index.php

<?php



$API_KEY = 'ur api key lol';
$GEMINI_MODEL = 'gemini-2.5-flash';
$GEMINI_URL = "https://generativelanguage.googleapis.com/v1beta/models/{$GEMINI_MODEL}:generateContent?key={$API_KEY}";


$infoPath = __DIR__ . '/info.txt';
$buttonsPath = __DIR__ . '/buttons.json';
$rateLimitDir = __DIR__ . '/rate_limit';






header("Access-Control-Allow-Origin: https://bio-sim.us"); 
header("Access-Control-Allow-Methods: POST, OPTIONS");
header("Access-Control-Allow-Headers: Content-Type, Authorization, X-Requested-With");
header('Content-Type: application/json; charset=utf-8');


if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
    http_response_code(200);
    exit;
}


if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    http_response_code(405);
    echo json_encode(['error' => 'Only POST is allowed.']);
    exit;
}





$MAX_REQUESTS = 10;
$WINDOW_SECONDS = 600;

try {
    if (!is_dir($rateLimitDir)) {
        @mkdir($rateLimitDir, 0755, true);
    }
    

    $clientIp = $_SERVER['HTTP_CF_CONNECTING_IP'] 
        ?? $_SERVER['HTTP_X_FORWARDED_FOR'] 
        ?? $_SERVER['REMOTE_ADDR'] 
        ?? 'unknown';
        
    $ipKey = sha1($clientIp);
    $rlFile = $rateLimitDir . '/' . $ipKey . '.json';
    $now = time();
    $history = [];


    if (file_exists($rlFile)) {
        $history = json_decode(file_get_contents($rlFile), true) ?? [];
    }


    $history = array_values(array_filter($history, function ($ts) use ($now, $WINDOW_SECONDS) {
        return is_int($ts) && ($ts > $now - $WINDOW_SECONDS);
    }));

    if (count($history) >= $MAX_REQUESTS) {
        echo json_encode(['reply' => 'Too Many Requests (Rate Limit Exceeded)', 'button' => 'none']);
        exit;
    }

    $history[] = $now;
    file_put_contents($rlFile, json_encode($history));

} catch (Exception $e) {


}




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

if (!isset($body['userinput']) || trim($body['userinput']) === '') {
    http_response_code(400);
    echo json_encode(['error' => 'Missing userinput']);
    exit;
}

$userInput = $body['userinput'];


$infoText = file_exists($infoPath) ? file_get_contents($infoPath) : "No background info provided.";

$buttonsMapping = [];
if (file_exists($buttonsPath)) {
    $buttonsMapping = json_decode(file_get_contents($buttonsPath), true) ?? [];
}
$buttonsKeys = array_keys($buttonsMapping);
$buttonsKeysJson = json_encode($buttonsKeys);





$systemPrompt = <<<EOT
Answer the prompt delimited by the triple apostrophes in the best way possible using your knowledge about biology.
When possible, incorporate information delimited by the triple backticks in your answer.

Limit yourself to 5 sentences unless otherwise specified by the prompt.

When possible, make your answer a bulleted list, adding "<br><br>" after each line break. 
Do not bold any texts by wrapping the texts with **.
Highlight any key/important words in your response. In order to highlight a text, wrap the text with <b> and </b>.
Use "-" before each bullet point.

If you are unable to respond to the prompt using either your knowledge about biology, or by using the information delimited by the triple backticks,
then add 'what is' in front of the prompt and then attempt to respond to it.

If you still are unable to respond to the prompt, then respond with the response "Sorry, I cannot help you with that".

Background Info:
```{$infoText}```

User Prompt:
'''{$userInput}'''
EOT;

$payloadChat = [
    'contents' => [
        [
            'parts' => [['text' => $userInput]]
        ]
    ],
    'systemInstruction' => [
        'parts' => [['text' => $systemPrompt]]
    ]
];

$responseChat = makeGeminiCall($GEMINI_URL, $payloadChat);
$replyText = "Sorry, I couldn't produce a response.";

if (isset($responseChat['candidates'][0]['content']['parts'][0]['text'])) {
    $replyText = $responseChat['candidates'][0]['content']['parts'][0]['text'];
}






$buttonPrompt = <<<EOT
The given prompt is delimited by the triple apostrophes.
The given Array is delimited by the triple backticks.

Your task is to pick one of the strings in the Array which is the most relevant to the prompt.
Your response should only include that string, and nothing else.
If none of the keys in the JSON text are relevant to the prompt, your response should be "none".

User Prompt:
'''{$userInput}'''

Available Buttons:
```{$buttonsKeysJson}```
EOT;

$payloadButton = [
    'contents' => [
        [
            'parts' => [['text' => $buttonPrompt]]
        ]
    ]
];

$responseButton = makeGeminiCall($GEMINI_URL, $payloadButton);
$selectedKey = 'none';

if (isset($responseButton['candidates'][0]['content']['parts'][0]['text'])) {
    $selectedKey = trim($responseButton['candidates'][0]['content']['parts'][0]['text']);

    $selectedKey = trim(preg_replace('/\s\s+/', ' ', $selectedKey));
}

$buttonValue = array_key_exists($selectedKey, $buttonsMapping) ? $buttonsMapping[$selectedKey] : 'none';

echo json_encode([
    'reply'  => $replyText,
    'button' => $buttonValue,
]);

function makeGeminiCall($url, $payload) {
    $ch = curl_init($url);
    curl_setopt_array($ch, [
        CURLOPT_POST => true,
        CURLOPT_HTTPHEADER => ['Content-Type: application/json'],
        CURLOPT_POSTFIELDS => json_encode($payload),
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_TIMEOUT => 30,
        CURLOPT_SSL_VERIFYPEER => true
    ]);
    
    $response = curl_exec($ch);
    
    if (curl_errno($ch)) {
        return null;
    }
    
    curl_close($ch);
    return json_decode($response, true);
}
?>