#!/usr/bin/env node
/**
 * scripts/defender-scan.mjs -- Windows Defender static scan smoke for APS build artifacts.
 *
 * Scans release artifacts (PyInstaller sidecar exe / frozen desktop package / NSIS
 * installer) with Windows Defender MpCmdRun.exe:
 *
 *   MpCmdRun.exe -Scan -ScanType 3 -File <path> -DisableRemediation
 *
 * Usage:
 *   node scripts/defender-scan.mjs                    auto-discover release artifacts and scan
 *   node scripts/defender-scan.mjs <file-or-dir> ...  scan explicit targets (dir scans are recursive)
 *   node scripts/defender-scan.mjs --timeout 900000   per-file timeout in ms (default 600000)
 *   node scripts/defender-scan.mjs --mpcmdrun <path>  strict MpCmdRun override (env MPCMDRUN otherwise honored)
 *   node scripts/defender-scan.mjs --json             emit a machine-readable JSON summary
 *   node scripts/defender-scan.mjs --no-copy-fallback scan in place even for non-ASCII paths (likely fails)
 *   node scripts/defender-scan.mjs --self-test        run internal parser/discovery smoke (no scanning)
 *
 * Exit codes:
 *   0  PASS -- every scanned artifact is clean (skipped artifacts are warnings, see notes)
 *   1  FAIL -- a threat was detected, a scan timed out, or a scan failed
 *   2  SKIP -- MpCmdRun.exe is unavailable (or not Windows)
 *   3  NONE -- no artifacts found to scan
 *
 * Notes:
 *   - -DisableRemediation keeps build artifacts untouched: detection is reported only.
 *   - MpCmdRun cannot resolve non-ASCII paths: scanning in place fails with
 *     "CmdTool: Failed with hr = 0x80508023" (exit 2) or reports "was skipped"
 *     (exit 0) depending on the invocation, e.g. for a non-ASCII workspace path.
 *     When a target path contains non-ASCII characters the file is copied to an
 *     ASCII temp path and the copy is scanned (same bytes -> same verdict).
 *     Directories are always scanned in place (recursive) and are subject to the
 *     same MpCmdRun limitation on non-ASCII roots.
 *   - "skipped" means Defender did not scan the file (path/policy). It is reported
 *     as a warning, does not fail the run, and should be reviewed (MpPreference
 *     exclusions) before treating the run as a release gate.
 */
import { spawnSync } from 'node:child_process';
import fs from 'node:fs';
import os from 'node:os';
import path from 'node:path';
import process from 'node:process';
import { fileURLToPath, pathToFileURL } from 'node:url';

const repoRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
const DEFAULT_MPCMDRUN = 'C:\\Program Files\\Windows Defender\\MpCmdRun.exe';
const DEFAULT_TIMEOUT_MS = 600000;
const MAX_OUTPUT_BYTES = 16 * 1024 * 1024;

const EXIT_PASS = 0;
const EXIT_FAIL = 1;
const EXIT_UNAVAILABLE = 2;
const EXIT_NOTHING_TO_SCAN = 3;

export function hasNonAscii(value) {
  return /[^\x00-\x7F]/.test(String(value));
}

export function findMpCmdRun(override) {
  if (process.platform !== 'win32') return null;
  // An explicit --mpcmdrun is authoritative: if it does not exist the scan is skipped
  // (exit 2) instead of silently falling back to a different engine binary.
  const candidates = [];
  if (override) {
    candidates.push(override);
  } else {
    if (process.env.MPCMDRUN) candidates.push(process.env.MPCMDRUN);
    candidates.push(DEFAULT_MPCMDRUN);
    if (process.env.ProgramW6432) {
      candidates.push(path.join(process.env.ProgramW6432, 'Windows Defender', 'MpCmdRun.exe'));
    }
    candidates.push('C:\\Program Files (x86)\\Windows Defender\\MpCmdRun.exe');
  }
  for (const candidate of candidates) {
    if (candidate && fs.existsSync(candidate)) return candidate;
  }
  return null;
}

