PHPでGemini APIを使う方法

$prompt = "日本の首相は誰ですか。";
$text = generate_content($prompt);
print $text;

function generate_content($prompt) {
  $apiKey = "自分のAPIキー";
  $url = "https://generativelanguage.googleapis.com/v1/models/gemini-1.5-flash:generateContent";
  $data = array(
    "contents" => array(
      array(
        "parts" => array(
          array(
            "text" => $prompt
          )
        )
      )
    )
  );
  $options = array(
    "http" => array(
      "header"  => "Content-type: application/json\r\n",
      "method"  => "POST",
      "content" => json_encode($data)
    )
  );
  $context  = stream_context_create($options);
  $result = file_get_contents($url . "?key=" . $apiKey, false, $context);
  $response = json_decode($result, true);
  $generatedText = $response["candidates"][0]["content"]["parts"][0]["text"];
  return $generatedText;
}