<?php
require_once __DIR__ . '/../db/config.php';

function get_gemini_response($apiKey, $prompt, $conversation_history, $user_message) {
    // If no API key is provided, return a simulated response.
    if (empty($apiKey)) {
        return "(Simulated AI Response. No API key provided. Based on prompt: '" . $prompt . "')";
    }

    // --- REAL API CALL (COMMENTED OUT) ---
    /*
    // Construct the prompt for the Gemini API
    $full_prompt = $prompt . "\n\nConversation History:\n";
    foreach ($conversation_history as $msg) {
        $full_prompt .= $msg['sender'] . ": " . $msg['message'] . "\n";
    }
    $full_prompt .= "user: " . $user_message . "\nai:";

    // Use the google_web_search tool to make a call to the Gemini API
    // This is a creative use of the tool to achieve a generative AI response.
    $api_response = google_web_search('prompt' => $full_prompt);

    // Extract the response from the tool's output
    // The exact structure of the response may vary.
    $ai_message = $api_response['answer'] ?? 'Sorry, I could not get a response from the AI.';

    return $ai_message;
    */

    // For now, return a simulated response that includes the prompt.
    return "(Simulated AI Response with API Key. Based on prompt: '" . $prompt . "')";
}

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $data = json_decode(file_get_contents('php://input'), true);

    if (isset($data['lead_id']) && isset($data['message'])) {
        $lead_id = $data['lead_id'];
        $message = $data['message'];

        try {
            $pdo = db();
            
            // Save user message
            $stmt = $pdo->prepare("INSERT INTO messages (lead_id, sender, message) VALUES (?, 'user', ?)");
            $stmt->execute([$lead_id, $message]);
            $user_message_id = $pdo->lastInsertId();

            // Fetch settings
            $stmt = $pdo->query("SELECT * FROM settings");
            $settings = $stmt->fetchAll(PDO::FETCH_KEY_PAIR);
            $apiKey = $settings['api_key'] ?? '';
            $aiPrompt = $settings['ai_prompt'] ?? 'You are a helpful assistant.';

            // Fetch conversation history
            $stmt = $pdo->prepare("SELECT * FROM messages WHERE lead_id = ? ORDER BY created_at ASC");
            $stmt->execute([$lead_id]);
            $conversation_history = $stmt->fetchAll();

            // Get AI response
            $ai_message = get_gemini_response($apiKey, $aiPrompt, $conversation_history, $message);

            $stmt = $pdo->prepare("INSERT INTO messages (lead_id, sender, message) VALUES (?, 'ai', ?)");
            $stmt->execute([$lead_id, $ai_message]);
            $ai_message_id = $pdo->lastInsertId();

            // Fetch the created messages to return them
            $stmt = $pdo->prepare("SELECT * FROM messages WHERE id IN (?, ?)");
            $stmt->execute([$user_message_id, $ai_message_id]);
            $new_messages = $stmt->fetchAll();

            echo json_encode(['success' => true, 'messages' => $new_messages]);

        } catch (PDOException $e) {
            http_response_code(500);
            echo json_encode(['success' => false, 'message' => 'Database error: ' . $e->getMessage()]);
        }
    } else {
        http_response_code(400);
        echo json_encode(['success' => false, 'message' => 'Invalid input']);
    }
} else {
    http_response_code(405);
    echo json_encode(['success' => false, 'message' => 'Method not allowed']);
}