ChestShop-3/src/main/java/com/Acrobot/Breeze/Utils/InventoryUtil.java

package com.Acrobot.Breeze.Utils;

import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import org.bukkit.inventory.Inventory;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.meta.BookMeta;

/**
 * @author Acrobot
 */
public class InventoryUtil {
    private static Boolean legacyContents = null;
   
    private static ItemStack[] getStorageContents(Inventory inventory) {
        if (legacyContents == null) {
            try {
                inventory.getStorageContents();
                legacyContents = false;
            } catch (NoSuchMethodError e) {
                legacyContents = true;
            }
        }

        return legacyContents ? inventory.getContents() : inventory.getStorageContents();
    }

    /**
     * Returns the amount of the item inside the inventory
     *
     * @param item      Item to check
     * @param inventory inventory
     * @return amount of the item
     */
    public static int getAmount(ItemStack item, Inventory inventory) {
        if (!inventory.contains(item.getType())) {
            return 0;
        }

        if (inventory.getType() == null) {
            return Integer.MAX_VALUE;
        }

        HashMap<Integer, ? extends ItemStack> items = inventory.all(item.getType());
        int itemAmount = 0;

        for (ItemStack iStack : items.values()) {
            if (!MaterialUtil.equals(iStack, item)) {
                continue;
            }

            itemAmount += iStack.getAmount();
        }

        return itemAmount;
    }

    /**
     * Tells if the inventory is empty
     *
     * @param inventory inventory
     * @return Is the inventory empty?
     */
    public static boolean isEmpty(Inventory inventory) {
        for (ItemStack stack : getStorageContents(inventory)) {
            if (!MaterialUtil.isEmpty(stack)) {
                return false;
            }
        }

        return true;
    }

    /**
     * Checks if the inventory has stock of this type
     *
     * @param items     items
     * @param inventory inventory
     * @return Does the inventory contain stock of this type?
     */
    public static boolean hasItems(ItemStack[] items, Inventory inventory) {
        for (ItemStack item : items) {
            if (getAmount(item, inventory) < item.getAmount()) {
                return false;
            }
        }

        return true;
    }

    /**
     * Checks if the item fits the inventory
     *
     * @param item      Item to check
     * @param inventory inventory
     * @return Does item fit inside inventory?
     */
    public static boolean fits(ItemStack item, Inventory inventory) {
        int left = item.getAmount();

        if (inventory.getMaxStackSize() == Integer.MAX_VALUE) {
            return true;
        }

        for (ItemStack iStack : getStorageContents(inventory)) {
            if (left <= 0) {
                return true;
            }

            if (MaterialUtil.isEmpty(iStack)) {
                left -= item.getMaxStackSize();
                continue;
            }

            if (!MaterialUtil.equals(iStack, item)) {
                continue;
            }

            left -= (iStack.getMaxStackSize() - iStack.getAmount());
        }

        return left <= 0;
    }

    /**
     * Adds an item to the inventory with given maximum stack size
     *
     * @param item         Item to add
     * @param inventory    Inventory
     * @param maxStackSize Maximum item's stack size
     * @return Number of leftover items
     */
    public static int add(ItemStack item, Inventory inventory, int maxStackSize) {
        if (item.getAmount() < 1) {
            return 0;
        }

        if (maxStackSize == item.getMaxStackSize()) {
            return add(item, inventory);
        }

        return addManually(item, inventory, maxStackSize);
    }

    private static int addManually(ItemStack item, Inventory inventory, int maxStackSize) {
        int amountLeft = item.getAmount();

        for (int currentSlot = 0; currentSlot < effectiveSize(inventory) && amountLeft > 0; currentSlot++) {
            ItemStack currentItem = inventory.getItem(currentSlot);

            if (MaterialUtil.isEmpty(currentItem)) {
                currentItem.setAmount(Math.min(amountLeft, maxStackSize));

                amountLeft -= currentItem.getAmount();
            } else if (currentItem.getAmount() < maxStackSize && MaterialUtil.equals(currentItem, item)) {
                int neededToAdd = Math.min(maxStackSize - currentItem.getAmount(), amountLeft);

                currentItem.setAmount(currentItem.getAmount() + neededToAdd);

                amountLeft -= neededToAdd;
            }
        }
        return amountLeft;
    }

