<?php
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

// Set the working directory to the project root
chdir(__DIR__ . '/..');

// --- Custom Error Handling ---
register_shutdown_function(function () {
    $error = error_get_last();
    if ($error !== null && !headers_sent()) {
        http_response_code(500);
        header('Content-Type: application/json');
        echo json_encode([
            'success' => false,
            'message' => 'A fatal server error occurred.',
            'error_details' => $error
        ]);
    }
});

require_once 'include/init.php';
require_once 'include/auth.php';

header('Content-Type: application/json');

if (!isset($_SESSION['user_id'])) {
    http_response_code(401);
    echo json_encode(['success' => false, 'message' => 'You must be logged in.']);
    exit;
}

/**
 * Recursively removes a directory and its contents.
 * @param string $dir The directory to remove.
 */
function rrmdir($dir) {
    if (is_dir($dir)) {
        $objects = scandir($dir);
        foreach ($objects as $object) {
            if ($object != "." && $object != "..") {
                is_dir($dir . DIRECTORY_SEPARATOR . $object) ? rrmdir($dir . DIRECTORY_SEPARATOR . $object) : unlink($dir . DIRECTORY_SEPARATOR . $object);
            }
        }
        rmdir($dir);
    }
}

// --- Main Logic ---
try {
    if (!isset($_FILES['backup_file']) || $_FILES['backup_file']['error'] !== UPLOAD_ERR_OK) {
        throw new Exception('File upload error.');
    }
    if (!isset($_POST['target_tab_id']) || empty($_POST['target_tab_id'])) {
        throw new Exception('Target tab not selected.');
    }

    $target_tab_id = (int)$_POST['target_tab_id'];
    $backup_file = $_FILES['backup_file']['tmp_name'];

    $temp_dir = sys_get_temp_dir() . '/bookmarkly_import_' . uniqid();
    if (!mkdir($temp_dir, 0777, true)) {
        throw new Exception('Failed to create temporary directory.');
    }
    
    $zip = new ZipArchive;
    if ($zip->open($backup_file) !== TRUE) {
        rrmdir($temp_dir);
        throw new Exception('Failed to open the backup file.');
    }
    
    $zip->extractTo($temp_dir);
    $zip->close();
    
    $backup_db_path = $temp_dir . '/database/bookmarkly.db';
    $manifest_path = $temp_dir . '/manifest.json';

    if (!file_exists($backup_db_path)) {
        throw new Exception('Invalid backup file: bookmarkly.db not found.');
    }
    
    $backup_pdo = new PDO('sqlite:' . $backup_db_path);
    $backup_pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $backup_pdo->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);

    // --- Begin Transaction ---
    $pdo->beginTransaction();
    try {
        $is_tab_backup = false;
        if (file_exists($manifest_path)) {
            $manifest = json_decode(file_get_contents($manifest_path), true);
            if (isset($manifest['type']) && $manifest['type'] === 'tab') {
                $is_tab_backup = true;
            }
        }
        
        // --- Import Logic ---
        $old_to_new_category_id_map = [];
        $imported_categories_count = 0;
        $imported_bookmarks_count = 0;
        
        // If it's a tab backup, also import tab settings and files
        if ($is_tab_backup) {
            $backup_tab = $backup_pdo->query("SELECT * FROM tabs LIMIT 1")->fetch();
            if ($backup_tab) {
                // Handle background image
                $new_background_url = $backup_tab['background_image_url'];
                if (!empty($new_background_url) && strpos($new_background_url, 'images/backgrounds/') === 0) {
                    $source_bg = $temp_dir . '/' . $new_background_url;
                    if (file_exists($source_bg)) {
                        $bg_filename = basename($new_background_url);
                        $dest_dir = 'data/images/backgrounds/';
                        if (!is_dir($dest_dir)) mkdir($dest_dir, 0755, true);
                        
