<?php

/**
 * Class to handle AJAX requests for the accessible-docs
 *
 *
 * @link       https://group107.com
 * @since      1.0.0
 *
 * @package    accessible-docs
 * @subpackage accessible-docs/includes
 * @author     Group107 <contact@group107.com>
*/

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

class Group107_AccessibleDocs_Ajax_Handler {

    /**
     * Handles the AJAX request to clear the AccessibleDocs table.
     * Verifies the nonce for security and calls the database handler to clear the table.
     * Sends a JSON response indicating success or failure.
     *
     * @return array
     */
    public function accessible_docs_clear_table() {
        // Verify nonce
        $this->accessible_docs_verify_admin_request();

        $result = Group107_AccessibleDocs_Db_Handler::accessible_docs_clear_table();

        if($result){
            wp_send_json_success(['status' => 'success']);
        } else {
            $this->accessible_docs_send_error(__('Error trying to clear AccessibleDocs table, please try again!', 'accessible-docs'));
        }
    }
    
    /**
     * Handles the AJAX request to delete selected records from the AccessibleDocs table.
     * Verifies the nonce for security and calls the database handler to remove selected records from the table.
     * Sends a JSON response indicating success or failure.
     *
     * @return array
     */
    public function accessible_docs_delete_selected() {
        // Verify nonce
        $this->accessible_docs_verify_admin_request();

        $selected_ids = isset($_POST['selectedIds']) ? sanitize_text_field(wp_unslash($_POST['selectedIds'])) : '';
        $ids = explode(',', $selected_ids);
        $ids = array_filter(array_map('absint', $ids));

        if ( empty($ids) ) {
            $this->accessible_docs_send_error(__('Missing required fields', 'accessible-docs'));
        }

        $result = Group107_AccessibleDocs_Db_Handler::accessible_docs_delete_selected_records($ids);

        if($result){
            wp_send_json_success(['status' => 'success']);
        } else {
            $this->accessible_docs_send_error(__('Error trying to delete records from AccessibleDocs table, please try again!', 'accessible-docs'));
        }
    }

    /**
     * Returns a fresh nonce for the public request form.
     *
     * Pages are often served from a page cache, where a nonce printed into the HTML
     * expires after 12–24 hours. The popup asks for a fresh one right before submitting.
     *
     * @return void
     */
    public function accessible_docs_nonce() {
        nocache_headers();
        wp_send_json_success(['nonce' => wp_create_nonce('accessible_docs_nonce')]);
    }

    /**
     * Handles the accessible_docs_request AJAX request.
     */
    public function accessible_docs_request() {
        // Verify nonce
        $nonce = isset($_POST['nonce']) ? sanitize_text_field(wp_unslash($_POST['nonce'])) : '';
        if ( empty($nonce) || !wp_verify_nonce($nonce, 'accessible_docs_nonce') ) {
            $this->accessible_docs_send_error(__('Something went wrong, please try again later', 'accessible-docs'));
        }

        // Sanitize and validate input
        $email = isset($_POST['email']) ? sanitize_email(wp_unslash($_POST['email'])) : '';
        $url = isset($_POST['url']) ? esc_url_raw(urldecode(wp_unslash($_POST['url']))) : '';
        $file_id = $url ? intval(attachment_url_to_postid($url)) : 0;

        if (empty($email) || empty($url) || empty($file_id)) {
            $this->accessible_docs_send_error(__( 'Missing required fields', 'accessible-docs' ));
        }

        // Only PDF files from the Media Library can be sent for processing
        if ('application/pdf' !== get_post_mime_type($file_id)) {
            $this->accessible_docs_send_error(__( 'Only PDF files can be processed.', 'accessible-docs' ));
        }

        // Check if the file already exists in the database
        $existing_record = Group107_AccessibleDocs_Db_Handler::check_existing_accessible_docs_file($email, $file_id);
        if ($existing_record) {
            $this->accessible_docs_handle_existing_record($existing_record, $file_id, $email);
        } else {
            $this->accessible_docs_handle_file_upload($file_id, $email, false);
        }

        wp_die();
    }

    /**
     * Handles an existing file record by checking its status.
     *
     * If the file is still in-process, the status is checked with the external API.
     * If it is completed, the status in the database is updated.
     *
     * @param array  $existing_record The existing record data from the database.
     * @param int    $file_id         The WordPress attachment file ID.
     * @param string $email           The user's email address.
     *
     * @return void
     */
    private function accessible_docs_handle_existing_record($existing_record, $file_id, $email) {
        if ($existing_record['accessible_docs_status'] === 'in-process') {
            $file_status = Group107_AccessibleDocs_API_Handler::accessible_docs_check_file_status($existing_record['accessible_docs_file_id']);

