<?php

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Adds the external stock field and ensures WooCommerce exposes combined stock values.
 */
class Siti_Stock_Inventory_Manager {

	/**
	 * @var string
	 */
	private $external_stock_key;

	/**
	 * @var string
	 */
	private $order_item_stock_source_key;

	/**
	 * @param string $meta_key Meta key used to store external stock.
	 */
	public function __construct( $meta_key ) {
		$this->external_stock_key         = $meta_key;
		$this->order_item_stock_source_key = '_siti_stock_source_breakdown';
	}

	/**
	 * Register relevant hooks.
	 */
	public function register_hooks() {
		add_action( 'woocommerce_product_options_stock_fields', array( $this, 'render_external_stock_field' ) );
		add_action( 'woocommerce_admin_process_product_object', array( $this, 'save_external_stock_value' ) );
		add_action( 'woocommerce_variation_options_inventory', array( $this, 'render_variation_external_stock_field' ), 10, 3 );
		add_action( 'woocommerce_save_product_variation', array( $this, 'save_variation_external_stock_value' ), 10, 2 );
		add_filter( 'woocommerce_product_get_stock_quantity', array( $this, 'filter_stock_quantity_with_external' ), 10, 2 );
		add_filter( 'woocommerce_product_variation_get_stock_quantity', array( $this, 'filter_stock_quantity_with_external' ), 10, 2 );
		add_filter( 'woocommerce_product_get_stock_status', array( $this, 'filter_stock_status_with_external' ), 10, 2 );
		add_filter( 'woocommerce_product_variation_get_stock_status', array( $this, 'filter_stock_status_with_external' ), 10, 2 );
		add_action( 'woocommerce_reduce_order_item_stock', array( $this, 'rebalance_stock_after_order_reduction' ), 20, 3 );
		add_action( 'woocommerce_after_order_itemmeta', array( $this, 'render_order_item_stock_source' ), 10, 3 );
		add_action( 'admin_enqueue_scripts', array( $this, 'enqueue_order_admin_assets' ) );
	}

	/**
	 * Render external stock field within the inventory tab.
	 */
	public function render_external_stock_field() {
		if ( ! function_exists( 'woocommerce_wp_text_input' ) ) {
			return;
		}

		global $product_object;

		if ( ! $product_object instanceof WC_Product ) {
			return;
		}

		$external_stock = $this->get_external_stock( $product_object );

		woocommerce_wp_text_input(
			array(
				'id'                => $this->external_stock_key,
				'value'             => $external_stock,
				'label'             => __( 'Externe voorraad', 'siti-stock-plugin' ),
				'desc_tip'          => true,
				'description'       => __( 'Voorraad beschikbaar op externe locatie(s).', 'siti-stock-plugin' ),
				'type'              => 'number',
				'custom_attributes' => array(
					'step' => '1',
					'min'  => '0',
				),
			)
		);
	}

	/**
	 * Persist external stock coming from the product edit screen.
	 *
	 * @param WC_Product $product Product being saved.
	 */
	public function save_external_stock_value( $product ) {
		if ( ! $product instanceof WC_Product ) {
			return;
		}

		if ( ! isset( $_POST[ $this->external_stock_key ] ) ) { // phpcs:ignore WordPress.Security.NonceVerification.Missing
			return;
		}

		$raw_value = wp_unslash( $_POST[ $this->external_stock_key ] ); // phpcs:ignore WordPress.Security.NonceVerification.Missing
		$value     = function_exists( 'wc_stock_amount' ) ? wc_stock_amount( $raw_value ) : (int) $raw_value;
		$value     = max( 0, (int) $value );

		$product->update_meta_data( $this->external_stock_key, $value );
	}

	/**
	 * Render the external stock field for each variation row.
	 *
	 * @param int        $loop           Loop index.
	 * @param array      $variation_data Raw variation data.
	 * @param WP_Post    $variation      Variation post object.
	 */
	public function render_variation_external_stock_field( $loop, $variation_data, $variation ) {
		unset( $variation_data );

		if ( ! function_exists( 'woocommerce_wp_text_input' ) ) {
			return;
		}

		$product = $variation instanceof WC_Product ? $variation : wc_get_product( $variation->ID );

		if ( ! $product instanceof WC_Product ) {
			return;
		}

		$external_stock = $this->get_external_stock( $product );
		$field_key      = 'variable_' . $this->external_stock_key;

		woocommerce_wp_text_input(
			array(
				'id'                => $this->external_stock_key . '_' . $loop,
				'name'              => $field_key . '[' . $loop . ']',
				'value'             => $external_stock,
				'label'             => __( 'Externe voorraad', 'siti-stock-plugin' ),
				'desc_tip'          => true,
				'description'       => __( 'Voorraad beschikbaar op externe locatie(s).', 'siti-stock-plugin' ),
				'type'              => 'number',
				'wrapper_class'     => 'form-row form-row-full',
				'custom_attributes' => array(
					'step' => '1',
					'min'  => '0',
				),
			)
		);
	}

