Add helper to detect HTTP-based timestampFormats

smithy-model/src/main/java/software/amazon/smithy/model/knowledge/HttpBindingIndex.java

@@ -41,6 +41,7 @@
 import software.amazon.smithy.model.traits.HttpQueryTrait;
 import software.amazon.smithy.model.traits.HttpTrait;
 import software.amazon.smithy.model.traits.MediaTypeTrait;
+import software.amazon.smithy.model.traits.TimestampFormatTrait;
 import software.amazon.smithy.model.traits.Trait;
 import software.amazon.smithy.utils.ListUtils;
 
@@ -220,6 +221,39 @@ public List<HttpBinding> getResponseBindings(ToShapeId shapeOrId, HttpBinding.Lo
                 .collect(Collectors.toList());
     }
 
+    /**
+     * Determines the appropriate timestamp format for a member shape bound to
+     * a specific location.
+     *
+     * @param member Member to derive the timestamp format.
+     * @param location Location the member is bound to.
+     * @param defaultFormat The format to use for the body or a default.
+     * @return Returns the determined timestamp format.
+     */
+    public TimestampFormatTrait.Format determineTimestampFormat(
+            ToShapeId member,
+            HttpBinding.Location location,
+            TimestampFormatTrait.Format defaultFormat
+    ) {
+        return index.getShape(member.toShapeId())
+                .flatMap(Shape::asMemberShape)
+                // Use the timestampFormat trait on the member or target if present.
+                .flatMap(shape -> shape.getMemberTrait(index, TimestampFormatTrait.class))
+                .map(TimestampFormatTrait::getFormat)
+                .orElseGet(() -> {
+                    // Determine the format based on the location.
+                    switch (location) {
+                        case HEADER:
+                            return TimestampFormatTrait.Format.HTTP_DATE;
+                        case QUERY:
+                        case LABEL:
+                            return TimestampFormatTrait.Format.DATE_TIME;
+                        default:
+                            return defaultFormat;
+                    }
+                });
+    }
+
     /**
      * Returns the expected request Content-Type of the given operation.
      *

smithy-model/src/main/java/software/amazon/smithy/model/traits/TimestampFormatTrait.java

@@ -35,9 +35,57 @@ public TimestampFormatTrait(String value) {
         this(value, SourceLocation.NONE);
     }
 
+    /**
+     * Gets the {@code timestampFormat} value as a {@code Format} enum.
+     *
+     * @return Returns the {@code Format} enum.
+     */
+    public Format getFormat() {
+        return Format.fromString(getValue());
+    }
+
     public static final class Provider extends StringTrait.Provider<TimestampFormatTrait> {
         public Provider() {
             super(ID, TimestampFormatTrait::new);
         }
     }
+
+    /**
+     * The known {@code timestampFormat} values.
+     */
+    public enum Format {
+        EPOCH_SECONDS(TimestampFormatTrait.EPOCH_SECONDS),
+        DATE_TIME(TimestampFormatTrait.DATE_TIME),
+        HTTP_DATE(TimestampFormatTrait.HTTP_DATE),
+        UNKNOWN("unknown");
+
+        private String value;
+
+        Format(String value) {
+            this.value = value;
+        }
+
+        /**
+         * Create a {@code Format} from a string that would appear in a model.
+         *
+         * <p>Any unknown value is returned as {@code Unknown}.
+         *
+         * @param value Value from a trait or model.
+         * @return Returns the Format enum value.
+         */
+        public static Format fromString(String value) {
+            for (Format format : values()) {
+                if (format.value.equals(value)) {
+                    return format;
+                }
+            }
+
+            return UNKNOWN;
+        }
+
+        @Override
+        public String toString() {
+            return value;
+        }
+    }
 }

smithy-model/src/test/java/software/amazon/smithy/model/knowledge/HttpBindingIndexTest.java

@@ -28,6 +28,7 @@
 import software.amazon.smithy.model.Model;
 import software.amazon.smithy.model.SourceLocation;
 import software.amazon.smithy.model.pattern.UriPattern;
+import software.amazon.smithy.model.shapes.ListShape;
 import software.amazon.smithy.model.shapes.MemberShape;
 import software.amazon.smithy.model.shapes.OperationShape;
 import software.amazon.smithy.model.shapes.ServiceShape;
@@ -42,6 +43,7 @@
 import software.amazon.smithy.model.traits.HttpPayloadTrait;
 import software.amazon.smithy.model.traits.HttpPrefixHeadersTrait;
 import software.amazon.smithy.model.traits.HttpTrait;
+import software.amazon.smithy.model.traits.TimestampFormatTrait;
 
