<?php
/**
 * SassScriptFunction class file.
 * @author      Chris Yates <chris.l.yates@gmail.com>
 * @copyright   Copyright (c) 2010 PBM Web Development
 * @license      http://phamlp.googlecode.com/files/license.txt
 * @package      PHamlP
 * @subpackage  Sass.script
 */

require_once('SassScriptFunctions.php');

/**
 * SassScriptFunction class.
 * Preforms a SassScript function.
 * @package      PHamlP
 * @subpackage  Sass.script
 */
class SassScriptFunction {
  /**@#+
   * Regexes for matching and extracting functions and arguments
   */
  const MATCH = '/^(((-\w)|(\w))[-\w]*)\(/';
  const MATCH_FUNC = '/^((?:(?:-\w)|(?:\w))[-\w]*)\((.*)\)/';
  const SPLIT_ARGS = '/\s*((?:[\'"].*?["\'])|(?:.+?(?:\(.*\).*?)?))\s*(?:,|$)/';
  const NAME = 1;
  const ARGS = 2;

  private $name;
  private $args;

  public static $context;

  /**
   * SassScriptFunction constructor
   * @param string name of the function
   * @param array arguments for the function
   * @return SassScriptFunction
   */
  public function __construct($name, $args) {
    $this->name = $name;
    $this->args = $args;
  }

  private function process_arguments($input) {
    if (is_array($input)) {
      $output = array();
      foreach ($input as $k => $token) {
        $output[$k] = trim($this->process_arguments($token), '\'"');
      }
      return $output;
    }

    $token = $input;
    if (is_null($token))
      return ' ';

    if (!is_object($token))
      return (string) $token;

    if (method_exists($token, 'toString'))
      return $token->toString();

    if (method_exists($token, '__toString'))
      return $token->__toString();

    if (method_exists($token, 'perform'))
      return $token->perform();

    return '';
  }

  /**
   * Evaluates the function.
   * Look for a user defined function first - this allows users to override
   * pre-defined functions, then try the pre-defined functions.
   * @return Function the value of this Function
   */
  public function perform() {
    self::$context = new SassContext(SassScriptParser::$context);

    $name = preg_replace('/[^a-z0-9_]/', '_', strtolower($this->name));
    $args = $this->process_arguments($this->args);

    foreach ($this->args as $k => $v) {
      if (!is_numeric($k)) {
        self::$context->setVariable($k, $v);
      }
    }

    try {
      if (SassScriptParser::$context->hasFunction($this->name)) {
        $return = SassScriptParser::$context->getFunction($this->name)->execute(SassScriptParser::$context, $this->args);
        return $return;
      }
      else if (SassScriptParser::$context->hasFunction($name)) {
        $return = SassScriptParser::$context->getFunction($name)->execute(SassScriptParser::$context, $this->args);
        return $return;
      }
    } catch (Exception $e) {
      throw $e;
    }

    if (isset(SassParser::$functions) && count(SassParser::$functions)) {
      foreach (SassParser::$functions as $fn => $callback) {
        if (($fn == $name || $fn == $this->name) && is_callable($callback)) {
          $result = call_user_func_array($callback, $args);
          if (!is_object($result)) {
            $lexed = SassScriptLexer::$instance->lex($result, self::$context);
            if (count($lexed) === 1) {
              return $lexed[0];
            }
            return new SassString(implode('', $this->process_arguments($lexed)));
          }
          return $result;
        }
      }
    }

    if (method_exists('SassScriptFunctions', $name) || method_exists('SassScriptFunctions', $name = '_' . $name)) {
      $sig = self::get_reflection(array('SassScriptFunctions', $name));
      list($args) = self::fill_parameters($sig, $this->args, SassScriptParser::$context, $this);
      return call_user_func_array(array('SassScriptFunctions', $name), $args);
    }

    foreach ($this->args as $i => $arg) {
      if (is_object($arg) && isset($arg->quote)) {
        $args[$i] = $arg->toString();
      }
      if (!is_numeric($i) && SassScriptParser::$context->hasVariable($i)) {
        $args[$i] = SassScriptParser::$context->getVariable($i);
      }
    }


    // CSS function: create a SassString that will emit the function into the CSS
    return new SassString($this->name . '(' . join(', ', $args) . ')');
  }

