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/*
 *  Copyright (C) 2022 github.com/REAndroid
 *
 *  Licensed 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 com.reandroid.utils.collection;

import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.function.Predicate;

public class InstanceIterator implements Iterator {
    private final Iterator iterator;
    private final Class instance;
    private final Predicate filter;
    private T mCurrent;

    public InstanceIterator(Iterator iterator, Class instance, Predicate filter){
        this.iterator = iterator;
        this.instance = instance;
        this.filter = filter;
    }

    public InstanceIterator(Iterator iterator, Class instance){
        this(iterator, instance, null);
    }

    @SuppressWarnings("unchecked")
    @Override
    public boolean hasNext() {
        T current = mCurrent;
        if(current != null){
            return true;
        }
        Iterator iterator = this.iterator;
        Class instance = this.instance;
        Predicate filter = this.filter;
        while (iterator.hasNext()){
            Object obj = iterator.next();
            if(obj == null){
                continue;
            }
            if(instance.isInstance(obj)){
                current = (T)obj;
                if(filter == null || filter.test(current)){
                    mCurrent = current;
                    return true;
                }
            }
        }
        return false;
    }
    @Override
    public T next() {
        T current = mCurrent;
        if(current == null){
            throw new NoSuchElementException();
        }
        mCurrent = null;
        return current;
    }
    public static Iterator of(Iterator iterator, Class instance){
        if(!iterator.hasNext()){
            return EmptyIterator.of();
        }
        return new InstanceIterator<>(iterator, instance);
    }
    public static Iterator of(Iterator iterator, Class instance, Predicate filter){
        if(!iterator.hasNext()){
            return EmptyIterator.of();
        }
        return new InstanceIterator<>(iterator, instance, filter);
    }
}