<?php
/**
 * Product Sync from Business Central to WooCommerce
 *
 * Iterates WooCommerce products and queries BC for each one (WooCommerce-first).
 * This is efficient when WooCommerce has far fewer products than BC.
 *
 * @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 {

    /**
     * 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 (WooCommerce-first approach)
     *
     * Instead of pulling all 60k+ items from BC, we iterate WooCommerce
     * products and query BC for each one by SKU/GTIN. This means ~100
     * targeted API calls instead of 600+ paginated calls.
     *
     * @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 (WooCommerce-first)' );

        $start_time = microtime( true );

        // Get all WooCommerce products that have a SKU
        $products = $this->get_wc_products_with_sku();

        if ( empty( $products ) ) {
            WBC_Logger::info( 'ProductSync', 'No WooCommerce products with SKU found' );
            return array(
                'success' => true,
                'message' => __( 'No WooCommerce products with SKU found.', 'woo-business-central' ),
            );
        }

        WBC_Logger::info( 'ProductSync', 'Found WooCommerce products to sync', array(
            'count' => count( $products ),
        ) );

        // Process each WooCommerce product
        foreach ( $products as $product ) {
            $this->process_wc_product( $product );

            // Small delay between API calls to avoid rate limiting
            usleep( 50000 ); // 50ms
        }

        $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( $this->results['errors'] ),
            'message'  => sprintf(
                /* translators: 1: duration, 2: success count, 3: failed count, 4: skipped count */
                __( 'Sync completed in %1$s seconds. Success: %2$d, Failed: %3$d, Skipped: %4$d', 'woo-business-central' ),
                $duration,
                $this->results['success'],
                $this->results['failed'],
                $this->results['skipped']
            ),
            'results'  => $this->results,
        );
    }

    /**
     * Get all WooCommerce products that have a SKU set
     *
     * @return WC_Product[] Array of WooCommerce products.
     */
    private function get_wc_products_with_sku() {
        $products = wc_get_products( array(
            'limit'  => -1,
            'status' => 'publish',
            'return' => 'objects',
        ) );

        // Filter to only products with SKUs
        return array_filter( $products, function ( $product ) {
            return ! empty( $product->get_sku() );
        } );
    }

    /**
     * Process a single WooCommerce product - find it in BC and sync
     *
     * @param WC_Product $product WooCommerce product.
     */
    private function process_wc_product( $product ) {
        $this->results['total']++;

        $sku = $product->get_sku();
        $product_id = $product->get_id();

        // Query BC for this item by GTIN (since SKU = EAN = GTIN)
        $bc_item = $this->find_bc_item_by_sku( $sku );

        if ( is_wp_error( $bc_item ) ) {
            $this->results['failed']++;
            $this->results['errors'][] = sprintf( 'Product %d (SKU: %s): %s', $product_id, $sku, $bc_item->get_error_message() );
            WBC_Logger::error( 'ProductSync', 'API error looking up product in BC', array(
                'product_id' => $product_id,
                'sku'        => $sku,
                'error'      => $bc_item->get_error_message(),
            ) );
            return;
        }

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

        // If location code is configured, get location-specific stock
        $location_code = get_option( 'wbc_location_code', '' );
        if ( ! empty( $location_code ) && get_option( 'wbc_enable_stock_sync', 'yes' ) === 'yes' ) {
            $location_stock = $this->get_location_stock( $bc_item, $location_code );
            if ( $location_stock !== false ) {
                $bc_item['inventory'] = $location_stock;
            }
        }

        // Update the WooCommerce product with BC data
        $updated = $this->update_product( $product, $bc_item );

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

    /**
     * Find a BC item by WooCommerce SKU (tries GTIN first, then item number)
     *
     * @param string $sku WooCommerce product SKU (which is the EAN code).
     * @return array|false|WP_Error BC item data, false if not found, or WP_Error.
     */
    private function find_bc_item_by_sku( $sku ) {
        $escaped_sku = WBC_API_Client::escape_odata_string( $sku );

        // Try by GTIN first (since SKU = EAN = GTIN in this setup)
        $result = WBC_API_Client::get( '/items', array(
            '$filter' => "gtin eq '" . $escaped_sku . "'",
            '$select' => self::SELECT_FIELDS,
            '$top'    => 1,
        ) );

        if ( is_wp_error( $result ) ) {
            return $result;
        }

        if ( ! empty( $result['value'] ) ) {
            return $result['value'][0];
        }

