private TextNode compactHistogramEncoding()

in ingestion-core/src/main/java/com/mozilla/telemetry/ingestion/core/transform/PubsubMessageToObjectNode.java [754:809]
22 lines of code
6 McCabe index (conditional complexity)

    private TextNode compactHistogramEncoding(JsonNode o, String fieldName) {
      final int histogramType = o.path("histogram_type").asInt(-1);
      if (histogramType < 0 || histogramType > 5) {
        incrementInvalidHistogramType();
        return jsonHistogramEncoding(o);
      }
      final long sum = o.path("sum").asLong(-1);
      if (sum < 0) {
        incrementInvalidHistogramSum();
        return jsonHistogramEncoding(o);
      }
      final JsonNode values = o.path("values");
      if (histogramType == 2 && fieldName.startsWith("use_counter2")) {
        // Histograms named as "use_counter" are reported as type 2 (boolean), but only ever have
        // a non-zero value in the "1" (true) bucket (and the "sum" field should match this count).
        // They can be encoded as a textual representation of that single number without any loss
        // of information, and since use counters make up the majority of histogram data volume,
        // this optimization case is the most important one. See
        // https://firefox-source-docs.mozilla.org/toolkit/components/telemetry/collection/use-counters.html
        if (sum == values.path("1").asLong(0)) {
          return TextNode.valueOf(Long.toString(sum));
        } else {
          incrementInvalidHistogramUseCounter();
          return jsonHistogramEncoding(o);
        }
      }
      return jsonHistogramEncoding(o);
      // TODO: Uncomment the following section and related test cases once we have transitioned
      // analysis use cases to tolerate the additional encodings.
      // spotless:off
      /*
      else if (histogramType == 4) {
        return TextNode.valueOf(Long.toString(sum));
      } else if (histogramType == 2) {
        // Type 2 are "boolean" histograms where bucket "0" is a count of false values and
        // bucket "1" is a count of true values.
        return TextNode.valueOf(
            String.format("%d,%d", values.path("0").longValue(), values.path("1").longValue()));
      } else {
        final int bucketCount = o.path("bucket_count").asInt(-1);
        final long rangeLo = o.path("range").path(0).asLong(-1);
        final long rangeHi = o.path("range").path(1).asLong(-1);
        final String valString = Json.asString(values) //
            .replace("{", "") //
            .replace("}", "") //
            .replace("\"", "");
        if (bucketCount <= 0 || rangeLo < 0 || rangeHi < 0) {
          incrementInvalidHistogramRange();
          return jsonHistogramEncoding(o);
        }
        return TextNode.valueOf(String.format("%d;%d;%d;%d,%d;%s", //
            bucketCount, histogramType, sum, rangeLo, rangeHi, valString));
      }
      */
      // spotless:on
    }