Adding Intent Impl and shell command to install simple intent
diff --git a/core/net/src/main/java/org/onlab/onos/net/intent/impl/IntentManager.java b/core/net/src/main/java/org/onlab/onos/net/intent/impl/IntentManager.java
new file mode 100644
index 0000000..f1c9de3
--- /dev/null
+++ b/core/net/src/main/java/org/onlab/onos/net/intent/impl/IntentManager.java
@@ -0,0 +1,363 @@
+package org.onlab.onos.net.intent.impl;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static org.onlab.onos.net.intent.IntentState.FAILED;
+import static org.onlab.onos.net.intent.IntentState.INSTALLED;
+import static org.onlab.onos.net.intent.IntentState.WITHDRAWING;
+import static org.onlab.onos.net.intent.IntentState.WITHDRAWN;
+import static org.slf4j.LoggerFactory.getLogger;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.CopyOnWriteArrayList;
+
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.apache.felix.scr.annotations.Service;
+import org.onlab.onos.event.AbstractListenerRegistry;
+import org.onlab.onos.event.EventDeliveryService;
+import org.onlab.onos.net.intent.InstallableIntent;
+import org.onlab.onos.net.intent.Intent;
+import org.onlab.onos.net.intent.IntentCompiler;
+import org.onlab.onos.net.intent.IntentEvent;
+import org.onlab.onos.net.intent.IntentException;
+import org.onlab.onos.net.intent.IntentExtensionService;
+import org.onlab.onos.net.intent.IntentId;
+import org.onlab.onos.net.intent.IntentInstaller;
+import org.onlab.onos.net.intent.IntentListener;
+import org.onlab.onos.net.intent.IntentOperations;
+import org.onlab.onos.net.intent.IntentService;
+import org.onlab.onos.net.intent.IntentState;
+import org.onlab.onos.net.intent.IntentStore;
+import org.onlab.onos.net.intent.IntentStoreDelegate;
+import org.slf4j.Logger;
+
+import com.google.common.collect.ImmutableMap;
+
+/**
+ * An implementation of Intent Manager.
+ */
+@Component(immediate = true)
+@Service
+public class IntentManager
+        implements IntentService, IntentExtensionService {
+    private final Logger log = getLogger(getClass());
+
+    public static final String INTENT_NULL = "Intent cannot be null";
+    public static final String INTENT_ID_NULL = "Intent ID cannot be null";
+
+    // Collections for compiler, installer, and listener are ONOS instance local
+    private final ConcurrentMap<Class<? extends Intent>,
+            IntentCompiler<? extends Intent>> compilers = new ConcurrentHashMap<>();
+    private final ConcurrentMap<Class<? extends InstallableIntent>,
+            IntentInstaller<? extends InstallableIntent>> installers = new ConcurrentHashMap<>();
+    private final CopyOnWriteArrayList<IntentListener> listeners = new CopyOnWriteArrayList<>();
+
+    private final AbstractListenerRegistry<IntentEvent, IntentListener>
+        listenerRegistry = new AbstractListenerRegistry<>();
+
+    private final IntentStoreDelegate delegate = new InternalStoreDelegate();
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected IntentStore store;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected EventDeliveryService eventDispatcher;
+
+    @Activate
+    public void activate() {
+        store.setDelegate(delegate);
+        eventDispatcher.addSink(IntentEvent.class, listenerRegistry);
+
+//        this.intentEvents = new IntentMap<>("intentState", IntentEvent.class, collectionsService);
+//        this.installableIntents =
+//                new IntentMap<>("installableIntents", IntentCompilationResult.class, collectionsService);
+//
+//
+//        this.intentEvents.addListener(new InternalEntryListener(new InternalIntentEventListener()));
+
+        log.info("Started");
+    }
+
+    @Deactivate
+    public void deactivate() {
+        store.unsetDelegate(delegate);
+        eventDispatcher.removeSink(IntentEvent.class);
+        log.info("Stopped");
+    }
+
+    @Override
+    public void submit(Intent intent) {
+        checkNotNull(intent, INTENT_NULL);
+        registerSubclassCompilerIfNeeded(intent);
