/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package net.sourceforge.phpdt.internal.ui.text.template.contentassist;

import java.util.ArrayList;

import net.sourceforge.phpdt.core.ICompilationUnit;
import net.sourceforge.phpdt.internal.corext.Assert;
import net.sourceforge.phpdt.internal.corext.template.php.CompilationUnitContext;
import net.sourceforge.phpdt.internal.corext.template.php.CompilationUnitContextType;
import net.sourceforge.phpdt.internal.ui.PHPUiImages;
import net.sourceforge.phpeclipse.PHPeclipsePlugin;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.templates.GlobalTemplateVariables;
import org.eclipse.jface.text.templates.Template;
import org.eclipse.jface.text.templates.TemplateContextType;
import org.eclipse.swt.graphics.Point;

public class TemplateEngine {

	private static final String $_LINE_SELECTION = "${" + GlobalTemplateVariables.LineSelection.NAME + "}"; //$NON-NLS-1$ //$NON-NLS-2$

	private static final String $_WORD_SELECTION = "${" + GlobalTemplateVariables.WordSelection.NAME + "}"; //$NON-NLS-1$ //$NON-NLS-2$

	/** The context type. */
	private TemplateContextType fContextType;

	/** The result proposals. */
	private ArrayList fProposals = new ArrayList();

	/**
	 * Creates the template engine for a particular context type. See
	 * <code>TemplateContext</code> for supported context types.
	 */
	public TemplateEngine(TemplateContextType contextType) {
		Assert.isNotNull(contextType);
		fContextType = contextType;
	}

	/**
	 * Empties the collector.
	 */
	public void reset() {
		fProposals.clear();
	}

	/**
	 * Returns the array of matching templates.
	 */
	public TemplateProposal[] getResults() {
		return (TemplateProposal[]) fProposals
				.toArray(new TemplateProposal[fProposals.size()]);
	}

	/**
	 * Inspects the context of the compilation unit around
	 * <code>completionPosition</code> and feeds the collector with proposals.
	 * 
	 * @param viewer
	 *            the text viewer
	 * @param completionPosition
	 *            the context position in the document of the text viewer
	 * @param compilationUnit
	 *            the compilation unit (may be <code>null</code>)
	 */
	public void complete(ITextViewer viewer, int completionPosition,
			ICompilationUnit compilationUnit) {
		IDocument document = viewer.getDocument();

		if (!(fContextType instanceof CompilationUnitContextType))
			return;

		Point selection = viewer.getSelectedRange();

		// remember selected text
		String selectedText = null;
		if (selection.y != 0) {
			try {
				selectedText = document.get(selection.x, selection.y);
			} catch (BadLocationException e) {
			}
		}

		CompilationUnitContext context = ((CompilationUnitContextType) fContextType)
				.createContext(document, completionPosition, selection.y,
						compilationUnit);
		context.setVariable("selection", selectedText); //$NON-NLS-1$
		int start = context.getStart();
		int end = context.getEnd();
		IRegion region = new Region(start, end - start);

		Template[] templates = PHPeclipsePlugin.getDefault().getTemplateStore()
				.getTemplates();

		if (selection.y == 0) {
			for (int i = 0; i != templates.length; i++)
				if (context.canEvaluate(templates[i]))
					fProposals.add(new TemplateProposal(templates[i], context,
							region, PHPUiImages
									.get(PHPUiImages.IMG_OBJS_TEMPLATE)));

		} else {

			if (context.getKey().length() == 0)
				context.setForceEvaluation(true);

			boolean multipleLinesSelected = areMultipleLinesSelected(viewer);

			for (int i = 0; i != templates.length; i++) {
				Template template = templates[i];
				if (context.canEvaluate(template)
						&& template.getContextTypeId().equals(
								context.getContextType().getId())
						&& (!multipleLinesSelected
								&& template.getPattern().indexOf(
										$_WORD_SELECTION) != -1 || (multipleLinesSelected && template
								.getPattern().indexOf($_LINE_SELECTION) != -1))) {
					fProposals.add(new TemplateProposal(templates[i], context,
							region, PHPUiImages
									.get(PHPUiImages.IMG_OBJS_TEMPLATE)));
				}
			}
		}
	}

	/**
	 * Returns <code>true</code> if one line is completely selected or if
	 * multiple lines are selected. Being completely selected means that all
	 * characters except the new line characters are selected.
	 * 
	 * @return <code>true</code> if one or multiple lines are selected
	 * @since 2.1
	 */
	private boolean areMultipleLinesSelected(ITextViewer viewer) {
		if (viewer == null)
			return false;

		Point s = viewer.getSelectedRange();
		if (s.y == 0)
			return false;

		try {

			IDocument document = viewer.getDocument();
			int startLine = document.getLineOfOffset(s.x);
			int endLine = document.getLineOfOffset(s.x + s.y);
			IRegion line = document.getLineInformation(startLine);
			return startLine != endLine
					|| (s.x == line.getOffset() && s.y == line.getLength());

		} catch (BadLocationException x) {
			return false;
		}
	}
}
