#!/usr/bin/env node

/**
 * Scans multi-platform SBOMs with Trivy, handles distro detection and fallbacks,
 * prints diagnostic overview, and invokes diff engine.
 */

const fs = require('node:fs');
const path = require('node:path');
const cp = require('node:child_process');
const { detectDistro } = require('./distro.js');
const { formatScanOverview, countVulnerabilities } = require('./diagnostics.js');

function parseArgs(argv) {
  const args = {
    headImage: process.env.INPUT_HEAD_IMAGE || '',
    targetImage: process.env.INPUT_TARGET_IMAGE || '',
    targetBranch: process.env.INPUT_TARGET_BRANCH || 'main',
    useInbuildSbom: process.env.INPUT_USE_INBUILD_SBOM || 'false',
    outputDelta: process.env.INPUT_OUTPUT_DELTA || 'cve-delta.md',
    outputSummary: process.env.INPUT_OUTPUT_SUMMARY || 'cve-summary.md',
  };

  for (let i = 2; i < argv.length; i++) {
    const arg = argv[i];
    if (arg === '--head-image' && i + 1 < argv.length) args.headImage = argv[++i];
    else if (arg === '--target-image' && i + 1 < argv.length) args.targetImage = argv[++i];
    else if (arg === '--target-branch' && i + 1 < argv.length) args.targetBranch = argv[++i];
    else if (arg === '--use-inbuild-sbom' && i + 1 < argv.length) args.useInbuildSbom = argv[++i];
    else if (arg === '--output-delta' && i + 1 < argv.length) args.outputDelta = argv[++i];
    else if (arg === '--output-summary' && i + 1 < argv.length) args.outputSummary = argv[++i];
  }

  return args;
}

function scanSbomFile({ sbomPath, image, outJson, errLog, useInbuild }) {
  const archMatch = path.basename(sbomPath, '.spdx.json').match(/^sbom-(.+)$/);
  const arch = archMatch ? archMatch[1] : 'default';

  console.log(`Scanning SBOM for architecture: ${arch}`);
  let distroArg = [];
  if (useInbuild) {
    try {
      const content = fs.readFileSync(sbomPath, 'utf8');
      const detected = detectDistro(content);
      if (detected) {
        console.log(`Detected distribution '${detected}' from in-build SBOM PURLs. Scanning with --distro.`);
        distroArg = ['--distro', detected];
      }
    } catch {
      // Ignore read error
    }
  }

  const runTrivySbom = () => {
    try {
      const errFd = fs.openSync(errLog, 'w');
      try {
        cp.execFileSync('trivy', [
          'sbom',
          ...distroArg,
          '--skip-version-check',
          '--format', 'json',
          '--output', outJson,
          sbomPath,
        ], { stdio: ['ignore', 'ignore', errFd] });
        return true;
      } finally {
        fs.closeSync(errFd);
      }
    } catch {
      return false;
    }
  };

  let scanSuccess = runTrivySbom();
  let vulnCount = 0;
  if (fs.existsSync(outJson) && fs.statSync(outJson).size > 0) {
    vulnCount = countVulnerabilities(fs.readFileSync(outJson, 'utf8'));
  }

  // Fallback if in-build scan produced 0 findings or failed
  if (useInbuild && (!scanSuccess || vulnCount === 0)) {
    console.warn(`::warning::In-build SBOM for image (${arch}) yielded ${vulnCount} CVE findings. Falling back to direct Trivy image scan...`);
    const platArgs = arch !== 'default' ? ['--platform', `linux/${arch}`] : [];
    try {
      cp.execFileSync('trivy', [
        'image',
        '--skip-version-check',
        ...platArgs,
        '--format', 'spdx-json',
        '--output', sbomPath,
        image,
      ], { stdio: 'inherit' });

      console.log('Re-scanning SBOM generated directly by Trivy...');
      // Re-scan without external distroArg (Trivy's generated SBOM has OS declarations)
      distroArg = [];
      scanSuccess = runTrivySbom();
      if (fs.existsSync(outJson) && fs.statSync(outJson).size > 0) {
        vulnCount = countVulnerabilities(fs.readFileSync(outJson, 'utf8'));
      }
    } catch (e) {
      console.warn(`::warning::Direct Trivy scan fallback failed for ${arch}: ${e.message}`);
    }
  }

  return { arch, scanSuccess, vulnCount, outJson, errLog };
}

function main() {
  const args = parseArgs(process.argv);
  const {
    headImage,
    targetImage,
    targetBranch,
    useInbuildSbom,
    outputDelta,
    outputSummary,
  } = args;
  const useInbuild = useInbuildSbom === 'true';

  fs.mkdirSync(path.join('cve-reports', 'head'), { recursive: true });
  fs.mkdirSync(path.join('cve-reports', 'target'), { recursive: true });

  const getSboms = (dir) => {
    if (!fs.existsSync(dir)) return [];
    return fs.readdirSync(dir)
      .filter((f) => f.startsWith('sbom-') && f.endsWith('.spdx.json'))
      .sort()
      .map((f) => path.join(dir, f));
  };

  const headSboms = getSboms(path.join('sboms', 'head'));
  const targetSboms = getSboms(path.join('sboms', 'target'));

  let headOk = true;
  let targetOk = true;
  let headReportCount = 0;
  let targetReportCount = 0;
  const headSummary = [];
  const targetSummary = [];

