/*******************************************************************************
 * Copyright (c) 2005, 2016 IBM Corporation and others.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 * 
 * SPDX-License-Identifier: EPL-2.0
 *
 *******************************************************************************/
package org.eclipse.dltk.core;

import org.eclipse.core.resources.ICommand;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IProjectDescription;
import org.eclipse.core.resources.IProjectNature;
import org.eclipse.core.runtime.CoreException;

public class ScriptNature implements IProjectNature {
	private IProject project;

	/**
	 * Configure the project with Java nature.
	 */
	@Override
	public void configure() throws CoreException {
		// register Script builder
		addToBuildSpec(DLTKCore.BUILDER_ID);
	}

	/**
	 * /** Removes the Java nature from the project.
	 */
	@Override
	public void deconfigure() throws CoreException {
		// deregister Script builder
		removeFromBuildSpec(DLTKCore.BUILDER_ID);
	}

	/**
	 * Adds a builder to the build spec for the given project.
	 */
	protected void addToBuildSpec(String builderID) throws CoreException {
		IProjectDescription description = this.project.getDescription();
		int scriptCommandIndex = getCommandIndex(description.getBuildSpec(),
				builderID);
		if (scriptCommandIndex == -1) {
			// Add a Java command to the build spec
			ICommand command = description.newCommand();
			command.setBuilderName(builderID);
			setScriptCommand(description, command);
		}
	}

	/**
	 * Update the Script command in the build spec (replace existing one if
	 * present, add one first if none).
	 */
	private void setScriptCommand(IProjectDescription description,
			ICommand newCommand) throws CoreException {

		ICommand[] oldBuildSpec = description.getBuildSpec();
		int oldScriptCommandIndex = getCommandIndex(oldBuildSpec,
				newCommand.getBuilderName());
		ICommand[] newCommands;

		if (oldScriptCommandIndex == -1) {
			// Add a Java build spec before other builders (1FWJK7I)
			newCommands = new ICommand[oldBuildSpec.length + 1];
			System.arraycopy(oldBuildSpec, 0, newCommands, 1,
					oldBuildSpec.length);
			newCommands[0] = newCommand;
		} else {
			oldBuildSpec[oldScriptCommandIndex] = newCommand;
			newCommands = oldBuildSpec;
		}

		// Commit the spec change into the project
		description.setBuildSpec(newCommands);
		this.project.setDescription(description, null);
	}

	/**
	 * Removes the given builder from the build spec for the given project.
	 */
	protected void removeFromBuildSpec(String builderID) throws CoreException {
		IProjectDescription description = this.project.getDescription();
		ICommand[] commands = description.getBuildSpec();
		for (int i = 0; i < commands.length; ++i) {
			if (commands[i].getBuilderName().equals(builderID)) {
				ICommand[] newCommands = new ICommand[commands.length - 1];
				System.arraycopy(commands, 0, newCommands, 0, i);
				System.arraycopy(commands, i + 1, newCommands, i,
						commands.length - i - 1);
				description.setBuildSpec(newCommands);
				this.project.setDescription(description, null);
				return;
			}
		}
	}

	/**
	 * Find the specific command amongst the given build spec and return its
	 * index or -1 if not found.
	 * 
	 * @param buildSpec
	 * @param builderID
	 * @return
	 * @since 3.0
	 */
	protected static int getCommandIndex(ICommand[] buildSpec, String builderID) {
		for (int i = 0; i < buildSpec.length; ++i) {
			if (buildSpec[i].getBuilderName().equals(builderID)) {
				return i;
			}
		}
		return -1;
	}

	/**
	 * Sets the underlying kernel project of this Java project, and fills in its
	 * parent and name. Called by IProject.getNature().
	 * 
	 * @see IProjectNature#setProject(IProject)
	 */
	@Override
	public void setProject(IProject project) {
		this.project = project;
	}

	@Override
	public IProject getProject() {
		return this.project;
	}
}