<?php

require_once __DIR__ . '/../lib/config.php';
require_once __DIR__ . '/../lib/OpenAIService.php';
require_once __DIR__ . '/../db/config.php';

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

session_start();
if (empty($_SESSION['session_id'])) {
    $_SESSION['session_id'] = bin2hex(random_bytes(16));
}
$session_id = $_SESSION['session_id'];

if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    echo json_encode(['error' => 'Invalid request method.']);
    exit;
}

$input = json_decode(file_get_contents('php://input'), true);

if (!isset($input['message']) || trim($input['message']) === '') {
    echo json_encode(['error' => 'Message is required.']);
    exit;
}

$user_message = trim($input['message']);

try {
    $pdo = db();
    
    // Save user message
    $stmt = $pdo->prepare("INSERT INTO chat_log (session_id, sender, message) VALUES (?, ?, ?)");
    $stmt->execute([$session_id, 'user', $user_message]);
    
    // Get AI response
    $response = OpenAIService::getCompletion($user_message);

    if (!empty($response['error'])) {
        http_response_code(500);
        echo json_encode($response);
        exit;
    }

    $ai_message = $response['reply'];

    // Save AI message
    $stmt = $pdo->prepare("INSERT INTO chat_log (session_id, sender, message) VALUES (?, ?, ?)");
    $stmt->execute([$session_id, 'ai', $ai_message]);

    echo json_encode(['reply' => $ai_message]);
    
} catch (PDOException $e) {
    // Log error and return a generic error message
    error_log("Database error: " . $e->getMessage());
    echo json_encode(['error' => 'An internal server error occurred.']);
    exit;
}