                        $unique_filename = 'tab' . $target_tab_id . '_' . time() . '_' . $bg_filename;
                        $dest_bg = $dest_dir . $unique_filename;
                        if (copy($source_bg, $dest_bg)) {
                            $new_background_url = $dest_bg . '?v=' . time();
                        }
                    }
                }
                
                // Update target tab with settings from backup
                $update_tab_stmt = $pdo->prepare(
                    "UPDATE tabs SET theme = ?, theme_transparency = ?, background_image_url = ?, background_brightness = ?, background_saturation = ? WHERE id = ?"
                );
                $update_tab_stmt->execute([
                    $backup_tab['theme'],
                    $backup_tab['theme_transparency'],
                    $new_background_url,
                    $backup_tab['background_brightness'],
                    $backup_tab['background_saturation'],
                    $target_tab_id
                ]);
            }
        }
        
        // Import Categories
        $categories = $backup_pdo->query("SELECT * FROM categories")->fetchAll();
        $stmt_insert_category = $pdo->prepare("INSERT INTO categories (name, sort_order, tab_id) VALUES (?, ?, ?)");
        foreach ($categories as $category) {
            $stmt_insert_category->execute([$category['name'], $category['sort_order'], $target_tab_id]);
            $old_to_new_category_id_map[$category['id']] = $pdo->lastInsertId();
            $imported_categories_count++;
        }
        
        // Import Bookmarks
        $bookmarks = $backup_pdo->query("SELECT * FROM bookmarks")->fetchAll();
        $stmt_insert_bookmark = $pdo->prepare("INSERT INTO bookmarks (category_id, title, url, icon, is_favorite, sort_order, tab_id) VALUES (?, ?, ?, ?, ?, ?, ?)");
        foreach ($bookmarks as $bookmark) {
            // Determine the new category ID, allowing for bookmarks without a category
            $new_category_id = null;
            if (!empty($bookmark['category_id']) && isset($old_to_new_category_id_map[$bookmark['category_id']])) {
                $new_category_id = $old_to_new_category_id_map[$bookmark['category_id']];
            }
            
            // Handle icon
            $new_icon_path = $bookmark['icon'];
            // In tab backups, icon paths are relative to the zip root, e.g., 'images/custom/icon.png'
            if ($is_tab_backup && !empty($new_icon_path) && strpos($new_icon_path, 'images/custom/') === 0) {
                $source_icon = $temp_dir . '/' . $new_icon_path;
                if (file_exists($source_icon)) {
                    $icon_filename = basename($new_icon_path);
                    $dest_dir = 'data/images/custom/'; // The correct destination for custom icons
                    if (!is_dir($dest_dir)) mkdir($dest_dir, 0755, true);
                    
                    $unique_filename = 'imported_' . time() . '_' . $icon_filename;
                    $dest_icon = $dest_dir . $unique_filename;
                    if (copy($source_icon, $dest_icon)) {
                        $new_icon_path = $dest_icon;
                    }
                }
            }
            
            $stmt_insert_bookmark->execute([
                $new_category_id, $bookmark['title'], $bookmark['url'],
                $new_icon_path, $bookmark['is_favorite'], $bookmark['sort_order'], $target_tab_id
            ]);
            $imported_bookmarks_count++;
        }

        $pdo->commit();
        $message = "Import successful. Added {$imported_categories_count} categories and {$imported_bookmarks_count} bookmarks.";
        echo json_encode(['success' => true, 'message' => $message]);

    } catch (Exception $e) {
        $pdo->rollBack();
        throw new Exception('Database error during import: ' . $e->getMessage());
    }

} catch (Exception $e) {
    http_response_code(400);
    echo json_encode(['success' => false, 'message' => $e->getMessage()]);

} finally {
    if (isset($temp_dir) && is_dir($temp_dir)) {
        rrmdir($temp_dir);
    }
    // Close DB connections
    $pdo = null;
    if(isset($backup_pdo)) {
        $backup_pdo = null;
    }
}