Copyright (c) 2000, 2018 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2018 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.core.manipulation;

import java.util.Iterator;

import org.eclipse.core.runtime.Assert;

import org.eclipse.core.resources.IProject;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DefaultLineTracker;
import org.eclipse.jface.text.ILineTracker;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.templates.Template;
import org.eclipse.jface.text.templates.TemplateBuffer;
import org.eclipse.jface.text.templates.TemplateContext;
import org.eclipse.jface.text.templates.TemplateException;
import org.eclipse.jface.text.templates.TemplateTranslator;
import org.eclipse.jface.text.templates.TemplateVariableResolver;

import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.manipulation.JavaManipulation;

public class CodeTemplateContext extends TemplateContext {

	private String fLineDelimiter;
	private IJavaProject fProject;

	public CodeTemplateContext(String contextTypeName, IJavaProject project, String lineDelim) {
		super(JavaManipulation.getCodeTemplateContextRegistry().getContextType(contextTypeName));
		fLineDelimiter= lineDelim;
		fProject= project;
	}

	@Override
	public <T> T getAdapter(Class<T> adapter) {
		if(adapter == IProject.class) {
			return adapter.cast(getJavaProject().getProject());
		}
		return super.getAdapter(adapter);
	}
	
	public IJavaProject getJavaProject() {
		return fProject;
	}

	/*
	 * @see org.eclipse.jdt.internal.corext.template.TemplateContext#evaluate(org.eclipse.jdt.internal.corext.template.Template)
	 */
	@Override
	public TemplateBuffer evaluate(Template template) throws BadLocationException, TemplateException {
		// test that all variables are defined
		Iterator<TemplateVariableResolver> iterator= getContextType().resolvers();
		while (iterator.hasNext()) {
			TemplateVariableResolver var= iterator.next();
			if (var instanceof CodeTemplateContextType.CodeTemplateVariableResolver) {
				Assert.isNotNull(getVariable(var.getType()), "Variable " + var.getType() + "not defined"); //$NON-NLS-1$ //$NON-NLS-2$
			}
		}

		if (!canEvaluate(template))
			return null;

		String pattern= changeLineDelimiter(template.getPattern(), fLineDelimiter);

		TemplateTranslator translator= new TemplateTranslator();
		TemplateBuffer buffer= translator.translate(pattern);
		getContextType().resolve(buffer, this);
		return buffer;
	}

	private static String changeLineDelimiter(String code, String lineDelim) {
		try {
			ILineTracker tracker= new DefaultLineTracker();
			tracker.set(code);
			int nLines= tracker.getNumberOfLines();
			if (nLines == 1) {
				return code;
			}

			StringBuilder buf= new StringBuilder();
			for (int i= 0; i < nLines; i++) {
				if (i != 0) {
					buf.append(lineDelim);
				}
				IRegion region = tracker.getLineInformation(i);
				String line= code.substring(region.getOffset(), region.getOffset() + region.getLength());
				buf.append(line);
			}
			return buf.toString();
		} catch (BadLocationException e) {
			// can not happen
			return code;
		}
	}

	@Override
	public boolean canEvaluate(Template template) {
		return true;
	}

	public void setCompilationUnitVariables(ICompilationUnit cu) {
		setVariable(CodeTemplateContextType.FILENAME, cu.getElementName());
		setVariable(CodeTemplateContextType.PACKAGENAME, cu.getParent().getElementName());
		setVariable(CodeTemplateContextType.PROJECTNAME, cu.getJavaProject().getElementName());
	}

}