1 files changed, 151 insertions, 0 deletions
diff --git a/src/main/java/com/redstoner/misc/VersionHelper.java b/src/main/java/com/redstoner/misc/VersionHelper.java
new file mode 100644
index 0000000..e4a9403
--- /dev/null
+++ b/src/main/java/com/redstoner/misc/VersionHelper.java
@@ -0,0 +1,151 @@
+package com.redstoner.misc;
+
+import java.lang.annotation.Annotation;
+
+import com.redstoner.annotations.Version;
+import com.redstoner.exceptions.MissingVersionException;
+
+/** This class can be used to compare modules against the loader version or against each other to prevent dependency issues.
+ * 
+ * @author Pepich */
+@Version(major = 2, minor = 1, revision = 3, compatible = 0)
+public final class VersionHelper
+{
+	private VersionHelper()
+	{}
+	
+	/** Checks two classes versions for compatibility.
+	 * 
+	 * @param base The API to compare to.
+	 * @param module The module to compare.
+	 * @return true, when the module is up to date with the API, or the API supports outdated modules.
+	 * @throws MissingVersionException When one of the parameters is not annotated with a @Version annotation. */
+	public static boolean isCompatible(Class<?> api, Class<?> module) throws MissingVersionException
+	{
+		if (!api.isAnnotationPresent(Version.class))
+			throw new MissingVersionException("The API is not annotated with a version.");
+		if (!module.isAnnotationPresent(Version.class))
+			throw new MissingVersionException("The module is not annotated with a version.");
+		Version apiVersion = api.getAnnotation(Version.class);
+		Version moduleVersion = module.getAnnotation(Version.class);
+		return isCompatible(apiVersion, moduleVersion);
+	}
+	
+	/** Checks two classes versions for compatibility.
+	 * 
+	 * @param base The API to compare to.
+	 * @param module The module to compare.
+	 * @return true, when the module is up to date with the API, or the API supports outdated modules.
+	 * @throws MissingVersionException When one of the parameters is not annotated with a @Version annotation. */
+	public static boolean isCompatible(Version apiVersion, Class<?> module) throws MissingVersionException
+	{
+		if (!module.isAnnotationPresent(Version.class))
+			throw new MissingVersionException("The module is not annotated with a version.");
+		Version moduleVersion = module.getAnnotation(Version.class);
+		return isCompatible(apiVersion, moduleVersion);
+	}
+	
+	/** Checks two classes versions for compatibility.
+	 * 
+	 * @param base The API to compare to.
+	 * @param module The module to compare.
+	 * @return true, when the module is up to date with the API, or the API supports outdated modules.
+	 * @throws MissingVersionException When one of the parameters is not annotated with a @Version annotation. */
+	public static boolean isCompatible(Class<?> api, Version moduleVersion) throws MissingVersionException
+	{
+		if (!api.isAnnotationPresent(Version.class))
+			throw new MissingVersionException("The API is not annotated with a version.");
+		Version apiVersion = api.getAnnotation(Version.class);
+		return isCompatible(apiVersion, moduleVersion);
+	}
+	
+	/** Checks two versions for compatibility.
+	 * 
+	 * @param base The API version to compare to.
+	 * @param module The module version to compare.
+	 * @return true, when the module is up to date with the API, or the API supports outdated modules. */
+	public static boolean isCompatible(Version apiVersion, Version moduleVersion)
+	{
+		if (apiVersion.major() >= moduleVersion.compatible())
+			return true;
+		if (apiVersion.compatible() == -1)
+			return false;
+		if (apiVersion.compatible() <= moduleVersion.major())
+			return true;
+		return false;
+	}
+	
+	/** Returns the version of a given class as a String.
+	 * 
+	 * @param clazz The class to grab the version number from.
+	 * @return The version number of the class in format major.minor.revision.compatible.
+	 * @throws MissingVersionException If the class is not annotated with @Version. */
+	public static String getVersion(Class<?> clazz) throws MissingVersionException
+	{
+		if (!clazz.isAnnotationPresent(Version.class))
+			throw new MissingVersionException("The given class is not associated with a version.");
+		Version ver = clazz.getAnnotation(Version.class);
+		return getString(ver);
+	}
+	
+	/** Returns the String representation of a version.
+	 * 
+	 * @param ver The version to be represented.
+	 * @return The String representation. */
+	public static String getString(Version ver)
+	{
+		return ver.major() + "." + ver.minor() + "." + ver.revision() + "." + ver.compatible();
+	}
+	
+	public static Version getVersion(String ver)
+	{
+		String[] raw = ver.split("\\.");
+		if (raw.length != 4)
+			return null;
+		return VersionHelper.create(Integer.parseInt(raw[0]), Integer.parseInt(raw[1]), Integer.parseInt(raw[2]),
+				Integer.parseInt(raw[3]));
+	}
+	
+	/** This method creates a new Version to use for compatibility checks.
+	 * 
+	 * @param major The major version
+	 * @param minor The minor version
+	 * @param revision The revision
+	 * @param compatible The compatibility tag
+	 * @return */
+	public static Version create(int major, int minor, int revision, int compatible)
+	{
+		return new Version()
+		{
+			@Override
+			public Class<? extends Annotation> annotationType()
+			{
+				return Version.class;
+			}
+			
+			@Override
+			public int revision()
+			{
+				return revision;
+			}
+			
+			@Override
+			public int minor()
+			{
+				return minor;
+			}
+			
+			@Override
+			public int major()
+			{
+				return major;
+			}
+			
+			@Override
+			public int compatible()
+			{
+				return compatible;
+			}
+		};
+	}
+}