com.trenako.web.infrastructure.PageLinksBuilder.java Source code

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Here is the source code for com.trenako.web.infrastructure.PageLinksBuilder.java

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/*
 * Copyright 2012 the original author or authors.
 *
 * 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.trenako.web.infrastructure;

import java.util.ArrayList;
import java.util.List;

import org.springframework.data.domain.Page;

/**
 * It represents a page links builder.
 *
 * @author Carlo Micieli
 */
public class PageLinksBuilder<T> {
    public static int DEFAULT_MAX_LINKED_PAGES = 10;
    public static int DEFAULT_PAGE_SIZE = 25;

    public PageLinksBuilder(Page<T> page) {
        this(page.getContent(), page.getNumberOfElements(), page.getTotalPages());
    }

    public PageLinksBuilder(List<T> data, long nrOfElements, int page) {
        this(data, nrOfElements, page, DEFAULT_PAGE_SIZE);
    }

    public PageLinksBuilder(List<T> data, long nrOfElements, int page, int pageSize) {
        if (pageSize <= 0)
            throw new IllegalArgumentException();

        this.data = data;
        this.page = page;
        this.pageSize = pageSize;
        this.nrOfElements = nrOfElements;

        this.pageCount = calculateNumberOfPages(nrOfElements, pageSize);
        this.links = initLinks();

        this.firstPageLink = Math.max(1, getPage() - (DEFAULT_MAX_LINKED_PAGES / 2) - 1);
        this.lastPageLink = Math.min(getFirstPageLink() + DEFAULT_MAX_LINKED_PAGES - 1, getPageCount());
    }

    private List<Integer> links;
    private List<T> data;
    private int page;
    private int pageSize;
    private int pageCount;
    private long nrOfElements;
    private int firstPageLink;
    private int lastPageLink;

    private int calculateNumberOfPages(long nrOfElements, int pageSize) {
        double d = Math.ceil((double) nrOfElements / pageSize);
        return (int) d;
    }

    private List<Integer> initLinks() {
        List<Integer> l = new ArrayList<>();

        for (int i = 1; i <= getPageCount(); i++)
            l.add(i);

        return l;
    }

    public List<T> getData() {
        return data;
    }

    public int getPageCount() {
        return pageCount;
    }

    public int getPage() {
        return page;
    }

    public int getPageSize() {
        return pageSize;
    }

    public long getNrOfElements() {
        return nrOfElements;
    }

    public boolean isLastPage() {
        return getPage() == getPageCount();
    }

    public boolean isFirstPage() {
        return getPage() == 1;
    }

    public int getFirstPageLink() {
        return firstPageLink;
    }

    public int getLastPageLink() {
        return lastPageLink;
    }

    public List<Integer> getPageLinks() {
        return links.subList(getFirstPageLink() - 1, getLastPageLink());
    }

    public boolean showPreviousLink() {
        return getPage() > 1;
    }

    public boolean showNextLink() {
        return getPage() < getPageCount();
    }
}