            // The platform no longer knows this file: send it again.
            if ($file_status['status'] === 'not-found') {
                $this->accessible_docs_handle_file_upload($file_id, $email, true);
            }

            if ($file_status['status'] === 'completed') {
                Group107_AccessibleDocs_Db_Handler::accessible_docs_update_file_status($file_id, $email);
                wp_send_json_success(['status' => 'completed']);
            }

            // Still processing – or the status could not be checked right now (the file is already queued,
            // so it is not uploaded again, which would cost another processing credit).
            wp_send_json_success(['status' => 'in-process']);
        }

        // Return the existing file status
        wp_send_json_success(['status' => $existing_record['accessible_docs_status']]);
    }

    /**
     * Handles both new file uploads and re-uploads to AccessibleDocs.
     *
     * This function uploads a file using the API, then either saves a new record 
     * or updates an existing one in the database based on whether the file is 
     * being uploaded for the first time or re-uploaded.
     *
     * @param int    $file_id      The ID of the file being uploaded.
     * @param string $email        The email associated with the file.
     * @param bool   $is_reupload  Determines if the file is being re-uploaded.
     */
    private function accessible_docs_handle_file_upload($file_id, $email, $is_reupload = false) {
        if ($this->accessible_docs_is_rate_limited()) {
            $this->accessible_docs_send_error(__('Too many requests, please try again later.', 'accessible-docs'));
        }

        $upload_response = Group107_AccessibleDocs_API_Handler::accessible_docs_upload_file($email, $file_id);

        if ($upload_response['status'] === 'error') {
            $this->accessible_docs_send_error($upload_response['error']);
        }

        if ($is_reupload) {
            // Update accessible_docs_file_id in the database
            $result = Group107_AccessibleDocs_Db_Handler::accessible_docs_update_file_id($file_id, $email, $upload_response['data']['id']);
            $error_message = __('Failed to update AccessibleDocs file ID in the database.', 'accessible-docs');
        } else {
            // Save the uploaded file record to the database
            $result = Group107_AccessibleDocs_Db_Handler::save_accessible_docs_file($email, $file_id, $upload_response['data']['id']);
            $error_message = __('Data was not saved to the database.', 'accessible-docs');
        }

        if ($result) {
            wp_send_json_success(['status' => 'in-process']);
        } else {
            $this->accessible_docs_send_error($error_message);
        }
    }

    /**
     * Verifies that an admin AJAX request has a valid admin nonce
     * and comes from a user allowed to manage the plugin.
     *
     * @return void
     */
    private function accessible_docs_verify_admin_request() {
        $nonce = isset($_POST['nonce']) ? sanitize_text_field(wp_unslash($_POST['nonce'])) : '';
        if ( empty($nonce) || !wp_verify_nonce($nonce, 'accessible_docs_admin_nonce') || !current_user_can('manage_options') ) {
            $this->accessible_docs_send_error(__('Something went wrong, please try again later', 'accessible-docs'));
        }
    }

    /**
     * Checks and increments the number of new file uploads made from the visitor's IP address.
     *
     * Only new uploads are counted, status checks of already requested files are not limited.
     * The limit can be changed or disabled (0) with the 'accessible_docs_rate_limit' filter.
     *
     * @return bool True if the limit is reached, false otherwise.
     */
    private function accessible_docs_is_rate_limited() {
        $limit = (int) apply_filters('accessible_docs_rate_limit', 30);
        if ($limit <= 0) {
            return false;
        }

        $ip = isset($_SERVER['REMOTE_ADDR']) ? sanitize_text_field(wp_unslash($_SERVER['REMOTE_ADDR'])) : '';
        $key = 'accessible_docs_rl_' . md5($ip);
        $count = (int) get_transient($key);

        if ($count >= $limit) {
            return true;
        }

        set_transient($key, $count + 1, HOUR_IN_SECONDS);

        return false;
    }

    /**
     * Sends a JSON error response and terminates the script.
     *
     * This method is used to send a standardized error response in JSON format.
     *
     * @param string $message The error message to send.
     *
     * @return void
     */
    private function accessible_docs_send_error($message) {
        wp_send_json_error(['status' => 'error', 'error' => $message]);
        wp_die();
    }
}