package net.geedge.util;

import java.io.IOException;
import java.io.Writer;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import io.prometheus.client.Collector;
import io.prometheus.client.Collector.MetricFamilySamples;

public class TextFormatUtils {
	
	private static final Logger logger = LoggerFactory.getLogger(TextFormatUtils.class);
	
	public static void write004(Writer writer, List<MetricFamilySamples> mfs) {
		try {
			String enter = "\n";
	        for(MetricFamilySamples mfSample:mfs) {
	            Collector.MetricFamilySamples metricFamilySamples = mfSample;
	            writer.write("# HELP ");
	            writer.write(metricFamilySamples.name);
	            writer.write(' ');
	            writeEscapedHelp(writer, metricFamilySamples.help);
	            writer.write(enter);

	            writer.write("# TYPE ");
	            writer.write(metricFamilySamples.name);
	            writer.write(' ');
	            writer.write(typeString(metricFamilySamples.type));
	            writer.write(enter);

	            for (Collector.MetricFamilySamples.Sample sample: metricFamilySamples.samples) {
		              writer.write(sample.name);
		              if (sample.labelNames.size() > 0) {
			                writer.write('{');
			                for (int i = 0; i < sample.labelNames.size(); ++i) {
				                  writer.write(sample.labelNames.get(i));
				                  writer.write("=\"");
				                  writeEscapedLabelValue(writer, sample.labelValues.get(i));
				                  writer.write("\",");
			                }
			                writer.write('}');
		              }
		              writer.write(' ');
		              writer.write(Collector.doubleToGoString(sample.value));
		              if (sample.timestampMs != null){
			                writer.write(' ');
			                writer.write(sample.timestampMs.toString());
		              }
		              writer.write(enter);
	            }
	          }
		}catch (Exception e) {
			logger.error(e.getMessage());
		}
	}
	
	private static void writeEscapedHelp(Writer writer, String s) throws IOException {
        for (int i = 0; i < s.length(); i++) {
          char c = s.charAt(i);
          switch (c) {
            case '\\':
              writer.append("\\\\");
              break;
            case '\n':
              writer.append("\\n");
              break;
            default:
              writer.append(c);
          }
        }
    }
    
    private static String typeString(Collector.Type t) {
        switch (t) {
          case GAUGE:
            return "gauge";
          case COUNTER:
            return "counter";
          case SUMMARY:
            return "summary";
          case HISTOGRAM:
            return "histogram";
          default:
            return "untyped";
        }
    }
    
    private static void writeEscapedLabelValue(Writer writer, String s) throws IOException {
        for (int i = 0; i < s.length(); i++) {
          char c = s.charAt(i);
          switch (c) {
            case '\\':
              writer.append("\\\\");
              break;
            case '\"':
              writer.append("\\\"");
              break;
            case '\n':
              writer.append("\\n");
              break;
            default:
              writer.append(c);
          }
        }
    }

}