+        IntentEvent event = store.createIntent(intent);
+        eventDispatcher.post(event);
+        processStoreEvent(event);
+    }
+
+    @Override
+    public void withdraw(Intent intent) {
+        checkNotNull(intent, INTENT_NULL);
+        IntentEvent event = store.setState(intent, WITHDRAWING);
+        eventDispatcher.post(event);
+        processStoreEvent(event);
+    }
+
+    // FIXME: implement this method
+    @Override
+    public void execute(IntentOperations operations) {
+        throw new UnsupportedOperationException("execute() is not implemented yet");
+    }
+
+    @Override
+    public Iterable<Intent> getIntents() {
+        return store.getIntents();
+    }
+
+    @Override
+    public long getIntentCount() {
+        return store.getIntentCount();
+    }
+
+    @Override
+    public Intent getIntent(IntentId id) {
+        checkNotNull(id, INTENT_ID_NULL);
+        return store.getIntent(id);
+    }
+
+    @Override
+    public IntentState getIntentState(IntentId id) {
+        checkNotNull(id, INTENT_ID_NULL);
+        return store.getIntentState(id);
+    }
+
+    @Override
+    public void addListener(IntentListener listener) {
+        listenerRegistry.addListener(listener);
+    }
+
+    @Override
+    public void removeListener(IntentListener listener) {
+        listenerRegistry.removeListener(listener);
+    }
+
+    @Override
+    public <T extends Intent> void registerCompiler(Class<T> cls, IntentCompiler<T> compiler) {
+        compilers.put(cls, compiler);
+    }
+
+    @Override
+    public <T extends Intent> void unregisterCompiler(Class<T> cls) {
+        compilers.remove(cls);
+    }
+
+    @Override
+    public Map<Class<? extends Intent>, IntentCompiler<? extends Intent>> getCompilers() {
+        return ImmutableMap.copyOf(compilers);
+    }
+
+    @Override
+    public <T extends InstallableIntent> void registerInstaller(Class<T> cls, IntentInstaller<T> installer) {
+        installers.put(cls, installer);
+    }
+
+    @Override
+    public <T extends InstallableIntent> void unregisterInstaller(Class<T> cls) {
+        installers.remove(cls);
+    }
+
+    @Override
+    public Map<Class<? extends InstallableIntent>, IntentInstaller<? extends InstallableIntent>> getInstallers() {
+        return ImmutableMap.copyOf(installers);
+    }
+
+    /**
+     * Invokes all of registered intent event listener.
+     *
+     * @param event event supplied to a listener as an argument
+     */
+    private void invokeListeners(IntentEvent event) {
+        for (IntentListener listener : listeners) {
+            listener.event(event);
+        }
+    }
+
+    /**
+     * Returns the corresponding intent compiler to the specified intent.
+     *
+     * @param intent intent
+     * @param <T> the type of intent
+     * @return intent compiler corresponding to the specified intent
+     */
+    private <T extends Intent> IntentCompiler<T> getCompiler(T intent) {
+        @SuppressWarnings("unchecked")
+        IntentCompiler<T> compiler = (IntentCompiler<T>) compilers.get(intent.getClass());
+        if (compiler == null) {
+            throw new IntentException("no compiler for class " + intent.getClass());
+        }
+        return compiler;
+    }
+
+    /**
+     * Returns the corresponding intent installer to the specified installable intent.
+     * @param intent intent
+     * @param <T> the type of installable intent
+     * @return intent installer corresponding to the specified installable intent
+     */
+    private <T extends InstallableIntent> IntentInstaller<T> getInstaller(T intent) {
+        @SuppressWarnings("unchecked")
+        IntentInstaller<T> installer = (IntentInstaller<T>) installers.get(intent.getClass());
+        if (installer == null) {
+            throw new IntentException("no installer for class " + intent.getClass());
+        }
+        return installer;
+    }
+
+    /**
+     * Compiles an intent.