	/**
	 * Persist external stock for variations.
	 *
	 * @param int $variation_id Variation post ID.
	 * @param int $index        Loop index.
	 */
	public function save_variation_external_stock_value( $variation_id, $index ) {
		$field_key = 'variable_' . $this->external_stock_key;

		if ( ! isset( $_POST[ $field_key ][ $index ] ) ) { // phpcs:ignore WordPress.Security.NonceVerification.Missing
			return;
		}

		$raw_value = wp_unslash( $_POST[ $field_key ][ $index ] ); // phpcs:ignore WordPress.Security.NonceVerification.Missing
		$value     = function_exists( 'wc_stock_amount' ) ? wc_stock_amount( $raw_value ) : (int) $raw_value;
		$value     = max( 0, (int) $value );

		update_post_meta( $variation_id, $this->external_stock_key, $value );
	}

	/**
	 * Ensure WooCommerce exposes combined stock (local + external) on the frontend.
	 *
	 * @param int|null   $stock   Stock reported by WooCommerce.
	 * @param WC_Product $product Product instance.
	 * @return int|null
	 */
	public function filter_stock_quantity_with_external( $stock, $product ) {
		if ( ! $product instanceof WC_Product || ! $product->managing_stock() ) {
			return $stock;
		}

		return $this->calculate_combined_stock( $product );
	}

	/**
	 * Mirror combined stock towards frontend stock status without touching edit context.
	 *
	 * @param string     $status  Current status.
	 * @param WC_Product $product Product instance.
	 * @return string
	 */
	public function filter_stock_status_with_external( $status, $product ) {
		if ( ! $product instanceof WC_Product || ! $product->managing_stock() ) {
			return $status;
		}

		$combined = $this->calculate_combined_stock( $product );

		if ( 'outofstock' === $status && $combined > 0 ) {
			return 'instock';
		}

		if ( 'instock' === $status && $combined <= 0 ) {
			return 'outofstock';
		}

		return $status;
	}

	/**
	 * Retrieve stored external stock value.
	 *
	 * @param WC_Product $product Product instance.
	 * @return int
	 */
	private function get_external_stock( $product ) {
		$raw = (int) $product->get_meta( $this->external_stock_key, true );

		return max( 0, $raw );
	}

	/**
	 * Calculate combined stock without triggering recursion.
	 *
	 * @param WC_Product $product Product instance.
	 * @return int
	 */
	private function calculate_combined_stock( $product ) {
		$raw_stock      = $product->get_stock_quantity( 'edit' );
		$base_stock     = function_exists( 'wc_stock_amount' ) ? wc_stock_amount( $raw_stock ) : (int) $raw_stock;
		$external_stock = $this->get_external_stock( $product );

		return max( 0, (int) $base_stock ) + $external_stock;
	}

	/**
	 * Determine the quantity reduced for the order item.
	 *
	 * @param WC_Order_Item_Product $item   Order line item.
	 * @param array<string,mixed>   $change Change context from WooCommerce.
	 * @return int
	 */
	private function determine_reduced_quantity( $item, $change ) {
		if ( ! is_array( $change ) ) {
			$change = array(
				'quantity' => $change,
			);
		}

		$from = isset( $change['from'] ) ? $change['from'] : null;
		$to   = isset( $change['to'] ) ? $change['to'] : null;

		if ( null !== $from && null !== $to ) {
			$qty = $from - $to;
		} elseif ( isset( $change['quantity'] ) ) {
			$qty = $change['quantity'];
		} elseif ( $item instanceof WC_Order_Item_Product ) {
			$qty = $item->get_quantity();
		} else {
			$qty = 0;
		}

		$qty = function_exists( 'wc_stock_amount' ) ? wc_stock_amount( $qty ) : (int) $qty;

		return max( 0, (int) $qty );
	}

	/**
	 * Record the stock source split for an order item.
	 *
	 * @param WC_Order_Item_Product $item         Order line item.
	 * @param WC_Product            $stock_holder Product that holds stock.
	 * @param int                   $quantity     Total reduced quantity.
	 */
	private function record_order_item_stock_source_breakdown( $item, $stock_holder, $quantity ) {
		$previous_local     = (int) $stock_holder->get_stock_quantity( 'edit' ) + $quantity;
		$local_available    = max( 0, $previous_local );
		$external_available = (int) $this->get_external_stock( $stock_holder );
		$from_local         = min( $quantity, $local_available );
		$remaining          = max( 0, $quantity - $from_local );
		$from_external      = min( $remaining, max( 0, $external_available ) );

		$existing = $item->get_meta( $this->order_item_stock_source_key, true );
		$existing = is_array( $existing )
			? array(
				'local'    => isset( $existing['local'] ) ? (int) $existing['local'] : 0,
				'external' => isset( $existing['external'] ) ? (int) $existing['external'] : 0,
			)
			: array(
				'local'    => 0,
				'external' => 0,
			);

