mae-api/src/main/java/org/apache/maven/mae/internal/container/ComponentKey.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.maven.mae.internal.container;

import static org.codehaus.plexus.util.StringUtils.isBlank;

import java.lang.reflect.Field;

import org.codehaus.plexus.component.annotations.Component;
import org.codehaus.plexus.component.annotations.Requirement;
import org.sonatype.guice.plexus.config.Roles;

import com.google.inject.Key;

public class ComponentKey<T>
{

    public static final String DEFAULT_HINT = "default".intern();

    public static final String LITERAL_SUFFIX = "_";

    private final Class<T> roleClass;

    private final String hint;

    public ComponentKey( final Class<T> role, final String hint )
    {
        roleClass = role;
        this.hint = isBlank( hint ) || DEFAULT_HINT.equals( hint ) ? DEFAULT_HINT : hint.intern();
    }

    public ComponentKey( final Class<T> role )
    {
        roleClass = role;
        hint = DEFAULT_HINT;
    }

    @SuppressWarnings( "unchecked" )
    public ComponentKey( final Component comp )
    {
        roleClass = (Class<T>) comp.role();

        String h = comp.hint();
        hint = ( isBlank( h ) || DEFAULT_HINT.equals( h ) ? DEFAULT_HINT : h );
    }

    @SuppressWarnings( { "unchecked", "rawtypes" } )
    public ComponentKey( final Requirement req, final Field field )
    {
        if ( req.hints() != null && req.hints().length > 0 )
        {
            throw new IllegalArgumentException( "Cannot construct ComponentKey for requirement listing multiple hints." );
        }

        Class role = req.role();
        if ( role == null || role.equals( Object.class ) )
        {
            role = field.getType();
        }

        roleClass = role;

        String h = req.hint();
        hint = ( isBlank( h ) || DEFAULT_HINT.equals( h ) ? DEFAULT_HINT : h );
    }

    public String getRole()
    {
        return roleClass.getName();
    }

    public String getHint()
    {
        return hint;
    }

    public String key()
    {
        return roleClass.getName() + ( DEFAULT_HINT.equals( hint ) ? "" : "#" + hint );
    }

    public Key<T> componentKey()
    {
        return Roles.componentKey( roleClass, hint );
    }

    public Key<T> literalComponentKey()
    {
        return isLiteral() ? componentKey() : Roles.componentKey( roleClass, hint + LITERAL_SUFFIX );
    }

    public Key<T> rawComponentKey()
    {
        return Roles.componentKey( roleClass, getLiteralHint( hint ) );
    }

    @Override
    public String toString()
    {
        return key();
    }

    @Override
    public int hashCode()
    {
        final int prime = 31;
        int result = 1;
        result = prime * result + hint.hashCode();
        result = prime * result + roleClass.getName().hashCode();
        return result;
    }

    @Override
    public boolean equals( final Object obj )
    {
        if ( this == obj )
        {
            return true;
        }
        if ( obj == null )
        {
            return false;
        }
        if ( getClass() != obj.getClass() )
        {
            return false;
        }

        final ComponentKey<?> other = ComponentKey.class.cast( obj );
        if ( !hint.equals( other.hint ) )
        {
            return false;
        }

        if ( !roleClass.getName().equals( other.roleClass.getName() ) )
        {
            return false;
        }

        return true;
    }

    public Class<T> getRoleClass()
    {
        return roleClass;
    }

    public T castValue( final Object instance )
    {
        return instance == null ? null : roleClass.cast( instance );
    }

    public boolean isLiteral()
    {
        return isLiteral( hint );
    }

    public static boolean isLiteral( final String value )
    {
        return value != null && value.length() > 1 && value.endsWith( LITERAL_SUFFIX );
    }

    public static String getLiteralHint( final String value )
    {
        return isLiteral( value ) ? value.substring( 0, value.length() - 1 ) : value;
    }

}