/*
 * Copyright 2018, OpenCensus Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.opencensus.contrib.logcorrelation.stackdriver;

import com.google.cloud.ServiceOptions;
import com.google.cloud.logging.LogEntry;
import com.google.cloud.logging.LoggingEnhancer;
import io.opencensus.common.ExperimentalApi;
import io.opencensus.trace.SpanContext;
import io.opencensus.trace.TraceId;
import io.opencensus.trace.Tracer;
import io.opencensus.trace.Tracing;

/**
 * Stackdriver {@link LoggingEnhancer} that adds OpenCensus tracing data to log entries.
 *
 * <p>This feature is currently experimental.
 */
@ExperimentalApi
public final class OpenCensusTraceLoggingEnhancer implements LoggingEnhancer {
  private static final String SAMPLED_KEY = "sampled";

  private static final Tracer tracer = Tracing.getTracer();

  /** Constructor to be called by Stackdriver logging. */
  public OpenCensusTraceLoggingEnhancer() {}

  @Override
  public void enhanceLogEntry(LogEntry.Builder builder) {
    SpanContext span = tracer.getCurrentSpan().getContext();
    builder.setTrace(formatTraceId(span.getTraceId()));
    builder.setSpanId(span.getSpanId().toLowerBase16());

    // TODO(sebright): Find the correct way to add the sampling decision.
    builder.addLabel(SAMPLED_KEY, Boolean.toString(span.getTraceOptions().isSampled()));
  }

  private static String formatTraceId(TraceId traceId) {
    // TODO(sebright): Should we cache the project ID, for efficiency?
    String projectId = ServiceOptions.getDefaultProjectId();
    return "projects/" + projectId + "/traces/" + traceId.toLowerBase16();
  }
}

@@ -1940,19 +1940,9 @@
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@@ -1960,25 +1960,9 @@
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Update TODO about caching the project ID.