Fixes smallrye#274. Added interceptor to activate a Configuration Pro…

…file.

doc/modules/ROOT/pages/interceptors/interceptors.adoc

@@ -41,6 +41,7 @@ interceptors are registered with the same priority, then their execution order m
 SmallRye Config provides the following built-in Interceptors:
 
 * <<expression-interceptor>>
+* <<profile-interceptor>>
 
 [[expression-interceptor]]
 === ExpressionConfigSourceInterceptor
@@ -68,3 +69,31 @@ If an expression cannot be expanded and no default is supplied a `NoSuchElementE
 
 The `ExpressionConfigSourceInterceptor` is not registered by default. You need to register it via the ServiceLoader
 mechanism with your application.
+
+[[profile-interceptor]]
+=== ProfileConfigSourceInterceptor
+
+The `ProfileConfigSourceInterceptor` allows you to have multiple configurations with the same name and select them via
+a profile property.
+
+To be able to set properties with the same name, you need to prefix each property with `%` followed by the profile name
+and a dot:
+
+[source,properties]
+----
+my.prop=1234
+%dev.my.prop=5678
+----
+
+Lookup is always done using the `my.prop` property name. If you want to use the profile `dev`, you need to set the
+configuration `smallrye.config.profile=dev` into any valid ConfigSource.
+
+When looking up the property `my.prop` with the `dev` profile active the value is `5678`.
+
+Only one profile can be active in any given time.
+
+==== Config Priority over Profiles
+
+A ConfigSource with a highest priority, that defines `my.prop` will take priority over another low priority
+ConfigSource that defines `%dev.my.prop`. This allows you to override profiles properties regardless of the active
+profile.

implementation/src/main/java/io/smallrye/config/ConfigSourceInterceptorFactory.java

@@ -0,0 +1,47 @@
+package io.smallrye.config;
+
+/**
+ * This ConfigSourceInterceptorFactory allows to initialize a {@link ConfigSourceInterceptor}, with access to the
+ * current {@link ConfigSourceInterceptorContext}.
+ *
+ * Interceptors in the chain are initialized in priority order and the current
+ * {@link ConfigSourceInterceptorContext} contains the current interceptor, plus all other interceptors already
+ * initialized.
+ */
+public interface ConfigSourceInterceptorFactory {
+    /**
+     * Gets the {@link ConfigSourceInterceptor} from the ConfigSourceInterceptorFactory. Implementations of this
+     * method must provide the instance of the {@link ConfigSourceInterceptor} to add into the Config Interceptor Chain.
+     *
+     * @param context the current {@link ConfigSourceInterceptorContext} with the interceptors already initialized.
+     * @return the {@link ConfigSourceInterceptor} to add to Config Interceptor Chain and initialize.
+     */
+    ConfigSourceInterceptor getInterceptor(final ConfigSourceInterceptorContext context);
+
+    /**
+     * Gets the Class of the Interceptor.
+     *
+     * This is required, because the interceptor priority needs to be sorted before doing initialization.
+     *
+     * @return the Class of the {@link ConfigSourceInterceptor}
+     */
+    Class<? extends ConfigSourceInterceptor> getInterceptorClass();
+
+    final class Delegate implements ConfigSourceInterceptorFactory {
+        private final ConfigSourceInterceptor interceptor;
+
+        Delegate(final ConfigSourceInterceptor interceptor) {
+            this.interceptor = interceptor;
+        }
+
+        @Override
+        public ConfigSourceInterceptor getInterceptor(final ConfigSourceInterceptorContext context) {
+            return interceptor;
+        }
+
+        @Override
+        public Class<? extends ConfigSourceInterceptor> getInterceptorClass() {
+            return interceptor.getClass();
+        }
+    }
+}

implementation/src/main/java/io/smallrye/config/ProfileConfigSourceInterceptor.java

@@ -0,0 +1,40 @@
+package io.smallrye.config;
+
+import java.util.Optional;
+
+import javax.annotation.Priority;
+
+@Priority(600)
+public class ProfileConfigSourceInterceptor implements ConfigSourceInterceptor {
+    public static final String SMALLRYE_PROFILE = "smallrye.config.profile";
+
+    private final String profile;
+
+    public ProfileConfigSourceInterceptor(final String profile) {
+        this.profile = profile;
+    }
+
+    public ProfileConfigSourceInterceptor(final ConfigSourceInterceptorContext context) {
+        this(context, SMALLRYE_PROFILE);
+    }
+
+    public ProfileConfigSourceInterceptor(
+            final ConfigSourceInterceptorContext context,
+            final String profileConfigName) {
+        this.profile = Optional.ofNullable(context.proceed(profileConfigName)).map(ConfigValue::getValue).orElse(null);
+    }
+
+    @Override
+    public ConfigValue getValue(final ConfigSourceInterceptorContext context, final String name) {
+        if (profile != null) {
+            final ConfigValue profileValue = context.proceed("%" + profile + "." + name);
+            if (profileValue != null) {
+                final ConfigValue originalValue = context.proceed(name);
+                return originalValue.getConfigSourceOrdinal() > profileValue.getConfigSourceOrdinal() ? originalValue
+                        : profileValue;
+            }
+        }
+
+        return context.proceed(name);
+    }
+}

