<?php
if (! class_exists('AI_APP_ONSITE_OpenAi_Api_Handler')) {
    class AI_APP_ONSITE_OpenAi_Api_Handler
    {
        public function __construct()
        {
            // Hook the AJAX action to the appropriate method in this class

            // Ajax handler
            add_action('wp_ajax_ai_app_onsite_openAi_api', array($this, 'ai_app_onsite_openAi_api'));
            add_action('wp_ajax_nopriv_ai_app_onsite_openAi_api', array($this, 'ai_app_onsite_openAi_api'));
        }

        public static function ai_app_onsite_openAi_api()
        {
            if (
                isset($_POST['aiappOnsitePropertiesNonce']) &&
                !wp_verify_nonce(
                    sanitize_text_field(wp_unslash($_POST['aiappOnsitePropertiesNonce'])),
                    'ai_app_onsite_properties_nonce'
                )
            ) {
                wp_send_json_error('Invalid nonce. Please refresh the page and try again.');
                return;
            }

            // Handle the AJAX request
            global $wpdb;
            $table_name_prompt_editor   = $wpdb->prefix . 'ai_app_onsite_prompt_editor';
            $table_name_model_settings  = $wpdb->prefix . 'ai_app_onsite_model_settings';
            $table_name_plugin_settings = $wpdb->prefix . 'ai_app_onsite_plugin_settings';
            $table_name_field_selector  = $wpdb->prefix . 'ai_app_onsite_field_selector_settings';
            $table_name_app_properties  = $wpdb->prefix . 'ai_app_onsite_app_properties';
            $table_name_models          = $wpdb->prefix . 'ai_app_onsite_models';

            $response_message = '';
            $app_name = '';
            $properties = $wpdb->get_results("SELECT response_message, app_name_show, app_name FROM $table_name_app_properties WHERE app_id = 1 LIMIT 1", ARRAY_A);

            if (!empty($properties[0])) {
                $response_message = $properties[0]['response_message'] ?? '';
                $app_name = !empty($properties[0]['app_name_show']) ? $properties[0]['app_name_show'] : ($properties[0]['app_name'] ?? '');
            } 

            $model_settings = $wpdb->get_results("SELECT * FROM $table_name_model_settings WHERE app_id = 1", ARRAY_A);

            $plugin_settings = $wpdb->get_results("SELECT * FROM $table_name_plugin_settings WHERE app_id = 1", ARRAY_A);

            $formData = $_POST;

            $field_names = array_keys($formData);
            $field_values = array_values($formData);
            $pairs = array_combine($field_names, $field_values);

            $field_selector_settings = $wpdb->get_results("SELECT `field_label`, `field_tag`, `field_id` FROM $table_name_field_selector WHERE app_id = 1", ARRAY_A);

            $map = [];
            foreach ($field_selector_settings as $r) {
                $cleanTag = preg_replace('/[{}\s]/', '', $r['field_tag']);
                $normalized = strtolower(preg_replace('/\s+/', '_', trim($r['field_label'])));
                $map[$r['field_label']] = $cleanTag;
                $map[$normalized] = $cleanTag;
                // Also map by field_id (form name attribute now uses field_id)
                $map[$r['field_id']] = $cleanTag;
            }
            // Replace label keys with their field_tag (keep unmapped as-is)
            $tag_pairs = [];
            foreach ($formData as $label => $value) {
                $normalized = strtolower(preg_replace('/\s+/', '_', trim($label)));
                if (isset($map[$label]) || isset($map[$normalized])) {
                    $key = $map[$label] ?? $map[$normalized]; 
                    $tag_pairs[$key] = sanitize_text_field($value);
                }
            }
            
            $field_tag_names  = array_keys($tag_pairs);
            $field_tag_values = array_values($tag_pairs);
            $field_tag_parirs = array_combine($field_tag_names, $field_tag_values);


            $banned_words = (!empty($plugin_settings) && isset($plugin_settings[0]['banned_words']) && !is_null($plugin_settings[0]['banned_words']))
            ? unserialize($plugin_settings[0]['banned_words'])
            : [];
            $app_email = isset($plugin_settings[0]['app_email']) ? $plugin_settings[0]['app_email'] : null;

            function containsBannedWordPart($value, $banned_word)
            {
                // Split banned word into parts by space
                $banned_parts = explode(' ', $banned_word);
                foreach ($banned_parts as $part) {
                    // Use preg_match to find exact words
                    if (preg_match('/\b' . preg_quote($part, '/') . '\b/i', $value)) {
                        return true;
                    }
                }
                return false;
            }

