/**********************************************
    * Copyright (C) 2009 Lukas Laag
    * This file is part of lib-gwt-svg-samples.
    * 
    * libgwtsvg-samples 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.
    * 
   * libgwtsvg-samples 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 libgwtsvg-samples.  If not, see http://www.gnu.org/licenses/
   **********************************************/
  package org.vectomatic.svg.samples.generator;
  
  import java.io.BufferedReader;
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.OutputStream;
  
  import org.apache.tools.ant.filters.StringInputStream;
  import org.vectomatic.svg.samples.client.SampleBase;
  
  import com.google.gwt.core.ext.Generator;
  import com.google.gwt.core.ext.GeneratorContext;
  import com.google.gwt.core.ext.TreeLogger;
  import com.google.gwt.core.ext.UnableToCompleteException;
  import com.google.gwt.core.ext.typeinfo.JClassType;
  import com.google.gwt.core.ext.typeinfo.NotFoundException;
  import com.uwyn.jhighlight.renderer.Renderer;
  import com.uwyn.jhighlight.renderer.XhtmlRendererFactory;
  
  public class SourceGenerator extends Generator {
  	/**
  	 * The class loader used to get resources.
  	 */
  	private ClassLoader classLoader = null;
  
  	/**
  	 * The generator context.
  	 */
  	private GeneratorContext context = null;
  
  	/**
  	 * The {@link TreeLogger} used to log messages.
  	 */
  	private TreeLogger logger = null;
  	
  	@Override
  	public String generate(TreeLogger logger, GeneratorContext context,
  			String typeName) throws UnableToCompleteException {
  	    this.logger = logger;
  	    this.context = context;
  	    this.classLoader = Thread.currentThread().getContextClassLoader();
  
  	    // Only generate files on the first permutation
  	    if (!isFirstPass()) {
  	      return null;
  	    }
  
  		JClassType sampleClass = null;
  		try {
  			sampleClass = context.getTypeOracle().getType(
  					SampleBase.class.getName());
  		} catch (NotFoundException e) {
  			logger.log(TreeLogger.ERROR, "Cannot find SampleBase class", e);
  			throw new UnableToCompleteException();
  		}
  		JClassType[] types = sampleClass.getSubtypes();
  
  		// Generate the source and raw source files
  		for (JClassType type : types) {
  			generateSourceFile(type);
  			generateUiBinderFile(type);
  		}
  		return null;
  	}
  
  	private void generateSourceFile(JClassType type) throws UnableToCompleteException {
  		Renderer javaRenderer = XhtmlRendererFactory.getRenderer(XhtmlRendererFactory.JAVA);
  	    String filename = type.getQualifiedSourceName().replace('.', '/') + ".java";
  		ByteArrayOutputStream byteArrayStream = null;
  		InputStream javaStream = null;
  		try {
  			javaStream = new StringInputStream(getResourceContents(filename));
  			byteArrayStream = new ByteArrayOutputStream();
  			javaRenderer.highlight(null, javaStream, byteArrayStream, "UTF-8", true);
  			javaStream.close();
  			byteArrayStream.close();
  			
  		    // Save the source code to a file
  		    String dstPath = SampleBase.HTML_SRC_DIR + type.getSimpleSourceName() + ".html";
  		    String contents = new String(byteArrayStream.toByteArray(), "UTF-8");
 		    createPublicResource(dstPath, contents);
 		} catch (IOException e) {
 			throw new RuntimeException(e);
 		}
 	}
 
 	private void generateUiBinderFile(JClassType type) throws UnableToCompleteException {
 		Renderer javaRenderer = XhtmlRendererFactory.getRenderer(XhtmlRendererFactory.XML);
 	    String filename = type.getQualifiedSourceName().replace('.', '/') + ".ui.xml";
 		ByteArrayOutputStream byteArrayStream = null;
 		InputStream javaStream = null;
 		try {
 			javaStream = new StringInputStream(getResourceContents(filename));
 			byteArrayStream = new ByteArrayOutputStream();
 			javaRenderer.highlight(null, javaStream, byteArrayStream, "UTF-8", true);
 			javaStream.close();
 			byteArrayStream.close();
 			
 		    // Save the source code to a file
 		    String dstPath = SampleBase.UIBINDER_SRC_DIR + type.getSimpleSourceName() + ".html";
 		    String contents = new String(byteArrayStream.toByteArray(), "UTF-8");
 		    createPublicResource(dstPath, contents);
 		} catch (IOException e) {
 			throw new RuntimeException(e);
 		}
 	}
 
 	/**
 	 * Set the full contents of a resource in the public directory.
 	 * @param partialPath
 	 * the path to the file relative to the public directory
 	 * @param contents
 	 * the file contents
 	 */
 	private void createPublicResource(String partialPath, String contents) {
 		try {
 			logger.log(TreeLogger.INFO, "Generating " + partialPath);
 			OutputStream outStream = context.tryCreateResource(logger, partialPath);
 			outStream.write(contents.getBytes());
 			context.commitResource(logger, outStream);
 		} catch (UnableToCompleteException e) {
 			logger.log(TreeLogger.ERROR, "Failed while writing", e);
 		} catch (IOException e) {
 			logger.log(TreeLogger.ERROR, "Failed while writing", e);
 		}
 	}
 	
 
 	  /**
 	   * Get the full contents of a resource.
 	   * @param path the path to the resource
 	   * @return the contents of the resource
 	   */
 	private String getResourceContents(String path) throws UnableToCompleteException {
 		InputStream in = classLoader.getResourceAsStream(path);
 		if (in == null) {
 			logger.log(TreeLogger.ERROR, "Resource not found: " + path);
 			throw new UnableToCompleteException();
 		}
 
 		StringBuffer fileContentsBuf = new StringBuffer();
 		BufferedReader br = null;
 		try {
 			br = new BufferedReader(new InputStreamReader(in));
 			String temp;
 			while ((temp = br.readLine()) != null) {
 				fileContentsBuf.append(temp).append('\n');
 			}
 		} catch (IOException e) {
 			logger.log(TreeLogger.ERROR, "Cannot read resource", e);
 			throw new UnableToCompleteException();
 		} finally {
 			if (br != null) {
 				try {
 					br.close();
 				} catch (IOException e) {
 				}
 			}
 		}
 
 		// Return the file contents as a string
 		return fileContentsBuf.toString();
 	}
 	
 
 	  /**
 	   * Ensure that we only generate files once by creating a placeholder file,
 	   * then looking for it on subsequent generates.
 	   * 
 	   * @return true if this is the first pass, false if not
 	   */
 	  private boolean isFirstPass() {
 	    String placeholder = SampleBase.HTML_SRC_DIR + "generated";
 	    try {
 	      OutputStream outStream = context.tryCreateResource(logger, placeholder);
 	      if (outStream == null) {
 	        return false;
 	      } else {
 	        context.commitResource(logger, outStream);
 	      }
 	    } catch (UnableToCompleteException e) {
 	      logger.log(TreeLogger.ERROR, "Unable to generate", e);
 	      return false;
 	    }
 	    return true;
 	  }
 
 }