/*
    * Copyright (c) 2003-2008 by Cosylab d. d.
    *
    * This file is part of CosyBeans.
    *
    * CosyBeans is free software: you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation, either version 3 of the License, or
    * (at your option) any later version.
   *
   * CosyBeans is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with CosyBeans.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  package com.cosylab.application;
  
  import java.io.BufferedInputStream;
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.InputStream;
  import java.net.URL;
  import java.util.Properties;
  import java.util.logging.ConsoleHandler;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  
  
  
  /**
   * This class searches for configuration file in several location in well defined order.
   * 
   * @author ikriznar
   *
   */
  public final class ConfigurationLoader {
  	
  	private ConfigurationLoader() {
  		super();
  	}
  	
  	/**
  	 * Tries to return class loader from provided class. If not possible, 
  	 * tries to return default class loader. If no usable class loader is found, then <code>null</code>
  	 * is returned.
  	 * 
  	 * @param c class for witch class loader is searched
  	 * @return class loader instance or <code>null</code>
  	 */
  	public static ClassLoader findClassLoader(Class c) {
  		Logger l= Logger.getLogger(ConfigurationLoader.class.getName());
  		ClassLoader cl=null;
  		
  		if (c == null) {
  			c= ConfigurationLoader.class;
  		}
  			
  		try {
  			cl= c.getClassLoader();
  		} catch (Exception e) {
  			l.log(Level.FINEST,"Failed to load class loader for '"+c.getName()+"'",e);
  		}
  		
  		if (cl!=null) {
  			return cl;
  		}
  		
  		try {
  			cl= ClassLoader.getSystemClassLoader();
  		} catch (Exception e) {
  			l.log(Level.FINEST,"Failed to load system class loader for '"+c.getName()+"'",e);
  		}
  		
  		return cl;
  	}
  	
  	/**
  	 * Loads the configuration from the file <code>name</code>.properties
  	 * @param c the class loader supplier
  	 * @param name the name of the file (without extension)
  	 * @return properties as read from the file
  	 */
  	public static Properties loadConfiguration(Class c, String name) {
  		return loadConfigurationFile(c,name+".properties");
  	}
  	
  	/**
  	 * Loads configuration from the file <code>name</code>.properties using
  	 * default class loader.
  	 * 
  	 * @param name the name of the file (without extension)
  	 * @return properties as read from the file
  	 */
  	public static Properties loadConfiguration(String name) {
  		return loadConfigurationFile(null,name+".properties");
 	}
 	
 	/**
 	 * Loads the configuration from the file with the given name using
 	 * the supplied class's classloader.
 	 * 
 	 * @param c class loader source
 	 * @param propFileName the name of the properties file (with extension)
 	 * @return properties as read from the file
 	 */
 	public static Properties loadConfigurationFile(Class c, String propFileName) {
 		Logger l= Logger.getLogger(ConfigurationLoader.class.getName());
 		
 		Properties p= new Properties();
 		
 		/*
 		 * Tries to load from classpath (eg. configuration in jar)
 		 */
 		
 		ClassLoader cl = findClassLoader(c);
 		if (cl!=null) {
 			
 			URL url= cl.getResource(".");
 			InputStream is=null;
 			File f= null;
 			try {
 				f= new File(url.toURI());
 				f= new File(f,propFileName);
 				if (f.exists()) {
 					is= new BufferedInputStream(new FileInputStream(f));
 					p.load(is);
 					is.close();
 					l.log(Level.CONFIG,"Configuration '"+propFileName+"' loaded from file '"+f.getAbsolutePath()+"'.");
 				} else {
 					l.log(Level.FINEST,"Configuration '"+propFileName+"' does not exist as file '"+f.getAbsolutePath()+"'.");
 				}
 			} catch (Exception e) {
 				l.log(Level.FINEST,"Failed to load '"+propFileName+"' from file '"+f+"'.",e);
 			} finally {
 				try {
 					if (is!=null) is.close();
 				} catch (Exception e) {
 					// ignore
 				}
 			}
 			
 			is= cl.getResourceAsStream(propFileName);
 			l.log(Level.FINE,"Configuration '"+propFileName+"' not found on classpath.");
 			if (is!=null) {
 				try {
 					p.load(is);
 					l.log(Level.CONFIG,"Configuration '"+propFileName+"' loaded from classpath.");
 					is.close();
 				} catch (Exception e) {
 					l.log(Level.FINEST,"Failed to load '"+propFileName+"' from classpath.",e);
 				} finally {
 					try {
 						if (is!=null) is.close();
 					} catch (Exception e) {
 						// ignore
 					}
 				}
 			}
 		}
 		
 		/*
 		 * Tries to load from current directory.
 		 */
 		File f= new File(System.getProperty("user.dir"));
 		InputStream is=null;
 		try {
 			if (f.exists()) {
 				f= new File(f,propFileName);
 				if (f.exists()) {
 					is= new BufferedInputStream(new FileInputStream(f));
 					p.load(is);
 					is.close();
 					l.log(Level.CONFIG,"Configuration '"+propFileName+"' loaded from file '"+f.getAbsolutePath()+"'.");
 				}
 			} else {
 				l.log(Level.FINEST,"Configuration '"+propFileName+"' does not exist as file '"+f.getAbsolutePath()+"'.");
 			}
 		} catch (Exception e) {
 			l.log(Level.FINEST,"Failed to load '"+propFileName+"' from file '"+f.getAbsolutePath()+"'.",e);
 		} finally {
 			try {
 				if (is!=null) is.close();
 			} catch (Exception e) {
 				// ignore
 			}
 		}
 		
 		
 		return p;
 	}
 	
 	public static void main(String[] args) {
 		Logger l= Logger.getLogger(ConfigurationLoader.class.getName());
 		l.setLevel(Level.ALL);
 		ConsoleHandler c= new ConsoleHandler();
 		c.setLevel(Level.ALL);
 		l.addHandler(c);
 		
 		Properties p= ConfigurationLoader.loadConfiguration("project");
 		c.flush();
 		p.list(System.out);
 		
 	}
 
 }