implementation/src/main/java/io/smallrye/config/SmallRyeConfig.java

@@ -40,12 +40,12 @@
 import java.util.function.IntFunction;
 import java.util.function.UnaryOperator;
 
-import javax.annotation.Priority;
-
 import org.eclipse.microprofile.config.Config;
 import org.eclipse.microprofile.config.spi.ConfigSource;
 import org.eclipse.microprofile.config.spi.Converter;
 
+import io.smallrye.config.SmallRyeConfigBuilder.InterceptorWithPriority;
+
 /**
  * @author <a href="http://jmesnil.net/">Jeff Mesnil</a> (c) 2017 Red Hat inc.
  */
@@ -125,19 +125,12 @@ private Map<Type, Converter<?>> buildConverters(final SmallRyeConfigBuilder buil
     }
 
     private ConfigSourceInterceptorContext buildInterceptorChain(final SmallRyeConfigBuilder builder) {
-        final List<ConfigSourceInterceptor> interceptors = new ArrayList<>(builder.getInterceptors());
+        final List<InterceptorWithPriority> interceptors = new ArrayList<>(builder.getInterceptors());
         if (builder.isAddDiscoveredInterceptors()) {
             interceptors.addAll(builder.discoverInterceptors());
         }
 
-        interceptors.sort((o1, o2) -> {
-            final Integer p1 = Optional.ofNullable(o1.getClass().getAnnotation(Priority.class)).map(Priority::value)
-                    .orElse(100);
-            final Integer p2 = Optional.ofNullable(o2.getClass().getAnnotation(Priority.class)).map(Priority::value)
-                    .orElse(100);
-
-            return Integer.compare(p2, p1);
-        });
+        interceptors.sort(Comparator.comparingInt(InterceptorWithPriority::getPriority).reversed());
 
         SmallRyeConfigSourceInterceptorContext current = new SmallRyeConfigSourceInterceptorContext(
                 (ConfigSourceInterceptor) (context, name) -> {
@@ -163,13 +156,29 @@ private ConfigSourceInterceptorContext buildInterceptorChain(final SmallRyeConfi
                     return null;
                 }, null);
 
-        for (int i = interceptors.size() - 1; i >= 0; i--) {
-            current = new SmallRyeConfigSourceInterceptorContext(interceptors.get(i), current);
+        List<ConfigSourceInterceptor> configSourceInterceptors = initInterceptors(interceptors, current);
+        for (int i = configSourceInterceptors.size() - 1; i >= 0; i--) {
+            current = new SmallRyeConfigSourceInterceptorContext(configSourceInterceptors.get(i), current);
         }
 
         return current;
     }
 
+    private List<ConfigSourceInterceptor> initInterceptors(final List<InterceptorWithPriority> interceptors,
+            final SmallRyeConfigSourceInterceptorContext context) {
+        final List<ConfigSourceInterceptor> configSourceInterceptors = new ArrayList<>();
+
+        SmallRyeConfigSourceInterceptorContext current = context;
+        for (InterceptorWithPriority interceptor : interceptors) {
+            for (ConfigSourceInterceptor sourceInterceptor : configSourceInterceptors) {
+                current = new SmallRyeConfigSourceInterceptorContext(sourceInterceptor, current);
+            }
+            configSourceInterceptors.add(interceptor.getInterceptor(current));
+        }
+
+        return configSourceInterceptors;
+    }
+
     // no @Override
     public <T, C extends Collection<T>> C getValues(String name, Class<T> itemClass, IntFunction<C> collectionFactory) {
         return getValues(name, getConverter(itemClass), collectionFactory);

implementation/src/main/java/io/smallrye/config/SmallRyeConfigBuilder.java

@@ -23,9 +23,12 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.ServiceLoader;
 import java.util.function.Function;
 import java.util.function.UnaryOperator;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import javax.annotation.Priority;
 
