import { spawn, execSync } from 'child_process';
import { join, dirname } from 'path';
import { fileURLToPath } from 'url';
import { existsSync } from 'fs';

const __dirname = dirname(fileURLToPath(import.meta.url));

// Resolve sitespeed.io binary.
// In Docker the global install is on PATH; outside Docker use the local clone.
function resolveBin() {
  if (process.env.SITESPEED_BIN) return { cmd: 'node', scriptArg: process.env.SITESPEED_BIN };

  // Try global install on PATH (works in Docker image)
  try {
    const globalPath = execSync('which sitespeed.io', { encoding: 'utf8' }).trim();
    if (globalPath) return { cmd: globalPath, scriptArg: null };
  } catch {}

  // Try common global npm location
  const candidates = [
    '/usr/local/lib/node_modules/sitespeed.io/bin/sitespeed.js',
    '/usr/lib/node_modules/sitespeed.io/bin/sitespeed.js',
    join(__dirname, '..', 'sitespeed.io', 'bin', 'sitespeed.js'),
  ];
  for (const p of candidates) {
    if (existsSync(p)) return { cmd: 'node', scriptArg: p };
  }

  throw new Error('sitespeed.io binary not found. Set SITESPEED_BIN env var.');
}

export function runTest(job, onLine) {
  return new Promise((resolve, reject) => {
    const outputFolder = join(__dirname, 'reports', job.id);

    let bin, scriptArg;
    try {
      ({ cmd: bin, scriptArg } = resolveBin());
    } catch (err) {
      return reject(err);
    }

    const sitespeedArgs = [
      job.url,
      '--browser', job.browser,
      '-n', String(job.runs),
      '--outputFolder', outputFolder,
      '--json',
      '--sustainable.enable',
      '--axe.enable',
      '--coach',
    ];

    if (job.mobile) sitespeedArgs.push('--mobile');

    // Chrome flags required in Docker
    if (process.env.IN_DOCKER) {
      sitespeedArgs.push('--browsertime.chrome.args', 'no-sandbox');
      sitespeedArgs.push('--browsertime.chrome.args', 'disable-dev-shm-usage');
      sitespeedArgs.push('--browsertime.chrome.args', 'disable-gpu');
    }

    // Build the final argv for spawn
    const spawnArgs = scriptArg
      ? [scriptArg, ...sitespeedArgs]   // node /path/to/sitespeed.js <args>
      : sitespeedArgs;                   // sitespeed.io <args>

    const env = { ...process.env, DISPLAY: process.env.DISPLAY || ':99' };

    onLine(`[runner] binary: ${bin}${scriptArg ? ' ' + scriptArg : ''}`);
    onLine(`[runner] DISPLAY: ${env.DISPLAY}`);
    onLine(`[runner] outputFolder: ${outputFolder}`);

    const child = spawn(bin, spawnArgs, { cwd: __dirname, env });

    // Collect all output lines — included in error if process fails
    const allLines = [];

    child.stdout.on('data', (data) => {
      const lines = data.toString().split('\n').filter(Boolean);
      for (const line of lines) { allLines.push(line); onLine(line); }
    });

    child.stderr.on('data', (data) => {
      const lines = data.toString().split('\n').filter(Boolean);
      for (const line of lines) { allLines.push('[stderr] ' + line); onLine('[stderr] ' + line); }
    });

    child.on('close', (code) => {
      if (code === 0) {
        resolve(outputFolder);
      } else {
        // Surface the last 20 lines of output so the error is visible in the UI
        const tail = allLines.slice(-20).join('\n');
        reject(new Error(`sitespeed.io exited with code ${code}\n${tail}`));
      }
    });

    child.on('error', (err) => {
      reject(new Error(`Failed to spawn sitespeed.io (${bin}): ${err.message}`));
    });
  });
}