Add base httpLabel trait support

Author: JordonPhillips

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/integrations/BuiltinsIntegration.java

@@ -16,6 +16,7 @@
 import software.amazon.smithy.docgen.core.interceptors.ErrorFaultInterceptor;
 import software.amazon.smithy.docgen.core.interceptors.ExternalDocsInterceptor;
 import software.amazon.smithy.docgen.core.interceptors.HttpInterceptor;
+import software.amazon.smithy.docgen.core.interceptors.HttpLabelInterceptor;
 import software.amazon.smithy.docgen.core.interceptors.HttpQueryInterceptor;
 import software.amazon.smithy.docgen.core.interceptors.IdempotencyInterceptor;
 import software.amazon.smithy.docgen.core.interceptors.InternalInterceptor;
@@ -90,6 +91,7 @@ public List<? extends CodeInterceptor<? extends CodeSection, DocWriter>> interce
                 new XmlNameInterceptor(),
                 new XmlFlattenedInterceptor(),
                 new HttpQueryInterceptor(),
+                new HttpLabelInterceptor(),
                 new HttpInterceptor(),
                 new PaginationInterceptor(),
                 new RequestCompressionInterceptor(),

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/interceptors/HttpInterceptor.java

@@ -30,10 +30,16 @@ protected ShapeId getTraitId() {
 
     @Override
     void write(DocWriter writer, String previousText, ProtocolSection section, HttpTrait trait) {
+        writer.putContext("hasLabels", !trait.getUri().getLabels().isEmpty());
         writer.write("""
                 $B $`
 
                 $B $`
+                ${?hasLabels}
+
+                To resolve the path segment of the URI, replace any segments surrounded with
+                brackets with the URI-escaped value of the corresponding member.
+                ${/hasLabels}
 
                 $L""", "HTTP Method:", trait.getMethod(), "URI:", trait.getUri(), previousText);
     }

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/interceptors/HttpLabelInterceptor.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package software.amazon.smithy.docgen.core.interceptors;
+
+import java.util.Optional;
+import software.amazon.smithy.docgen.core.DocGenerationContext;
+import software.amazon.smithy.docgen.core.sections.ProtocolSection;
+import software.amazon.smithy.docgen.core.writers.DocWriter;
+import software.amazon.smithy.model.shapes.OperationShape;
+import software.amazon.smithy.model.shapes.Shape;
+import software.amazon.smithy.model.shapes.ShapeId;
+import software.amazon.smithy.model.traits.HttpLabelTrait;
+import software.amazon.smithy.model.traits.HttpTrait;
+import software.amazon.smithy.utils.SmithyInternalApi;
+
+/**
+ * Adds information about label bindings from the
+ * <a href="https://smithy.io/2.0/spec/http-bindings.html#httplabel-trait">
+ * httpLabel trait</a> if the protocol supports it.
+ */
+@SmithyInternalApi
+public final class HttpLabelInterceptor extends ProtocolTraitInterceptor<HttpLabelTrait> {
+    @Override
+    protected Class<HttpLabelTrait> getTraitClass() {
+        return HttpLabelTrait.class;
+    }
+
+    @Override
+    protected ShapeId getTraitId() {
+        return HttpLabelTrait.ID;
+    }
+
+    @Override
+    void write(DocWriter writer, String previousText, ProtocolSection section, HttpLabelTrait trait) {
+        writer.putContext("greedy", getOperation(section.context(), section.shape())
+                .map(operation -> operation.expectTrait(HttpTrait.class))
+                .flatMap(httpTrait -> httpTrait.getUri().getGreedyLabel())
+                .map(segment -> segment.getContent().equals(section.shape().getId().getName()))
+                .orElse(false));
+        var segment = "{" + section.shape().getId().getName() + "}";
+        writer.write("""
+                This is bound to the path of the URI. Its value should be URI-escaped and \
+                and inserted in place of the $` segment.\
+                ${?greedy}
+                 When escaping this value, do not escape any backslashes ($`).
+                ${/greedy}
+
+                $L""", segment, "/", previousText);
+    }
+
+    private Optional<OperationShape> getOperation(DocGenerationContext context, Shape shape) {
+        var member = shape.asMemberShape().get();
+        for (var operation : context.model().getOperationShapes()) {
+            if (operation.getInputShape().equals(member.getContainer())) {
+                return Optional.of(operation);
+            }
+        }
+        return Optional.empty();
+    }
+}