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Silk Java dependency injection framework
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/*
 *  Copyright (c) 2012, Jan Bernitt 
 *			
 *  Licensed under the Apache License, Version 2.0, http://www.apache.org/licenses/LICENSE-2.0
 */
package se.jbee.inject;

import java.util.Arrays;

/**
 * A set of {@link Package}s described one or more root packages (on the same hierarchy level/depth)
 * with or without their sub-packages.
 * 
 * @author Jan Bernitt ([email protected])
 */
public final class Packages
		implements PreciserThan {

	/**
	 * Contains all packages including the (default) package.
	 */
	public static final Packages ALL = new Packages( new String[0], true );

	/**
	 * The (default) package.
	 */
	public static final Packages DEFAULT = new Packages( new String[0], false );

	public static Packages packageAndSubPackagesOf( Class type ) {
		return new Packages( packageNameOf( type ), true );
	}

	public static Packages packageAndSubPackagesOf( Class type, Class... types ) {
		commonPackageDepth( type, types );
		return new Packages( packageNamesOf( type, "", types ), true );
	}

	public static Packages packageOf( Class type ) {
		return new Packages( packageNameOf( type ), false );
	}

	public static Packages packageOf( Class type, Class... types ) {
		return new Packages( packageNamesOf( type, "", types ), false );
	}

	public static Packages subPackagesOf( Class type ) {
		return new Packages( packageNameOf( type ) + ".", true );
	}

	public static Packages subPackagesOf( Class type, Class... types ) {
		commonPackageDepth( type, types );
		return new Packages( packageNamesOf( type, ".", types ), true );
	}

	private static String[] packageNamesOf( Class packageOf, String suffix,
			Class... packagesOf ) {
		String[] names = new String[packagesOf.length + 1];
		names[0] = packageNameOf( packageOf ) + suffix;
		for ( int i = 1; i <= packagesOf.length; i++ ) {
			names[i] = packageNameOf( packagesOf[i - 1] ) + suffix;
		}
		return names;
	}

	private static String packageNameOf( Class packageOf ) {
		return packageOf.getPackage().getName();
	}

	private static String packageNameOf( Type packageOf ) {
		return packageOf.isLowerBound()
			? "-NONE-"
			: packageNameOf( packageOf.getRawType() );
	}

	private final String[] roots;
	private final boolean includingSubpackages;
	private final int rootDepth;

	private Packages( String root, boolean includingSubpackages ) {
		this( new String[] { root }, includingSubpackages );
	}

	private Packages( String[] roots, boolean includingSubpackages ) {
		super();
		this.roots = roots;
		this.includingSubpackages = includingSubpackages;
		this.rootDepth = rootDepth( roots );
	}

	public Packages parents() {
		if ( rootDepth == 0 ) {
			return this;
		}
		if ( rootDepth == 1 ) {
			return includingSubpackages
				? ALL
				: DEFAULT;
		}
		String[] parentRoots = new String[roots.length];
		for ( int i = 0; i < roots.length; i++ ) {
			parentRoots[i] = parent( roots[i] );
		}
		return new Packages( parentRoots, includingSubpackages );
	}

	/**
	 * 	 * foo.bar.baz -> foo.bar 
	 * foo.bar. -> foo.
	 * 
	 */
	private static String parent( String root ) {
		return root.substring( 0,
				root.lastIndexOf( '.', root.length() - 2 ) + ( root.endsWith( "." )
					? 1
					: 0 ) );
	}

	private static void commonPackageDepth( Class type, Class[] types ) {
		int p0 = dotsIn( type.getPackage().getName() );
		for ( int i = 0; i < types.length; i++ ) {
			if ( dotsIn( types[i].getPackage().getName() ) != p0 ) {
				throw new IllegalArgumentException(
						"All classes of a packages set have to be on same depth level." );
			}
		}
	}

	private static int rootDepth( String[] roots ) {
		return roots.length == 0
			? 0
			: dotsIn( roots[0] );
	}

	private static int dotsIn( String s ) {
		int c = 0;
		for ( int i = s.length() - 1; i > 0; i-- ) {
			if ( s.charAt( i ) == '.' ) {
				c++;
			}
		}
		return c;
	}

	public boolean contains( Type type ) {
		if ( includesAll() ) {
			return true;
		}
		final String packageNameOfType = packageNameOf( type );
		for ( String root : roots ) {
			if ( regionEqual( root, packageNameOfType, includingSubpackages
				? root.length()
				: packageNameOfType.length() ) ) {
				return true;
			}
		}
		return false;
	}

	public static boolean regionEqual( String p1, String p2, int length ) {
		if ( p1.length() < length || p2.length() < length ) {
			return false;
		}
		if ( p1 == p2 ) {
			return true;
		}
		for ( int i = length - 1; i > 0; i-- ) {
			if ( p1.charAt( i ) != p2.charAt( i ) ) {
				return false;
			}
		}
		return true;
	}

	public boolean includesAll() {
		return roots.length == 0 && includingSubpackages;
	}

	@Override
	public boolean equals( Object obj ) {
		return obj instanceof Packages && equalTo( ( (Packages) obj ) );
	}

	@Override
	public int hashCode() {
		return Arrays.hashCode( roots );
	}

	@Override
	public boolean morePreciseThan( Packages other ) {
		if ( includingSubpackages != other.includingSubpackages ) {
			return !includingSubpackages;
		}
		if ( rootDepth != other.rootDepth ) {
			return rootDepth > other.rootDepth;
		}
		return false;
	}

	@Override
	public String toString() {
		if ( roots.length == 0 ) {
			return includingSubpackages
				? "*"
				: "(default)";
		}
		if ( roots.length == 1 ) {
			return toString( roots[0] );
		}
		StringBuilder b = new StringBuilder();
		for ( int i = 0; i < roots.length; i++ ) {
			b.append( '+' ).append( toString( roots[i] ) );
		}
		return b.substring( 1 );
	}

	private String toString( String root ) {
		return root + ( includingSubpackages
			? "*"
			: "" );
	}

	public boolean equalTo( Packages other ) {
		return other.includingSubpackages == includingSubpackages // 
				&& other.rootDepth == rootDepth
				&& other.roots.length == roots.length
				&& Arrays.equals( roots, other.roots );
	}

}