export function readDesktopPackage(root) {
  const file = path.join(root, 'apps', 'desktop', 'package.json');
  const raw = JSON.parse(fs.readFileSync(file, 'utf8'));
  const build = raw.build || {};
  return {
    file,
    version: raw.version || '0.0.0',
    productName: build.productName || raw.name || 'aps-agent',
    artifactName: (build.win && build.win.artifactName) || 'aps-agent-desktop-' + '$' + '{version}' + '.' + '$' + '{ext}',
    outputDir: (build.directories && build.directories.output) || 'release',
  };
}

export function resolveInstallerName(config) {
  const versionToken = '$' + '{version}';
  const extToken = '$' + '{ext}';
  return String(config.artifactName || '')
    .replace(versionToken, config.version)
    .replace(extToken, 'exe');
}

export function discoverArtifacts(root) {
  const config = readDesktopPackage(root);
  const desktopDir = path.join(root, 'apps', 'desktop', config.outputDir);
  const entries = [
    { id: 'sidecar-exe', label: 'Sidecar exe (PyInstaller one-dir)', file: path.join(root, 'dist', 'sidecar', 'aps-sidecar', 'aps-sidecar.exe') },
    { id: 'desktop-frozen-exe', label: 'Desktop frozen exe (win-unpacked)', file: path.join(desktopDir, 'win-unpacked', config.productName + '.exe') },
    { id: 'bundled-sidecar-exe', label: 'Bundled sidecar exe (win-unpacked)', file: path.join(desktopDir, 'win-unpacked', 'resources', 'sidecar', 'aps-sidecar.exe') },
    { id: 'nsis-installer', label: 'NSIS installer', file: path.join(desktopDir, resolveInstallerName(config)) },
  ];
  return entries.map((entry) => {
    const stat = fs.existsSync(entry.file) ? fs.statSync(entry.file) : null;
    return Object.assign({}, entry, { exists: Boolean(stat), bytes: stat ? stat.size : 0 });
  });
}

export function parseScanOutput(text) {
  const clean = String(text || '');
  const noThreats = /\bfound\s+no\s+threats?\b/i.test(clean);
  const countMatch = /found\s+(\d+)\s+threats?/i.exec(clean);
  const threatCount = noThreats ? 0 : countMatch ? Number(countMatch[1]) : null;
  const threatNames = [];
  const nameRe = /^Threat\s*:\s*(.+)$/gim;
  let match;
  while ((match = nameRe.exec(clean)) !== null) {
    const name = String(match[1]).trim();
    if (name && threatNames.indexOf(name) === -1) threatNames.push(name);
  }
  const skipped = /was\s+skipped/i.test(clean);
  const listed = /LIST\s+OF\s+DETECTED\s+THREATS/i.test(clean);
  const hasThreats = listed || threatNames.length > 0 || (threatCount !== null && threatCount > 0);
  let status;
  if (skipped) status = 'skipped';
  else if (hasThreats) status = 'threat';
  else if (threatCount === 0) status = 'clean';
  else status = 'unknown';
  return { status, threatCount, threatNames, skipped, hasThreats };
}

export function formatBytes(bytes) {
  if (!Number.isFinite(bytes)) return '?';
  const units = ['B', 'KB', 'MB', 'GB'];
  let value = bytes;
  let unit = 0;
  while (value >= 1024 && unit < units.length - 1) {
    value /= 1024;
    unit += 1;
  }
  return (unit === 0 ? String(value) : value.toFixed(1)) + ' ' + units[unit];
}

export function formatDuration(ms) {
  const totalSeconds = ms / 1000;
  if (totalSeconds < 60) {
    const rounded = Math.round(totalSeconds);
    return (rounded < 10 ? totalSeconds.toFixed(1) : String(rounded)) + 's';
  }
  const minutes = Math.floor(totalSeconds / 60);
  return minutes + 'm ' + Math.round(totalSeconds % 60) + 's';
}

