Add validator to warn on ignored idempotency token trait (#2358)

* Add validator to warn on ignored idempotency token trait

* Address PR comments

* Remove unsued code

---------

smithy-model/src/main/java/software/amazon/smithy/model/validation/validators/IdempotencyTokenIgnoredValidator.java

@@ -0,0 +1,110 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package software.amazon.smithy.model.validation.validators;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.TreeSet;
+import java.util.stream.Collectors;
+import software.amazon.smithy.model.Model;
+import software.amazon.smithy.model.knowledge.NeighborProviderIndex;
+import software.amazon.smithy.model.neighbor.NeighborProvider;
+import software.amazon.smithy.model.neighbor.Relationship;
+import software.amazon.smithy.model.neighbor.RelationshipType;
+import software.amazon.smithy.model.shapes.MemberShape;
+import software.amazon.smithy.model.shapes.Shape;
+import software.amazon.smithy.model.shapes.ShapeId;
+import software.amazon.smithy.model.shapes.StructureShape;
+import software.amazon.smithy.model.traits.IdempotencyTokenTrait;
+import software.amazon.smithy.model.traits.MixinTrait;
+import software.amazon.smithy.model.traits.Trait;
+import software.amazon.smithy.model.validation.AbstractValidator;
+import software.amazon.smithy.model.validation.ValidationEvent;
+
+/**
+ * Emits warnings when a structure member has an idempotency token trait that will be ignored.
+ */
+public final class IdempotencyTokenIgnoredValidator extends AbstractValidator {
+
+    @Override
+    public List<ValidationEvent> validate(Model model) {
+        if (!model.getAppliedTraits().contains(IdempotencyTokenTrait.ID)) {
+            return Collections.emptyList();
+        }
+        List<ValidationEvent> events = new ArrayList<>();
+        NeighborProvider reverse = NeighborProviderIndex.of(model).getReverseProvider();
+        for (MemberShape memberShape : model.getMemberShapesWithTrait(IdempotencyTokenTrait.class)) {
+            Shape container = model.expectShape(memberShape.getContainer());
+            // Skip non-structures (invalid) and mixins (handled at mixed site).
+            if (!container.isStructureShape() || container.hasTrait(MixinTrait.class)) {
+                continue;
+            }
+            Trait trait = memberShape.expectTrait(IdempotencyTokenTrait.class);
+            checkRelationships(container.asStructureShape().get(), memberShape, trait, reverse, events);
+        }
+        return events;
+    }
+
+    private void checkRelationships(
+        StructureShape containerShape,
+        MemberShape memberShape,
+        Trait trait,
+        NeighborProvider reverse,
+        List<ValidationEvent> events
+    ) {
+
+        // Store relationships so we can emit one event per ignored binding.
+        Map<RelationshipType, List<ShapeId>> ignoredRelationships = new TreeMap<>();
+        List<Relationship> relationships = reverse.getNeighbors(containerShape);
+        for (Relationship relationship : relationships) {
+            // Skip members of the container.
+            if (relationship.getRelationshipType() == RelationshipType.MEMBER_CONTAINER) {
+                continue;
+            }
+            if (relationship.getRelationshipType() != RelationshipType.INPUT) {
+                ignoredRelationships.computeIfAbsent(relationship.getRelationshipType(), x -> new ArrayList<>())
+                                    .add(relationship.getShape().getId());
+            }
+        }
+
+        // If we detected invalid relationships, build the right event message.
+        if (!ignoredRelationships.isEmpty()) {
+            events.add(emit(memberShape, trait, ignoredRelationships));
+        }
+    }
+
+    private ValidationEvent emit(
+        MemberShape memberShape,
+        Trait trait,
+        Map<RelationshipType, List<ShapeId>> ignoredRelationships
+    ) {
+        String message =
+            "The `idempotencyToken` trait only has an effect when applied to a top-level operation input member, "
+            + "but it was applied and ignored in the following contexts: "
+            + formatIgnoredRelationships(ignoredRelationships);
+        return warning(memberShape, trait, message);
+    }
+
+    private String formatIgnoredRelationships(Map<RelationshipType, List<ShapeId>> ignoredRelationships) {
+        List<String> relationshipTypeBindings = new ArrayList<>();
+        for (Map.Entry<RelationshipType, List<ShapeId>> ignoredRelationshipType : ignoredRelationships.entrySet()) {
+            StringBuilder buf = new StringBuilder(ignoredRelationshipType.getKey().toString()
+                                                                         .toLowerCase(Locale.US)
+                                                                         .replace("_", " "));
+            Set<String> bindings = ignoredRelationshipType.getValue().stream()
+                                                          .map(ShapeId::toString)
+                                                          .collect(Collectors.toCollection(TreeSet::new));
+            buf.append(": [").append(String.join(", ", bindings)).append("]");
+            relationshipTypeBindings.add(buf.toString());
+        }
+        return "{" + String.join(", ", relationshipTypeBindings) + "}";
+    }
+}

smithy-model/src/main/resources/META-INF/services/software.amazon.smithy.model.validation.Validator

@@ -22,6 +22,7 @@ software.amazon.smithy.model.validation.validators.HttpResponseCodeSemanticsVali
 software.amazon.smithy.model.validation.validators.HttpUriGreedyLabelValidator
 software.amazon.smithy.model.validation.validators.HttpUriConflictValidator
 software.amazon.smithy.model.validation.validators.HttpUriFormatValidator
+software.amazon.smithy.model.validation.validators.IdempotencyTokenIgnoredValidator
 software.amazon.smithy.model.validation.validators.JsonNameValidator
 software.amazon.smithy.model.validation.validators.LengthTraitValidator
 software.amazon.smithy.model.validation.validators.MediaTypeValidator

smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/validators/idempotency-token-trait-ignored.errors

@@ -0,0 +1,3 @@
+[WARNING] io.smithy.example#StructureOne$stringMember: The `idempotencyToken` trait only has an effect when applied to a top-level operation input member, but it was applied and ignored in the following contexts: {member target: [io.smithy.example#StructureTwo$structureOne]} | IdempotencyTokenIgnored
+[WARNING] io.smithy.example#StructureThree$stringMember: The `idempotencyToken` trait only has an effect when applied to a top-level operation input member, but it was applied and ignored in the following contexts: {output: [io.smithy.example#OperationFour]} | IdempotencyTokenIgnored
+

smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/validators/idempotency-token-trait-ignored.smithy

@@ -0,0 +1,62 @@
+$version: "2"
+
+namespace io.smithy.example
+
+service SmithyExample {
+    operations: [
+        OperationOne
+        OperationTwo
+        OperationThree
+        OperationFour
+    ]
+}
+
+operation OperationOne {
+    input := {
+        @idempotencyToken
+        stringMember: String
+        integerMember: Integer
+    }
+    output: Unit
+}
+
+operation OperationTwo {
+    input: StructureOne
+    output: Unit
+}
+
+operation OperationThree {
+    input: StructureTwo
+    output: Unit
+}
+
+operation OperationFour {
+    input: StructureThree
+    output: StructureThree
+}
+
+
+structure StructureOne {
+    @idempotencyToken
+    stringMember: String
+    integerMember: Integer
+}
+
+
+structure StructureTwo {
+    stringMember: String
+    structureOne: StructureOne
+}
+
+
+@mixin
+structure StructureMixin {
+    @idempotencyToken
+    stringMember: String
+}
+
+
+structure StructureThree with [StructureMixin] {
+    integerMember: Integer
+}
+