<?php

// Posted for Stack Overflow:
// @see https://stackoverflow.com/questions/77198717/temporary-global-sale-price-discount-for-all-products-in-woocommerce

// Note this code supports WooCommerce Subscriptions.
// If you aren't using that, you need to remove the references to WC_Subscriptions_Product and the related functions.

// 1. Custom function that should return true if the user is a member.
// Modified to just check if you are an admin, but you could change this to look at your previous subscriptions
function MyPluginName_get_user_membership() {
	// $subscriptions = wcs_get_users_subscriptions( get_current_user_id() );
	return current_user_can('administrator');
}

// 2. Custom function that returns the membership product ID
// In my case, we only have one membership product
function MyPluginName_get_membership_product_id() {
	return 1234;
}

// 3. Object which handles all the hooks and logic for applying a membership discount
// Applies a 30% discount to all products except for the membership product itself
// Discount is also applied immediately if membership product is added to cart while not being a member yet.
class MyPluginName_Membership_Discount {
	
	public function __construct() {
		
		// Do not apply to the dashboard
		if ( is_admin() && ! is_ajax() ) return;
		
		// Add initial hooks
		$this->add_hooks();
		
	}
	
	/**
	 * Adds multiple hooks to apply the membership discount
	 *
	 * @return void
	 */
	public function add_hooks() {
		
		// Display the product price and membership price by default
		add_filter( 'woocommerce_get_price_html', array( $this, 'display_membership_price' ), 10, 2 );
		
		// Display the membership price for subscriptions
		add_filter( 'woocommerce_subscriptions_product_price_string', array( $this, 'display_membership_price_for_subscriptions' ), 10, 3 );
		
		// Replace the product prices with the membership prices
		add_filter( 'woocommerce_product_get_price', array( $this, 'replace_product_price_with_discount' ), 20, 2 );
		add_filter( 'woocommerce_product_variation_get_price', array( $this, 'replace_product_price_with_discount' ), 20, 2 );
		
		// Display the original product price below the product title on the cart page
		// (Without this, the sale price will show as the original price)
		add_filter( 'woocommerce_cart_product_price', array( $this, 'apply_member_discount_on_cart_price' ), 10, 2 );
		
		// Apply membership price to displayed cart subtotals
		// (Works for displayed subtotal on cart. Does not affect calculations)
		add_filter( 'woocommerce_cart_product_subtotal', array( $this, 'apply_member_discount_on_cart_product_subtotal' ), 10, 4 );
		
		// ❌ These filters did not work as expected:
		// --- add_filter( 'woocommerce_variable_subscription_price_html', array( $this, 'display_membership_price_for_subscriptions' ), 10, 2 );
		// --- add_filter( 'woocommerce_get_discounted_price', array( $this, 'apply_member_discount_on_cart_item' ), 10, 4 );
		// --- add_action( 'woocommerce_cart_calculate_fees', array( $this, 'add_membership_discount_on_checkout' ) );
		// --- add_filter( 'woocommerce_subscriptions_cart_get_price', array( $this, 'apply_member_discount_to_subscription_products' ), 10, 2 );
		
	}
	
	/**
	 * Removes hooks that apply a membership discount
	 *
	 * @return void
	 */
	public function remove_hooks() {
		remove_filter( 'woocommerce_get_price_html', array( $this, 'display_membership_price' ), 10, 2 );
		
		remove_filter( 'woocommerce_subscriptions_product_price_string', array( $this, 'display_membership_price_for_subscriptions' ), 10, 3 );
		
		remove_filter( 'woocommerce_product_get_price', array( $this, 'replace_product_price_with_discount' ), 20, 2);
		remove_filter( 'woocommerce_product_variation_get_price', array( $this, 'replace_product_price_with_discount' ), 20, 2);
		
		remove_filter( 'woocommerce_cart_product_price', array( $this, 'apply_member_discount_on_cart_price' ), 10, 2 );
		
		remove_filter( 'woocommerce_cart_product_subtotal', array( $this, 'apply_member_discount_on_cart_product_subtotal' ), 10, 4 );
	}
	
	// Singleton instance
	protected static $instance = null;
	
	public static function get_instance() {
		if ( !isset( self::$instance ) ) self::$instance = new static();
		return self::$instance;
	}
	
	// Utilities
	/**
	 * Returns the amount of discount to apply as a float. 0.3 = 30%
	 *
	 * @return float
	 */
	public function get_discount_amount() {
		return 0.3;
	}
	
	/**
	 * Returns true if the membership discount should apply to the current order.
	 * You must either already be a member, or have the membership product in your cart.
	 *
	 * @return bool
	 */
	public function is_discount_applied() {
		$has_membership = false; // already a member, or product in cart
		
