<?php

namespace App\Service\Cart;

use App\Entity\CartItem;
use App\DTO\CartTreeNode;
use App\Entity\Category;
use App\Service\Utils\CategoryUtils;

/**
 * Class CartTreeBuilder.
 */
class CartTreeBuilder
{
    /**
     * @var array|CartItem[]
     */
    private $cartItems = [];

    /**
     * @var array|Category[]
     */
    private $categories = [];

    /**
     * @var array|CartTreeNode[]
     */
    private $tree = [];

    /**
     * CartTreeBuilder constructor.
     *
     * @param CategoryUtils $categoryUtils
     */
    public function __construct(CategoryUtils $categoryUtils)
    {
        $this->categories = $categoryUtils->getAllCategories();
    }

    /**
     * @param array $cartItems
     *
     * @return array|CartTreeNode[]
     */
    public function build(array $cartItems): array
    {
        $this->cartItems = $cartItems;

        $this->buildRootNodes();

        foreach ($this->tree as $rootNode) {
            $this->buildBranch($this->fillRootNodeWithCartItems($rootNode));

            if (0 === $rootNode->getCartItemsCount()) {
                unset($this->tree[array_search($rootNode, $this->tree)]);
            }
        }

        $result = $this->tree;

        $this->clearProperties();

        return $result;
    }

    private function buildRootNodes(): void
    {
        foreach ($this->categories as $category) {
            if (is_null($category->getParent())) {
                $node = new CartTreeNode();
                $node->setParent(null);
                $node->setCategory($category);

                $this->tree[] = $node;
            }
        }
    }

    /**
     * @param CartTreeNode $rootNode
     *
     * @return CartTreeNode
     */
    private function fillRootNodeWithCartItems(CartTreeNode $rootNode): CartTreeNode
    {
        foreach ($this->cartItems as $cartItem) {
            if ($cartItem->getItem()->getCategory() === $rootNode->getCategory()) {
                $remainsCount = $this->getRemainsCountByCartItem($cartItem);

                $rootNode->addCartItem($cartItem);
                $rootNode->setTotalPrice($rootNode->getTotalPrice() + $cartItem->getItem()->getPrice() * $remainsCount);
                $rootNode->setCartItemsCount($rootNode->getCartItemsCount() + $remainsCount);

                unset($this->cartItems[array_search($cartItem, $this->cartItems)]);
            }
        }

        return $rootNode;
    }

    /**
     * @param CartTreeNode $rootNode
     */
    private function buildBranch(CartTreeNode $rootNode): void
    {
        foreach ($this->categories as $category) {
            foreach ($this->cartItems as $cartItem) {
                if ($cartItem->getItem()->getCategory() === $category) {
                    $currentNode = $this->getChildNode($rootNode, $category, $cartItem);
                    $remainsCount = $this->getRemainsCountByCartItem($cartItem);

                    $currentNode->addCartItem($cartItem);
                    $currentNode->setTotalPrice($currentNode->getTotalPrice() + $cartItem->getItem()->getPrice() * $remainsCount);
                    $currentNode->setCartItemsCount($currentNode->getCartItemsCount() + $remainsCount);

                    unset($this->cartItems[array_search($cartItem, $this->cartItems)]);

                    $rootNode->setTotalPrice($rootNode->getTotalPrice() + $currentNode->getTotalPrice());
                    $rootNode->setCartItemsCount($rootNode->getCartItemsCount() + $remainsCount);
                }
            }
        }
    }

    /**
     * Возвращает существующую ноду-потомок или создает ее.
     *
     * @param CartTreeNode $cartTreeNode
     * @param Category     $category
     * @param CartItem     $cartItem
     *
     * @return CartTreeNode
     */
    private function getChildNode(CartTreeNode $cartTreeNode, Category $category, CartItem $cartItem): CartTreeNode
    {
        foreach ($cartTreeNode->getChildren() as $children) {
            if ($children->getCategory() === $category && $cartItem->getItem()->getCategory() === $category) {
                return $children;
            }
        }

        $childNode = new CartTreeNode();
        $childNode->setCategory($category);
        $childNode->setParent($cartTreeNode);

        $cartTreeNode->addChild($childNode);

        return $childNode;
    }

    /**
     * @param CartItem $cartItem
     *
     * @return int
     */
    private function getRemainsCountByCartItem(CartItem $cartItem): int
    {
        $count = 0;

        foreach ($cartItem->getCartItemRemains() as $remain) {
            $count += $remain->getCount();
        }

        return $count;
    }

    private function clearProperties(): void
    {
        $this->tree = [];
        $this->cartItems = [];
        $this->categories = [];
    }
}