<?php

/**

 * @file

 * Drupal placeholder/token replacement system.

 *

 * API functions for replacing placeholders in text with meaningful values.

 *

 * For example: When configuring automated emails, an administrator enters

 * standard text for the email. Variables like the title of a node and the date

 * the email was sent can be entered as placeholders like [node:title] and

 * [date:short]. When a Drupal module prepares to send the email, it can call

 * the token_replace() function, passing in the text. The token system will

 * scan the text for placeholder tokens, give other modules an opportunity to

 * replace them with meaningful text, then return the final product to the

 * original module.

 *

 * Tokens follow the form: [$type:$name], where $type is a general class of

 * tokens like 'node', 'user', or 'comment' and $name is the name of a given

 * placeholder. For example, [node:title] or [node:created:since].

 *

 * In addition to raw text containing placeholders, modules may pass in an array

 * of objects to be used when performing the replacement. The objects should be

 * keyed by the token type they correspond to. For example:

 *

 * @code

 * // Load a node and a user, then replace tokens in the text.

 * $text = 'On [date:short], [user:name] read [node:title].';

 * $node = node_load(1);

 * $user = user_load(1);

 *

 * // [date:...] tokens use the current date automatically.

 * $data = array('node' => $node, 'user' => $user);

 * return token_replace($text, $data);

 * @endcode

 *

 * Some tokens may be chained in the form of [$type:$pointer:$name], where $type

 * is a normal token type, $pointer is a reference to another token type, and

 * $name is the name of a given placeholder. For example, [node:author:mail]. In

 * that example, 'author' is a pointer to the 'user' account that created the

 * node, and 'mail' is a placeholder available for any 'user'.

 *

 * @see token_replace()

 * @see hook_tokens()

 * @see hook_token_info()

 */

/**

 * Replaces all tokens in a given string with appropriate values.

 *

 * @param $text

 *   A string potentially containing replaceable tokens.

 * @param $data

 *   (optional) An array of keyed objects. For simple replacement scenarios

 *   'node', 'user', and others are common keys, with an accompanying node or

 *   user object being the value. Some token types, like 'site', do not require

 *   any explicit information from $data and can be replaced even if it is

 *   empty.

 * @param $options

 *   (optional) A keyed array of settings and flags to control the token

 *   replacement process. Supported options are:

 *   - language: A language object to be used when generating locale-sensitive

 *     tokens.

 *   - callback: A callback function that will be used to post-process the array

 *     of token replacements after they are generated. For example, a module

 *     using tokens in a text-only email might provide a callback to strip HTML

 *     entities from token values before they are inserted into the final text.

 *   - clear: A boolean flag indicating that tokens should be removed from the

 *     final text if no replacement value can be generated.

 *   - sanitize: A boolean flag indicating that tokens should be sanitized for

 *     display to a web browser. Defaults to TRUE. Developers who set this

 *     option to FALSE assume responsibility for running filter_xss(),

 *     check_plain() or other appropriate scrubbing functions before displaying

 *     data to users.

 *

 * @return

 *   Text with tokens replaced.

 */

function token_replace($text, array $data = array(), array $options = array()) {

  $text_tokens = token_scan($text);

  if (empty($text_tokens)) {

    return $text;

  }

  $replacements = array();

  foreach ($text_tokens as $type => $tokens) {

    $replacements += token_generate($type, $tokens, $data, $options);

    if (!empty($options['clear'])) {

      $replacements += array_fill_keys($tokens, '');

    }

  }

  // Optionally alter the list of replacement values.

  if (!empty($options['callback']) && function_exists($options['callback'])) {

    $function = $options['callback'];

    $function($replacements, $data, $options);

  }

  $tokens = array_keys($replacements);

  $values = array_values($replacements);

  return str_replace($tokens, $values, $text);

}

/**

 * Builds a list of all token-like patterns that appear in the text.

 *

 * @param $text

 *   The text to be scanned for possible tokens.

 *

 * @return

 *   An associative array of discovered tokens, grouped by type.

 */

function token_scan($text) {

  // Matches tokens with the following pattern: [$type:$name]

  // $type and $name may not contain  [ ] characters.