            // Iterate through field values and check against banned words
            if (!empty($banned_words)) {
                foreach ($field_tag_values as $value) {
                    foreach ($banned_words as $banned_word) {
                        if (containsBannedWordPart($value, $banned_word)) {
                            wp_send_json_error("Banned word included in: " . $value);
                            break 2;
                        }
                    }
                }
            }
           
            $fieldLabels = array_column($field_selector_settings, 'field_label');
            // Process each element of the array
            $fieldLabels = array_map(function ($item) {
                // Replace spaces with underscores in each item
                return preg_replace('/\s+/', '_', $item);
            }, $fieldLabels);

            $fieldTagLabels = array_column($field_selector_settings, 'field_tag');
            // Process each element of the array
            $fieldTagLabels = array_map(function ($item) {
                // Remove {{ and }} from each item
                return trim(str_replace(['{{', '}}'], '', $item));
            }, $fieldTagLabels);

            if (empty($model_settings)) {
                wp_send_json_error('Plugin Model settings are missing');
            }

            $model_setting = $model_settings[0];

            // Determine the active provider
            $active_provider = isset($model_setting['active_provider']) ? $model_setting['active_provider'] : 'openai';

            // Get the provider handler
            if ( class_exists( 'AI_App_Onsite_Provider_Factory' ) ) {
                try {
                    $provider = AI_App_Onsite_Provider_Factory::get_provider( $active_provider );
                } catch ( \InvalidArgumentException $e ) {
                    wp_send_json_error('Unsupported AI provider configured.');
                    return;
                }
            } else {
                // Fallback: assume OpenAI if provider factory not loaded
                $active_provider = 'openai';
                $provider = null;
            }

            // Get the correct API key based on provider
            $api_key_column = $provider ? $provider->get_key_column() : 'openai_key';
            $key_status_column = $provider ? $provider->get_key_status_column() : 'key_status';

            $api_key    = $model_setting[$api_key_column] ?? '';
            $key_status = $model_setting[$key_status_column] ?? 'true';
            $model      = $model_setting['model'];
            $temperature = $model_setting['temperature'] ?: '';
            $f_penalty = $model_setting['f_penalty'] ?: '';
            $p_penalty = $model_setting['p_penalty'] ?: '';
            $max_tokens = $model_setting['max_tokens'] ?: '';
            $top_p = $model_setting['top_p'] ?: '';

            // Check for missing keys
            if (empty($api_key)) {
                wp_send_json_error( ucfirst($active_provider) . ' API key is missing. Please add your API key in Model Settings.');
            }

            if (empty($model)) {
                wp_send_json_error('No AI model is selected. Please go to Model Settings, select a model, and click "Save Settings".');
            }

            // Block API calls for shut-down models (deprecated models with future shutdown dates remain usable)
            $model_shutdown_date = $wpdb->get_var(
                $wpdb->prepare(
                    "SELECT shutdown_date FROM $table_name_models WHERE model = %s",
                    $model
                )
            );
            if ( $model_shutdown_date !== null && $model_shutdown_date < current_time( 'Y-m-d' ) ) {
                wp_send_json_error('The selected AI model "' . $model . '" has been shut down by OpenAI and is no longer available. Please contact the site administrator to update the model in settings.');
            }

            if ($key_status === 'false') {
                wp_send_json_error( ucfirst($active_provider) . ' API key is disabled');
            }

            $formatted_field_names = array_map(function ($key) {
                return '{{' . strtolower($key) . '}}';
            }, $field_tag_names);

            $replace_array = array_combine($formatted_field_names, $field_tag_values);
           
            $prompt_results = $wpdb->get_results("SELECT * FROM $table_name_prompt_editor WHERE app_id = 1", ARRAY_A);
           
            if (empty($prompt_results)) {
                wp_send_json_error('No prompt results found');
            }