 public class HttpBindingIndexTest {
 
@@ -209,7 +211,7 @@ public void findsUnboundMembers() {
     @Test
     public void checksForHttpRequestAndResponseBindings() {
         Shape shape = MemberShape.builder()
-                .target("smithy.api#String")
+                .target("smithy.api#Timestamp")
                 .id("smithy.example#Baz$bar")
                 .addTrait(new HttpLabelTrait(SourceLocation.NONE))
                 .build();
@@ -221,7 +223,7 @@ public void checksForHttpRequestAndResponseBindings() {
     @Test
     public void checksForHttpResponseBindings() {
         Shape shape = MemberShape.builder()
-                .target("smithy.api#String")
+                .target("smithy.api#Timestamp")
                 .id("smithy.example#Baz$bar")
                 .addTrait(new HttpHeaderTrait("hello", SourceLocation.NONE))
                 .build();
@@ -270,4 +272,80 @@ private static MemberShape expectMember(Model model, String id) {
         ShapeId shapeId = ShapeId.from(id);
         return model.getShapeIndex().getShape(shapeId).get().asMemberShape().get();
     }
+
+    @Test
+    public void usesTimestampFormatMemberTraitToDetermineFormat() {
+        MemberShape member = MemberShape.builder()
+                .id("foo.bar#Baz$member")
+                .target("smithy.api#Timestamp")
+                .addTrait(new TimestampFormatTrait(TimestampFormatTrait.EPOCH_SECONDS))
+                .build();
+        Model model = Model.assembler()
+                .addShape(member)
+                .addShape(ListShape.builder().member(member).id("foo.bar#Baz").build())
+                .assemble()
+                .unwrap();
+        HttpBindingIndex index = model.getKnowledge(HttpBindingIndex.class);
+        TimestampFormatTrait.Format format = index.determineTimestampFormat(
+                member, HttpBinding.Location.HEADER, TimestampFormatTrait.Format.DATE_TIME);
+
+        assertThat(format, equalTo(TimestampFormatTrait.Format.EPOCH_SECONDS));
+    }
+
+    @Test
+    public void headerLocationUsesHttpDateTimestampFormat() {
+        MemberShape member = MemberShape.builder()
+                .id("foo.bar#Baz$member")
+                .target("smithy.api#Timestamp")
+                .build();
+        Model model = Model.assembler()
+                .addShape(member)
+                .addShape(ListShape.builder().member(member).id("foo.bar#Baz").build())
+                .assemble()
+                .unwrap();
+        HttpBindingIndex index = model.getKnowledge(HttpBindingIndex.class);
+
+        assertThat(index.determineTimestampFormat(
+                member, HttpBinding.Location.HEADER, TimestampFormatTrait.Format.EPOCH_SECONDS),
+                   equalTo(TimestampFormatTrait.Format.HTTP_DATE));
+    }
+
+    @Test
+    public void queryAndLabelLocationUsesDateTimeTimestampFormat() {
+        MemberShape member = MemberShape.builder()
+                .id("foo.bar#Baz$member")
+                .target("smithy.api#Timestamp")
+                .build();
+        Model model = Model.assembler()
+                .addShape(member)
+                .addShape(ListShape.builder().member(member).id("foo.bar#Baz").build())
+                .assemble()
+                .unwrap();
+        HttpBindingIndex index = model.getKnowledge(HttpBindingIndex.class);
+
+        assertThat(index.determineTimestampFormat(
+                member, HttpBinding.Location.QUERY, TimestampFormatTrait.Format.EPOCH_SECONDS),
+                   equalTo(TimestampFormatTrait.Format.DATE_TIME));
+        assertThat(index.determineTimestampFormat(
+                member, HttpBinding.Location.LABEL, TimestampFormatTrait.Format.EPOCH_SECONDS),
+                   equalTo(TimestampFormatTrait.Format.DATE_TIME));
+    }
+
+    @Test
+    public void otherLocationsUseDefaultTimestampFormat() {
+        MemberShape member = MemberShape.builder()
+                .id("foo.bar#Baz$member")
+                .target("smithy.api#Timestamp")
+                .build();
+        Model model = Model.assembler()
+                .addShape(member)
+                .addShape(ListShape.builder().member(member).id("foo.bar#Baz").build())
+                .assemble()
+                .unwrap();
+        HttpBindingIndex index = model.getKnowledge(HttpBindingIndex.class);
+
+        assertThat(index.determineTimestampFormat(
+                member, HttpBinding.Location.DOCUMENT, TimestampFormatTrait.Format.EPOCH_SECONDS),
+                   equalTo(TimestampFormatTrait.Format.EPOCH_SECONDS));
+    }
 }

smithy-model/src/test/java/software/amazon/smithy/model/traits/TimestampFormatTraitTest.java

@@ -0,0 +1,33 @@
+package software.amazon.smithy.model.traits;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.equalTo;
+
+import org.junit.jupiter.api.Test;
+
+public class TimestampFormatTraitTest {
+    @Test
+    public void createsFromString() {
+        assertThat(TimestampFormatTrait.Format.fromString("date-time"),
+                   equalTo(TimestampFormatTrait.Format.DATE_TIME));
+        assertThat(TimestampFormatTrait.Format.fromString("http-date"),
+                   equalTo(TimestampFormatTrait.Format.HTTP_DATE));
+        assertThat(TimestampFormatTrait.Format.fromString("epoch-seconds"),
+                   equalTo(TimestampFormatTrait.Format.EPOCH_SECONDS));
+        assertThat(TimestampFormatTrait.Format.fromString("foo-baz"),
+                   equalTo(TimestampFormatTrait.Format.UNKNOWN));
+    }
+
+    @Test
+    public void convertsFormatToString() {
+        assertThat(TimestampFormatTrait.Format.fromString("date-time").toString(),
+                   equalTo("date-time"));
+    }
+
+    @Test
+    public void createsFormatFromTrait() {
+        TimestampFormatTrait trait = new TimestampFormatTrait("date-time");
+
+        assertThat(trait.getFormat(), equalTo(TimestampFormatTrait.Format.DATE_TIME));
+    }
+}