<?php
/**
 * Product import class
 *
 * Handles product import from CSV files
 *
 * @since      1.4.0
 * @package    Studiou_WC_Product_Cat_Manage
 * @subpackage Studiou_WC_Product_Cat_Manage/includes
 */

// If this file is called directly, abort.
if (!defined('WPINC')) {
    die;
}

class Studiou_WC_Product_Manage_Product_Import {

    /**
     * @var Studiou_WC_Product_Manage_Product_DB
     */
    private $db;

    /**
     * Constructor
     *
     * @param Studiou_WC_Product_Manage_Product_DB $db Database instance
     */
    public function __construct($db) {
        $this->db = $db;
    }

    /**
     * Parse CSV file and store data for batch processing
     *
     * @param string $file_path Path to CSV file
     * @return array Result with total count and transient key
     */
    public function parse_csv_for_batch($file_path) {
        if (!file_exists($file_path)) {
            return array('error' => __('File not found', 'studiou-wc-product-cat-manage'));
        }

        // Open CSV file
        $handle = fopen($file_path, 'r');
        if (!$handle) {
            return array('error' => __('Could not open file', 'studiou-wc-product-cat-manage'));
        }

        // Read header row
        $header = fgetcsv($handle, 0, ',', '"');
        if (!$header) {
            fclose($handle);
            return array('error' => __('Invalid CSV format', 'studiou-wc-product-cat-manage'));
        }

        // Read all data rows
        $rows = array();
        $row_number = 1;
        while (($row = fgetcsv($handle, 0, ',', '"')) !== false) {
            $row_number++;

            // Skip empty rows
            if (empty(array_filter($row))) {
                continue;
            }

            // Combine header with row data
            $data = array_combine($header, $row);
            $rows[] = array(
                'row_number' => $row_number,
                'data' => $data
            );
        }

        fclose($handle);

        // Store data in transient (expires in 1 hour)
        $transient_key = 'studiou_wcpcm_import_' . uniqid();
        set_transient($transient_key, $rows, 3600);

        return array(
            'transient_key' => $transient_key,
            'total' => count($rows)
        );
    }

    /**
     * Process batch of products
     *
     * @param string $transient_key Transient key with CSV data
     * @param int $offset Starting offset
     * @param int $batch_size Number of items to process
     * @return array Result with statistics
     */
    public function process_batch($transient_key, $offset = 0, $batch_size = 5) {
        $rows = get_transient($transient_key);

        if (!$rows) {
            return array('error' => __('Import data not found or expired', 'studiou-wc-product-cat-manage'));
        }

        $result = array(
            'success' => 0,
            'failed' => 0,
            'skipped' => 0,
            'failed_items' => array(),
            'messages' => array(),
            'processed' => 0,
            'total' => count($rows)
        );

        // Get batch of rows to process
        $batch = array_slice($rows, $offset, $batch_size);

        foreach ($batch as $item) {
            $row_number = $item['row_number'];
            $data = $item['data'];

            // Process the product
            $process_result = $this->process_product_row($data, $row_number);

            if ($process_result['status'] === 'success') {
                $result['success']++;
                // Don't add success messages to log
            } elseif ($process_result['status'] === 'skipped') {
                $result['skipped']++;
                $result['messages'][] = sprintf(
                    __('Row %d: SKIPPED - %s', 'studiou-wc-product-cat-manage'),
                    $row_number,
                    $process_result['message']
                );
                // Add to failed items for re-processing
                $result['failed_items'][] = $data;
            } else {
                $result['failed']++;
                $result['messages'][] = sprintf(
                    __('Row %d: FAILED - %s', 'studiou-wc-product-cat-manage'),
                    $row_number,
                    $process_result['message']
                );
                // Add to failed items
                $result['failed_items'][] = $data;
            }
        }

        $result['processed'] = $offset + count($batch);

        return $result;
    }

    /**
     * Process single product row
     *
     * @param array $data Product data
     * @param int $row_number Row number for error reporting
     * @return array Result with status and message
     */
    private function process_product_row($data, $row_number) {
        // Validate required fields
        if (!isset($data['Typ']) || empty($data['Typ'])) {
            return array(
                'status' => 'skipped',
                'message' => __('Missing product type', 'studiou-wc-product-cat-manage')
            );
        }