export function scanTarget(mpCmdRun, targetFile, options) {
  const timeoutMs = options.timeoutMs || DEFAULT_TIMEOUT_MS;
  const copyFallback = options.copyFallback !== false;
  const stat = fs.existsSync(targetFile) ? fs.statSync(targetFile) : null;
  const isDir = Boolean(stat && stat.isDirectory());
  const useCopy = copyFallback && !isDir && hasNonAscii(targetFile);
  let scanPath = targetFile;
  let tempDir = null;
  let copyError = null;
  if (useCopy) {
    try {
      tempDir = fs.mkdtempSync(path.join(os.tmpdir(), 'aps-defender-'));
      scanPath = path.join(tempDir, 'scan-target' + path.extname(targetFile));
      fs.copyFileSync(targetFile, scanPath);
    } catch (error) {
      copyError = error;
      scanPath = targetFile;
    }
  }
  const startedAt = Date.now();
  const spawned = spawnSync(mpCmdRun, ['-Scan', '-ScanType', '3', '-File', scanPath, '-DisableRemediation'], {
    encoding: 'utf8',
    windowsHide: true,
    timeout: timeoutMs,
    maxBuffer: MAX_OUTPUT_BYTES,
  });
  const durationMs = Date.now() - startedAt;
  const output = String(spawned.stdout || '') + String(spawned.stderr || '');
  const parsed = parseScanOutput(output);
  let status = parsed.status;
  let error = null;
  if (spawned.error) {
    error = String(spawned.error.message || spawned.error);
    status = (spawned.error.code === 'ETIMEDOUT' || spawned.signal) ? 'timeout' : 'error';
  } else if (status === 'unknown') {
    status = spawned.status === 0 ? 'clean' : 'error';
  }
  if (status === 'error' && !error) {
    const failMatch = /CmdTool:\s+Failed[^\r\n]*/i.exec(output);
    error = failMatch ? failMatch[0] : 'MpCmdRun exited with code ' + spawned.status;
  }
  const outcome = {
    file: targetFile,
    strategy: useCopy ? 'temp-copy' : isDir ? 'in-place-dir' : 'in-place',
    exitCode: spawned.status,
    error,
    copyError: copyError ? String(copyError.message || copyError) : null,
    durationMs,
    status,
    threatCount: parsed.threatCount,
    threatNames: parsed.threatNames,
    outputTail: output.slice(-800),
  };
  if (tempDir) {
    try {
      fs.rmSync(tempDir, { recursive: true, force: true });
    } catch {
      // best-effort cleanup
    }
  }
  return outcome;
}

export function classifyVerdict(outcomes) {
  if (outcomes.some((outcome) => outcome.status === 'threat')) return 'THREAT';
  if (outcomes.some((outcome) => outcome.status === 'error' || outcome.status === 'timeout')) return 'FAIL';
  return 'PASS';
}

export function printSummary(outcomes, mpCmdRun, skippedCount) {
  const lines = [];
  lines.push('Defender scan summary');
  lines.push('  MpCmdRun: ' + mpCmdRun);
  for (const outcome of outcomes) {
    const tag = outcome.status === 'clean' ? 'PASS' : outcome.status === 'threat' ? 'THREAT' : outcome.status === 'skipped' ? 'SKIP' : 'FAIL';
    let detail;
    if (outcome.status === 'clean') detail = 'clean';
    else if (outcome.status === 'threat') {
      detail = outcome.threatNames.length > 0 ? outcome.threatNames.join(', ') : String(outcome.threatCount) + ' threat(s)';
    } else if (outcome.status === 'skipped') detail = 'not scanned by MpCmdRun (path/policy)';
    else if (outcome.status === 'timeout') detail = 'timed out';
    else detail = outcome.error || outcome.copyError || 'scan failed';
    lines.push('  [' + tag + '] ' + outcome.label + ' -- ' + outcome.file + ' (' + formatBytes(outcome.bytes) + ') ' + detail + ' in ' + formatDuration(outcome.durationMs) + ' [' + outcome.strategy + ']');
  }
  if (skippedCount > 0) {
    lines.push('  WARNING: ' + skippedCount + ' artifact(s) were skipped and NOT scanned; review MpPreference exclusions before gating.');
  }
  console.log(lines.join('\n'));
}

export function parseArgs(argv) {
  const args = {
    positional: [],
    mpCmdRun: null,
    timeoutMs: DEFAULT_TIMEOUT_MS,
    json: false,
    copyFallback: true,
    selfTest: false,
    help: false,
  };
  for (let i = 0; i < argv.length; i += 1) {
    const arg = argv[i];
    if (arg === '--json') args.json = true;
    else if (arg === '--self-test') args.selfTest = true;
    else if (arg === '--no-copy-fallback') args.copyFallback = false;
    else if (arg === '--help' || arg === '-h') args.help = true;
    else if (arg === '--mpcmdrun') {
      i += 1;
      args.mpCmdRun = argv[i];
    } else if (arg === '--timeout') {
      i += 1;
      args.timeoutMs = Number(argv[i]) || DEFAULT_TIMEOUT_MS;
    } else if (arg.startsWith('--')) {
      throw new Error('Unknown option: ' + arg);
    } else {
      args.positional.push(arg);
    }
  }
  return args;
}

