Simplify the Reader/Writer implementations, reducing the knowledge of spec details (#309)

* Messing up stuff

Signed-off-by: Francesco Guardiani <[email protected]>

* Collapse CloudEventAttributesWriter and CloudEventAttributesWriter into CloudEventContextWriter

Signed-off-by: Francesco Guardiani <[email protected]>

* Rebase fix

Signed-off-by: Francesco Guardiani <[email protected]>

Author: slinkydeveloper

amqp/src/main/java/io/cloudevents/amqp/impl/ProtonAmqpMessageWriter.java

@@ -17,22 +17,20 @@
 
 package io.cloudevents.amqp.impl;
 
-import java.util.HashMap;
-
-import org.apache.qpid.proton.amqp.Binary;
-import org.apache.qpid.proton.amqp.messaging.ApplicationProperties;
-import org.apache.qpid.proton.amqp.messaging.Data;
-import org.apache.qpid.proton.message.Message;
-
 import io.cloudevents.CloudEventData;
 import io.cloudevents.SpecVersion;
 import io.cloudevents.core.format.EventFormat;
 import io.cloudevents.core.message.MessageWriter;
 import io.cloudevents.core.v1.CloudEventV1;
-import io.cloudevents.rw.CloudEventAttributesWriter;
-import io.cloudevents.rw.CloudEventExtensionsWriter;
+import io.cloudevents.rw.CloudEventContextWriter;
 import io.cloudevents.rw.CloudEventRWException;
 import io.cloudevents.rw.CloudEventWriter;
+import org.apache.qpid.proton.amqp.Binary;
+import org.apache.qpid.proton.amqp.messaging.ApplicationProperties;
+import org.apache.qpid.proton.amqp.messaging.Data;
+import org.apache.qpid.proton.message.Message;
+
+import java.util.HashMap;
 
 /**
  * A proton-based MessageWriter capable of writing both structured and binary CloudEvent messages to an AMQP 1.0 representation as
@@ -53,33 +51,28 @@ public ProtonAmqpMessageWriter() {
     }
 
     @Override
-    public CloudEventAttributesWriter withAttribute(final String name, final String value) throws CloudEventRWException {
+    public CloudEventContextWriter withContextAttribute(String name, String value) throws CloudEventRWException {
         if (name.equals(CloudEventV1.DATACONTENTTYPE)) {
             message.setContentType(value);
         } else {
+            // for now, extensions are mapped to application-properties
+            // see https://github.com/cloudevents/sdk-java/issues/30#issuecomment-723982190
             if (applicationProperties == null) {
                 throw new IllegalStateException("This Writer is not initialized");
             }
-            applicationProperties.getValue().put(AmqpConstants.ATTRIBUTES_TO_PROPERTYNAMES.get(name), value);
-        }
-        return null;
-    }
-
-    @Override
-    public CloudEventExtensionsWriter withExtension(final String name, final String value) throws CloudEventRWException {
-        // for now, extensions are mapped to application-properties 
-        // see https://github.com/cloudevents/sdk-java/issues/30#issuecomment-723982190
-        if (applicationProperties == null) {
-            throw new IllegalStateException("This Writer is not initialized");
+            String propName = AmqpConstants.ATTRIBUTES_TO_PROPERTYNAMES.get(name);
+            if (propName == null) {
+                propName = name;
+            }
+            applicationProperties.getValue().put(propName, value);
         }
-        applicationProperties.getValue().put(name, value);
-        return null;
+        return this;
     }
 
     @Override
     public ProtonAmqpMessageWriter<R> create(final SpecVersion version) {
         if (applicationProperties == null) {
-            applicationProperties = new ApplicationProperties(new HashMap<String, Object>());
+            applicationProperties = new ApplicationProperties(new HashMap<>());
         }
         applicationProperties.getValue().put(AmqpConstants.APP_PROPERTY_SPEC_VERSION, version.toString());
         return this;
@@ -105,5 +98,4 @@ public Message end() {
         message.setApplicationProperties(applicationProperties);
         return message;
     }
-
 }

api/src/main/java/io/cloudevents/rw/CloudEventAttributesWriter.java

@@ -28,19 +28,11 @@
 public interface CloudEventContextReader {
 
     /**
-     * Visit self attributes using the provided writer
+     * Read the context attributes and extensions using the provided writer
      *
-     * @param writer Attributes writer
-     * @throws CloudEventRWException if something went wrong during the visit.
+     * @param writer context writer
+     * @throws CloudEventRWException if something went wrong during the read.
      */
-    void readAttributes(CloudEventAttributesWriter writer) throws CloudEventRWException;
-
-    /**
-     * Visit self extensions using the provided writer
-     *
-     * @param visitor Extensions writer
-     * @throws CloudEventRWException if something went wrong during the visit.
-     */
-    void readExtensions(CloudEventExtensionsWriter visitor) throws CloudEventRWException;
+    void readContext(CloudEventContextWriter writer) throws CloudEventRWException;
 