        // Rule 3: Only allow "variable" or "variation" types
        $type = trim($data['Typ']);
        if (!in_array($type, array('variable', 'variation'))) {
            return array(
                'status' => 'skipped',
                'message' => sprintf(
                    __('Invalid product type: %s (only "variable" or "variation" allowed)', 'studiou-wc-product-cat-manage'),
                    $type
                )
            );
        }

        // Get product ID
        $product_id = isset($data['ID']) ? intval($data['ID']) : 0;
        $sku = isset($data['Katalogové číslo']) ? trim($data['Katalogové číslo']) : '';

        // Rule 4: SKU must be unique
        if (empty($sku)) {
            return array(
                'status' => 'skipped',
                'message' => __('Missing SKU (Katalogové číslo)', 'studiou-wc-product-cat-manage')
            );
        }

        if (!$this->db->is_sku_unique($sku, $product_id)) {
            return array(
                'status' => 'skipped',
                'message' => sprintf(
                    __('SKU "%s" already exists', 'studiou-wc-product-cat-manage'),
                    $sku
                )
            );
        }

        // Rule 5: Validate image URL if provided
        $image_url = isset($data['Obrázky']) ? trim($data['Obrázky']) : '';
        if (!empty($image_url) && !$this->db->validate_image_url($image_url)) {
            return array(
                'status' => 'skipped',
                'message' => sprintf(
                    __('Invalid image URL: %s', 'studiou-wc-product-cat-manage'),
                    $image_url
                )
            );
        }

        // Process based on product type
        if ($type === 'variation') {
            return $this->process_variation($data, $product_id);
        } else {
            return $this->process_variable_product($data, $product_id);
        }
    }

    /**
     * Process variable product
     *
     * @param array $data Product data
     * @param int $product_id Product ID (0 for new product)
     * @return array Result with status and message
     */
    private function process_variable_product($data, $product_id) {
        try {
            // Create or update product
            if ($product_id == 0) {
                $product = new WC_Product_Variable();
            } else {
                $product = wc_get_product($product_id);
                if (!$product || !$product->is_type('variable')) {
                    return array(
                        'status' => 'error',
                        'message' => sprintf(
                            __('Product ID %d is not a variable product', 'studiou-wc-product-cat-manage'),
                            $product_id
                        )
                    );
                }
            }

            // Set basic data
            $product->set_name(isset($data['Jméno']) ? $data['Jméno'] : '');
            $product->set_sku(isset($data['Katalogové číslo']) ? $data['Katalogové číslo'] : '');
            $product->set_short_description(isset($data['Krátký popis']) ? $data['Krátký popis'] : '');
            $product->set_description(isset($data['Popis']) ? $data['Popis'] : '');

            // Set categories
            if (isset($data['Kategorie']) && !empty($data['Kategorie'])) {
                $categories = array_map('trim', explode('|', $data['Kategorie']));
                $category_ids = array();

                error_log('STUDIOU WC IMPORT: Processing categories for product: ' . $product->get_name());
                error_log('STUDIOU WC IMPORT: Categories string from CSV: ' . $data['Kategorie']);

                foreach ($categories as $category_name) {
                    if (empty($category_name)) {
                        continue;
                    }

                    $category_id = $this->find_category_by_name($category_name);
                    error_log('STUDIOU WC IMPORT: Looking for category "' . $category_name . '" - Result: ' . ($category_id ? 'FOUND ID=' . $category_id : 'NOT FOUND'));

                    if ($category_id) {
                        $category_ids[] = $category_id;
                    }
                }

                error_log('STUDIOU WC IMPORT: Total category IDs found: ' . count($category_ids) . ' - IDs: ' . implode(',', $category_ids));

                if (!empty($category_ids)) {
                    $product->set_category_ids($category_ids);
                    error_log('STUDIOU WC IMPORT: Categories assigned to product via set_category_ids()');
                } else {
                    error_log('STUDIOU WC IMPORT: WARNING - No valid category IDs found for: ' . $data['Kategorie']);
                }
            } else {
                error_log('STUDIOU WC IMPORT: No categories in CSV for product: ' . $product->get_name());
            }

