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/**
 * JBoss, Home of Professional Open Source.
 * Copyright 2014-2022 Red Hat, Inc., and individual contributors
 * as indicated by the @author tags.
 *
 * 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 org.jboss.pnc.client;

import org.jboss.pnc.dto.response.Page;
import org.jboss.pnc.rest.api.parameters.PageParameters;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.function.Consumer;
import java.util.function.Function;

/**
 * @author Matej Lazar
 */
public class DefaultRemoteCollection implements RemoteCollection {

    private final Logger logger = LoggerFactory.getLogger(DefaultRemoteCollection.class);

    private Function> endpoint;

    private RemoteCollectionConfig config;

    protected Page currentPage;

    public DefaultRemoteCollection(Function> endpoint, RemoteCollectionConfig config) {
        this.endpoint = endpoint;
        this.config = config;
        PageParameters intialPageParameters = new PageParameters();
        intialPageParameters.setPageIndex(0);
        intialPageParameters.setPageSize(config.getPageSize());
        logger.debug("Loading first page.");
        currentPage = endpoint.apply(intialPageParameters);
    }

    @Override
    public int size() {
        return currentPage.getTotalHits();
    }

    @Override
    public Iterator iterator() {
        return new RemoteIterator();
    }

    @Override
    public Collection getAll() {
        List list = new ArrayList<>();
        forEach(list::add);
        return list;
    }

    @Override
    public void forEach(Consumer action) {
        final Iterator iterator = iterator();
        while (iterator.hasNext()) {
            action.accept(iterator.next());
        }
    }

    private Page loadNextPage(Function> endpoint, Page currentPage) {
        int newPageIndex = currentPage.getPageIndex() + 1;
        logger.debug("Loading new page. Index {}", newPageIndex);
        PageParameters pageParametersNext = new PageParameters();
        pageParametersNext.setPageSize(currentPage.getPageSize());
        pageParametersNext.setPageIndex(newPageIndex);
        return endpoint.apply(pageParametersNext);
    }

    private class RemoteIterator implements Iterator {

        private Iterator iterator;

        public RemoteIterator() {
            this.iterator = currentPage.getContent().iterator();
        }

        @Override
        public boolean hasNext() {
            if (iterator.hasNext()) {
                return true;
            } else if (currentPage.getPageIndex() < currentPage.getTotalPages() - 1) {
                currentPage = loadNextPage(endpoint, currentPage);
                iterator = currentPage.getContent().iterator();
                return iterator.hasNext();
            } else {
                return false;
            }
        }

        @Override
        public T next() {
            if (hasNext()) {
                return iterator.next();
            } else {
                throw new NoSuchElementException();
            }
        }
    }
}