1 files changed, 157 insertions, 0 deletions
diff --git a/core/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/LogEntry.java b/core/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/LogEntry.java
new file mode 100644
index 0000000..d108c81
--- /dev/null
+++ b/core/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/LogEntry.java
@@ -0,0 +1,157 @@
+package eu.mulk.quarkus.googlecloud.jsonlogging;
+
+import io.smallrye.common.constraint.Nullable;
+import java.time.Instant;
+import java.util.List;
+import java.util.Map;
+import javax.json.Json;
+import javax.json.JsonObject;
+import javax.json.JsonObjectBuilder;
+
+/**
+ * A JSON log entry compatible with Google Cloud Logging.
+ *
+ * <p>Roughly (but not quite) corresponds to Google Cloud Logging's <a
+ * href="https://cloud.google.com/logging/docs/reference/v2/rest/v2/LogEntry">LogEntry</a>
+ * structure.
+ *
+ * <p>A few of the fields are <a href="https://cloud.google.com/logging/docs/structured-logging">
+ * treated specially</a> by the fluentd instance running in Google Kubernetes Engine. All other
+ * fields end up in the jsonPayload field on the Google Cloud Logging side.
+ */
+final class LogEntry {
+
+  private final String message;
+  private final String severity;
+  private final Timestamp timestamp;
+  @Nullable private final String trace;
+  @Nullable private final String spanId;
+  private final SourceLocation sourceLocation;
+  private final Map<String, String> labels;
+  private final List<StructuredParameter> parameters;
+  private final Map<String, String> mappedDiagnosticContext;
+  @Nullable private final String nestedDiagnosticContext;
+  @Nullable private final String type;
+
+  LogEntry(
+      String message,
+      String severity,
+      Timestamp timestamp,
+      @Nullable String trace,
+      @Nullable String spanId,
+      SourceLocation sourceLocation,
+      Map<String, String> labels,
+      List<StructuredParameter> parameters,
+      Map<String, String> mappedDiagnosticContext,
+      @Nullable String nestedDiagnosticContext,
+      @Nullable String type) {
+    this.message = message;
+    this.severity = severity;
+    this.timestamp = timestamp;
+    this.trace = trace;
+    this.spanId = spanId;
+    this.sourceLocation = sourceLocation;
+    this.labels = labels;
+    this.parameters = parameters;
+    this.mappedDiagnosticContext = mappedDiagnosticContext;
+    this.nestedDiagnosticContext = nestedDiagnosticContext;
+    this.type = type;
+  }
+
+  static final class SourceLocation {
+
+    @Nullable private final String file;
+    @Nullable private final String line;
+    @Nullable private final String function;
+
+    SourceLocation(@Nullable String file, @Nullable String line, @Nullable String function) {
+      this.file = file;
+      this.line = line;
+      this.function = function;
+    }
+
+    JsonObject json() {
+      var b = Json.createObjectBuilder();
+
+      if (file != null) {
+        b.add("file", file);
+      }
+
+      if (line != null) {
+        b.add("line", line);
+      }
+
+      if (function != null) {
+        b.add("function", function);
+      }
+
+      return b.build();
+    }
+  }
+
+  static final class Timestamp {
+
+    private final long seconds;
+    private final int nanos;
+
+    Timestamp(long seconds, int nanos) {
+      this.seconds = seconds;
+      this.nanos = nanos;
+    }
+
+    Timestamp(Instant t) {
+      this(t.getEpochSecond(), t.getNano());
+    }
+
+    JsonObject json() {
+      return Json.createObjectBuilder().add("seconds", seconds).add("nanos", nanos).build();
+    }
+  }
+
+  JsonObjectBuilder json() {
+    var b = Json.createObjectBuilder();
+
+    if (trace != null) {
+      b.add("logging.googleapis.com/trace", trace);
+    }
+
+    if (spanId != null) {
+      b.add("logging.googleapis.com/spanId", spanId);
+    }
+
+    if (nestedDiagnosticContext != null && !nestedDiagnosticContext.isEmpty()) {
+      b.add("nestedDiagnosticContext", nestedDiagnosticContext);
+    }
+
+    if (!labels.isEmpty()) {
+      b.add("logging.googleapis.com/labels", jsonOfStringMap(labels));
+    }
+
+    if (type != null) {
+      b.add("@type", type);
+    }
+
+    return b.add("message", message)
+        .add("severity", severity)
+        .add("timestamp", timestamp.json())
+        .add("logging.googleapis.com/sourceLocation", sourceLocation.json())
+        .addAll(jsonOfStringMap(mappedDiagnosticContext))
+        .addAll(jsonOfParameterMap(parameters));
+  }
+
+  private static JsonObjectBuilder jsonOfStringMap(Map<String, String> stringMap) {
+    return stringMap.entrySet().stream()
+        .reduce(
+            Json.createObjectBuilder(),
+            (acc, x) -> acc.add(x.getKey(), x.getValue()),
+            JsonObjectBuilder::addAll);
+  }
+
+  private static JsonObjectBuilder jsonOfParameterMap(List<StructuredParameter> parameters) {
+    return parameters.stream()
+        .reduce(
+            Json.createObjectBuilder(),
+            (acc, p) -> acc.addAll(p.json()),
+            JsonObjectBuilder::addAll);
+  }
+}