            // Handle image
            if (isset($data['Obrázky']) && !empty($data['Obrázky'])) {
                $image_id = $this->upload_image_from_url($data['Obrázky']);
                if ($image_id) {
                    $product->set_image_id($image_id);
                }
            }

            // Set reviews enabled
            $reviews_enabled = isset($data['Povolit zákaznické recenze?']) && $data['Povolit zákaznické recenze?'] === '1';
            $product->set_reviews_allowed($reviews_enabled);

            // Handle product attribute
            if (isset($data['Název 1 vlastnosti']) && !empty($data['Název 1 vlastnosti'])) {
                $attribute_name = $data['Název 1 vlastnosti'];
                $attribute_values = isset($data['Hodnota(y) 1 vlastnosti']) ? $data['Hodnota(y) 1 vlastnosti'] : '';
                $is_visible = isset($data['Vlastnost 1 viditelnost']) && $data['Vlastnost 1 viditelnost'] === '1';
                $is_variation = isset($data['Vlastnost 1 varianta']) && $data['Vlastnost 1 varianta'] === '1';

                // Create attribute taxonomy if it doesn't exist
                $this->db->create_attribute_if_not_exists($attribute_name);

                $attribute = new WC_Product_Attribute();
                $attribute->set_name(wc_attribute_taxonomy_name($attribute_name));
                $attribute->set_visible($is_visible);
                $attribute->set_variation($is_variation);

                // Set attribute options (terms)
                $values = array_map('trim', explode('|', $attribute_values));
                $attribute->set_options($values);

                $product->set_attributes(array($attribute));
            }

            // Handle minimum/maximum quantity
            if (isset($data['Minimum Quantity']) && !empty($data['Minimum Quantity'])) {
                $product->update_meta_data('_minimum_quantity', intval($data['Minimum Quantity']));
            }
            if (isset($data['Maximum Quantity']) && !empty($data['Maximum Quantity'])) {
                $product->update_meta_data('_maximum_quantity', intval($data['Maximum Quantity']));
            }

            // Save product
            $saved_id = $product->save();

            $message = $product_id == 0 ?
                sprintf(__('Created variable product: %s', 'studiou-wc-product-cat-manage'), $product->get_name()) :
                sprintf(__('Updated variable product: %s', 'studiou-wc-product-cat-manage'), $product->get_name());

            return array(
                'status' => 'success',
                'message' => $message
            );

        } catch (Exception $e) {
            return array(
                'status' => 'error',
                'message' => $e->getMessage()
            );
        }
    }

    /**
     * Process product variation
     *
     * @param array $data Product data
     * @param int $variation_id Variation ID (0 for new variation)
     * @return array Result with status and message
     */
    private function process_variation($data, $variation_id) {
        try {
            // Rule 6: Must have parent reference
            if (!isset($data['Nadřazené']) || empty($data['Nadřazené'])) {
                return array(
                    'status' => 'skipped',
                    'message' => __('Missing parent product reference (Nadřazené)', 'studiou-wc-product-cat-manage')
                );
            }

            // Rule 7: Must have regular price
            if (!isset($data['Běžná cena']) || empty($data['Běžná cena'])) {
                return array(
                    'status' => 'skipped',
                    'message' => __('Missing regular price (Běžná cena)', 'studiou-wc-product-cat-manage')
                );
            }

            // Find parent product by SKU
            $parent_sku = trim($data['Nadřazené']);
            $parent_product = $this->db->get_product_by_sku($parent_sku);

            if (!$parent_product || !$parent_product->is_type('variable')) {
                return array(
                    'status' => 'skipped',
                    'message' => sprintf(
                        __('Parent product with SKU "%s" not found or not variable', 'studiou-wc-product-cat-manage'),
                        $parent_sku
                    )
                );
            }

