From: David ‘Bombe’ Roden <bombe@pterodactylus.net>
Date: Fri, 4 Jan 2013 16:54:41 +0000 (+0100)
Subject: Add loader for reactions from chains.
X-Git-Tag: 0.1~79
X-Git-Url: https://git.pterodactylus.net/?p=rhynodge.git;a=commitdiff_plain;h=0851c5adfd968e50227dc037a3c2175af2a5ca9e

Add loader for reactions from chains.
---

diff --git a/src/main/java/net/pterodactylus/reactor/loader/ReactionLoader.java b/src/main/java/net/pterodactylus/reactor/loader/ReactionLoader.java
new file mode 100644
index 0000000..7016edb
--- /dev/null
+++ b/src/main/java/net/pterodactylus/reactor/loader/ReactionLoader.java
@@ -0,0 +1,177 @@
+/*
+ * Reactor - Loader.java - Copyright © 2013 David Roden
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.pterodactylus.reactor.loader;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+import net.pterodactylus.reactor.Action;
+import net.pterodactylus.reactor.Filter;
+import net.pterodactylus.reactor.Query;
+import net.pterodactylus.reactor.Reaction;
+import net.pterodactylus.reactor.Trigger;
+import net.pterodactylus.reactor.loader.Chain.Parameter;
+import net.pterodactylus.reactor.loader.Chain.Part;
+
+/**
+ * Creates {@link Reaction}s from {@link Chain}s.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class ReactionLoader {
+
+	/**
+	 * Creates a {@link Reaction} from the given {@link Chain}.
+	 *
+	 * @param chain
+	 *            The chain to create a reaction from
+	 * @return The created reaction
+	 * @throws LoaderException
+	 *             if a class can not be loaded
+	 */
+	@SuppressWarnings("static-method")
+	public Reaction loadReaction(Chain chain) throws LoaderException {
+
+		/* check if chain is enabled. */
+		if (!chain.enabled()) {
+			throw new IllegalArgumentException("Chain is not enabled.");
+		}
+
+		/* create query. */
+		Query query = createObject(chain.query().name(), "net.pterodactylus.reactor.queries", extractParameters(chain.query().parameters()));
+
+		/* create filters. */
+		List<Filter> filters = new ArrayList<Filter>();
+		for (Part filterPart : chain.filters()) {
+			filters.add(ReactionLoader.<Filter> createObject(filterPart.name(), "net.pterodactylus.reactor.filters", extractParameters(filterPart.parameters())));
+		}
+
+		/* create trigger. */
+		Trigger trigger = createObject(chain.trigger().name(), "net.pterodactylus.reactor.triggers", extractParameters(chain.trigger().parameters()));
+
+		/* create action. */
+		Action action = createObject(chain.action().name(), "net.pterodactylus.reactor.actions", extractParameters(chain.action().parameters()));
+
+		return new Reaction(query, filters, trigger, action).setUpdateInterval(TimeUnit.SECONDS.toMillis(chain.updateInterval()));
+	}
+
+	//
+	// STATIC METHODS
+	//
+
+	/**
+	 * Extracts all parameter values from the given parameters.
+	 *
+	 * @param parameters
+	 *            The parameters to extract the values from
+	 * @return The extracted values
+	 */
+	private static List<String> extractParameters(List<Parameter> parameters) {
+		List<String> parameterValues = new ArrayList<String>();
+
+		for (Parameter parameter : parameters) {
+			parameterValues.add(parameter.value());
+		}
+
+		return parameterValues;
+	}
+
+	/**
+	 * Creates a new object.
+	 * <p>
+	 * First, {@code className} is used to try to load a {@link Class} with that
+	 * name. If that fails, {@code packageName} is prepended to the class name.
+	 * If no class can be found, a {@link LoaderException} will be thrown.
+	 * <p>
+	 * If a class could be located using the described method, a constructor
+	 * will be searched that has the same number of {@link String} parameters as
+	 * the given parameters. The parameters from the given parameters are then
+	 * used in a constructor call to create the new object.
+	 *
+	 * @param className
+	 *            The name of the class
+	 * @param packageName
+	 *            The optional name of the package to prepend
+	 * @param parameters
+	 *            The parameters for the constructor call
+	 * @return The created object
+	 * @throws LoaderException
+	 *             if the object can not be created
+	 */
+	@SuppressWarnings("unchecked")
+	private static <T> T createObject(String className, String packageName, List<String> parameters) throws LoaderException {
+
+		/* try to load class without package name. */
+		Class<?> objectClass = null;
+		try {
+			objectClass = Class.forName(className);
+		} catch (ClassNotFoundException cnfe1) {
+			/* ignore, we’ll try again. */
+		}
+
+		if (objectClass == null) {
+			try {
+				objectClass = Class.forName(packageName + "." + className);
+			} catch (ClassNotFoundException cnfe1) {
+				/* okay, now we need to throw. */
+				throw new LoaderException(String.format("Could find neither class “%s” nor class “%s.”", className, packageName + "." + className), cnfe1);
+			}
+		}
+
+		/* locate an eligible constructor. */
+		Constructor<?> wantedConstructor = null;
+		for (Constructor<?> constructor : objectClass.getConstructors()) {
+			Class<?>[] parameterTypes = constructor.getParameterTypes();
+			if (parameterTypes.length != parameters.size()) {
+				continue;
+			}
+			boolean compatibleTypes = true;
+			for (Class<?> parameterType : parameterTypes) {
+				if (parameterType != String.class) {
+					compatibleTypes = false;
+					break;
+				}
+			}
+			if (!compatibleTypes) {
+				continue;
+			}
+			wantedConstructor = constructor;
+		}
+
+		if (wantedConstructor == null) {
+			throw new LoaderException("Could not find eligible constructor.");
+		}
+
+		try {
+			return (T) wantedConstructor.newInstance(parameters.toArray());
+		} catch (IllegalArgumentException iae1) {
+			throw new LoaderException("Could not invoke constructor.", iae1);
+		} catch (InstantiationException ie1) {
+			throw new LoaderException("Could not invoke constructor.", ie1);
+		} catch (IllegalAccessException iae1) {
+			throw new LoaderException("Could not invoke constructor.", iae1);
+		} catch (InvocationTargetException ite1) {
+			throw new LoaderException("Could not invoke constructor.", ite1);
+		}
+
+	}
+
+}