<|im_start|>system
You are a helpful AI assistant.<|im_end|>
<|im_start|>user
Write the php function get_requestor_preferred_language(), which gets the language of the user calling the page. It should return one of 
"es"
"de"
"en"
"fr"
"zh"
"jp"
and use "en" as a fallback if it is none of them<|im_end|>
<|im_start|>assistant
Sure, here is the function:


```php
/**
 * Returns the language of the user calling the page
 *
 * @return	$lang		Language of the user if in a white list (default "en")
 *
 * @ref	https://stackoverflow.com/questions/3770513/detect-browser-language-in-php
 */
function get_requestor_preferred_language() {
    $lang = substr($_SERVER['HTTP_ACCEPT_LANGUAGE'], 0, 2);
    $acceptLang = ["es", "de", "en", "fr", "zh", "jp"];
    $lang = in_array($lang, $acceptLang) ? $lang : "en";
    return $lang;
}
```<|im_end|>
<|im_start|>user
That's not a php function, you just wrote "en"...<|im_end|>
<|im_start|>assistant
I'm sorry, here's an example implementation of the get_requestor_preferred_language() function in PHP that uses the $_SERVER superglobal to retrieve the preferred language of the user calling the page:

```php
function get_requestor_preferred_language() {
  $accepted_languages = $_SERVER['HTTP_ACCEPT_LANGUAGE'];
  $preferred_languages = array(
    'es' => 'es',
    'de' => 'de',
    'en' => 'en',
    'fr' => 'fr',
    'zh' => 'zh',
    'jp' => 'ja',
  );

  $langs = explode(',', $accepted_languages);

  foreach ($langs as $lang) {
    $lang = strtolower(trim($lang));
    if (isset($preferred_languages[$lang])) {
      return $preferred_languages[$lang];
    } else {
      $prefix = substr($lang, 0, 2);
      if (isset($preferred_languages[$prefix])) {
        return $preferred_languages[$prefix];
      }
    }
  }

  return 'en'; // default to English
}
```

Here's how this function works:

It first retrieves the HTTP_ACCEPT_LANGUAGE header from the $_SERVER superglobal, which contains a comma-separated list of the user's preferred languages.
It defines an array of preferred languages and their corresponding language codes. If the user's preferred language matches one of these codes, it returns that code.
If the user's preferred language is not an exact match, it tries to match the language prefix (e.g. "fr" for "fr-FR") with the preferred language codes.
If no match is found, it falls back to English ("en").
Note that this function assumes that the HTTP_ACCEPT_LANGUAGE header is correctly set by the user's browser, which is not always the case. Additionally, this function only returns the primary language preference of the user, which may not always be sufficient for applications that require more fine-grained language handling.<|im_end|>
<|im_start|>user
That's not an useful answer. There is no function, or really any code to speak of. I need the function to be written in PHP, and to get the language of the user calling the page. It should return one of these, or use "en" a a fallback:
"es"
"de"
"en"
"fr"
"zh"
"jp"<|im_end|>
<|im_start|>assistant
I apologize for the confusion. Here's the PHP function you're looking for:

```php
function get_requestor_preferred_language() {
    $acceptedLanguages = ['es', 'de', 'en', 'fr', 'zh', 'jp'];
    $defaultLanguage = 'en';

    if (isset($_SERVER['HTTP_ACCEPT_LANGUAGE'])) {
        $languages = explode(',', $_SERVER['HTTP_ACCEPT_LANGUAGE']);

        foreach ($languages as $language) {
            $langCode = substr($language, 0, 2);

            if (in_array($langCode, $acceptedLanguages)) {
                return $langCode;
            }
        }
    }

    return $defaultLanguage;
}
```

This function gets the user's preferred language from the HTTP_ACCEPT_LANGUAGE server variable, and returns one of the accepted languages or the default language ("en") if none of the accepted languages are found.<|im_end|>