export function printHelp() {
  console.log([
    'Usage: node scripts/defender-scan.mjs [options] [target ...]',
    '',
    'Scan APS build artifacts with Windows Defender MpCmdRun.exe (static, no remediation).',
    '',
    'Options:',
    '  --timeout <ms>         per-file timeout (default 600000)',
    '  --mpcmdrun <path>      MpCmdRun.exe path override (env MPCMDRUN also honored)',
    '  --json                 machine-readable JSON summary',
    '  --no-copy-fallback     scan non-ASCII paths in place (MpCmdRun will likely skip them)',
    '  --self-test            internal parser/discovery smoke, no scanning',
    '  -h, --help             this help',
    '',
    'Exit codes: 0 PASS / 1 FAIL / 2 MpCmdRun unavailable / 3 nothing to scan',
  ].join('\n'));
}

export function runSelfTest() {
  const checks = [];
  const check = (name, fn) => {
    try {
      fn();
      checks.push({ name, pass: true });
    } catch (error) {
      checks.push({ name, pass: false, error: String((error && error.message) || error) });
    }
  };
  check('parse clean output', () => {
    const parsed = parseScanOutput('Scan starting...\nScan finished.\nScanning X found no threats.\n');
    if (parsed.status !== 'clean' || parsed.threatCount !== 0) throw new Error('expected clean');
  });
  check('parse threat output (DisableRemediation block)', () => {
    const text = 'Scanning X found 1 threats.\n\n<===========================LIST OF DETECTED THREATS==========================>\nThreat : Virus:DOS/EICAR_Test_File\nResources : 1 total\n    file : X\n';
    const parsed = parseScanOutput(text);
    if (parsed.status !== 'threat') throw new Error('expected threat, got ' + parsed.status);
    if (parsed.threatCount !== 1) throw new Error('expected threatCount 1');
    if (parsed.threatNames.indexOf('Virus:DOS/EICAR_Test_File') === -1) throw new Error('missing threat name');
  });
  check('parse remediating-mode threat output', () => {
    const parsed = parseScanOutput('Scanning X found 2 threats.\nCleaning started...\nCleaning finished.\n');
    if (parsed.status !== 'threat' || parsed.threatCount !== 2) throw new Error('bad remediating parse');
  });
  check('parse skipped output', () => {
    const parsed = parseScanOutput('Scan starting...\nScan finished.\nScanning D:\\abc was skipped.\n');
    if (parsed.status !== 'skipped') throw new Error('expected skipped, got ' + parsed.status);
  });
  check('findMpCmdRun override', () => {
    if (findMpCmdRun(DEFAULT_MPCMDRUN) !== DEFAULT_MPCMDRUN) throw new Error('expected DEFAULT_MPCMDRUN match');
    if (findMpCmdRun('C:\\definitely-missing\\MpCmdRun.exe') !== null) throw new Error('expected null for missing override');
  });
  check('installer name resolution', () => {
    const config = { artifactName: 'aps-agent-desktop-' + '$' + '{version}' + '.' + '$' + '{ext}', version: '0.1.0' };
    if (resolveInstallerName(config) !== 'aps-agent-desktop-0.1.0.exe') throw new Error('got ' + resolveInstallerName(config));
  });
  check('discover artifacts from desktop config', () => {
    const artifacts = discoverArtifacts(repoRoot);
    const ids = artifacts.map((a) => a.id);
    const expectedIds = 'sidecar-exe,desktop-frozen-exe,bundled-sidecar-exe,nsis-installer';
    if (ids.join(',') !== expectedIds) throw new Error('unexpected ids: ' + ids.join(','));
    const installer = artifacts.find((a) => a.id === 'nsis-installer');
    if (!installer.file.endsWith('aps-agent-desktop-0.1.0.exe')) throw new Error('unexpected installer path: ' + installer.file);
    if (!installer.exists) throw new Error('expected a built NSIS installer on this machine');
  });
  check('verdict classification', () => {
    if (classifyVerdict([{ status: 'clean' }]) !== 'PASS') throw new Error('clean should be PASS');
    if (classifyVerdict([{ status: 'clean' }, { status: 'threat' }]) !== 'THREAT') throw new Error('threat should be THREAT');
    if (classifyVerdict([{ status: 'error' }]) !== 'FAIL') throw new Error('error should be FAIL');
    if (classifyVerdict([{ status: 'timeout' }]) !== 'FAIL') throw new Error('timeout should be FAIL');
    if (classifyVerdict([{ status: 'skipped' }]) !== 'PASS') throw new Error('skipped-only should be PASS with warning');
  });
  let failed = 0;
  for (const entry of checks) {
    if (entry.pass) {
      console.log('  [PASS] ' + entry.name);
    } else {
      failed += 1;
      console.log('  [FAIL] ' + entry.name + ': ' + entry.error);
    }
  }
  console.log('defender-scan self-test: ' + (failed === 0 ? 'PASS (' + checks.length + '/' + checks.length + ')' : 'FAIL (' + (checks.length - failed) + '/' + checks.length + ')'));
  process.exitCode = failed === 0 ? EXIT_PASS : EXIT_FAIL;
}

