server.php

<?php

ini_set('session.use_cookies', 0);

session_id($_POST['sess'] ?? uniqid() . uniqid()); // Falling back to a random ID even though we'll not have context then
session_start();

$config = require 'config.php';

$api_key = $config['apikey'];
$base_url = 'https://api.openai.com/v1/completions';

$prompts = array(
//    'What is five times three?',
//    'Multiply that by two',
//    'Please explain how you calculated the previous two responses',
    'Explain in 50 words or less why the sky is blue',
    'How many words did you use?',
    'Try again with only 20 words',
);


$prompt = $_POST['message'] ?? null;
$prompt = trim($prompt);

if (empty($prompt)) {
    echo 'No prompt sent.';
    exit;
}

if ( ! isset( $_SESSION['history'] ) ) {
    $_SESSION['history'] = [];
}



$enriched_prompt = <<<PROMPT
If the prompt is about code, always enclose code samples in "--CODESTART--" and "--CODEEND--"

For example:
--CODESTART--
<?php
echo "hello world";
--CODEEND--
PROMPT;

foreach ( $_SESSION['history'] as $key => $pair ) {
    $enriched_prompt .= 'Prompt:' . $key . ': ' . $pair['prompt'] . PHP_EOL;
    $enriched_prompt .= 'Response:' . $key . ': ' . $pair['response'] . PHP_EOL;
}

//$enriched_prompt .= 'Please only respond to the new prompt below: ' . PHP_EOL;

$enriched_prompt .= PHP_EOL . 'New prompt: ' . $prompt . PHP_EOL;
$enriched_prompt .= 'Response: ';


// For English text, 1 token is approximately 4 characters or 0.75 words.
// Make sure we don't go over 2048 tokens for the prompt - leave 25% margin. --> allow only 6144 chars in prompt
$max_prompt_chars = 6144;
if (strlen($enriched_prompt) > $max_prompt_chars) {
    // take max_prompt_chars from the end of enriched_prompt
     $enriched_prompt = substr($enriched_prompt, strlen($enriched_prompt) - $max_prompt_chars);
}


$data = array(
    'model' => 'text-davinci-003',
    'prompt' => $enriched_prompt,
    'temperature' => 0.5,
    //'top_p' => 0.1,
    'stop' => [
        'Prompt:',
        'Response:',
    ],
    'stream' => true,
    'max_tokens' => 2048,
);

//    echo '------------------------------' . PHP_EOL;
//    echo 'Request params: ' . PHP_EOL;
//    var_dump($data);
$data_string = json_encode($data);

$headers = array(
    'Content-Type: application/json',
    'Authorization: Bearer ' . $api_key
);

$this_response = '';

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $base_url);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_WRITEFUNCTION, function($ch, $data) use (&$this_response) {
    $lines = explode("\n", $data);
    foreach ($lines as $line) {
        $line = trim($line);
        if ($line == '') {
            continue;
        }
        if ($line == 'data: [DONE]') {
            return strlen($data);
        }

        // cut off the 'data: ' prefix
        $line = substr($line, 6);

        $response = json_decode($line, true);

        if (!isset($response['choices'][0]['text'])) {
            echo "Could not generate response: ";
            var_dump($line);
        }

        $actual_data = $response['choices'][0]['text'];

        $this_response .= $actual_data;
        echo $actual_data;
        flush();
        ob_flush();
    }
    return strlen($data);
});

$result = curl_exec($ch);
$error = curl_error($ch);

curl_close($ch);

if ($error) {
    echo 'Error: ' . $error . PHP_EOL;
} else {

    //$response = json_decode($result, true);
    $_SESSION['history'][] = [
        'prompt' => $prompt,
        'response' => trim( $this_response ),
    ];
}


//echo PHP_EOL . PHP_EOL . ' HISTORY: ' . PHP_EOL . PHP_EOL;
//
//// Output history
//foreach ($history as $item) {
//    echo 'Prompt: ' . $item['prompt'] . PHP_EOL;
//    echo 'Response: ' . print_r($item['response'], true) . PHP_EOL;
//    echo '------------------------------' . PHP_EOL;
//}