            // Create or update variation
            if ($variation_id == 0) {
                $variation = new WC_Product_Variation();
                $variation->set_parent_id($parent_product->get_id());
            } else {
                $variation = wc_get_product($variation_id);
                if (!$variation || !$variation->is_type('variation')) {
                    return array(
                        'status' => 'error',
                        'message' => sprintf(
                            __('Product ID %d is not a variation', 'studiou-wc-product-cat-manage'),
                            $variation_id
                        )
                    );
                }
            }

            // Set basic data
            $variation->set_name(isset($data['Jméno']) ? $data['Jméno'] : '');
            $variation->set_sku(isset($data['Katalogové číslo']) ? $data['Katalogové číslo'] : '');
            $variation->set_description(isset($data['Popis']) ? $data['Popis'] : '');
            $variation->set_regular_price($data['Běžná cena']);

            // Handle image
            if (isset($data['Obrázky']) && !empty($data['Obrázky'])) {
                $image_id = $this->upload_image_from_url($data['Obrázky']);
                if ($image_id) {
                    $variation->set_image_id($image_id);
                }
            }

            // Set variation attributes
            if (isset($data['Název 1 vlastnosti']) && !empty($data['Název 1 vlastnosti']) &&
                isset($data['Hodnota(y) 1 vlastnosti']) && !empty($data['Hodnota(y) 1 vlastnosti'])) {

                $attribute_name = wc_attribute_taxonomy_name($data['Název 1 vlastnosti']);
                $attribute_value = $data['Hodnota(y) 1 vlastnosti'];

                $variation->set_attributes(array(
                    $attribute_name => $attribute_value
                ));
            }

            // Handle minimum/maximum quantity
            if (isset($data['Minimum Quantity']) && !empty($data['Minimum Quantity'])) {
                $variation->update_meta_data('_minimum_quantity', intval($data['Minimum Quantity']));
            }
            if (isset($data['Maximum Quantity']) && !empty($data['Maximum Quantity'])) {
                $variation->update_meta_data('_maximum_quantity', intval($data['Maximum Quantity']));
            }

            // Save variation
            $saved_id = $variation->save();

            $message = $variation_id == 0 ?
                sprintf(__('Created variation: %s', 'studiou-wc-product-cat-manage'), $variation->get_name()) :
                sprintf(__('Updated variation: %s', 'studiou-wc-product-cat-manage'), $variation->get_name());

            return array(
                'status' => 'success',
                'message' => $message
            );

        } catch (Exception $e) {
            return array(
                'status' => 'error',
                'message' => $e->getMessage()
            );
        }
    }

    /**
     * Upload image from URL
     *
     * @param string $url Image URL
     * @return int|null Attachment ID or null on failure
     */
    private function upload_image_from_url($url) {
        require_once(ABSPATH . 'wp-admin/includes/media.php');
        require_once(ABSPATH . 'wp-admin/includes/file.php');
        require_once(ABSPATH . 'wp-admin/includes/image.php');

        // Set shorter timeout for image download (30 seconds)
        add_filter('http_request_timeout', function() { return 30; });

        try {
            $tmp = download_url($url, 30);

            if (is_wp_error($tmp)) {
                if (defined('WP_DEBUG') && WP_DEBUG) {
                    error_log('STUDIOU WC: Image download failed for URL: ' . $url . ' - ' . $tmp->get_error_message());
                }
                return null;
            }

            $file_array = array(
                'name' => basename($url),
                'tmp_name' => $tmp
            );

            // Disable image processing to speed up import
            add_filter('intermediate_image_sizes_advanced', function() { return array(); });

            $id = media_handle_sideload($file_array, 0);

            // Re-enable image processing
            remove_filter('intermediate_image_sizes_advanced', function() { return array(); });

            if (is_wp_error($id)) {
                @unlink($file_array['tmp_name']);
                if (defined('WP_DEBUG') && WP_DEBUG) {
                    error_log('STUDIOU WC: Image upload failed for URL: ' . $url . ' - ' . $id->get_error_message());
                }
                return null;
            }

            return $id;

        } catch (Exception $e) {
            if (defined('WP_DEBUG') && WP_DEBUG) {
                error_log('STUDIOU WC: Image upload exception for URL: ' . $url . ' - ' . $e->getMessage());
            }
            return null;
        }
    }

