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package org.unidal.helper;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public class Properties {
   public static StringPropertyAccessor forString() {
      return new StringPropertyAccessor();
   }

   public static class MapPropertyProvider implements PropertyProvider {
      private String m_name;

      private Map m_map;

      public MapPropertyProvider(Map map) {
         m_map = map;
      }

      @Override
      public Object getProperty(String name) {
         T value = null;

         if (m_name != null) {
            name = m_name;
         }

         if (value == null && m_map != null) {
            value = m_map.get(name);
         }

         return value;
      }

      public MapPropertyProvider setName(String name) {
         m_name = name;
         return this;
      }
   }

   public static abstract class PropertyAccessor {
      private List m_providers = new ArrayList();

      public PropertyAccessor fromEnv() {
         return fromEnv(null);
      }

      public PropertyAccessor fromEnv(String name) {
         m_providers.add(new SystemPropertyProvider(false, true).setName(name));

         return this;
      }

      public PropertyAccessor fromMap(Map map) {
         return fromMap(map, null);
      }

      public PropertyAccessor fromMap(Map map, String name) {
         m_providers.add(new MapPropertyProvider(map).setName(name));

         return this;
      }

      public PropertyAccessor fromSystem() {
         return fromSystem(null);
      }

      public PropertyAccessor fromSystem(String name) {
         m_providers.add(new SystemPropertyProvider(true, false).setName(name));

         return this;
      }

      protected Object getProperty(String name) {
         Object value = null;

         for (PropertyProvider provider : m_providers) {
            value = provider.getProperty(name);

            if (value != null) {
               break;
            }
         }

         return value;
      }

      public abstract T getProperty(String name, T defaultValue);
   }

   public static interface PropertyProvider {
      public Object getProperty(String name);
   }

   public static class StringPropertyAccessor extends PropertyAccessor {
      @Override
      public String getProperty(String name, String defaultValue) {
         Object value = name == null ? null : getProperty(name);

         if (value == null) {
            return defaultValue;
         } else {
            return value.toString();
         }
      }
   }

   public static class SystemPropertyProvider implements PropertyProvider {
      private boolean m_properties;

      private boolean m_env;

      private String m_name;

      public SystemPropertyProvider(boolean properties, boolean env) {
         m_properties = properties;
         m_env = env;
      }

      @Override
      public Object getProperty(String name) {
         String value = null;

         if (m_name != null) {
            name = m_name;
         }

         if (value == null && m_properties) {
            value = System.getProperty(name);
         }

         if (value == null && m_env) {
            value = System.getenv(name);
         }

         return value;
      }

      public SystemPropertyProvider setName(String name) {
         m_name = name;
         return this;
      }
   }
}