            $prompt_result = $prompt_results[0];

            if (!isset($prompt_result['prompt']) || empty($prompt_result['prompt'])) {
                wp_send_json_error('Prompt string is empty');
            }

            $prompt = str_replace(array_keys($replace_array), array_values($replace_array), $prompt_result['prompt']);

            // Check for empty prompt
            if (empty($prompt)) {
                wp_send_json_error('Prompt is missing');
            }

            $model_parameters = $wpdb->get_row(
                $wpdb->prepare("SELECT * FROM $table_name_models WHERE model = %s LIMIT 1", $model),
                ARRAY_A
            );

            if (empty($model_parameters)) {
                wp_send_json_error('Model parameters not found for the selected model');
            }

            // Validate provider/model match — prevent sending to wrong API endpoint
            $model_provider = $model_parameters['provider'] ?? 'openai';
            if ( $provider && $model_provider !== $active_provider ) {
                $provider_label = ucfirst( $active_provider );
                $model_provider_label = ucfirst( $model_provider );
                error_log('[AI App Onsite] Provider/model mismatch: active_provider=' . $active_provider . ' but model "' . $model . '" belongs to provider "' . $model_provider . '"');
                wp_send_json_error(
                    'Provider mismatch: Your AI provider is set to ' . $provider_label . ', but the currently saved model "' . $model . '" is a ' . $model_provider_label . ' model. Please go to Model Settings, select a ' . $provider_label . ' model from the dropdown, and click "Save Settings".'
                );
                return;
            }

            $api_url = $model_parameters['endpoint'] ?? 'https://api.openai.com/v1/chat/completions';
            $model   = $model_parameters['model'] ?? $model;

            $model_parameters['supported_parameters'] = json_decode($model_parameters['supported_parameters'], true);
            $supported_parameters = $model_parameters['supported_parameters'] ?? [];

            // Build request using provider abstraction
            if ( $provider ) {
                $headers = $provider->build_headers( $api_key );
                $data = $provider->build_payload([
                    'model'                => $model,
                    'prompt'               => $prompt,
                    'endpoint'             => $api_url,
                    'max_tokens'           => $max_tokens,
                    'temperature'          => $temperature,
                    'top_p'                => $top_p,
                    'f_penalty'            => $f_penalty,
                    'p_penalty'            => $p_penalty,
                    'supported_parameters' => $supported_parameters,
                    'default_tools'        => $model_parameters['default_tools'] ?? '',
                ]);
            } else {
                // Legacy fallback for OpenAI
                $headers = [
                    "Content-Type" => "application/json",
                    "Authorization" => "Bearer $api_key"
                ];

                $is_reasoning = (strpos($api_url, '/v1/responses') !== false);
                if ($is_reasoning) {
                    // Responses API: only model, input, max_output_tokens
                    // Do NOT send temperature, top_p, frequency_penalty, presence_penalty
                    $data = [
                        "model"             => $model,
                        "input"             => $prompt,
                        "max_output_tokens" => !empty($max_tokens) ? (int)$max_tokens : 3000,
                    ];
                } else {
                    $data = [
                        "model"    => $model,
                        "messages" => [["role" => "user", "content" => $prompt]],
                        "max_tokens" => !empty($max_tokens) ? (int)$max_tokens : 3000,
                    ];
                    // Only add these parameters for Chat Completions API
                    if (in_array('temperature', $supported_parameters) && !empty($temperature)) {
                        $data["temperature"] = (float)$temperature;
                    }
                    if (in_array('top_p', $supported_parameters) && !empty($top_p)) {
                        $data["top_p"] = (float)$top_p;
                    }
                    if (in_array('frequency_penalty', $supported_parameters) && !empty($f_penalty)) {
                        $data["frequency_penalty"] = (float)$f_penalty;
                    }
                    if (in_array('presence_penalty', $supported_parameters) && !empty($p_penalty)) {
                        $data["presence_penalty"] = (float)$p_penalty;
                    }
                }
                if (!empty($model_parameters['default_tools'])) {
                    $data['tools'] = [['type' => trim($model_parameters['default_tools'])]];
                }
            }

          
            // Send request (with automatic retry for transient network errors)
            $response = ai_app_onsite_remote_post_with_retry($api_url, [
                'headers'     => $headers,
                'body'        => wp_json_encode($data),
                'timeout'     => 120,
                'data_format' => 'body',
            ]);