		$existing['local']   += $from_local;
		$existing['external'] += $from_external;

		$item->update_meta_data( $this->order_item_stock_source_key, $existing );
		$item->save();
	}

	/**
	 * Ensure local stock only dips below zero when the external stock is depleted.
	 *
	 * @param WC_Order_Item_Product $item   Order line item that triggered the reduction.
	 * @param array                 $change Change context provided by WooCommerce.
	 * @param WC_Order              $order  Order instance (unused).
	 */
	public function rebalance_stock_after_order_reduction( $item, $change, $order ) {
		unset( $order );

		if ( ! $item instanceof WC_Order_Item_Product ) {
			return;
		}

		$product = $item->get_product();

		if ( ! $product instanceof WC_Product || ! $product->managing_stock() ) {
			return;
		}

		$managed_id   = $product->get_stock_managed_by_id();
		$stock_holder = ( $managed_id === $product->get_id() ) ? $product : wc_get_product( $managed_id );

		if ( ! $stock_holder instanceof WC_Product ) {
			return;
		}

		$quantity = $this->determine_reduced_quantity( $item, $change );

		if ( $quantity > 0 ) {
			$this->record_order_item_stock_source_breakdown( $item, $stock_holder, $quantity );
		}

		$current_local  = (int) $stock_holder->get_stock_quantity( 'edit' );
		$external_stock = $this->get_external_stock( $stock_holder );

		if ( $current_local >= 0 || $external_stock <= 0 ) {
			return;
		}

		$shortage     = min( abs( $current_local ), $external_stock );
		$new_local    = $current_local + $shortage;
		$new_external = $external_stock - $shortage;
		$needs_save   = false;

		if ( $new_local !== $current_local ) {
			$stock_holder->set_stock_quantity( $new_local );
			$needs_save = true;
		}

		if ( $new_external !== $external_stock ) {
			$stock_holder->update_meta_data( $this->external_stock_key, $new_external );
			$needs_save = true;
		}

		if ( $needs_save ) {
			$stock_holder->save();
		}
	}

	/**
	 * Display the recorded stock source on the admin order screen.
	 *
	 * @param int                     $item_id Order item ID.
	 * @param WC_Order_Item           $item    Order item instance.
	 * @param WC_Product|false        $product Product (unused).
	 */
	public function render_order_item_stock_source( $item_id, $item, $product ) {
		unset( $item_id, $product );

		if ( ! is_admin() || ! $item instanceof WC_Order_Item_Product ) {
			return;
		}

		$data = $item->get_meta( $this->order_item_stock_source_key, true );

		if ( ! is_array( $data ) ) {
			return;
		}

		$local    = isset( $data['local'] ) ? max( 0, (int) $data['local'] ) : 0;
		$external = isset( $data['external'] ) ? max( 0, (int) $data['external'] ) : 0;

		if ( $local <= 0 && $external <= 0 ) {
			return;
		}

		echo '<div class="siti-stock-order-item-sources">';
		echo '<span class="siti-stock-order-item-sources__label">' . esc_html__( 'Voorraadbron', 'siti-stock-plugin' ) . ':</span>';

		if ( $local > 0 ) {
			$local_label = sprintf(
				/* translators: %d: quantity fulfilled from regular stock. */
				_n( '%d uit reguliere voorraad', '%d uit reguliere voorraad', $local, 'siti-stock-plugin' ),
				$local
			);

			printf(
				'<span class="siti-stock-order-item-sources__badge is-local"><span class="dashicons dashicons-archive" aria-hidden="true"></span>%s</span>',
				esc_html( $local_label )
			);
		}

		if ( $external > 0 ) {
			$external_label = sprintf(
				/* translators: %d: quantity fulfilled from external stock. */
				_n( '%d uit externe voorraad', '%d uit externe voorraad', $external, 'siti-stock-plugin' ),
				$external
			);

			printf(
				'<span class="siti-stock-order-item-sources__badge is-external"><span class="dashicons dashicons-cloud" aria-hidden="true"></span>%s</span>',
				esc_html( $external_label )
			);
		}

		echo '</div>';
	}

	/**
	 * Enqueue lightweight styling on the order edit screen.
	 *
	 * @param string $hook Current admin hook.
	 */
	public function enqueue_order_admin_assets( $hook ) {
		if ( 'post.php' !== $hook && 'post-new.php' !== $hook ) {
			return;
		}

		if ( ! function_exists( 'get_current_screen' ) ) {
			return;
		}

		$screen = get_current_screen();

		if ( ! $screen || 'shop_order' !== $screen->post_type ) {
			return;
		}

		wp_enqueue_style(
			'siti-stock-order-admin',
			plugins_url( 'assets/css/order-admin.css', SITI_STOCK_PLUGIN_FILE ),
			array(),
			SITI_STOCK_PLUGIN_VERSION
		);
	}
}