  // 1. Scan Head SBOMs
  if (headSboms.length === 0) {
    headOk = false;
    headSummary.push('  - ❌ No SBOM files found in sboms/head/');
  } else {
    for (const f of headSboms) {
      const arch = path.basename(f, '.spdx.json').replace(/^sbom-/, '');
      const outJson = path.join('cve-reports', 'head', `cve-${arch}.json`);
      const errLog = path.join('cve-reports', 'head', `cve-${arch}.err`);

      const res = scanSbomFile({
        sbomPath: f,
        image: headImage,
        outJson,
        errLog,
        useInbuild,
      });

      if (res.scanSuccess && fs.existsSync(outJson) && fs.statSync(outJson).size > 0) {
        if (res.vulnCount === 0) {
          console.warn(`::warning::Head image architecture '${arch}' has 0 CVE findings. Verify that OS/packages were recognized.`);
          headSummary.push(`  - ${arch}: ⚠️ WARNING (0 vulnerability findings detected)`);
        } else {
          headSummary.push(`  - ${arch}: ✅ OK (${res.vulnCount} vulnerability findings)`);
        }
        headReportCount++;
      } else {
        headOk = false;
        let errMsg = 'Trivy scan exited with non-zero status';
        if (fs.existsSync(errLog)) {
          const errLines = fs.readFileSync(errLog, 'utf8').trim().split('\n');
          errMsg = errLines.slice(-2).join(' ').replace(/\s+/g, ' ') || errMsg;
        }
        headSummary.push(`  - ${arch}: ❌ FAILED (${errMsg})`);
      }
    }
  }

  // 2. Scan Target SBOMs
  if (targetSboms.length === 0) {
    targetOk = false;
    targetSummary.push('  - ❌ No SBOM files found in sboms/target/');
  } else {
    for (const f of targetSboms) {
      const arch = path.basename(f, '.spdx.json').replace(/^sbom-/, '');
      const outJson = path.join('cve-reports', 'target', `cve-${arch}.json`);
      const errLog = path.join('cve-reports', 'target', `cve-${arch}.err`);

      const res = scanSbomFile({
        sbomPath: f,
        image: targetImage,
        outJson,
        errLog,
        useInbuild,
      });

      if (res.scanSuccess && fs.existsSync(outJson) && fs.statSync(outJson).size > 0) {
        if (res.vulnCount === 0) {
          console.warn(`::warning::Target baseline image architecture '${arch}' has 0 CVE findings. Verify that OS/packages were recognized.`);
          targetSummary.push(`  - ${arch}: ⚠️ WARNING (0 vulnerability findings detected)`);
        } else {
          targetSummary.push(`  - ${arch}: ✅ OK (${res.vulnCount} vulnerability findings)`);
        }
        targetReportCount++;
      } else {
        targetOk = false;
        let errMsg = 'Trivy scan exited with non-zero status';
        if (fs.existsSync(errLog)) {
          const errLines = fs.readFileSync(errLog, 'utf8').trim().split('\n');
          errMsg = errLines.slice(-2).join(' ').replace(/\s+/g, ' ') || errMsg;
        }
        targetSummary.push(`  - ${arch}: ❌ FAILED (${errMsg})`);
      }
    }
  }

  // 3. Print Comprehensive Diagnostic Overview
  const strategy = useInbuild
    ? 'Built-in OCI Attestation (Syft/Docker Scout) with distro detection'
    : 'Direct Trivy Image Scan (Full rootfs & source package mapping)';

  const overview = formatScanOverview({
    headImage,
    targetImage,
    targetBranch,
    strategy,
    headSummary,
    targetSummary,
  });
  console.log(overview);

  // 4. Enforce Gating
  let hasError = false;
  if (!headOk || headReportCount === 0) {
    console.error('::error::Head image CVE analysis failed or produced no reports.');
    hasError = true;
  }
  if (!targetOk || targetReportCount === 0) {
    console.error('::error::Target baseline CVE analysis failed or produced no reports.');
    hasError = true;
  }

  if (hasError) {
    console.error('::error::Aborting differential analysis: both head and target scans must succeed before diffing.');
    process.exit(1);
  }

  // 5. Run multi-arch set-based diff and generate reports
  console.log('Both head and target scans succeeded. Computing set-based vulnerability delta...');
  const cveDiffScript = path.resolve(__dirname, '..', 'cve-diff.js');
  try {
    const deltaOutput = cp.execFileSync(process.execPath, [
      cveDiffScript,
      path.join('cve-reports', 'target'),
      path.join('cve-reports', 'head'),
      targetBranch,
      outputSummary,
    ], { encoding: 'utf8' });

    fs.writeFileSync(outputDelta, deltaOutput, 'utf8');
    console.log(`CVE delta written to ${outputDelta} and full summary written to ${outputSummary}`);
  } catch (e) {
    console.error(`::error::Failed to generate CVE differential report: ${e.message}`);
    process.exit(1);
  }
}

if (require.main === module) {
  main();
}

module.exports = {
  parseArgs,
  scanSbomFile,
  main,
};