Discount Plugin and Adjuster

Friendsdiscount.php

<?php
/**
 * Friendsdiscount plugin for Craft CMS 3.x
 *
 * Price adjuster that gives discount if a specific product type has been purchased in a specific time frame
 *
 * @link      https://github.com/hendrikeng
 * @copyright Copyright (c) 2018 Hendrik Werner
 */

namespace hendrikeng\friendsdiscount;

use Craft;
use craft\base\Plugin;
use craft\services\Plugins;
use craft\events\PluginEvent;

use craft\commerce\services\OrderAdjustments;
use craft\events\RegisterComponentTypesEvent;
use hendrikeng\friendsdiscount\adjusters\FriendsDiscountAdjuster;

use yii\base\Event;

/**
 * Craft plugins are very much like little applications in and of themselves. We’ve made
 * it as simple as we can, but the training wheels are off. A little prior knowledge is
 * going to be required to write a plugin.
 *
 * For the purposes of the plugin docs, we’re going to assume that you know PHP and SQL,
 * as well as some semi-advanced concepts like object-oriented programming and PHP namespaces.
 *
 * https://craftcms.com/docs/plugins/introduction
 *
 * @author    Hendrik Werner
 * @package   Friendsdiscount
 * @since     1.0.0
 *
 */
class Friendsdiscount extends Plugin
{
    // Static Properties
    // =========================================================================

    /**
     * Static property that is an instance of this plugin class so that it can be accessed via
     * Friendsdiscount::$plugin
     *
     * @var Friendsdiscount
     */
    public static $plugin;

    // Public Properties
    // =========================================================================

    /**
     * To execute your plugin’s migrations, you’ll need to increase its schema version.
     *
     * @var string
     */
    public $schemaVersion = '1.0.0';


    // Public Methods
    // =========================================================================

    /**
     * Set our $plugin static property to this class so that it can be accessed via
     * Friendsdiscount::$plugin
     *
     * Called after the plugin class is instantiated; do any one-time initialization
     * here such as hooks and events.
     *
     * If you have a '/vendor/autoload.php' file, it will be loaded for you automatically;
     * you do not need to load it in your init() method.
     *
     */
    public function init()
    {
        parent::init();
        self::$plugin = $this;

        // Do something after we're installed
        Event::on(
            Plugins::class,
            Plugins::EVENT_AFTER_INSTALL_PLUGIN,
            function(PluginEvent $event) {
                if ($event->plugin === $this) {
                    // We were just installed
                }
            }
        );


        Event::on(
            OrderAdjustments::class,
            OrderAdjustments::EVENT_REGISTER_ORDER_ADJUSTERS,
            function(RegisterComponentTypesEvent $event) {
                $event->types[] = FriendsDiscountAdjuster::class;
            }
        );

        /**
         * Logging in Craft involves using one of the following methods:
         *
         * Craft::trace(): record a message to trace how a piece of code runs. This is mainly for development use.
         * Craft::info(): record a message that conveys some useful information.
         * Craft::warning(): record a warning message that indicates something unexpected has happened.
         * Craft::error(): record a fatal error that should be investigated as soon as possible.
         *
         * Unless `devMode` is on, only Craft::warning() & Craft::error() will log to `craft/storage/logs/web.log`
         *
         * It's recommended that you pass in the magic constant `__METHOD__` as the second parameter, which sets
         * the category to the method (prefixed with the fully qualified class name) where the constant appears.
         *
         * To enable the Yii debug toolbar, go to your user account in the AdminCP and check the
         * [] Show the debug toolbar on the front end & [] Show the debug toolbar on the Control Panel
         *
         * http://www.yiiframework.com/doc-2.0/guide-runtime-logging.html
         */
        Craft::info(
            Craft::t(
                'friendsdiscount',
                '{name} plugin loaded',
                ['name' => $this->name]
            ),
            __METHOD__
        );
    }

