function metricSpecToSqlExpression()

in web-console/src/helpers/spec-conversion.ts [454:516]
47 lines of code
27 McCabe index (conditional complexity)

function metricSpecToSqlExpression(metricSpec: MetricSpec): string | undefined {
  if (metricSpec.type === 'count') {
    return `COUNT(*)`; // count is special as it does not have a fieldName
  }

  if (!metricSpec.fieldName) return;
  const column = C(metricSpec.fieldName);

  switch (metricSpec.type) {
    case 'longSum':
    case 'floatSum':
    case 'doubleSum':
      return `SUM(${column})`;

    case 'longMin':
    case 'floatMin':
    case 'doubleMin':
      return `MIN(${column})`;

    case 'longMax':
    case 'floatMax':
    case 'doubleMax':
      return `MAX(${column})`;

    case 'doubleFirst':
    case 'floatFirst':
    case 'longFirst':
      return `EARLIEST(${column})`;

    case 'stringFirst':
      return `EARLIEST(${column}, ${L(metricSpec.maxStringBytes || 128)})`;

    case 'doubleLast':
    case 'floatLast':
    case 'longLast':
      return `LATEST(${column})`;

    case 'stringLast':
      return `LATEST(${column}, ${L(metricSpec.maxStringBytes || 128)})`;

    case 'thetaSketch':
      return `APPROX_COUNT_DISTINCT_DS_THETA(${column}${extraArgs([metricSpec.size, 16384])})`;

    case 'HLLSketchBuild':
    case 'HLLSketchMerge':
      return `APPROX_COUNT_DISTINCT_DS_HLL(${column}${extraArgs(
        [metricSpec.lgK, 12],
        [metricSpec.tgtHllType, 'HLL_4'],
      )})`;

    case 'quantilesDoublesSketch':
      // For consistency with the above this should be APPROX_QUANTILE_DS but that requires a post agg so it does not work quite right.
      return `DS_QUANTILES_SKETCH(${column}${extraArgs([metricSpec.k, 128])})`;

    case 'hyperUnique':
      return `APPROX_COUNT_DISTINCT_BUILTIN(${column})`;

    default:
      // The following things are (knowingly) not supported:
      // tDigestSketch, momentSketch, fixedBucketsHistogram
      return;
  }
}