    // Don't use the armor slots or extra slots
    private static int effectiveSize(Inventory inventory)
    {
        return getStorageContents(inventory).length;
    }

    /**
     * Adds an item to the inventor
     *
     * @param item      Item to add
     * @param inventory Inventory
     * @return Number of leftover items
     */
    public static int add(ItemStack item, Inventory inventory) {
        Map<Integer, ItemStack> leftovers = inventory.addItem(item.clone()); // item needs to be cloned as cb changes the amount of the stack size

        if (!leftovers.isEmpty()) {
            for (Iterator<ItemStack> iterator = leftovers.values().iterator(); iterator.hasNext(); ) {
                ItemStack left = iterator.next();
                int amountLeft = addManually(left, inventory, left.getMaxStackSize());
                if (amountLeft == 0) {
                    iterator.remove();
                } else {
                    left.setAmount(amountLeft);
                }
            }
        }

        return countItems(leftovers);
    }

    /**
     * Removes an item from the inventory
     *
     * @param item      Item to remove
     * @param inventory Inventory
     * @return Number of items that couldn't be removed
     */
    public static int remove(ItemStack item, Inventory inventory) {
        Map<Integer, ItemStack> leftovers = inventory.removeItem(item);

        if (!leftovers.isEmpty()) {
            for (Iterator<ItemStack> iterator = leftovers.values().iterator(); iterator.hasNext(); ) {
                ItemStack left = iterator.next();
                if (removeManually(left, inventory) == 0) {
                    iterator.remove();
                }
            }
        }

        return countItems(leftovers);
    }

    private static int removeManually(ItemStack item, Inventory inventory) {
        int amountLeft = item.getAmount();

        for (int currentSlot = 0; currentSlot < effectiveSize(inventory) && amountLeft > 0; currentSlot++) {
            ItemStack currentItem = inventory.getItem(currentSlot);

            if (currentItem != null && MaterialUtil.equals(currentItem, item)) {
                int neededToRemove = Math.min(currentItem.getAmount(), amountLeft);

                currentItem.setAmount(currentItem.getAmount() - neededToRemove);

                amountLeft -= neededToRemove;
            }
        }
        return amountLeft;
    }

    /**
     * If items in arguments are similar, this function merges them into stacks of the same type
     *
     * @param items Items to merge
     * @return Merged stack array
     */
    public static ItemStack[] mergeSimilarStacks(ItemStack... items) {
        if (items.length <= 1) {
            return items;
        }

        List<ItemStack> itemList = new LinkedList<ItemStack>();

        Iterating:
        for (ItemStack item : items) {
            for (ItemStack iStack : itemList) {
                if (MaterialUtil.equals(item, iStack)) {
                    iStack.setAmount(iStack.getAmount() + item.getAmount());
                    continue Iterating;
                }
            }

            itemList.add(item);
        }

        return itemList.toArray(new ItemStack[itemList.size()]);
    }

    /**
     * Counts the amount of items in ItemStacks
     *
     * @param items ItemStacks of items to count
     * @return How many items are there?
     */
    public static int countItems(ItemStack... items) {
        int count = 0;

        for (ItemStack item : items) {
            count += item.getAmount();
        }

        return count;
    }

    /**
     * Counts leftovers from a map
     *
     * @param items Leftovers
     * @return Number of leftovers
     */
    public static int countItems(Map<Integer, ItemStack> items) {
        int totalLeft = 0;

        for (ItemStack left : items.values()) {
            totalLeft += left.getAmount();
        }

        return totalLeft;
    }
}