 }

api/src/main/java/io/cloudevents/rw/CloudEventContextReader.java

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2018-Present The CloudEvents Authors
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package io.cloudevents.rw;
+
+import io.cloudevents.types.Time;
+
+import javax.annotation.ParametersAreNonnullByDefault;
+import java.net.URI;
+import java.time.OffsetDateTime;
+
+/**
+ * Interface to write the context attributes/extensions from a {@link io.cloudevents.rw.CloudEventContextReader} to a new representation.
+ */
+@ParametersAreNonnullByDefault
+public interface CloudEventContextWriter {
+
+    /**
+     * Set attribute with type {@link String}.
+     * This setter should not be invoked for specversion, because the writer should
+     * already know the specversion or because it doesn't need it to correctly write the value.
+     *
+     * @param name  name of the attribute
+     * @param value value of the attribute
+     * @return self
+     * @throws CloudEventRWException    if anything goes wrong while writing this attribute.
+     * @throws IllegalArgumentException if you're trying to set the specversion attribute.
+     */
+    CloudEventContextWriter withContextAttribute(String name, String value) throws CloudEventRWException;
+
+    /**
+     * Set attribute with type {@link URI}.
+     * This setter should not be invoked for specversion, because the writer should
+     * already know the specversion or because it doesn't need it to correctly write the value.
+     *
+     * @param name  name of the attribute
+     * @param value value of the attribute
+     * @return self
+     * @throws CloudEventRWException if anything goes wrong while writing this attribute.
+     * @throws IllegalArgumentException if you're trying to set the specversion attribute.
+     */
+    default CloudEventContextWriter withContextAttribute(String name, URI value) throws CloudEventRWException {
+        return withContextAttribute(name, value.toString());
+    }
+
+    /**
+     * Set attribute with type {@link OffsetDateTime} attribute.
+     * This setter should not be invoked for specversion, because the writer should
+     * already know the specversion or because it doesn't need it to correctly write the value.
+     *
+     * @param name  name of the attribute
+     * @param value value of the attribute
+     * @return self
+     * @throws CloudEventRWException if anything goes wrong while writing this attribute.
+     * @throws IllegalArgumentException if you're trying to set the specversion attribute.
+     */
+    default CloudEventContextWriter withContextAttribute(String name, OffsetDateTime value) throws CloudEventRWException {
+        return withContextAttribute(name, Time.writeTime(name, value));
+    }
+
+    /**
+     * Set attribute with type {@link URI}.
+     * This setter should not be invoked for specversion, because the writer should
+     * already know the specversion or because it doesn't need it to correctly write the value.
+     *
+     * @param name  name of the attribute
+     * @param value value of the attribute
+     * @return self
+     * @throws CloudEventRWException if anything goes wrong while writing this extension.
+     * @throws IllegalArgumentException if you're trying to set the specversion attribute.
+     */
+    default CloudEventContextWriter withContextAttribute(String name, Number value) throws CloudEventRWException {
+        return withContextAttribute(name, value.toString());
+    }
+
+    /**
+     * Set attribute with type {@link Boolean} attribute.
+     * This setter should not be invoked for specversion, because the writer should
+     * already know the specversion or because it doesn't need it to correctly write the value.
+     *
+     * @param name  name of the attribute
+     * @param value value of the attribute
+     * @return self
+     * @throws CloudEventRWException if anything goes wrong while writing this extension.
+     * @throws IllegalArgumentException if you're trying to set the specversion attribute.
+     */
+    default CloudEventContextWriter withContextAttribute(String name, Boolean value) throws CloudEventRWException {
+        return withContextAttribute(name, value.toString());
+    }
+
+}

api/src/main/java/io/cloudevents/rw/CloudEventContextWriter.java

@@ -25,7 +25,7 @@
  *
  * @param <R> return value at the end of the write process
  */
-public interface CloudEventWriter<R> extends CloudEventAttributesWriter, CloudEventExtensionsWriter {
+public interface CloudEventWriter<R> extends CloudEventContextWriter {
 
     /**
      * End the visit with a data field