LinkedButton

package com.landonjw.togapi.implementation.inventory.linked;

import com.landonjw.togapi.api.inventory.Button;
import com.landonjw.togapi.api.inventory.linked.LinkedButtonType;
import com.landonjw.togapi.api.inventory.linked.LinkedPage;
import net.minecraft.entity.player.EntityPlayerMP;
import net.minecraft.inventory.ClickType;
import net.minecraft.item.ItemStack;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.Objects;
import java.util.Optional;

/**
 * Creates a button that links to or characterizes a {@link LinkedPage}.
 *
 * @author landonjw
 * @since  2.1.0
 */
public class LinkedButton implements Button {

    /** The placeholder to substitute current page button is on. */
    public static final String CURRENT_PAGE_PLACEHOLDER = "{current}";
    /** The placeholder to substitute total page number. */
    public static final String TOTAL_PAGES_PLACEHOLDER = "{total}";

    /** The button that links to a page. */
    private Button button;
    /** The page that is being linked to. */
    private LinkedPage page;
    /** The {@link LinkedButtonType} of the button. */
    private LinkedButtonType buttonType;

    /**
     * Constructor for a linked button.
     *
     * @param button     the button that links to a page.
     * @param buttonType the page that is being linked to.
     */
    public LinkedButton(@Nonnull Button button, @Nonnull LinkedButtonType buttonType, @Nullable LinkedPage page){
        this.button = Objects.requireNonNull(button, "button must not be null");
        this.buttonType = Objects.requireNonNull(buttonType, "button type must not be null");
        this.page = page;
    }

    /**
     * Constructor for a linked button.
     *
     * @param button     the button that links to a page.
     * @param buttonType the page that is being linked to.
     */
    public LinkedButton(@Nonnull Button button, @Nonnull LinkedButtonType buttonType){
        this(button, buttonType, null);
    }

    /**
     * Sets the page the button links to.
     *
     * @param page the page the button links to
     */
    public void setLinkedPage(LinkedPage page){
        this.page = page;
    }

    /**
     * Gets the page the button is linked to.
     *
     * @return the page the button is linked to, if present
     */
    public Optional<LinkedPage> getLinkedPage(){
        return Optional.ofNullable(page);
    }

    /**
     * Gets the {@link LinkedButtonType} of the button.
     *
     * @return the button type
     */
    public LinkedButtonType getButtonType() {
        return buttonType;
    }

    /**
     * {@inheritDoc}
     *
     * <p>This will modify the display of the button if it is set as a 'current' linked button,
     * to replace current and total page numbers if the '{current}' or '{total}' placeholders are given.</p>
     */
    @Override
    public ItemStack getDisplay() {
        if(page != null){
            if(buttonType == LinkedButtonType.Current){
                ItemStack itemDisplay = button.getDisplay().copy();
                String displayName = itemDisplay.getDisplayName();
                displayName = displayName.replace(CURRENT_PAGE_PLACEHOLDER, "" + page.getPageNumber());
                displayName = displayName.replace(TOTAL_PAGES_PLACEHOLDER, "" + page.getTotalPages());
                itemDisplay.setStackDisplayName(displayName);
                return itemDisplay;
            }
        }
        return button.getDisplay();
    }

    /** {@inheritDoc} */
    @Override
    public void onClick(@Nonnull EntityPlayerMP player, @Nonnull ClickType clickType) {
        button.onClick(player, clickType);
        if(page != null){
            if(buttonType == LinkedButtonType.Previous){
                page.getPreviousPage().ifPresent((previousPage) -> {
                    previousPage.forceOpenPage(player);
                });
            }
            else if(buttonType == LinkedButtonType.Next){
                page.getNextPage().ifPresent((nextPage) -> {
                    nextPage.forceOpenPage(player);
                });
            }
        }
    }

}