package eu.univento.core.api.items;

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

/***************************
*    Pagifier by leNic    *
***************************/

/**
 * @author leNic
 * @version 1.0
 */
	public class Pagifier<T> {
	    // Properties
	    private int pageSize;
	    // List of pages
	    private List<List<T>> pages;
	    // Constructor
	    public Pagifier(int pageSize){
	        this.pageSize = pageSize;
	        this.pages = new ArrayList<>();
	        // Create first page
	        this.pages.add(new ArrayList<>());
	    }
	    /**
	     * Add item to pages
	     * (Creates a new page if the previous page is not existing or full)
	     * @param item The item you want to add
	     */
	    public void addItem(T item){
	        int pageNum = pages.size() - 1;
	        List<T> currentPage = this.pages.get(pageNum);
	        // Add page if full
	        if(currentPage.size() >= this.pageSize) {
	            currentPage = new ArrayList<>();
	            this.pages.add(currentPage);
	            pageNum++;
	        }
	        currentPage.add(item);
	    }
	    /**
	     * Get the items of a page
	     * @param pageNum Number of the page (beginning at 0)
	     * @return Optional with a list of the page's items
	     */
	    public Optional<List<T>> getPage(int pageNum){
	        if(this.pages.size() == 0)
	            return Optional.empty();
	        return Optional.of(this.pages.get(pageNum));
	    }
	    /**
	     * Get all pages
	     * @return List containing all pages
	     */
	    public List<List<T>> getPages(){
	        return this.pages;
	    }
	    /**
	     * Get the current set page size
	     * @return The current page size
	     */
	    public int getPageSize(){
	        return this.pageSize;
	    }
}