@@ -46,7 +49,7 @@ public class SmallRyeConfigBuilder implements ConfigBuilder {
     private List<ConfigSource> sources = new ArrayList<>();
     private Function<ConfigSource, ConfigSource> sourceWrappers = UnaryOperator.identity();
     private Map<Type, ConverterWithPriority> converters = new HashMap<>();
-    private List<ConfigSourceInterceptor> interceptors = new ArrayList<>();
+    private List<InterceptorWithPriority> interceptors = new ArrayList<>();
     private ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
     private boolean addDefaultSources = false;
     private boolean addDiscoveredSources = false;
@@ -93,11 +96,16 @@ List<Converter> discoverConverters() {
         return discoveredConverters;
     }
 
-    List<ConfigSourceInterceptor> discoverInterceptors() {
-        List<ConfigSourceInterceptor> interceptors = new ArrayList<>();
+    List<InterceptorWithPriority> discoverInterceptors() {
+        List<InterceptorWithPriority> interceptors = new ArrayList<>();
         ServiceLoader<ConfigSourceInterceptor> interceptorLoader = ServiceLoader.load(ConfigSourceInterceptor.class,
                 classLoader);
-        interceptorLoader.forEach(interceptors::add);
+        interceptorLoader.forEach(interceptor -> interceptors.add(new InterceptorWithPriority(interceptor)));
+
+        ServiceLoader<ConfigSourceInterceptorFactory> interceptorFactoryLoader = ServiceLoader
+                .load(ConfigSourceInterceptorFactory.class, classLoader);
+        interceptorFactoryLoader.forEach(interceptor -> interceptors.add(new InterceptorWithPriority(interceptor)));
+
         return interceptors;
     }
 
@@ -138,7 +146,9 @@ public SmallRyeConfigBuilder withSources(Collection<ConfigSource> configSources)
     }
 
     public SmallRyeConfigBuilder withInterceptors(ConfigSourceInterceptor... interceptors) {
-        Collections.addAll(this.interceptors, interceptors);
+        this.interceptors.addAll(Stream.of(interceptors)
+                .map(InterceptorWithPriority::new)
+                .collect(Collectors.toList()));
         return this;
     }
 
@@ -203,7 +213,7 @@ Map<Type, ConverterWithPriority> getConverters() {
         return converters;
     }
 
-    List<ConfigSourceInterceptor> getInterceptors() {
+    List<InterceptorWithPriority> getInterceptors() {
         return interceptors;
     }
 
@@ -245,4 +255,28 @@ int getPriority() {
             return priority;
         }
     }
+
+    static class InterceptorWithPriority {
+        private final ConfigSourceInterceptorFactory factory;
+        private final int priority;
+
+        private InterceptorWithPriority(ConfigSourceInterceptor interceptor) {
+            this(new ConfigSourceInterceptorFactory.Delegate(interceptor));
+        }
+
+        private InterceptorWithPriority(ConfigSourceInterceptorFactory factory) {
+            this.factory = factory;
+            this.priority = Optional.ofNullable(factory.getInterceptorClass().getAnnotation(Priority.class))
+                    .map(Priority::value)
+                    .orElse(100);
+        }
+
+        public ConfigSourceInterceptor getInterceptor(ConfigSourceInterceptorContext context) {
+            return factory.getInterceptor(context);
+        }
+
+        public int getPriority() {
+            return priority;
+        }
+    }
 }

implementation/src/test/java/io/smallrye/config/ConfigSourceInterceptorTest.java

@@ -37,25 +37,25 @@ public void priority() {
     public void serviceLoader() {
         SmallRyeConfig config = new SmallRyeConfigBuilder()
                 .addDefaultSources()
-                .withSources(KeyValuesConfigSource.config("my.prop", "1234"))
+                .withSources(KeyValuesConfigSource.config("my.prop.loader", "1234"))
                 .addDiscoveredInterceptors()
                 .build();
 
-        final String value = config.getValue("my.prop", String.class);
+        final String value = config.getValue("my.prop.loader", String.class);
         Assert.assertEquals("loader", value);
     }
 
     @Test
     public void serviceLoaderAndPriorities() {
         SmallRyeConfig config = new SmallRyeConfigBuilder()
                 .addDefaultSources()
-                .withSources(KeyValuesConfigSource.config("my.prop", "1234"))
+                .withSources(KeyValuesConfigSource.config("my.prop.loader", "1234"))
                 .addDiscoveredInterceptors()
                 .withInterceptors(new LowerPriorityConfigSourceInterceptor(),
                         new HighPriorityConfigSourceInterceptor())
                 .build();
 
-        final String value = config.getValue("my.prop", String.class);
+        final String value = config.getValue("my.prop.loader", String.class);
         Assert.assertEquals("higher", value);
     }