  // $type may not contain : or whitespace characters, but $name may.

  preg_match_all('/

    \[             # [ - pattern start

    ([^\s\[\]:]*)  # match $type not containing whitespace : [ or ]

    :              # : - separator

    ([^\[\]]*)     # match $name not containing [ or ]

    \]             # ] - pattern end

    /x', $text, $matches);

  $types = $matches[1];

  $tokens = $matches[2];

  // Iterate through the matches, building an associative array containing

  // $tokens grouped by $types, pointing to the version of the token found in

  // the source text. For example, $results['node']['title'] = '[node:title]';

  $results = array();

  for ($i = 0; $i < count($tokens); $i++) {

    $results[$types[$i]][$tokens[$i]] = $matches[0][$i];

  }

  return $results;

}

/**

 * Generates replacement values for a list of tokens.

 *

 * @param $type

 *   The type of token being replaced. 'node', 'user', and 'date' are common.

 * @param $tokens

 *   An array of tokens to be replaced, keyed by the literal text of the token

 *   as it appeared in the source text.

 * @param $data

 *   (optional) An array of keyed objects. For simple replacement scenarios

 *   'node', 'user', and others are common keys, with an accompanying node or

 *   user object being the value. Some token types, like 'site', do not require

 *   any explicit information from $data and can be replaced even if it is

 *   empty.

 * @param $options

 *   (optional) A keyed array of settings and flags to control the token

 *   replacement process. Supported options are:

 *   - language: A language object to be used when generating locale-sensitive

 *     tokens.

 *   - callback: A callback function that will be used to post-process the

 *     array of token replacements after they are generated. Can be used when

 *     modules require special formatting of token text, for example URL

 *     encoding or truncation to a specific length.

 *   - sanitize: A boolean flag indicating that tokens should be sanitized for

 *     display to a web browser. Developers who set this option to FALSE assume

 *     responsibility for running filter_xss(), check_plain() or other

 *     appropriate scrubbing functions before displaying data to users.

 *

 * @return

 *   An associative array of replacement values, keyed by the original 'raw'

 *   tokens that were found in the source text. For example:

 *   $results['[node:title]'] = 'My new node';

 *

 * @see hook_tokens()

 * @see hook_tokens_alter()

 */

function token_generate($type, array $tokens, array $data = array(), array $options = array()) {

  $options += array('sanitize' => TRUE);

  $replacements = module_invoke_all('tokens', $type, $tokens, $data, $options);

  // Allow other modules to alter the replacements.

  $context = array(

    'type' => $type,

    'tokens' => $tokens,

    'data' => $data,

    'options' => $options,

  );

  drupal_alter('tokens', $replacements, $context);

  return $replacements;

}

/**

 * Returns a list of tokens that begin with a specific prefix.

 *

 * Used to extract a group of 'chained' tokens (such as [node:author:name])

 * from the full list of tokens found in text. For example:

 * @code

 *   $data = array(

 *     'author:name' => '[node:author:name]',

 *     'title'       => '[node:title]',

 *     'created'     => '[node:created]',

 *   );

 *   $results = token_find_with_prefix($data, 'author');

 *   $results == array('name' => '[node:author:name]');

 * @endcode

 *

 * @param $tokens

 *   A keyed array of tokens, and their original raw form in the source text.

 * @param $prefix

 *   A textual string to be matched at the beginning of the token.

 * @param $delimiter

 *   An optional string containing the character that separates the prefix from

 *   the rest of the token. Defaults to ':'.

 *

 * @return

 *   An associative array of discovered tokens, with the prefix and delimiter

 *   stripped from the key.

 */

function token_find_with_prefix(array $tokens, $prefix, $delimiter = ':') {

  $results = array();

  foreach ($tokens as $token => $raw) {

    $parts = explode($delimiter, $token, 2);

    if (count($parts) == 2 && $parts[0] == $prefix) {

      $results[$parts[1]] = $raw;

    }

  }

  return $results;

}

/**

 * Returns metadata describing supported tokens.

 *

 * The metadata array contains token type, name, and description data as well

 * as an optional pointer indicating that the token chains to another set of

 * tokens.

 *

 * For example:

 * @code

 *   $data['types']['node'] = array(

 *     'name' => t('Nodes'),

 *     'description' => t('Tokens related to node objects.'),

 *   );

 *   $data['tokens']['node']['title'] = array(

 *     'name' => t('Title'),

 *     'description' => t('The title of the current node.'),

 *   );

 *   $data['tokens']['node']['author'] = array(

 *     'name' => t('Author'),

 *     'description' => t('The author of the current node.'),

 *     'type' => 'user',

 *   );

 * @endcode

 *

 * @return

 *   An associative array of token information, grouped by token type.

 */

function token_info() {

  $data = &drupal_static(__FUNCTION__);

  if (!isset($data)) {

    $data = module_invoke_all('token_info');

    drupal_alter('token_info', $data);

  }

  return $data;

}