async function main() {
  let args;
  try {
    args = parseArgs(process.argv.slice(2));
  } catch (error) {
    console.error('defender-scan: ' + String((error && error.message) || error));
    process.exitCode = EXIT_FAIL;
    return;
  }
  if (args.help) {
    printHelp();
    return;
  }
  if (args.selfTest) {
    runSelfTest();
    return;
  }
  const mpCmdRun = findMpCmdRun(args.mpCmdRun);
  if (!mpCmdRun) {
    console.log(JSON.stringify({ verdict: 'SKIPPED', reason: 'MpCmdRun.exe unavailable (not Windows or not installed)', mpCmdRun: null }));
    process.exitCode = EXIT_UNAVAILABLE;
    return;
  }
  let targets;
  if (args.positional.length > 0) {
    targets = args.positional.map((file) => {
      const stat = fs.existsSync(file) ? fs.statSync(file) : null;
      return { id: path.basename(file), label: file, file, exists: Boolean(stat), bytes: stat ? stat.size : 0 };
    });
  } else {
    targets = discoverArtifacts(repoRoot);
  }
  const present = targets.filter((target) => target.exists);
  const missing = targets.filter((target) => !target.exists);
  if (!args.json) {
    for (const target of missing) {
      console.log('  [MISSING] ' + target.label + ' -- ' + target.file + ' (not found; skipped)');
    }
  }
  if (present.length === 0) {
    console.log('No build artifacts found to scan. Build them first (npm run build:desktop) or pass explicit paths.');
    process.exitCode = EXIT_NOTHING_TO_SCAN;
    return;
  }
  const outcomes = [];
  for (const target of present) {
    const outcome = scanTarget(mpCmdRun, target.file, { timeoutMs: args.timeoutMs, copyFallback: args.copyFallback });
    outcome.id = target.id;
    outcome.label = target.label;
    outcome.bytes = target.bytes;
    outcomes.push(outcome);
  }
  const skippedCount = outcomes.filter((outcome) => outcome.status === 'skipped').length;
  const verdict = classifyVerdict(outcomes);
  if (args.json) {
    console.log(JSON.stringify({
      verdict,
      mpCmdRun,
      timeoutMs: args.timeoutMs,
      skippedCount,
      missing: missing.map((target) => ({ id: target.id, file: target.file })),
      artifacts: outcomes,
    }, null, 2));
  } else {
    printSummary(outcomes, mpCmdRun, skippedCount);
    console.log('Verdict: ' + verdict + (verdict === 'PASS' ? ' -- no threats found in scanned artifacts' : ''));
  }
  process.exitCode = verdict === 'PASS' ? EXIT_PASS : EXIT_FAIL;
}

const isMain = process.argv[1] && import.meta.url === pathToFileURL(path.resolve(process.argv[1])).href;
if (isMain) {
  await main();
}