            // Handle WP_Error (network failure, timeout, DNS, connection reset, etc.)
            if ( is_wp_error( $response ) ) {
                error_log('[AI App Onsite] wp_remote_post WP_Error: ' . $response->get_error_message());
                wp_send_json_error( 'API request failed: ' . $response->get_error_message() );
                return;
            }

            $response_code = wp_remote_retrieve_response_code($response);
            $response_body = wp_remote_retrieve_body($response);
            $result        = json_decode($response_body, true);

            // Parse response using provider abstraction
            if ( $provider ) {
                // Some models now reject `temperature` as deprecated. When the API says
                // so, retry once without it — this is model-agnostic and self-heals as
                // providers deprecate the parameter on more models over time.
                if ( ( $response_code >= 400 || ( is_array($result) && isset($result['error']) ) )
                    && isset($data['temperature'])
                    && stripos((string) $response_body, 'temperature') !== false
                    && stripos((string) $response_body, 'deprecat') !== false ) {
                    unset($data['temperature']);
                    $response = ai_app_onsite_remote_post_with_retry($api_url, [
                        'headers'     => $headers,
                        'body'        => wp_json_encode($data),
                        'timeout'     => 120,
                        'data_format' => 'body',
                    ]);
                    if ( is_wp_error( $response ) ) {
                        error_log('[AI App Onsite] wp_remote_post WP_Error (temperature retry): ' . $response->get_error_message());
                        wp_send_json_error( 'API request failed: ' . $response->get_error_message() );
                        return;
                    }
                    $response_code = wp_remote_retrieve_response_code($response);
                    $response_body = wp_remote_retrieve_body($response);
                    $result        = json_decode($response_body, true);
                }

                if ( $response_code >= 400 || ( is_array($result) && isset($result['error']) ) ) {
                    $error_msg = $provider->parse_error( is_array($result) ? $result : [], $response_code );
                    error_log('[AI App Onsite] Provider error (' . ($provider->get_id()) . '): ' . $error_msg . ' | HTTP ' . $response_code . ' | Raw: ' . substr($response_body, 0, 500));
                    wp_send_json_error( $error_msg );
                }
                $response_content = $provider->parse_response( is_array($result) ? $result : [], $api_url );
            } else {
                // Legacy OpenAI response parsing
                $is_reasoning = (strpos($api_url, '/v1/responses') !== false);
                if ($is_reasoning) {
                    $output = $result['output'] ?? [];
                    $response_content = null;
                    foreach ($output as $item) {
                        if (isset($item['type'], $item['content']) && $item['type'] === 'message' && is_array($item['content'])) {
                            foreach ($item['content'] as $content) {
                                if (!empty($content['text'])) {
                                    $response_content = $content['text'];
                                    break 2;
                                }
                            }
                        }
                    }
                } else {
                    $response_content = $result['choices'][0]['message']['content'] ?? null;
                }
            }

            if (!$response_content) {
                error_log('[AI App Onsite] Null response_content. HTTP code: ' . $response_code . ' | model: ' . $model . ' | Response body: ' . substr((string) $response_body, 0, 1000));
                wp_send_json_error( ai_app_onsite_explain_empty_ai_response( $result, $model ) );
            }

            // Format raw provider text into safe HTML via shared formatter.
            $response_content = ai_app_onsite_format_ai_response_html( (string) $response_content );


            if (!empty($app_email)) {
                $resultArray = array_filter(
                    $pairs,
                    function ($key) use ($fieldLabels) {
                        return in_array($key, $fieldLabels);
                    },
                    ARRAY_FILTER_USE_KEY
                );

                self::ai_app_onsite_send_email($app_email, $resultArray, $response_content, $app_name);
            }

            $user_stats_handler = new AI_APP_ONSITE_User_Stats_Handler();
            $response_Id = $user_stats_handler->ai_app_onsite_save_user_stats($result, $prompt, $formData,$response_content);


