]+(\d+\.?\d*%)\s+(\d+) out of (\d+)/,
    checks:            /checks[\s.]+(\d+\.?\d*%)\s+(\d+) out of (\d+)/,
    iterations:        /iterations[\s.]+(\d+)\s+([\d.]+\/s)/,
    vus:               /vus[\s.]+(\d+)\s+min=(\d+)\s+max=(\d+)/,
    data_received:     /data_received[\s.]+([\d.]+ \w+)\s+([\d.]+ \w+\/s)/,
    data_sent:         /data_sent[\s.]+([\d.]+ \w+)\s+([\d.]+ \w+\/s)/,
  };

  for (const [key, re] of Object.entries(patterns)) {
    const m = plain.match(re);
    if (m) summary[key] = m.slice(1);
  }

  // Extract threshold results (✓ / ✗ lines)
  const thresholds = [];
  for (const m of plain.matchAll(/(✓|✗)\s+(.+)/g)) {
    thresholds.push({ pass: m[1] === '✓', label: m[2].trim() });
  }
  if (thresholds.length) summary.thresholds = thresholds;

  return summary;
}

const PORT = process.env.PORT || 8118;
app.listen(PORT, () => console.log(`k6 Web UI running on http://0.0.0.0:${PORT}`));