/*
 * 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.commons.collections4.functors;

import java.io.Serializable;
import java.util.Map;

import org.apache.commons.collections4.Closure;
import org.apache.commons.collections4.Predicate;

Closure implementation calls the closure whose predicate returns true,
like a switch statement.
Since:
3.0/**
 * Closure implementation calls the closure whose predicate returns true,
 * like a switch statement.
 *
 * @since 3.0
 */
public class SwitchClosure<E> implements Closure<E>, Serializable {

    
Serial version UID /** Serial version UID */
    private static final long serialVersionUID = 3518477308466486130L;

    
The tests to consider /** The tests to consider */
    private final Predicate<? super E>[] iPredicates;
    
The matching closures to call /** The matching closures to call */
    private final Closure<? super E>[] iClosures;
    
The default closure to call if no tests match /** The default closure to call if no tests match */
    private final Closure<? super E> iDefault;

    
Factory method that performs validation and copies the parameter arrays.
Params:
predicates –  array of predicates, cloned, no nulls
closures –  matching array of closures, cloned, no nulls
defaultClosure –  the closure to use if no match, null means nop
Type parameters:
<E> – the type that the closure acts on
Throws:
NullPointerException – if array is null
NullPointerException – if any element in the array is null
IllegalArgumentException – if the array lengths of predicates and closures do not match
Returns:
the chained closure/**
     * Factory method that performs validation and copies the parameter arrays.
     *
     * @param <E> the type that the closure acts on
     * @param predicates  array of predicates, cloned, no nulls
     * @param closures  matching array of closures, cloned, no nulls
     * @param defaultClosure  the closure to use if no match, null means nop
     * @return the <code>chained</code> closure
     * @throws NullPointerException if array is null
     * @throws NullPointerException if any element in the array is null
     * @throws IllegalArgumentException if the array lengths of predicates and closures do not match
     */
    @SuppressWarnings("unchecked")
    public static <E> Closure<E> switchClosure(final Predicate<? super E>[] predicates,
                                               final Closure<? super E>[] closures,
                                               final Closure<? super E> defaultClosure) {
        FunctorUtils.validate(predicates);
        FunctorUtils.validate(closures);
        if (predicates.length != closures.length) {
            throw new IllegalArgumentException("The predicate and closure arrays must be the same size");
        }
        if (predicates.length == 0) {
            return (Closure<E>) (defaultClosure == null ? NOPClosure.<E>nopClosure(): defaultClosure);
        }
        return new SwitchClosure<>(predicates, closures, defaultClosure);
    }

    
Create a new Closure that calls one of the closures depending
on the predicates.

The Map consists of Predicate keys and Closure values. A closure
is called if its matching predicate returns true. Each predicate is evaluated
until one returns true. If no predicates evaluate to true, the default
closure is called. The default closure is set in the map with a
null key. The ordering is that of the iterator() method on the entryset
collection of the map.
Params:
predicatesAndClosures –  a map of predicates to closures
Type parameters:
<E> – the type that the closure acts on
Throws:
NullPointerException – if the map is null
NullPointerException – if any closure in the map is null
ClassCastException –  if the map elements are of the wrong type
Returns:
the switch closure/**
     * Create a new Closure that calls one of the closures depending
     * on the predicates.
     * <p>
     * The Map consists of Predicate keys and Closure values. A closure
     * is called if its matching predicate returns true. Each predicate is evaluated
     * until one returns true. If no predicates evaluate to true, the default
     * closure is called. The default closure is set in the map with a
     * null key. The ordering is that of the iterator() method on the entryset
     * collection of the map.
     *
     * @param <E> the type that the closure acts on
     * @param predicatesAndClosures  a map of predicates to closures
     * @return the <code>switch</code> closure
     * @throws NullPointerException if the map is null
     * @throws NullPointerException if any closure in the map is null
     * @throws ClassCastException  if the map elements are of the wrong type
     */
    @SuppressWarnings("unchecked")
    public static <E> Closure<E> switchClosure(final Map<Predicate<E>, Closure<E>> predicatesAndClosures) {
        if (predicatesAndClosures == null) {
            throw new NullPointerException("The predicate and closure map must not be null");
        }
        // convert to array like this to guarantee iterator() ordering
        final Closure<? super E> defaultClosure = predicatesAndClosures.remove(null);
        final int size = predicatesAndClosures.size();
        if (size == 0) {
            return (Closure<E>) (defaultClosure == null ? NOPClosure.<E>nopClosure() : defaultClosure);
        }
        final Closure<E>[] closures = new Closure[size];
        final Predicate<E>[] preds = new Predicate[size];
        int i = 0;
        for (final Map.Entry<Predicate<E>, Closure<E>> entry : predicatesAndClosures.entrySet()) {
            preds[i] = entry.getKey();
            closures[i] = entry.getValue();
            i++;
        }
        return new SwitchClosure<>(false, preds, closures, defaultClosure);
    }