    // Protected Methods
    // =========================================================================

}

FriendsDiscountAdjuster.php

<?php

namespace craft\commerce\adjusters;

use Craft;
use craft\commerce\base\AdjusterInterface;
use craft\commerce\elements\Order;
use craft\commerce\models\OrderAdjustment;
use craft\commerce\Plugin;

class FriendsDiscountAdjuster implements AdjusterInterface
{

    /**
     * Check if the customer has lineItems with product.type 'donation'
     * in his current cart and if the donation is more than $75.
     */
    public function checkIfInCart($order)
    {
        // get current cart
        $cart = Plugin::getInstance()->getCart();
        $didDonate = false;

        // get lineItems from current cart and check if rules apply
        foreach ($cart->getLineItems() as $lineItem) {
            $purchable = $lineItem->getPurchasable();
            if ($purchable && $purchable instanceof \craft\commerce\elements\Variant && $purchable->getProduct()->getType()->handle == 'donation' && $purchable->getPrice() >= '75') {
                $didDonate = true;
            }
        }
        return $didDonate;
    }

    /**
     * Check if the customer has bought a lineItem with product.type 'donation'
     * in his previous orders and if the donation was more than $75.
     * and not older than 365 days
     */
    public function checkIfDonated($order)
    {
        // get users email
        $email = $order->getEmail();

        if (!$email) {
            return false;
        }

        // get previous orders by users email
        $orders = Plugin::getInstance()->getOrders()->getOrdersByEmail($email);

        $didDonate = false;

        // get pervious orders and check if rules apply
        foreach ($orders as $previousOrder) {
            // get amount of days since the order has been placed
            $timeDiff = abs(strtotime(date('Y/m/d', time())) - strtotime($previousOrder->dateOrdered->format('Y/m/d')));
            $numberDays = intval($timeDiff / 86400);
            // if order is not older than 365 days return didDontate with true
            if ($numberDays <= '365') {
                foreach ($previousOrder->getLineItems() as $lineItem) {
                    $purchable = $lineItem->getPurchasable();
                    if ($purchable && $purchable instanceof \craft\commerce\elements\Variant && $purchable->getProduct()->getType()->handle == 'donation' && $purchable->getPrice() >= '75' && $purchable) {
                        $didDonate = true;
                    }
                }
            }
        }
        return $didDonate;
    }
    
    /**
     * Apply dicount if customer donated
     */
    public function adjust(Order $order): array
    {

        // get the current cart
        $cart = Plugin::getInstance()->getCart();

        // check if a donation is in current cart or in a previous order
        if ($this->checkIfInCart($order) == true || $this->checkIfDonated($order) == true) {
            // get lineitems from cart to apply discount on
            foreach ($cart->getLineItems() as $lineItem) {
                $purchable = $lineItem->getPurchasable();
                $quantity = $lineItem->qty;
                // check if lineitems belong to the productype shop
                if ($purchable && $purchable instanceof \craft\commerce\elements\Variant && $purchable->getProduct()->getType()->handle == 'shop') {
                    // apply discount
                    $purchablePrice = $purchable->getPrice();
                    $discountValues[] = $purchablePrice * 0.4 * $quantity;
                }
            }

            // sum up all dicountValues
            $totalDiscount = array_sum($discountValues);

            // set new OrderAdjustment $friendAdjuster
            $friendsDiscountAdjuster = new OrderAdjustment();
            $friendsDiscountAdjuster->type = "Freundesrabatt";
            $friendsDiscountAdjuster->name = "40% Freundesrabatt";
            $friendsDiscountAdjuster->amount = -$totalDiscount;
            $friendsDiscountAdjuster->description = $friendsDiscountAdjuster->amount;
            $friendsDiscountAdjuster->orderId = $order->id;
            $friendsDiscountAdjuster->included = false;

            return [$friendsDiscountAdjuster];
        }
        return [];
    }
}