        // Fall back to item number match
        $result = WBC_API_Client::get( '/items', array(
            '$filter' => "number eq '" . $escaped_sku . "'",
            '$select' => self::SELECT_FIELDS,
            '$top'    => 1,
        ) );

        if ( is_wp_error( $result ) ) {
            return $result;
        }

        if ( ! empty( $result['value'] ) ) {
            return $result['value'][0];
        }

        return false;
    }

    /**
     * Get stock quantity for a specific BC location
     *
     * Uses the OData web services endpoint for Item Ledger Entries.
     * Requires the BC admin to publish "Item Ledger Entries" (Table 32)
     * as an OData v4 web service named "ItemLedgerEntries".
     *
     * Falls back to the item's total inventory if the OData call fails.
     *
     * @param array  $bc_item       BC item data.
     * @param string $location_code BC location code (e.g. 'ICP').
     * @return float|false Stock quantity at location, or false to use default.
     */
    private function get_location_stock( $bc_item, $location_code ) {
        $item_number = $bc_item['number'] ?? '';

        if ( empty( $item_number ) ) {
            return false;
        }

        // Build OData web services URL for Item Ledger Entries
        $environment = WBC_OAuth::get_environment();
        $company_id = WBC_OAuth::get_company_id();
        $escaped_number = WBC_API_Client::escape_odata_string( $item_number );
        $escaped_location = WBC_API_Client::escape_odata_string( $location_code );

        // Query Item Ledger Entries filtered by item number and location
        // Sum the "quantity" field to get current stock at this location
        $endpoint = '/itemLedgerEntries';
        $params = array(
            '$filter' => "itemNumber eq '" . $escaped_number . "' and locationCode eq '" . $escaped_location . "'",
            '$select' => 'quantity',
        );

        $result = WBC_API_Client::get( $endpoint, $params );

        if ( is_wp_error( $result ) ) {
            WBC_Logger::warning( 'ProductSync', 'Failed to get location stock, using total inventory', array(
                'item_number'   => $item_number,
                'location_code' => $location_code,
                'error'         => $result->get_error_message(),
            ) );
            return false;
        }

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

        if ( empty( $entries ) ) {
            // No ledger entries for this location = 0 stock
            WBC_Logger::debug( 'ProductSync', 'No ledger entries for location', array(
                'item_number'   => $item_number,
                'location_code' => $location_code,
            ) );
            return 0.0;
        }

        // Sum all quantities (entries can be positive or negative)
        $total_qty = 0.0;
        foreach ( $entries as $entry ) {
            $total_qty += (float) ( $entry['quantity'] ?? 0 );
        }

        WBC_Logger::debug( 'ProductSync', 'Got location-specific stock', array(
            'item_number'   => $item_number,
            'location_code' => $location_code,
            'stock'         => $total_qty,
        ) );

        return $total_qty;
    }

    /**
     * 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();

        try {
            $changed = false;

            // 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 ) {
                    if ( ! $product->get_manage_stock() ) {
                        $product->set_manage_stock( true );
                    }

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

                    WBC_Logger::debug( 'ProductSync', 'Updated stock', array(
                        'product_id' => $product_id,
                        'sku'        => $product->get_sku(),
                        '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 );

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

                    $changed = true;

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

            // Store BC item info in meta
            $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();

            if ( ! $changed ) {
                WBC_Logger::debug( 'ProductSync', 'Product already up to date', array(
                    'product_id' => $product_id,
                    'sku'        => $product->get_sku(),
                ) );
            }

            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' ),
            );
        }

        // Find item in BC by SKU
        $bc_item = $this->find_bc_item_by_sku( $sku );

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

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

        // Check location stock
        $location_code = get_option( 'wbc_location_code', '' );
        if ( ! empty( $location_code ) ) {
            $location_stock = $this->get_location_stock( $bc_item, $location_code );
            if ( $location_stock !== false ) {
                $bc_item['inventory'] = $location_stock;
            }
        }

        $updated = $this->update_product( $product, $bc_item );

        return array(
            'success' => true,
            'message' => $updated
                ? __( 'Product synced successfully.', 'woo-business-central' )
                : __( 'Product sync failed.', 'woo-business-central' ),
        );
    }
}