<?php
/**
 * @file
 * The Token Logic module.
 *
 * The Token logic module allows for basic branching/conditionals based on tokens.
 * Currently it supports if statements with a single comparison, either [equals] or [notequals]
 * However, this comparison can contain as many tokens as the user wants, so ands can be achieved this way,
 * and ors can be done through duplicating the statement.
 * If statements can be nested within the [then]...[endif] portion but not within the [if]...[then] portion.
 * Example: [if][type][equals]story[then]This is a story[endif]
 *
 * @ingroup token
 */

/**
 * Implementation of hook_token_replace_alter
 *
 * Return the value of $original, with all logic parsed out. Tokens in the
 * sections to be displayed will remain, as the output is meant to be subsequently
 * passed through the base Token module's replace function.
 *
 * @param original
 *   A string, or an array of strings, to perform token substitutions
 *   on.
 * @param tokens
 *   An array of token names to be passed on to calls to the default token replace methods
 * @param values
 *   An array of the respective values for the tokens.
 * @param leading
 *   Character(s) to prepend to the token key before searching for
 *   matches. Defaults to an open-bracket.
 * @param trailing
 *   Character(s) to append to the token key before searching for
 *   matches. Defaults to a close-bracket.
 * @return The modified version of $original, with all substitutions
 *   made.
 */

function token_logic_token_replace_alter($original, $tokens, $values, $leading, $trailing) {
  if(is_array($original)) {
    foreach($original as $key => $val) {
      $original[$key] = token_logic_token_replace_alter($val, $tokens, $values, $leading, $trailing);
    }
    return $original;
  }
  $return = '';
  $if = $leading.'if'.$trailing;
  $then = $leading.'then'.$trailing;
  $equals = $leading.'equals'.$trailing;
  $notequals = $leading.'notequals'.$trailing;
  $endif = $leading.'endif'.$trailing;

  $start = strpos($original, $if);
  if ($start === FALSE ) {
    // no if's there
    return $original;
  }
  $equalsp = strpos($original, $equals, $start);
  $thenp = strpos($original, $thenp, $start);
  $end = strpos($original, $endif, $start) + strlen($endif);
  $within = $start;
  while ($within = strpos($original, $if, $within + strlen($if)) && $within < $end) {
    //we have an [if] between our [if] and [endif], we need to grab more
    $end = strpos($original, $endif, $end);
    if($end === FALSE) {
      //not enough [endif]s
      return $original;
    }
    $end += strlen($endif);
  }

  //we now have one overarching if statement between $start and $end, including the tags themselves
  $return = substr($original, 0, $start);

  //evaluate logic
  $evaluate = substr($original, $start+strlen($if), $end-$start-strlen($if)-strlen($endif));
  $evaluate = explode($then, $evaluate, 2);

  $arg = explode($equals, $evaluate[0]);
  if (count($arg) == 2) {
    if (_token_replace_tokens($arg[0], $tokens, $values, $leading, $trailing) == _token_replace_tokens($arg[1], $tokens, $values, $leading, $trailing)) {
       $return .= token_logic_token_replace_alter($evaluate[1], $tokens, $values, $leading, $trailing);
    }
  } else {
    $arg = explode($notequals, $evaluate[0]);
    if (_token_replace_tokens($arg[0], $tokens, $values, $leading, $trailing) != _token_replace_tokens($arg[1], $tokens, $values, $leading, $trailing)) {
       $return .= token_logic_token_replace_alter($evaluate[1], $tokens, $values, $leading, $trailing);
    }
  }
  $return .= token_logic_token_replace_alter(substr($original, $end), $tokens, $values, $leading, $trailing);
  return $return;
}