    
Hidden constructor for the use by the static factory methods.
Params:
clone –  if true the input arguments will be cloned
predicates –  array of predicates, no nulls
closures –  matching array of closures, no nulls
defaultClosure –  the closure to use if no match, null means nop/**
     * Hidden constructor for the use by the static factory methods.
     *
     * @param clone  if {@code true} the input arguments will be cloned
     * @param predicates  array of predicates, no nulls
     * @param closures  matching array of closures, no nulls
     * @param defaultClosure  the closure to use if no match, null means nop
     */
    @SuppressWarnings("unchecked")
    private SwitchClosure(final boolean clone, final Predicate<? super E>[] predicates,
                          final Closure<? super E>[] closures, final Closure<? super E> defaultClosure) {
        super();
        iPredicates = clone ? FunctorUtils.copy(predicates) : predicates;
        iClosures = clone ? FunctorUtils.copy(closures) : closures;
        iDefault = (Closure<? super E>) (defaultClosure == null ? NOPClosure.<E>nopClosure() : defaultClosure);
    }

    
Constructor that performs no validation.
Use switchClosure if you want that.
Params:
predicates –  array of predicates, cloned, no nulls
closures –  matching array of closures, cloned, no nulls
defaultClosure –  the closure to use if no match, null means nop/**
     * Constructor that performs no validation.
     * Use <code>switchClosure</code> if you want that.
     *
     * @param predicates  array of predicates, cloned, no nulls
     * @param closures  matching array of closures, cloned, no nulls
     * @param defaultClosure  the closure to use if no match, null means nop
     */
    public SwitchClosure(final Predicate<? super E>[] predicates, final Closure<? super E>[] closures,
                         final Closure<? super E> defaultClosure) {
        this(true, predicates, closures, defaultClosure);
    }

    
Executes the closure whose matching predicate returns true
Params:
input –  the input object/**
     * Executes the closure whose matching predicate returns true
     *
     * @param input  the input object
     */
    @Override
    public void execute(final E input) {
        for (int i = 0; i < iPredicates.length; i++) {
            if (iPredicates[i].evaluate(input) == true) {
                iClosures[i].execute(input);
                return;
            }
        }
        iDefault.execute(input);
    }

    
Gets the predicates.
Returns:
a copy of the predicates
Since:
3.1/**
     * Gets the predicates.
     *
     * @return a copy of the predicates
     * @since 3.1
     */
    public Predicate<? super E>[] getPredicates() {
        return FunctorUtils.<E>copy(iPredicates);
    }

    
Gets the closures.
Returns:
a copy of the closures
Since:
3.1/**
     * Gets the closures.
     *
     * @return a copy of the closures
     * @since 3.1
     */
    public Closure<? super E>[] getClosures() {
        return FunctorUtils.<E>copy(iClosures);
    }

    
Gets the default closure.
Returns:
the default closure
Since:
3.1/**
     * Gets the default closure.
     *
     * @return the default closure
     * @since 3.1
     */
    public Closure<? super E> getDefaultClosure() {
        return iDefault;
    }

}