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/*! ******************************************************************************
 *
 * Pentaho Data Integration
 *
 * Copyright (C) 2002-2017 by Hitachi Vantara : http://www.pentaho.com
 *
 *******************************************************************************
 *
 * 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.
 *
 ******************************************************************************/

package org.pentaho.libformula.editor.function;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import org.pentaho.di.core.exception.KettleXMLException;
import org.pentaho.di.core.xml.XMLHandler;
import org.w3c.dom.Document;
import org.w3c.dom.Node;

public class FunctionLib {

  private List functions;

  public FunctionLib( String filename ) throws KettleXMLException {
    functions = new ArrayList();

    Document document = XMLHandler.loadXMLFile( getClass().getResourceAsStream( filename ) );
    Node functionsNode = XMLHandler.getSubNode( document, "libformula-functions" );
    int nrFunctions = XMLHandler.countNodes( functionsNode, FunctionDescription.XML_TAG );
    for ( int i = 0; i < nrFunctions; i++ ) {
      Node functionNode = XMLHandler.getSubNodeByNr( functionsNode, FunctionDescription.XML_TAG, i );
      this.functions.add( new FunctionDescription( functionNode ) );
    }
  }

  /**
   * @return the functions
   */
  public List getFunctions() {
    return functions;
  }

  /**
   * @param functions
   *          the functions to set
   */
  public void setFunctions( List functions ) {
    this.functions = functions;
  }

  /**
   * @return A sorted array of function names, extracted from the function descriptions...
   */
  public String[] getFunctionNames() {
    String[] names = new String[functions.size()];
    for ( int i = 0; i < functions.size(); i++ ) {
      names[i] = functions.get( i ).getName();
    }
    Arrays.sort( names );
    return names;
  }

  /**
   * @return A sorted array of unique categories, extracted from the function descriptions...
   */
  public String[] getFunctionCategories() {
    List categories = new ArrayList();
    for ( FunctionDescription function : functions ) {
      String category = function.getCategory();
      if ( !categories.contains( category ) ) {
        categories.add( category );
      }
    }
    Collections.sort( categories );
    return categories.toArray( new String[categories.size()] );
  }

  /**
   * Get all the function names for a certain category
   *
   * @param category
   *          the category name to look for
   * @return the sorted array of function names for the specified category
   */
  public String[] getFunctionsForACategory( String category ) {
    List names = new ArrayList();
    for ( FunctionDescription function : functions ) {
      if ( function.getCategory().equalsIgnoreCase( category ) ) {
        names.add( function.getName() );
      }
    }
    Collections.sort( names );
    return names.toArray( new String[names.size()] );
  }

  /**
   * @param functionName
   *          the name of the function to look for
   * @return the corresponding function description or null if nothing was found.
   */
  public FunctionDescription getFunctionDescription( String functionName ) {
    for ( FunctionDescription function : functions ) {
      if ( function.getName().equalsIgnoreCase( functionName ) ) {
        return function;
      }
    }
    return null;
  }
}