<?php
/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

class GadgetFeatureRegistry {
  private $features = array();
  private $core = array();
  private $coreDone = false;

  public function __construct($featurePath) {
    $this->registerFeatures($featurePath);
  }

  public function registerFeatures($featurePath) {
    if (empty($featurePath) || $featurePath == null) {
      return;
    }
    $loader = new JsFeatureLoader();
    $jsFeatures = $loader->loadFeatures($featurePath, $this);
    if (! $this->coreDone) {
      foreach ($jsFeatures as $entry) {
        if (strtolower(substr($entry->name, 0, strlen('core'))) == 'core') {
          $this->core[$entry->name] = $entry->name;
        }
      }
      // Make sure non-core features depend on core.
      foreach ($jsFeatures as $entry) {
        if (strtolower(substr($entry->name, 0, strlen('core'))) != 'core') {
          $entry->deps = array_merge($entry->deps, $this->core);
        }
      }
      $this->coreDone = true;
    }
  }

  public function register($name, $deps, $feature) {
    // Core entries must come first.
    $entry = isset($this->features[$name]) ? $this->features[$name] : null;
    if ($entry == null) {
      $entry = new GadgetFeatureRegistryEntry($name, $deps, $feature, $this);
      if ($this->coreDone) {
        $entry->deps = array_merge($entry->deps, $this->core);
      }
      $this->features[$name] = $entry;
      $this->validateFeatureGraph();
    }
    return $entry;
  }

  private function validateFeatureGraph() {  // TODO: ensure that features form a DAG and that all deps are provided
  }

  public function getAllFeatures() {
    return $this->features;
  }

  public function getIncludedFeatures($needed, &$resultsFound, &$resultsMissing) {
    $resultsFound = array();
    $resultsMissing = array();
    if (! count($needed)) {
      // Shortcut for gadgets that don't have any explicit dependencies.
      $resultsFound = $this->core;
      return true;
    }
    foreach ($needed as $featureName) {
      $feature = isset($this->features[$featureName]) ? $this->features[$featureName] : null;
      if ($feature == null) {
        $resultsMissing[] = $featureName;
      } else {
        $this->addFeatureToResults($resultsFound, $feature);
      }
    }
    return count($resultsMissing) == 0;
  }

  private function addFeatureToResults(&$results, $feature) {
    if (in_array($feature->name, $results)) {
      return;
    }
    foreach ($feature->deps as $dep) {
      //TODO: Temporal fix, double check where empty dependencies are being added
      if (! empty($dep)) {
        $this->addFeatureToResults($results, $this->features[$dep]);
      }
    }
    $results[$feature->name] = $feature->name;
  }

  public function getEntry($name) {
    return $this->features[$name];
  }
}

// poor man's namespacing
class GadgetFeatureRegistryEntry {
  public $name;
  public $deps = array();
  public $feature;

  public function __construct($name, $deps, $feature, $registry) {
    $this->name = $name;
    if ($deps != null) {
      foreach ($deps as $dep) {
        $entry = $registry->getEntry($dep);
        $this->deps[$entry->name] = $entry->name;
      }
    }
    $this->feature = $feature;
  }

  public function getName() {
    return $this->name;
  }

  public function getDependencies() {
    return $this->deps;
  }

  public function getFeature() {
    return $this->feature;
  }
}