            // Optionally handle response from external URL
            $response = [
                'success'     => true,
                'message'     => 'Form data received successfully',
                'data'        => $response_content,
                'response_message' => $response_message,
                'response_id' => $response_Id,
            ];

            wp_send_json($response);
        }

        // Sending email with dynamic data
	    public static function ai_app_onsite_send_email($to, $data, $ai_output, $app_name): void
	    {
		    // Normalize $data -> safe HTML list items
		    $dynamic_list = '';
		    foreach ($data as $key => $value) {
			    if (is_array($value) || is_object($value)) {
				    $value = json_encode($value, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
			    }
			    // Convert simple newlines to <br> for readability
			    $safeValue = nl2br(htmlspecialchars((string)$value, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8'));
			    $safeKey = htmlspecialchars(ucfirst(str_replace('_', ' ', (string)$key)), ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8');
			    $dynamic_list .= "<tr><td style=\"padding:6px 0;border-bottom:1px solid #eee;\"><strong>{$safeKey}:</strong> {$safeValue}</td></tr>";
		    }

		    // If AI output is plain text, keep formatting; if HTML, it will pass through.
		    $ai_output_block = $ai_output;
		    // Best-effort: if it looks plain (no tags), escape then nl2br
		    if ($ai_output === strip_tags($ai_output)) {
			    $ai_output_block = nl2br(htmlspecialchars($ai_output, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8'));
		    }

		    $brand   = 'AIappOnsite';
		    $suffix  = !empty($app_name) ? " – " . htmlspecialchars($app_name, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8') : '';
		    $site_name = get_bloginfo('name');
		    $safe_site_name = htmlspecialchars($site_name ?: 'this site', ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8');
		    $subject = "{$brand} App Usage{$suffix}";

		    // Hidden preheader (appears in inbox preview)
		    $preheader = "Your {$brand} submission and AI response{$suffix}.";

		    // NOTE: Keep styles inline & table-based for broad client support
		    $email_template = <<<HTML
					<!doctype html>
					<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
					  <head>
					    <meta http-equiv="x-ua-compatible" content="ie=edge">
					    <meta name="viewport" content="width=device-width, initial-scale=1"> 
					    <meta charset="UTF-8">
					    <title>{$brand}{$suffix}</title>
					    <!--[if mso]>
					      <style type="text/css">
					        body, table, td {font-family: Arial, sans-serif !important;}
					      </style>
					    <![endif]-->
					    <style>
					      /* Minimal mobile fluidity without relying on head CSS */
					      @media only screen and (max-width: 620px) {
					        .container {width: 100% !important;}
					        .p-24 {padding:16px !important;}
					        .h1 {font-size: 20px !important; line-height: 26px !important;}
					      }
					    </style>
					  </head>
					  <body style="margin:0;padding:0;background-color:#f5f7fb;">
					    <span style="display:none!important;visibility:hidden;opacity:0;color:transparent;height:0;width:0;overflow:hidden;">{$preheader}</span>
					    <table role="presentation" cellpadding="0" cellspacing="0" border="0" width="100%" style="background:#f5f7fb;">
					      <tr>
					        <td align="center" style="padding:24px;">
					          <table role="presentation" cellpadding="0" cellspacing="0" border="0" width="720" class="container" style="width:720px;max-width:720px;background:#ffffff;border-radius:8px;box-shadow:0 2px 8px rgba(16,24,40,0.06);">
					            <tr>
					              <td class="p-24" style="padding:24px 24px 0 24px;">
					                <table width="100%" role="presentation" cellpadding="0" cellspacing="0" border="0">
					                  <tr>
					                    <td align="left" style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Arial, sans-serif; color:#111827;">
					 
					                      <h1 class="h1" style="margin:0;font-size:22px;line-height:28px;font-weight:700;">{$brand} App Input Data{$suffix}</h1>
					                    </td>
					                  </tr>
					                </table>
					              </td>
					            </tr>
					
					            <tr>
					              <td class="p-24" style="padding:16px 24px 0 24px;">
					                <p style="margin:0 0 12px 0;font-family:-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Arial, sans-serif; font-size:14px; line-height:20px; color:#374151;">
					                  This is the data you provided:
					                </p>
					                <table role="presentation" cellpadding="0" cellspacing="0" border="0" width="100%">
					                  {$dynamic_list}
					                </table>
					              </td>
					            </tr>
					