		// Remove hooks to prevent infinite loops when getting membership product
		$this->remove_hooks();
		
		// Check if the user is a member or has the membership product in their cart
		do {
			
			// 1. Check if the user is a member
			$current_membership = MyPluginName_get_user_membership();
			if ( $current_membership ) {
				$has_membership = true;
				break;
			}
			
			// 2. Check if the membership product is in the cart
			if ( WC()->cart ) foreach ( WC()->cart->get_cart() as $item ) {
				$product = wc_get_product( $item['product_id'] );
				if ( $product->is_type( 'membership' ) ) {
					$has_membership = true;
					break 2;
				}
			}
			
		}while(false);
		
		// Re-add hooks
		$this->add_hooks();
		
		return $has_membership;
	}
	
	/**
	 * Checks if a product supports membership discount
	 * @param WC_Product|int $product
	 * @return bool
	 */
	public function is_product_eligible_for_discount( $product ) {
		$product = wc_get_product( $product );
		
		// 1. Do not apply membership discount to the membership itself
		$membership_product_id = MyPluginName_get_membership_product_id();
		
		if ( $product->get_id() === $membership_product_id || $product->get_parent_id() === $membership_product_id ) {
			return false;
		}
		
		return true;
	}
	
	/**
	 * Gets the text to add after membership prices
	 *
	 * @return string
	 */
	public function get_membership_discount_suffix() {
		$discount = $this->get_discount_amount();
		return ' (' . $discount * 100 . '% Member Discount)';
	}
	
	/**
	 * Get the regular price for a product
	 *
	 * @param WC_Product $product
	 *
	 * @return string
	 */
	public function get_regular_price( $product ) {
		$this->remove_hooks();
		
		// Prefer regular price by default
		$regular_price = $product->get_regular_price();
		
		// If blank, use the default price (For variations)
		if ( ! $regular_price ) $regular_price = $product->get_price();
		
		$this->add_hooks();
		
		return $regular_price;
	}
	
	/**
	 * Get the membership price for a product
	 * @param WC_Product|int $product
	 * @return float
	 */
	public function get_product_membership_price( $product ) {
		$this->remove_hooks();
		
		$product = wc_get_product( $product );
		$current_price = $product->get_price();
		$discount = $this->get_discount_amount();
		
		$this->add_hooks();
		
		if ( ! $current_price ) {
			return $current_price;
		}else{
			return $current_price - ( $current_price * $discount );
		}
	}
	
	/**
	 * Convert a price to a subscription term, for a subscription product. For example "$1 / month"
	 *
	 * @param string|float $price
	 * @param WC_Product $product
	 *
	 * @return string
	 */
	public function apply_subscription_formatting( $price, $product ) {
		$this->remove_hooks();
		
		if ( ! str_contains($price, '$') ) {
			$price = wc_price($price);
		}
		
		$formatted_price = WC_Subscriptions_Product::get_price_string( $product, array( 'price' => $price ) );
		
		$this->add_hooks();
		
		return $formatted_price;
	}

	/**
	 * Check if a product is a subscription
	 *
	 * @param WC_Product|int $product
	 *
	 * @return bool
	 */
	public function is_product_subscription( $product ) {
		return WC_Subscriptions_Product::is_subscription( $product );
	}

	/**
	 * Apply the membership discount formatting to products on the product page
	 *
	 * @param string $regular_price    Should already be formatted with wc_price()
	 * @param string $membership_price Should already be formatted with wc_price()
	 *
	 * @return string
	 */
	public function apply_product_discount_html( $regular_price, $membership_price ) {
		$discount_html = $this->get_membership_discount_suffix();
		
		return
			'<span class="woocommerce-Price-amount amount">' .
				'<span class="regular-price"><span class="label screen-reader-text">Price: </span>'. $regular_price . ' </span>' .
				'<span class="membership-price"><span class="label">Member\'s Price: </span>'. $membership_price . ' <span class="discount">'. $discount_html .'</span> </span>' .
			'</span>';
	}
	
	/**
	 * Apply the membership discount formatting to products on the cart
	 *
	 * @param string $regular_price    Should already be formatted with wc_price()
	 * @param string $membership_price Should already be formatted with wc_price()
	 *
	 * @return string
	 */
	public function apply_cart_discount_html( $regular_price, $membership_price ) {
		$discount_html = $this->get_membership_discount_suffix();
		
		return
			'<span class="cart-product-subtotal">'.
			'<span class="regular-price"><del>'. $regular_price . '</del> </span>'.
			'<span class="membership-price">' . $membership_price . '</span>'.
			'<span class="membership-discount">' . $discount_html . '</span>'.
			'</span>';
	}
	
