gwt generator for dust.js

package glwt.dust.rebind;

import java.io.PrintWriter;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Set;

import com.google.gwt.core.ext.CachedGeneratorResult;
import com.google.gwt.core.ext.Generator;
import com.google.gwt.core.ext.GeneratorContext;
import com.google.gwt.core.ext.IncrementalGenerator;
import com.google.gwt.core.ext.RebindMode;
import com.google.gwt.core.ext.RebindResult;
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.google.gwt.core.ext.typeinfo.TypeOracle;
import com.google.gwt.dev.resource.Resource;
import com.google.gwt.dev.resource.ResourceOracle;
import com.google.gwt.user.rebind.ClassSourceFileComposerFactory;
import com.google.gwt.user.rebind.SourceWriter;

public class DustBundleGenerator extends IncrementalGenerator {

	private HashMap<String, Serializable> clientDataMap;
	private ArrayList<String> paths;
	private ArrayList<String> files;
	private String packageName;
	JClassType userType;
	private HashMap<String, Long> pathToModifiedMap;

	@Override
	public RebindResult generateIncrementally(TreeLogger logger,
			GeneratorContext context, String typeName)
			throws UnableToCompleteException {

		String clientDataKey = typeName + "_clientDataKey";
		CachedGeneratorResult cachedGeneratorResult = context
				.getCachedGeneratorResult();
		if (cachedGeneratorResult != null)
			clientDataMap = (HashMap<String, Serializable>) cachedGeneratorResult
					.getClientData(clientDataKey);
		if (clientDataMap == null) {
			clientDataMap = new HashMap<String, Serializable>();
		}

		initTypeAndPackageNames(logger, context, typeName);

		boolean filesChanged = scanFiles(context);

		if (filesChanged)
			incrementVersion();

		String lastName = (String) clientDataMap.get("lastName");
		if (!filesChanged && lastName != null)
			return new RebindResult(RebindMode.USE_ALL_CACHED, lastName);

		String name = doGenerate(logger, context, typeName);
		clientDataMap.put("lastName", name);

		RebindResult result = new RebindResult(RebindMode.USE_ALL_NEW, name);
		result.putClientData(clientDataKey, clientDataMap);
		return result;
	}

	private void incrementVersion() {
		clientDataMap.put("version", System.currentTimeMillis());
	}

	private String getVersion() {
		Serializable version = clientDataMap.get("version");
		if (version == null) {
			incrementVersion();
			version = clientDataMap.get("version");
		}

		return String.valueOf(version);
	}

	public void initTypeAndPackageNames(TreeLogger logger,
			GeneratorContext context, String typeName)
			throws UnableToCompleteException {
		TypeOracle typeOracle = context.getTypeOracle();

		try {
			userType = typeOracle.getType(typeName);
		} catch (NotFoundException e) {
			logger.log(TreeLogger.ERROR, "Unable to find metadata for type: "
					+ typeName, e);
			throw new UnableToCompleteException();
		}

		if (userType.isInterface() == null) {
			logger.log(TreeLogger.ERROR, userType.getQualifiedSourceName()
					+ " is not an interface", null);
			throw new UnableToCompleteException();
		}

		packageName = userType.getPackage().getName();
	}

	private boolean scanFiles(GeneratorContext context) {
		ResourceOracle resourcesOracle = context.getResourcesOracle();
		String packagePath = packageName.replace(".", "/");
		String fileSuffix = ".dust.html";
		int suffixLength = fileSuffix.length();
		pathToModifiedMap = (HashMap<String, Long>) clientDataMap
				.get("fileModifyMap");
		if (pathToModifiedMap == null)
			clientDataMap.put("fileModifyMap",
					pathToModifiedMap = new HashMap<String, Long>());
		paths = new ArrayList<String>();
		files = new ArrayList<String>();
		boolean changed = false;
		Set<String> allPaths = new HashSet<String>(pathToModifiedMap.keySet());
		for (Resource r : resourcesOracle.getResources()) {
			String path = r.getPath();
			if (path.startsWith(packagePath) && path.endsWith(fileSuffix)) {
				String file = path.replaceFirst(packagePath, "");
				file = file.substring(1, file.length() - suffixLength);
				paths.add(path);
				files.add(file);

				Long oldTime = pathToModifiedMap.put(path, r.getLastModified());
				if (oldTime == null || oldTime < r.getLastModified())
					changed = true;

				allPaths.remove(path);
			}
		}
		if (allPaths.size() > 0) {
			// file has been deleted
			changed = true;
		}
		return changed;
	}

	@Override
	public long getVersionId() {
		return 1L;
	}

	/**
	 * Java compiler has a limit of 2^16 bytes for encoding string constants in
	 * a class file. Since the max size of a character is 4 bytes, we'll limit
	 * the number of characters to (2^14 - 1) to fit within one record.
	 */
	private static final int MAX_STRING_CHUNK = 16383;

	public String doGenerate(TreeLogger logger, GeneratorContext context,
			String typeName) throws UnableToCompleteException {

		String className = getClassName();

		ClassSourceFileComposerFactory composerFactory = new ClassSourceFileComposerFactory(
				packageName, className);
		composerFactory.addImplementedInterface(userType
				.getQualifiedSourceName());

		composerFactory
				.addImport("com.google.gwt.resources.client.ClientBundle");
		composerFactory
				.addImport("com.google.gwt.resources.client.TextResource");
		composerFactory.addImport("java.util.ArrayList");
		composerFactory.addImport("java.util.HashMap");
		composerFactory.addImport("com.google.gwt.core.client.GWT");

		PrintWriter pw = context.tryCreate(logger, packageName, className);
		if (pw != null) {

