/**
    * Copyright 2010-2013 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.common.util.execute;
  
  import java.io.File;
  import java.util.Properties;
  
  import org.kuali.common.util.LocationUtils;
  import org.kuali.common.util.PropertyUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.util.Assert;
  
  public class RunOnceExecutable implements Executable {
  
  	private static final Logger logger = LoggerFactory.getLogger(RunOnceExecutable.class);
  
  	Executable executable;
  	File propertiesFile;
  	String property;
  	String encoding;
  	boolean skip;
  
  	@Override
  	public void execute() {
  		if (skip) {
  			logger.info("Skipping execution");
  			return;
  		}
  		Assert.notNull(propertiesFile);
  		Assert.notNull(property);
  		Assert.notNull(executable);
  
  		if (!propertiesFile.exists()) {
  			logger.info("Skipping execution. File does not exist - [{}]", LocationUtils.getCanonicalPath(propertiesFile));
  			return;
  		}
  
  		logger.info("Examining run once property [{}] in [{}]", property, LocationUtils.getCanonicalPath(propertiesFile));
  
  		// Load the properties
  		Properties properties = PropertyUtils.load(propertiesFile, encoding);
  
  		// Translate the property value into an execution mode
  		ExecutionMode mode = getExecutionMode(properties, property);
  
  		// Are we going to run once?
  		if (!isRunOnce(mode)) {
  			logger.info("Skipping execution - [{}={}]", property, mode);
  			return;
  		}
  
  		// Show the execution mode we are in
  		logger.info("{}={}", property, mode);
  
  		// Make sure we have the ability to successfully store updated properties back to the file
  		if (!isAlways(mode)) {
  			setState(properties, property, ExecutionMode.INPROGRESS);
  		}
  
  		try {
  			// Invoke execute now that we have successfully transitioned things to INPROGRESS
  			executable.execute();
  			// There is always a chance that the executable finishes correctly and we encounter some kind of
  			// issue just storing the properties back to the file. This should be pretty rare considering
  			// we were able to successfully store the properties just prior to the executable commencing.
  			// In any event, the executable won't run again in the normal use case because we can only get to this point
  			// if the original execution mode was "TRUE" and we were able to successfully change it to "INPROGRESS"
  			if (!isAlways(mode)) {
  				setState(properties, property, ExecutionMode.COMPLETED);
  			}
  		} catch (Exception e) {
  			if (!isAlways(mode)) {
  				setState(properties, property, ExecutionMode.FAILED);
  			}
  			throw new IllegalStateException("Unexpected execution error", e);
  		}
  	}
  
  	protected boolean isAlways(ExecutionMode mode) {
  		return ExecutionMode.ALWAYS.equals(mode);
  	}
  
  	protected boolean isRunOnce(ExecutionMode mode) {
  		if (ExecutionMode.RUNONCE.equals(mode)) {
  			return true;
 		}
 		if (isAlways(mode)) {
 			return true;
 		}
 		return ExecutionMode.TRUE.equals(mode);
 	}
 
 	protected ExecutionMode getExecutionMode(Properties properties, String key) {
 		String value = properties.getProperty(property);
 		if (value == null) {
 			return ExecutionMode.NULL;
 		} else {
 			return ExecutionMode.valueOf(value.toUpperCase());
 		}
 
 	}
 
 	protected void setState(Properties properties, String key, ExecutionMode mode) {
 		logger.info("{}={}", key, mode);
 		properties.setProperty(property, mode.name());
 		PropertyUtils.store(properties, propertiesFile, encoding);
 	}
 
 	public Executable getExecutable() {
 		return executable;
 	}
 
 	public void setExecutable(Executable executable) {
 		this.executable = executable;
 	}
 
 	public File getPropertiesFile() {
 		return propertiesFile;
 	}
 
 	public void setPropertiesFile(File propertiesFile) {
 		this.propertiesFile = propertiesFile;
 	}
 
 	public String getProperty() {
 		return property;
 	}
 
 	public void setProperty(String property) {
 		this.property = property;
 	}
 
 	public String getEncoding() {
 		return encoding;
 	}
 
 	public void setEncoding(String encoding) {
 		this.encoding = encoding;
 	}
 
 	public boolean isSkip() {
 		return skip;
 	}
 
 	public void setSkip(boolean skip) {
 		this.skip = skip;
 	}
 }