feat: Instant support

feat: Instant support

Author: eranl

google-cloud-firestore/src/main/java/com/google/cloud/firestore/CustomClassMapper.java

@@ -36,6 +36,7 @@
 import java.lang.reflect.TypeVariable;
 import java.lang.reflect.WildcardType;
 import java.math.BigDecimal;
+import java.time.Instant;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -175,6 +176,9 @@ private static <T> Object serialize(T o, ErrorPath path) {
         || o instanceof FieldValue
         || o instanceof Value) {
       return o;
+    } else if (o instanceof Instant) {
+      Instant instant = (Instant) o;
+      return Timestamp.ofTimeSecondsAndNanos(instant.getEpochSecond(), instant.getNano());
     } else {
       Class<T> clazz = (Class<T>) o.getClass();
       BeanMapper<T> mapper = loadOrCreateBeanMapperForClass(clazz);
@@ -233,6 +237,8 @@ private static <T> T deserializeToClass(Object o, Class<T> clazz, DeserializeCon
       return (T) convertDate(o, context);
     } else if (Timestamp.class.isAssignableFrom(clazz)) {
       return (T) convertTimestamp(o, context);
+    } else if (Instant.class.isAssignableFrom(clazz)) {
+      return (T) convertInstant(o, context);
     } else if (Blob.class.isAssignableFrom(clazz)) {
       return (T) convertBlob(o, context);
     } else if (GeoPoint.class.isAssignableFrom(clazz)) {
@@ -557,6 +563,19 @@ private static Timestamp convertTimestamp(Object o, DeserializeContext context)
     }
   }
 
+  private static Instant convertInstant(Object o, DeserializeContext context) {
+    if (o instanceof Timestamp) {
+      Timestamp timestamp = (Timestamp) o;
+      return Instant.ofEpochSecond(timestamp.getSeconds(), timestamp.getNanos());
+    } else if (o instanceof Date) {
+      return Instant.ofEpochMilli(((Date) o).getTime());
+    } else {
+      throw deserializeError(
+          context.errorPath,
+          "Failed to convert value of type " + o.getClass().getName() + " to Instant");
+    }
+  }
+
   private static Blob convertBlob(Object o, DeserializeContext context) {
     if (o instanceof Blob) {
       return (Blob) o;
@@ -976,13 +995,13 @@ Map<String, Object> serialize(T object, ErrorPath path) {
     private void applyFieldAnnotations(Field field) {
       if (field.isAnnotationPresent(ServerTimestamp.class)) {
         Class<?> fieldType = field.getType();
-        if (fieldType != Date.class && fieldType != Timestamp.class) {
+        if (fieldType != Date.class && fieldType != Timestamp.class && fieldType != Instant.class) {
           throw new IllegalArgumentException(
               "Field "
                   + field.getName()
                   + " is annotated with @ServerTimestamp but is "
                   + fieldType
-                  + " instead of Date or Timestamp.");
+                  + " instead of Date, Timestamp, or Instant.");
         }
         serverTimestamps.add(propertyName(field));
       }
@@ -997,13 +1016,15 @@ private void applyFieldAnnotations(Field field) {
     private void applyGetterAnnotations(Method method) {
       if (method.isAnnotationPresent(ServerTimestamp.class)) {
         Class<?> returnType = method.getReturnType();
-        if (returnType != Date.class && returnType != Timestamp.class) {
+        if (returnType != Date.class
+            && returnType != Timestamp.class
+            && returnType != Instant.class) {
           throw new IllegalArgumentException(
               "Method "
                   + method.getName()
                   + " is annotated with @ServerTimestamp but returns "
                   + returnType
-                  + " instead of Date or Timestamp.");
+                  + " instead of Date, Timestamp, or Instant.");
         }
         serverTimestamps.add(propertyName(method));
       }

google-cloud-firestore/src/test/java/com/google/cloud/firestore/DocumentReferenceTest.java

@@ -872,6 +872,7 @@ public void extractFieldMaskFromMerge() throws Exception {
             "second.foo",
             "second.geoPointValue",
             "second.infValue",
+            "second.instantValue",
             "second.longValue",
             "second.nanValue",
             "second.negInfValue",

google-cloud-firestore/src/test/java/com/google/cloud/firestore/LocalFirestoreHelper.java

@@ -75,6 +75,7 @@
 import java.nio.charset.StandardCharsets;
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
+import java.time.Instant;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -148,6 +149,7 @@ public final class LocalFirestoreHelper {
 
   public static final Date DATE;
   public static final Timestamp TIMESTAMP;
+  public static final Instant INSTANT;
   public static final GeoPoint GEO_POINT;
   public static final Blob BLOB;
   public static final FooList<SingleField> FOO_LIST = new FooList<>();
@@ -942,6 +944,7 @@ public static class AllSupportedTypes {
     public SingleField objectValue = new SingleField();
     public Date dateValue = DATE;
     public Timestamp timestampValue = TIMESTAMP;
+    public Instant instantValue = INSTANT;
     public List<String> arrayValue = ImmutableList.of("foo");
     public String nullValue = null;
     public Blob bytesValue = BLOB;
@@ -968,6 +971,7 @@ public boolean equals(Object o) {
           && Objects.equals(objectValue, that.objectValue)
           && Objects.equals(dateValue, that.dateValue)
           && Objects.equals(timestampValue, that.timestampValue)
+          && Objects.equals(instantValue, that.instantValue)
           && Objects.equals(arrayValue, that.arrayValue)
           && Objects.equals(nullValue, that.nullValue)
           && Objects.equals(bytesValue, that.bytesValue)
@@ -989,6 +993,10 @@ public boolean equals(Object o) {
         Timestamp.ofTimeSecondsAndNanos(
             TimeUnit.MILLISECONDS.toSeconds(DATE.getTime()),
             123000); // Firestore truncates to microsecond precision.
+    INSTANT =
+        Instant.ofEpochSecond(
+            TimeUnit.MILLISECONDS.toSeconds(DATE.getTime()),
+            123000); // Firestore truncates to microsecond precision.
     GEO_POINT = new GeoPoint(50.1430847, -122.9477780);
     BLOB = Blob.fromBytes(new byte[] {1, 2, 3});
     SINGLE_FLOAT_MAP = map("float", 0.1F);
@@ -1083,6 +1091,7 @@ public boolean equals(Object o) {
     ALL_SUPPORTED_TYPES_MAP.put("objectValue", map("foo", (Object) "bar"));
     ALL_SUPPORTED_TYPES_MAP.put("dateValue", Timestamp.of(DATE));
     ALL_SUPPORTED_TYPES_MAP.put("timestampValue", TIMESTAMP);
+    ALL_SUPPORTED_TYPES_MAP.put("instantValue", TIMESTAMP);
     ALL_SUPPORTED_TYPES_MAP.put("arrayValue", ImmutableList.of("foo"));
     ALL_SUPPORTED_TYPES_MAP.put("nullValue", null);
     ALL_SUPPORTED_TYPES_MAP.put("bytesValue", BLOB);
@@ -1119,6 +1128,14 @@ public boolean equals(Object o) {
                             .setSeconds(479978400)
                             .setNanos(123000)) // Timestamps supports microsecond precision.
                     .build())
+            .put(
+                "instantValue",
+                Value.newBuilder()
+                    .setTimestampValue(
+                        com.google.protobuf.Timestamp.newBuilder()
+                            .setSeconds(479978400)
+                            .setNanos(123000)) // Instants supports microsecond precision.
+                    .build())
             .put(
                 "arrayValue",
                 Value.newBuilder()