    /**
     * Find category by name (simple lookup, categories have unique names)
     *
     * @param string $category_name Category name
     * @return int|null Category ID or null if not found
     */
    private function find_category_by_name($category_name) {
        // Trim and normalize the category name
        $category_name = trim($category_name);

        if (empty($category_name)) {
            return null;
        }

        // Simple name lookup only (no hierarchy detection)
        // Categories have unique names throughout the system

        error_log('STUDIOU WC IMPORT: find_category_by_name() called for: "' . $category_name . '"');

        // Method 1: Exact name match
        $term = get_term_by('name', $category_name, 'product_cat');
        if ($term) {
            error_log('STUDIOU WC IMPORT: Found by exact name match - ID: ' . $term->term_id);
            return $term->term_id;
        }

        // Method 2: Try by slug
        $slug = sanitize_title($category_name);
        error_log('STUDIOU WC IMPORT: Exact name failed, trying slug: "' . $slug . '"');
        $term = get_term_by('slug', $slug, 'product_cat');
        if ($term) {
            error_log('STUDIOU WC IMPORT: Found by slug match - ID: ' . $term->term_id);
            return $term->term_id;
        }

        // Method 3: Search case-insensitively through all categories
        $all_terms = get_terms(array(
            'taxonomy' => 'product_cat',
            'hide_empty' => false
        ));

        error_log('STUDIOU WC IMPORT: Slug failed, searching ' . count($all_terms) . ' categories case-insensitively');

        foreach ($all_terms as $t) {
            if (strcasecmp($t->name, $category_name) === 0) {
                error_log('STUDIOU WC IMPORT: Found by case-insensitive match - ID: ' . $t->term_id . ', name: "' . $t->name . '"');
                return $t->term_id;
            }
        }

        // Not found - try to create it
        error_log('STUDIOU WC IMPORT: Category NOT FOUND: "' . $category_name . '" - Attempting to create it');

        $new_term = wp_insert_term(
            $category_name,
            'product_cat',
            array(
                'slug' => $slug
            )
        );

        if (is_wp_error($new_term)) {
            error_log('STUDIOU WC IMPORT: Failed to create category "' . $category_name . '": ' . $new_term->get_error_message());
            error_log('STUDIOU WC IMPORT: Total available categories: ' . count($all_terms));

            // Show first 20 categories for debugging
            $sample_cats = array_slice($all_terms, 0, 20);
            foreach ($sample_cats as $cat) {
                error_log('STUDIOU WC IMPORT: Available: "' . $cat->name . '" (ID: ' . $cat->term_id . ', slug: ' . $cat->slug . ')');
            }

            return null;
        } else {
            $term_id = $new_term['term_id'];
            error_log('STUDIOU WC IMPORT: Successfully created category "' . $category_name . '" with ID: ' . $term_id);
            return $term_id;
        }
    }

    /**
     * Generate CSV with failed items
     *
     * @param array $failed_items Array of failed product data
     * @return string CSV content
     */
    public function generate_failed_csv($failed_items) {
        if (empty($failed_items)) {
            return '';
        }

        // Define CSV header
        $header = array(
            'ID', 'Typ', 'Katalogové číslo', 'Jméno', 'Nadřazené', 'Krátký popis', 'Popis',
            'Název 1 vlastnosti', 'Hodnota(y) 1 vlastnosti', 'Kategorie', 'Obrázky', 'Běžná cena',
            'Vlastnost 1 viditelnost', 'Vlastnost 1 globální', 'Vlastnost 1 varianta',
            'Povolit zákaznické recenze?', 'Minimum Quantity', 'Maximum Quantity'
        );

        // Start CSV output
        $csv = '';
        $csv .= '"' . implode('","', $header) . '"' . "\n";

        // Add failed items
        foreach ($failed_items as $item) {
            $row = array();
            foreach ($header as $column) {
                $value = isset($item[$column]) ? $item[$column] : '';
                $row[] = '"' . str_replace('"', '""', $value) . '"';
            }
            $csv .= implode(',', $row) . "\n";
        }

        return $csv;
    }
}