					            <tr>
					              <td class="p-24" style="padding:16px 24px 0 24px;">
					                <p style="margin:0 0 8px 0;font-family:-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Arial, sans-serif; font-size:14px; line-height:20px; color:#374151;"><strong>App Results:</strong></p>
					                <div style="border:1px solid #e5e7eb; background:#f9fafb; border-radius:6px; padding:16px; font-family:-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Arial, sans-serif; font-size:13px; line-height:20px; color:#111827;">
					                  {$ai_output_block}
					                </div>
					              </td>
					            </tr>
					
					            <tr>
					              <td class="p-24" style="padding:16px 24px 24px 24px;">
					                <p style="margin:12px 0 0 0;font-family:-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Arial, sans-serif; font-size:13px; line-height:20px; color:#6b7280;">
					                  Thanks for using {$brand}, provided by {$safe_site_name}!
					                </p>
					              </td>
					            </tr>
					          </table>
					
					          <table role="presentation" cellpadding="0" cellspacing="0" border="0" width="720" class="container" style="width:720px;max-width:720px;">
					            <tr>
					              <td align="center" style="padding:12px 8px 0 8px;">
					                <p style="margin:0;font-family:-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Arial, sans-serif; font-size:11px; line-height:16px; color:#9ca3af;">
					                This email was requested by the recipient and sent by the {$safe_site_name} website using AIappOnsite.
					                </p>
					              </td>
					            </tr>
					            <tr><td style="height:24px; line-height:24px;">&nbsp;</td></tr>
					          </table>
					        </td>
					      </tr>
					    </table>
					  </body>
					</html>
					HTML;

		    // Build headers (prefer wp_mail when available)
		    $headers = [];
		    $headers[] = 'MIME-Version: 1.0';
		    $headers[] = 'Content-Type: text/html; charset=UTF-8';

		    $fromEmail = defined('AIAPP_FROM_EMAIL') ? AIAPP_FROM_EMAIL : null;
		    if ($fromEmail) {
			    $headers[] = 'From: AIappOnsite <' . $fromEmail . '>';
			    $headers[] = 'Reply-To: ' . $fromEmail;
		    }

		    // Use wp_mail if available; fallback to mail()
		    if (function_exists('wp_mail')) {
			    wp_mail($to, $subject, $email_template, $headers);
		    } else {
			    // mail() expects headers as a string
			    $headers_str = implode("\r\n", $headers);
			    @mail($to, $subject, $email_template, $headers_str);
		    }
	    }
    }

    new AI_APP_ONSITE_OpenAi_Api_Handler(); // Instantiate the class
}


function AI_APP_ONSITE_Break_Paragraph($text, $words_per_chunk = 200)
{
    // Split the text into an array of words
    $words = preg_split('/\s+/', $text);

    $chunks = array_chunk($words, $words_per_chunk);

    $result = '';
    foreach ($chunks as $chunk) {
        $result .= implode(' ', $chunk) . "\n\n";
    }

    return $result;
}

if (! function_exists('ai_app_onsite_remote_post_with_retry')) {
    /**
     * wp_remote_post wrapper that automatically retries transient network errors
     * (e.g. cURL 56 "Connection reset by peer", timeouts, connection/SSL failures,
     * empty replies). These are momentary transport-level drops that usually
     * succeed on a second attempt.
     *
     * Any successful HTTP response (including 4xx/5xx from the provider) is
     * returned immediately without retrying, and non-transient WP_Errors are not
     * retried either — so only genuine connection blips trigger a retry.
     *
     * @param string $url         Endpoint URL.
     * @param array  $args        Arguments passed to wp_remote_post().
     * @param int    $max_retries Number of extra attempts after the first (default 1).
     * @return array|WP_Error     The wp_remote_post() result (or last WP_Error).
     */
    function ai_app_onsite_remote_post_with_retry($url, $args, $max_retries = 1)
    {
        $transient_needles = array(
            'cURL error 7',   // couldn't connect to host
            'cURL error 28',  // operation timed out
            'cURL error 35',  // SSL connect error
            'cURL error 52',  // empty reply from server
            'cURL error 56',  // recv failure: connection reset by peer
            'Connection reset',
            'Recv failure',
            'Empty reply',
            'timed out',
        );

