<?php

/*
 * Copyright 2011 Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

final class CelerityResourceMap {

  private static $instance;
  private $resourceMap;

  public static function getInstance() {
    if (empty(self::$instance)) {
      self::$instance = new CelerityResourceMap();
      $root = phutil_get_library_root('phabricator');
      $ok = @include_once $root.'/__celerity_resource_map__.php';
      if (!$ok) {
        throw new Exception("Failed to load Celerity resource map!");
      }
    }
    return self::$instance;
  }

  public function setResourceMap($resource_map) {
    $this->resourceMap = $resource_map;
    return $this;
  }

  public function resolveResources(array $symbols) {
    $map = array();
    foreach ($symbols as $symbol) {
      if (!empty($map[$symbol])) {
        continue;
      }
      $this->resolveResource($map, $symbol);
    }

    return $map;
  }

  private function resolveResource(array &$map, $symbol) {
    if (empty($this->resourceMap[$symbol])) {
      throw new Exception(
        "Attempting to resolve unknown resource, '{$symbol}'.");
    }

    $info = $this->resourceMap[$symbol];
    foreach ($info['requires'] as $requires) {
      if (!empty($map[$requires])) {
        continue;
      }
      $this->resolveResource($map, $requires);
    }

    $map[$symbol] = $info;
  }

}

function celerity_register_resource_map(array $map) {
  $instance = CelerityResourceMap::getInstance();
  $instance->setResourceMap($map);
}