			SourceWriter sw = composerFactory.createSourceWriter(context, pw);

			// Write the expression to create the subtype.
			sw.indent();

			sw.indent();
			sw.println("private ArrayList<String> templates = new ArrayList<String>();");
			sw.println("private HashMap<String,String> sourceMap = new HashMap<String,String>();");
			sw.println("private HashMap<String,String> compiledMap = new HashMap<String,String>();");
			sw.println("private HashMap<String,Long> modifiedMap = new HashMap<String,Long>();");
			sw.println("private boolean hasError = false;");

			sw.println("");

			sw.println("public interface Resources extends ClientBundle {");
			sw.indent();

			for (int i = 0; i < paths.size(); i++) {
				String path = paths.get(i);
				String file = files.get(i);
				sw.println("//template for " + file);
				sw.println("@Source(\"" + path + "\")");
				String name = getMethodName(i, path, file);
				sw.println("TextResource " + name + "();");
			}

			sw.println("}");
			sw.outdent();
			sw.println("private Resources resources = GWT.create(Resources.class); ");

			sw.println("");

			// create constructor
			sw.println(className + "(){");
			sw.indent();

			for (int i = 0; i < paths.size(); i++) {
				String path = paths.get(i);
				String file = files.get(i);
				String method = getMethodName(i, path, file);
				generateDustLoader2(sw, file, method, path);
			}

			sw.println("}");
			sw.outdent();

			sw.println("");
			sw.println("public void showError(String file,String path,String source, String message) {");
			sw.indent();
			sw.println(" glwt.dust.client.ErrorWindow.show(file,path,source,message);");
			sw.outdent();
			sw.println("}");

			sw.println("");
			sw.println("public java.util.List<String> getTemplates() {");
			sw.indent();
			sw.println("return templates;");
			sw.outdent();
			sw.println("}");

			sw.println("public String getSource(String file) {");
			sw.indent();
			sw.println("return sourceMap.get(file);");
			sw.outdent();
			sw.println("}");

			sw.println("public String getCompiled(String file) {");
			sw.indent();
			sw.println("return compiledMap.get(file);");
			sw.outdent();
			sw.println("}");

			sw.println("public Long getModified(String file) {");
			sw.indent();
			sw.println("return modifiedMap.get(file);");
			sw.outdent();
			sw.println("}");

			sw.println("");
			sw.println("public boolean hasError() {");
			sw.indent();
			sw.println("return hasError;");
			sw.outdent();
			sw.println("}");

			sw.outdent();

			sw.commit(logger);
		}
		return composerFactory.getCreatedClassName();
	}

	public String getClassName() {
		String className = userType.getName();
		className = className.replace('.', '_') + "Impl" + getVersion();
		return className;
	}

	public String getMethodName(int i, String path, String file) {
		return "file" + i;
	}

	// public void generateDustLoader(SourceWriter sw, String file, String
	// source,
	// String path) {
	// sw.println("try {");
	// sw.indent();
	// sw.println("String file = \"" + file + "\";");
	// sw.println("String source;");
	// writeString(sw, "source", source);
	// sw.println("String compiled = glwt.dust.client.Dust.compile(file, source);");
	// sw.println("glwt.dust.client.Dust.loadSource(compiled);");
	// sw.println("templates.add(file);");
	// sw.outdent();
	// sw.println("}");
	// sw.println("catch (Exception e){ e.printStackTrace(); com.google.gwt.user.client.Window.alert(\"Failed to compile : "
	// + path + " :: \" +  e.getMessage());}");
	// }

	public void generateDustLoader2(SourceWriter sw, String file,
			String sourceMethod, String path) {
		sw.indent();
		sw.println("{");

		sw.println("String file = \"" + file + "\";");
		sw.println("String source = resources." + sourceMethod
				+ "().getText();");
		sw.println("try {");
		sw.indent();
		sw.println("String compiled = glwt.dust.client.Dust.compile(file, source);");
		sw.println("glwt.dust.client.Dust.loadSource(compiled);");
		sw.println("templates.add(file);");
		sw.println("String old = sourceMap.put(file,source);");
		sw.println("assert(old==null):\"Template name '" + file
				+ "' has been stored twice\";");
		sw.println("compiledMap.put(file,compiled);");
		Long modified = pathToModifiedMap.get(path);
		if (modified != null) {
			sw.println("modifiedMap.put(file," + modified + "L);");
		}
		sw.outdent();
		sw.println("}");
		sw.println("catch (com.google.gwt.core.client.JavaScriptException e){ e.printStackTrace(); showError(file,\""
				+ path + "\",source,e.getMessage()); hasError=true; }");

		sw.outdent();
		sw.println("}");

	}

	private void writeString(SourceWriter sw, String var, String toWrite) {
		if (toWrite.length() > MAX_STRING_CHUNK) {
			writeLongStringToVar(sw, var, toWrite);
		} else {
			sw.println(var + " = \"" + Generator.escape(toWrite) + "\";");
		}

	}

	/**
	 * A single constant that is too long will crash the compiler with an out of
	 * memory error. Break up the constant and generate code that appends using
	 * a buffer.
	 */
	private void writeLongStringToVar(SourceWriter sw, String var,
			String toWrite) {
		sw.println("StringBuilder builder = new StringBuilder();");
		int offset = 0;
		int length = toWrite.length();
		while (offset < length - 1) {
			int subLength = Math.min(MAX_STRING_CHUNK, length - offset);
			sw.print("builder.append(\"");
			sw.print(Generator.escape(toWrite.substring(offset, offset
					+ subLength)));
			sw.println("\");");
			offset += subLength;
		}
		sw.println(var + " = builder.toString();");
	}

}