<?php
/**
 * Product Sync from Business Central to WooCommerce
 *
 * @package WooBusinessCentral
 */

// Prevent direct access
if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

/**
 * Class WBC_Product_Sync
 *
 * Handles syncing stock and pricing from Business Central to WooCommerce.
 */
class WBC_Product_Sync {

    /**
     * Items per page for BC API pagination
     */
    const ITEMS_PER_PAGE = 100;

    /**
     * Fields to select from BC items
     */
    const SELECT_FIELDS = 'id,number,gtin,displayName,unitPrice,inventory';

    /**
     * Sync results
     *
     * @var array
     */
    private $results = array(
        'success'  => 0,
        'failed'   => 0,
        'skipped'  => 0,
        'total'    => 0,
        'errors'   => array(),
    );

    /**
     * Run the product sync
     *
     * @return array Sync results.
     */
    public function run_sync() {
        // Check if sync is enabled
        if ( get_option( 'wbc_enable_stock_sync', 'yes' ) !== 'yes' && get_option( 'wbc_enable_price_sync', 'yes' ) !== 'yes' ) {
            WBC_Logger::info( 'ProductSync', 'Sync skipped - both stock and price sync are disabled' );
            return array(
                'success' => true,
                'message' => __( 'Sync skipped - both stock and price sync are disabled.', 'woo-business-central' ),
            );
        }

        // Check if credentials are configured
        if ( ! WBC_OAuth::is_configured() ) {
            WBC_Logger::error( 'ProductSync', 'Sync failed - API credentials not configured' );
            return array(
                'success' => false,
                'message' => __( 'Sync failed - API credentials not configured.', 'woo-business-central' ),
            );
        }

        WBC_Logger::info( 'ProductSync', 'Starting product sync' );

        $start_time = microtime( true );
        $skip = 0;
        $has_more = true;

        // Fetch all items from BC with pagination
        while ( $has_more ) {
            $items = $this->fetch_items( $skip );

            if ( is_wp_error( $items ) ) {
                $this->results['errors'][] = $items->get_error_message();
                WBC_Logger::error( 'ProductSync', 'Failed to fetch items from BC', array(
                    'error' => $items->get_error_message(),
                    'skip'  => $skip,
                ) );
                break;
            }

            // Check if we have items
            $item_list = isset( $items['value'] ) ? $items['value'] : array();

            if ( empty( $item_list ) ) {
                $has_more = false;
                break;
            }

            // Process each item
            foreach ( $item_list as $item ) {
                $this->process_item( $item );
            }

            // Check for more pages
            $skip += self::ITEMS_PER_PAGE;
            $has_more = count( $item_list ) >= self::ITEMS_PER_PAGE;

            // Add a small delay to avoid rate limiting
            if ( $has_more ) {
                usleep( 100000 ); // 100ms
            }
        }

        $duration = round( microtime( true ) - $start_time, 2 );

        WBC_Logger::info( 'ProductSync', 'Product sync completed', array(
            'duration_seconds' => $duration,
            'total'            => $this->results['total'],
            'success'          => $this->results['success'],
            'failed'           => $this->results['failed'],
            'skipped'          => $this->results['skipped'],
        ) );

        return array(
            'success'  => empty( $this->results['errors'] ),
            'message'  => sprintf(
                __( 'Sync completed in %s seconds. Success: %d, Failed: %d, Skipped: %d', 'woo-business-central' ),
                $duration,
                $this->results['success'],
                $this->results['failed'],
                $this->results['skipped']
            ),
            'results'  => $this->results,
        );
    }

    /**
     * Fetch items from Business Central
     *
     * @param int $skip Number of items to skip.
     * @return array|WP_Error Items data or error.
     */
    private function fetch_items( $skip = 0 ) {
        return WBC_API_Client::get_items( self::ITEMS_PER_PAGE, $skip, self::SELECT_FIELDS );
    }

    /**
     * Process a single BC item
     *
     * @param array $item BC item data.
     */
    private function process_item( $item ) {
        $this->results['total']++;

        // Get item number and GTIN
        $item_number = isset( $item['number'] ) ? $item['number'] : '';
        $gtin = isset( $item['gtin'] ) ? $item['gtin'] : '';

        if ( empty( $item_number ) && empty( $gtin ) ) {
            $this->results['skipped']++;
            WBC_Logger::debug( 'ProductSync', 'Skipping item without number or GTIN', array( 'item' => $item ) );
            return;
        }

        // Try to find WooCommerce product
        $product_id = $this->find_wc_product( $item_number, $gtin );

        if ( ! $product_id ) {
            $this->results['skipped']++;
            WBC_Logger::debug( 'ProductSync', 'No matching WC product found', array(
                'item_number' => $item_number,
                'gtin'        => $gtin,
            ) );
            return;
        }

        // Get the product
        $product = wc_get_product( $product_id );

        if ( ! $product ) {
            $this->results['skipped']++;
            WBC_Logger::warning( 'ProductSync', 'Product ID found but product not loaded', array(
                'product_id' => $product_id,
            ) );
            return;
        }