        $response = null;

        for ($attempt = 0; $attempt <= $max_retries; $attempt++) {
            $response = wp_remote_post($url, $args);

            // Got an actual HTTP response (any status) — done.
            if (! is_wp_error($response)) {
                return $response;
            }

            $message      = $response->get_error_message();
            $is_transient = false;
            foreach ($transient_needles as $needle) {
                if (stripos($message, $needle) !== false) {
                    $is_transient = true;
                    break;
                }
            }

            // Stop on non-transient errors or after the final attempt.
            if (! $is_transient || $attempt === $max_retries) {
                break;
            }

            error_log('[AI App Onsite] Transient network error (attempt ' . ($attempt + 1) . '): ' . $message . ' — retrying...');

            // Linear backoff: 0.5s, then 1.0s.
            usleep(500000 * ($attempt + 1));
        }

        return $response;
    }
}

if (! function_exists('ai_app_onsite_explain_empty_ai_response')) {
    /**
     * Build a detailed, user-friendly message when the AI returned HTTP 200 but
     * no usable text (e.g. a reasoning model that spent all its output tokens on
     * internal reasoning, an incomplete response, a content-filter block, or a
     * refusal). Replaces the old generic "Invalid response from AI provider".
     *
     * @param mixed  $result Decoded response body (associative array) or null.
     * @param string $model  Model name, for context in the message.
     * @return string        Human-readable explanation.
     */
    function ai_app_onsite_explain_empty_ai_response($result, $model = '')
    {
        $model_label = ($model !== '' && $model !== null) ? '"' . $model . '"' : 'The selected model';

        if (is_array($result)) {
            $status = isset($result['status']) ? (string) $result['status'] : '';
            $reason = isset($result['incomplete_details']['reason']) ? (string) $result['incomplete_details']['reason'] : '';

            // OpenAI Responses API: output-token budget exhausted (common with reasoning models).
            if ($reason === 'max_output_tokens') {
                $limit      = isset($result['max_output_tokens']) ? (int) $result['max_output_tokens'] : 0;
                $limit_text = $limit > 0 ? ' (limit: ' . $limit . ' tokens)' : '';
                return $model_label . ' ran out of output tokens' . $limit_text . ' before it could finish its answer. '
                    . 'Reasoning models such as GPT-5 spend part of the output budget on internal reasoning, so a low "Max Tokens" value can leave no room for the reply. '
                    . 'Please increase "Max Tokens" in Model Settings and try again.';
            }

            // Blocked by the provider's safety/content filter.
            if ($reason === 'content_filter' || $status === 'content_filter') {
                return 'The response from ' . $model_label . ' was blocked by the provider\'s content filter. Please rephrase your input and try again.';
            }

            // Responses API refusal item.
            if (isset($result['output']) && is_array($result['output'])) {
                foreach ($result['output'] as $item) {
                    if (isset($item['content']) && is_array($item['content'])) {
                        foreach ($item['content'] as $content) {
                            if (isset($content['type']) && $content['type'] === 'refusal' && ! empty($content['refusal'])) {
                                return $model_label . ' declined to answer: ' . (string) $content['refusal'];
                            }
                        }
                    }
                }
            }

            // Chat Completions API: truncated / filtered finish reasons.
            if (isset($result['choices'][0]['finish_reason'])) {
                $finish = (string) $result['choices'][0]['finish_reason'];
                if ($finish === 'length') {
                    return $model_label . ' ran out of output tokens before finishing its answer. Please increase "Max Tokens" in Model Settings and try again.';
                }
                if ($finish === 'content_filter') {
                    return 'The response from ' . $model_label . ' was blocked by the provider\'s content filter. Please rephrase your input and try again.';
                }
            }

            // Generic incomplete status.
            if ($status === 'incomplete') {
                $reason_text = $reason !== '' ? ' (reason: ' . $reason . ')' : '';
                return $model_label . ' returned an incomplete response' . $reason_text . '. Please try again, and consider increasing "Max Tokens" in Model Settings.';
            }
        }

        return 'The AI provider returned an empty response for ' . $model_label . '. This can happen when the model uses all available tokens on reasoning. Please try again or increase "Max Tokens" in Model Settings.';
    }
}