[CESQL] Cleanup CloudEventUtils

sql/src/main/java/io/cloudevents/sql/impl/expressions/AccessAttributeExpression.java

@@ -1,28 +1,60 @@
 package io.cloudevents.sql.impl.expressions;
 
 import io.cloudevents.CloudEvent;
+import io.cloudevents.SpecVersion;
+import io.cloudevents.sql.EvaluationException;
 import io.cloudevents.sql.EvaluationRuntime;
-import io.cloudevents.sql.impl.CloudEventUtils;
 import io.cloudevents.sql.impl.ExceptionThrower;
 import org.antlr.v4.runtime.misc.Interval;
 
+import java.util.Base64;
+import java.util.Objects;
+import java.util.function.Function;
+
 public class AccessAttributeExpression extends BaseExpression {
 
     private final String key;
+    private final Function<CloudEvent, Object> getter;
 
     public AccessAttributeExpression(Interval expressionInterval, String expressionText, String key) {
         super(expressionInterval, expressionText);
-        this.key = key.toLowerCase();
+        this.key = key;
+        this.getter = generateGetter(key);
     }
 
     @Override
     public Object evaluate(EvaluationRuntime runtime, CloudEvent event, ExceptionThrower thrower) {
-        return CloudEventUtils.accessContextAttribute(thrower, expressionInterval(), expressionText(), event, key);
+        Object value = this.getter.apply(event);
+        if (value == null) {
+            thrower.throwException(
+                EvaluationException.missingAttribute(this.expressionInterval(), this.expressionText(), key)
+            );
+            return "";
+        }
+
+        // Because the CESQL type system is smaller than the CE type system,
+        // we need to coherce some values to string
+        return coherceTypes(value);
     }
 
     @Override
     public <T> T visit(ExpressionInternalVisitor<T> visitor) {
         return visitor.visitAccessAttributeExpression(this);
     }
 
+    private static Function<CloudEvent, Object> generateGetter(String key) {
+        return SpecVersion.V1.getAllAttributes().contains(key) ? ce -> ce.getAttribute(key) : ce -> ce.getExtension(key);
+    }
+
+    private static Object coherceTypes(Object value) {
+        if (value instanceof Boolean || value instanceof String || value instanceof Integer) {
+            // No casting required
+            return value;
+        }
+        if (value instanceof byte[]) {
+            return Base64.getEncoder().encodeToString((byte[]) value);
+        }
+        return Objects.toString(value);
+    }
+
 }

sql/src/main/java/io/cloudevents/sql/impl/expressions/ExistsExpression.java

@@ -2,7 +2,6 @@
 
 import io.cloudevents.CloudEvent;
 import io.cloudevents.sql.EvaluationRuntime;
-import io.cloudevents.sql.impl.CloudEventUtils;
 import io.cloudevents.sql.impl.ExceptionThrower;
 import org.antlr.v4.runtime.misc.Interval;
 
@@ -17,7 +16,7 @@ public ExistsExpression(Interval expressionInterval, String expressionText, Stri
 
     @Override
     public Object evaluate(EvaluationRuntime runtime, CloudEvent event, ExceptionThrower thrower) {
-        return CloudEventUtils.hasContextAttribute(event, key);
+        return hasContextAttribute(event, key);
     }
 
     @Override
@@ -28,4 +27,9 @@ public <T> T visit(ExpressionInternalVisitor<T> visitor) {
     public String getKey() {
         return key;
     }
+
+    private static boolean hasContextAttribute(CloudEvent event, String key) {
+        return event.getAttributeNames().contains(key) || event.getExtensionNames().contains(key);
+    }
+
 }