// Generate a "software footprint" detection rule from simple inputs, in the
// shape the deployment model already uses (`detectionType` + `detectionRule`).
// MSI maps to a product-code rule; file/registry produce Intune-style custom
// PowerShell detection scripts so they flow straight through publishing without
// extra mapping. Pure + unit-tested.

function fileDetectionScript({ path, version }) {
  const lines = [`$path = '${path.replace(/'/g, "''")}'`, 'if (Test-Path -LiteralPath $path) {'];
  if (version) {
    lines.push("  $found = (Get-Item -LiteralPath $path).VersionInfo.ProductVersion");
    lines.push(`  if ($found -and [version]$found -ge [version]'${version}') { Write-Output 'Detected'; exit 0 }`);
  } else {
    lines.push("  Write-Output 'Detected'; exit 0");
  }
  lines.push('}');
  lines.push('exit 1');
  return lines.join('\n');
}

function registryDetectionScript({ keyPath, valueName, valueData }) {
  const key = keyPath.replace(/'/g, "''");
  const lines = [`$key = '${key}'`];
  if (valueName) {
    lines.push("$value = (Get-ItemProperty -LiteralPath $key -ErrorAction SilentlyContinue).'" + valueName.replace(/'/g, "''") + "'");
    if (valueData) {
      lines.push(`if ($value -eq '${valueData.replace(/'/g, "''")}') { Write-Output 'Detected'; exit 0 }`);
    } else {
      lines.push("if ($null -ne $value) { Write-Output 'Detected'; exit 0 }");
    }
  } else {
    lines.push("if (Test-Path -LiteralPath $key) { Write-Output 'Detected'; exit 0 }");
  }
  lines.push('exit 1');
  return lines.join('\n');
}

export function buildDetectionRule(input = {}) {
  switch (input.type) {
    case 'msi': {
      if (!input.productCode) throw new Error('productCode is required for MSI detection');
      return {
        detectionType: 'msi-product-code',
        detectionRule: input.productCode,
        description: `MSI product code ${input.productCode}`
      };
    }
    case 'file': {
      if (!input.path) throw new Error('path is required for file detection');
      return {
        detectionType: 'custom-script',
        detectionRule: fileDetectionScript(input),
        description: input.version ? `File ${input.path} version ≥ ${input.version}` : `File exists: ${input.path}`
      };
    }
    case 'registry': {
      if (!input.keyPath) throw new Error('keyPath is required for registry detection');
      return {
        detectionType: 'custom-script',
        detectionRule: registryDetectionScript(input),
        description: input.valueName ? `Registry ${input.keyPath}\\${input.valueName}` : `Registry key ${input.keyPath}`
      };
    }
    default:
      throw new Error(`Unknown detection type "${input.type}" (expected msi, file, or registry)`);
  }
}