package org.lcsim.material;
   
   import java.io.PrintStream;
   import java.util.ArrayList;
   import java.util.HashMap;
   import java.util.List;
   import java.util.Map;
   
   /**
   * This class is the repository for Material and MaterialElement objects loaded into LCSim. 
   * It is a singleton with only one existing per process.
   * @author jeremym
   * @version $Id: MaterialManager.java,v 1.14 2011/03/11 19:22:20 jeremy Exp $
   */
  // TODO Figure out best place to reset when new Detector is defined (geometry.Detector?  conditions?  event?)
  public class MaterialManager
  {
      // The global manager instanec.
      private static MaterialManager _instance = null;
  
      // FIXME These should not be static. Use mgr.instance() instead.
      private static Map<String, Material> _materials = new HashMap<String, Material>();
      private static Map<String, MaterialElement> _elements = new HashMap<String, MaterialElement>();
  
      /** 
       * Direct instantiation is not allowed.  Use the {@link instance()} method. 
       **/
      private MaterialManager()
      {}
  
      /**
       * Get manager and create if necessary.
       * @return The global MaterialManager.
       */
      public static MaterialManager instance()
      {
          if (_instance == null)
          {
              _instance = new MaterialManager();
          }
  
          return _instance;
      }
      
      public List<String> getMaterialNames()
      {
          // TODO Make list immutable.
          return new ArrayList<String>(_materials.keySet());
      }
      
      public List<String> getElementNames()
      {
          // TODO Make list immutable.
          return new ArrayList<String>(_elements.keySet());
      }
  
      // FIXME Remove this method.  Use getMaterialNames() with getMaterial() instead.
      public Map<String, Material> materials()
      {
          return _materials;
      }
    
      // FIXME Remove this method.  Use getElementNames() with getElement() instead.
      public static Map<String, MaterialElement> elements()
      {
          return _elements;
      }
    
      protected void addMaterial(Material material)
      {
          if (material == null)
          {
              throw new IllegalArgumentException("Argument points to null.");
          }
  
          if (getMaterial(material.getName()) != null)
          {
              throw new RuntimeException("Material with name " + material.getName() + " already exists.");
          }
  
          _materials.put(material.getName(), material);
      }
  
      /**
       * Get a material from the manager.
       * @param materialName
       * @return The material with name materialName. 
       */
      public Material getMaterial(String materialName)
      {
          return _materials.get(materialName);
      }
  
      public MaterialElement getElement(String elementName)
      {
          return _elements.get(elementName);
      }
  
      protected void addElement(MaterialElement me)
     {
         if (MaterialManager.instance().getElement(me.getName()) == null)        
         {
             _elements.put(me.getName(), me);
         }
         else
         {
             throw new RuntimeException("MaterialElement already exists: " + me.getName());
         }
     }
     
     public String toString()
     {
         StringBuffer buff = new StringBuffer();
         for (MaterialElement me : _elements.values())
         {
             buff.append(me.toString());
         }
         for (Material m : _materials.values())
         {
             buff.append(m.toString());
         }
         return buff.toString();
     }
 
     public void printMaterials(PrintStream ps)
     {
         for (Material m : materials().values())
         {
             ps.println(m.toString());
         }
     }
 
     public void printElements(PrintStream ps)
     {
         for (MaterialElement me : elements().values())
         {
             ps.println(me.toString());
         }
     }
     
     /**
      * Reset the MaterialManager instance between runs.  This is currently
      * called from XMLMaterialManager only.
      */
     void clear()
     {
         // Reset maps.
         _materials = new HashMap<String, Material>();
         _elements = new HashMap<String, MaterialElement>();
         
         // Set instance to null;
         _instance = null;
     }
 }