<?php
// Replace 'YOUR_API_KEY' with your actual OpenAI API key
$api_key = "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";

// Function to send a message to ChatGPT and receive a response
function chatWithGPT($message, $api_key) {
    $data = array(
        'model' => 'davinci', // You can choose from different GPT-3 engines
        'messages' => array(
            array(
                'role' => 'system',
                'content' => 'You are a helpful assistant.'
            ),
            array(
                'role' => 'user',
                'content' => $message
            )
        )
    );
    $url = 'https://api.openai.com/v1/chat/completions';
    $url = 'https://api.openai.com/v1/engines/davinci/completions';
    $headers = array(
        'Content-Type: application/json',
        'Authorization: Bearer ' . $api_key
    );

    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

    $response = curl_exec($ch);
    curl_close($ch);

    $decoded_response = json_decode($response, true);
    $message = $decoded_response['choices'][0]['message']['content'];

    return $message;
}

// Example usage
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $user_input = $_POST['user_input'];
    $response = chatWithGPT($user_input, $api_key);
    echo json_encode(array('message' => $response));
}
?>