        // Update the product
        $updated = $this->update_product( $product, $item );

        if ( $updated ) {
            $this->results['success']++;
        } else {
            $this->results['failed']++;
        }
    }

    /**
     * Find WooCommerce product by SKU (item number or GTIN)
     *
     * @param string $item_number BC item number.
     * @param string $gtin        BC GTIN/EAN.
     * @return int|false Product ID or false if not found.
     */
    private function find_wc_product( $item_number, $gtin ) {
        // First try to match by item number (SKU)
        if ( ! empty( $item_number ) ) {
            $product_id = wc_get_product_id_by_sku( $item_number );
            if ( $product_id ) {
                return $product_id;
            }
        }

        // Fall back to GTIN match
        if ( ! empty( $gtin ) ) {
            $product_id = wc_get_product_id_by_sku( $gtin );
            if ( $product_id ) {
                return $product_id;
            }
        }

        return false;
    }

    /**
     * Update WooCommerce product with BC data
     *
     * @param WC_Product $product WooCommerce product.
     * @param array      $item    BC item data.
     * @return bool Whether the product was updated.
     */
    private function update_product( $product, $item ) {
        $product_id = $product->get_id();
        $updated = false;

        try {
            // Update stock if enabled
            if ( get_option( 'wbc_enable_stock_sync', 'yes' ) === 'yes' ) {
                $stock = isset( $item['inventory'] ) ? (float) $item['inventory'] : 0;
                $current_stock = (float) $product->get_stock_quantity();

                if ( $stock !== $current_stock ) {
                    // Enable stock management if not already enabled
                    if ( ! $product->get_manage_stock() ) {
                        $product->set_manage_stock( true );
                    }

                    wc_update_product_stock( $product, $stock );
                    $updated = true;

                    WBC_Logger::debug( 'ProductSync', 'Updated stock', array(
                        'product_id' => $product_id,
                        'old_stock'  => $current_stock,
                        'new_stock'  => $stock,
                    ) );
                }
            }

            // Update price if enabled
            if ( get_option( 'wbc_enable_price_sync', 'yes' ) === 'yes' ) {
                $price = isset( $item['unitPrice'] ) ? (float) $item['unitPrice'] : 0;
                $current_price = (float) $product->get_regular_price();

                if ( $price > 0 && $price !== $current_price ) {
                    $product->set_regular_price( $price );

                    // Also update sale price if it's higher than the new regular price
                    $sale_price = (float) $product->get_sale_price();
                    if ( $sale_price > 0 && $sale_price >= $price ) {
                        $product->set_sale_price( '' );
                    }

                    $product->save();
                    $updated = true;

                    WBC_Logger::debug( 'ProductSync', 'Updated price', array(
                        'product_id' => $product_id,
                        'old_price'  => $current_price,
                        'new_price'  => $price,
                    ) );
                }
            }

            // Store BC item info in meta via WooCommerce CRUD
            $product->update_meta_data( '_wbc_bc_item_id', $item['id'] ?? '' );
            $product->update_meta_data( '_wbc_bc_item_number', $item['number'] ?? '' );
            $product->update_meta_data( '_wbc_last_sync', current_time( 'mysql' ) );
            $product->save();

            return true;

        } catch ( Exception $e ) {
            WBC_Logger::error( 'ProductSync', 'Failed to update product', array(
                'product_id' => $product_id,
                'error'      => $e->getMessage(),
            ) );
            $this->results['errors'][] = sprintf( 'Product %d: %s', $product_id, $e->getMessage() );
            return false;
        }
    }

    /**
     * Get sync results
     *
     * @return array
     */
    public function get_results() {
        return $this->results;
    }

    /**
     * Sync a single product by WooCommerce product ID
     *
     * @param int $product_id WooCommerce product ID.
     * @return array Sync result.
     */
    public function sync_single_product( $product_id ) {
        $product = wc_get_product( $product_id );

        if ( ! $product ) {
            return array(
                'success' => false,
                'message' => __( 'Product not found.', 'woo-business-central' ),
            );
        }

        $sku = $product->get_sku();

        if ( empty( $sku ) ) {
            return array(
                'success' => false,
                'message' => __( 'Product has no SKU.', 'woo-business-central' ),
            );
        }

        // Fetch item from BC
        $result = WBC_API_Client::get_item_by_number( $sku );

        if ( is_wp_error( $result ) ) {
            return array(
                'success' => false,
                'message' => $result->get_error_message(),
            );
        }

        $items = isset( $result['value'] ) ? $result['value'] : array();

        if ( empty( $items ) ) {
            return array(
                'success' => false,
                'message' => __( 'Item not found in Business Central.', 'woo-business-central' ),
            );
        }

        $item = $items[0];
        $updated = $this->update_product( $product, $item );

        return array(
            'success' => true,
            'message' => $updated
                ? __( 'Product updated successfully.', 'woo-business-central' )
                : __( 'Product is already up to date.', 'woo-business-central' ),
        );
    }
}