  /**
   * Imports files in the specified directory.
   * @param string path to directory to import
   * @return array filenames imported
   */
  private function import($dir) {
    $files = array();

    foreach (array_slice(scandir($dir), 2) as $file) {
      if (is_file($dir . DIRECTORY_SEPARATOR . $file)) {
        $files[] = $file;
        require_once($dir . DIRECTORY_SEPARATOR . $file);
      }
    } // foreach
    return $files;
  }

  /**
   * Returns a value indicating if a token of this type can be matched at
   * the start of the subject string.
   * @param string the subject string
   * @return mixed match at the start of the string or false if no match
   */
  public static function isa($subject) {
    if (!preg_match(self::MATCH, $subject, $matches))
      return false;

    $match = $matches[0];
    $paren = 1;
    $strpos = strlen($match);
    $strlen = strlen($subject);
    $subject_str = (string) $subject;

    while($paren && $strpos < $strlen) {
      $c = $subject_str[$strpos++];

      $match .= $c;
      if ($c === '(') {
        $paren += 1;
      }
      elseif ($c === ')') {
        $paren -= 1;
      }
    }
    return $match;
  }

  public static function extractArgs($string, $include_null = TRUE, $context) {
    $args = array();
    $arg = '';
    $paren = 0;
    $strpos = 0;
    $strlen = strlen($string);

    $list = SassList::_build_list($string, ',');
    $return = array();

    foreach ($list as $k => $value) {
      if (substr($value, -3, 3) == '...' && preg_match(SassVariableNode::MATCH, substr($value, 0, -3) . ':', $match)) {
        $list = new SassList($context->getVariable($match[SassVariableNode::NAME]));
        if (count($list->value) > 1) {
          $return = array_merge($return, $list->value);
          continue;
        }
      }

      if (strpos($value, ':') !== false && preg_match(SassVariableNode::MATCH, $value, $match)) {
        $return[$match[SassVariableNode::NAME]] = $match[SassVariableNode::VALUE];
      } else if(substr($value, 0, 1) == '$' && $include_null) {
        $return[str_replace('$', '', $value)] = NULL;
      } elseif ($include_null || $value !== NULL) {
        $return[] = $value;
      }
    }

    return $return;
  }

  public static function get_reflection($method) {
    if (is_array($method)) {
      $class = new ReflectionClass($method[0]);
      $function = $class->getMethod($method[1]);
    }
    else {
      $function = new ReflectionFunction($method);
    }

    $return = array();
    foreach ($function->getParameters() as $parameter) {
      $default = $parameter->isDefaultValueAvailable() ? $parameter->getDefaultValue() : NULL;
      if ($default !== NULL) {
        $parsed = is_bool($default) ? new SassBoolean($default) : SassScriptParser::$instance->evaluate($default, new SassContext());
        $parsed = ($parsed === NULL) ? new SassString($default) : $parsed;
      } else {
        $parsed = $default;
      }
      $return[$parameter->getName()] = $parsed; # we evaluate the defaults to get Sass objects.
    }
    return $return;
  }

  public static function fill_parameters($required, $provided, $context, $source) {
    $context = new SassContext($context);
    $_required = array_merge(array(), $required); // need to array_merge?
    $fill = $_required;


    foreach ($required as $name=>$default) {
      // we require that named variables provide a default.
      if (isset($provided[$name]) && $default !== NULL) {
        $_required[$name] = $provided[$name];
        unset($provided[$name]);
        unset($required[$name]);
      }
    }

    // print_r(array($required, $provided, $_required));

    foreach ($required as $name=>$default) {
      if (count($provided)) {
        $arg = array_shift($provided);
      }
      elseif ($default !== NULL) {
        $arg = $default;
      }
      else {
        throw new SassMixinNodeException("Function::$name: Required variable ($name) not given.\nFunction defined: " . $source->token->filename . '::' . $source->token->line . "\nFunction used", $source);
      }
      // splats
      if (substr($name, -3, 3) == '...') {
        unset ($_required[$name]);
        $name = substr($name, 0, -3);
        $_required[$name] = new SassList('', ',');
        $_required[$name]->value = array_merge(array($arg), $provided);
        continue;
      } else {
        $_required[$name] = $arg;
      }
    }

    $_required = array_merge($_required, $provided); // any remaining args get tacked onto the end

    foreach ($_required as $key => $value) {
      if (!is_object($value)) {
        $_required[$key] = SassScriptParser::$instance->evaluate($value, $context);
      }
    }

    return array($_required, $context);
  }
}