+     *
+     * @param intent intent
+     */
+    private void compileIntent(Intent intent) {
+        // FIXME: To make SDN-IP workable ASAP, only single level compilation is implemented
+        // TODO: implement compilation traversing tree structure
+        List<InstallableIntent> installable = new ArrayList<>();
+        for (Intent compiled : getCompiler(intent).compile(intent)) {
+            installable.add((InstallableIntent) compiled);
+        }
+        IntentEvent event = store.addInstallableIntents(intent.getId(), installable);
+        eventDispatcher.post(event);
+        processStoreEvent(event);
+    }
+
+    /**
+     * Installs an intent.
+     *
+     * @param intent intent
+     */
+    private void installIntent(Intent intent) {
+        for (InstallableIntent installable : store.getInstallableIntents(intent.getId())) {
+            registerSubclassInstallerIfNeeded(installable);
+            getInstaller(installable).install(installable);
+        }
+
+        IntentEvent event = store.setState(intent, INSTALLED);
+        eventDispatcher.post(event);
+        processStoreEvent(event);
+
+    }
+
+    /**
+     * Uninstalls an intent.
+     *
+     * @param intent intent
+     */
+    private void uninstallIntent(Intent intent) {
+        for (InstallableIntent installable : store.getInstallableIntents(intent.getId())) {
+            getInstaller(installable).uninstall(installable);
+        }
+
+        store.removeInstalledIntents(intent.getId());
+        store.setState(intent, WITHDRAWN);
+    }
+
+    /**
+     * Registers an intent compiler of the specified intent if an intent compiler
+     * for the intent is not registered. This method traverses the class hierarchy of
+     * the intent. Once an intent compiler for a parent type is found, this method
+     * registers the found intent compiler.
+     *
+     * @param intent intent
+     */
+    private void registerSubclassCompilerIfNeeded(Intent intent) {
+        if (!compilers.containsKey(intent.getClass())) {
+            Class<?> cls = intent.getClass();
+            while (cls != Object.class) {
+                // As long as we're within the Intent class descendants
+                if (Intent.class.isAssignableFrom(cls)) {
+                    IntentCompiler<?> compiler = compilers.get(cls);
+                    if (compiler != null) {
+                        compilers.put(intent.getClass(), compiler);
+                        return;
+                    }
+                }
+                cls = cls.getSuperclass();
+            }
+        }
+    }
+
+    /**
+     * Registers an intent installer of the specified intent if an intent installer
+     * for the intent is not registered. This method traverses the class hierarchy of
+     * the intent. Once an intent installer for a parent type is found, this method
+     * registers the found intent installer.
+     *
+     * @param intent intent
+     */
+    private void registerSubclassInstallerIfNeeded(InstallableIntent intent) {
+        if (!installers.containsKey(intent.getClass())) {
+            Class<?> cls = intent.getClass();
+            while (cls != Object.class) {
+                // As long as we're within the InstallableIntent class descendants
+                if (InstallableIntent.class.isAssignableFrom(cls)) {
+                    IntentInstaller<?> installer = installers.get(cls);
+                    if (installer != null) {
+                        installers.put(intent.getClass(), installer);
+                        return;
+                    }
+                }
+                cls = cls.getSuperclass();
+            }
+        }
+    }
+
+    /**
+     * Handles state transition of submitted intents.
+     */
+    private void processStoreEvent(IntentEvent event) {
+            invokeListeners(event);
+            Intent intent = event.getIntent();
+
+            try {
+                switch (event.getState()) {
+                    case SUBMITTED:
+                        compileIntent(intent);
+                        break;
+                    case COMPILED:
+                        installIntent(intent);
+                        break;
+                    case INSTALLED:
+                        break;
+                    case WITHDRAWING:
+                        uninstallIntent(intent);
+                        break;
+                    case WITHDRAWN:
+                        break;
+                    case FAILED:
+                        break;
+                    default:
+                        throw new IllegalStateException(
+                                "the state of IntentEvent is illegal: " + event.getState());
+                }
+            } catch (IntentException e) {
+                store.setState(intent, FAILED);
+            }
+
+    }
+
+    // Store delegate to re-post events emitted from the store.
+    private class InternalStoreDelegate implements IntentStoreDelegate {
+        @Override
+        public void notify(IntentEvent event) {
+            processStoreEvent(event);
+            eventDispatcher.post(event);
+        }
+    }
+
+}