	
	// Hooks
	
	/**
	 * Display the membership price
	 */
	public function display_membership_price( $price, $product ) {
		// Do not apply to admin
		if ( is_admin() ) return $price;
		
		// Do not apply to subscriptions
		/** @see self::display_membership_price_for_subscriptions() */
		if ( $this->is_product_subscription( $product ) ) {
			return $price;
		}
		
		// Product must support discount
		if ( ! $this->is_product_eligible_for_discount( $product ) ) {
			return $price;
		}
		
		// Ignore for grouped products, shows a price range instead
		if ( $product->is_type( 'grouped' ) ) {
			return $price;
		}
		
		// Get the regular price
		$regular_price = $this->get_regular_price( $product );
		
		// Do not format if price is empty
		if ( ! $regular_price ) {
			return $price;
		}
		
		// Get the membership price
		$membership_price = $this->get_product_membership_price( $product );
		
		return $this->apply_product_discount_html( wc_price( $regular_price ), wc_price( $membership_price ) );
	}
	
	/**
	 * Display the membership price for subscriptions
	 *
	 * @param string $price
	 * @param WC_Product $product
	 * @param array $include
	 *
	 * @return string
	 */
	public function display_membership_price_for_subscriptions( $price, $product, $include ) {
		// Do not apply to admin
		if ( is_admin() ) return $price;
		
		// Product must support discount
		if ( ! $this->is_product_eligible_for_discount( $product ) ) {
			return $price;
		}
		
		$this->remove_hooks();
		
		// Get the regular price
		$regular_price = $this->get_regular_price($product);
		
		// Do not show if price is empty
		if ( ! $regular_price ) {
			$this->add_hooks();
			return $regular_price;
		}
		
		// Get the membership price
		$membership_price = $this->get_product_membership_price( $product );
		
		$regular_price_subscription = $this->apply_subscription_formatting( $regular_price, $product );
		$membership_price_subscription = $this->apply_subscription_formatting( $membership_price, $product );
		
		// Display regular and membership prices
		if ( is_cart() ) {
			$html = $this->apply_cart_discount_html( $regular_price_subscription, $membership_price_subscription );
		}else{
			$html = $this->apply_product_discount_html( $regular_price_subscription, $membership_price_subscription );
		}
		
		$this->add_hooks();
		
		return $html;
	}
	
	/**
	 * Replace the product price with the membership price
	 *
	 * @param float $price
	 * @param WC_Product $product
	 *
	 * @return float
	 */
	public function replace_product_price_with_discount( $price, $product ) {
		
		// Product must support discount
		if ( ! $this->is_product_eligible_for_discount( $product ) ) {
			return $price;
		}
		
		if ( $this->is_discount_applied() ) {
			// Return the membership price
			return $this->get_product_membership_price( $product );
		}else{
			// Return the regular price
			return $price;
		}
		
	}
	
	/**
	 * Display the original product price below the product title on the cart page
	 *
	 * @param string $price
	 * @param WC_Product $product
	 *
	 * @return string
	 */
	public function apply_member_discount_on_cart_price( $price, $product ) {
		if ( ! $this->is_discount_applied() ) {
			return $price;
		}
		
		// Product must support discount
		if ( ! $this->is_product_eligible_for_discount( $product ) ) {
			return $price;
		}
		
		// Disable hooks to prevent infinite loops
		$this->remove_hooks();
		
		// Get the product
		$product = wc_get_product( $product );
		
		// Get the regular price
		$regular_price = $product->get_price();
		
		// Re-add hooks
		$this->add_hooks();
		
		return wc_price( $regular_price );
	}
	
	/**
	 * Apply the member discount on the cart subtotal
	 *
	 * @param string $subtotal
	 * @param WC_Product $product
	 * @param int $quantity
	 * @param WC_Cart $cart
	 *
	 * @return string
	 */
	public function apply_member_discount_on_cart_product_subtotal( $subtotal, $product, $quantity, $cart ) {
		if ( ! $this->is_discount_applied() ) {
			return $subtotal;
		}
		
		// Product must support discount
		if ( ! $this->is_product_eligible_for_discount( $product ) ) {
			return $subtotal;
		}
		
		// Remove hooks to prevent infinite loops
		$this->remove_hooks();
		
		// Get the product
		$product = wc_get_product( $product );
		
		// Get the regular price
		$regular_price = $product->get_price() * $quantity;
		$regular_price_html = wc_price( $regular_price );
		
		// Get the membership price
		$membership_price = $this->get_product_membership_price( $product ) * $quantity;
		$membership_price_html = wc_price( $membership_price );
		
		return $this->apply_cart_discount_html( $regular_price_html, $membership_price_html );
	}
	
}

// Initialize the object
MyPluginName_Membership_Discount::get_instance();