/*******************************************************************************
 * 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 org.eclipse.jface.text.Assert;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DocumentEvent;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.Position;
import org.eclipse.jface.text.contentassist.ICompletionProposal;
import org.eclipse.jface.text.contentassist.ICompletionProposalExtension;
import org.eclipse.jface.text.contentassist.ICompletionProposalExtension2;
import org.eclipse.jface.text.contentassist.IContextInformation;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;

/**
 * An enhanced implementation of the <code>ICompletionProposal</code>
 * interface implementing all the extension interfaces. It uses a position to
 * track its replacement offset and length. The position must be set up
 * externally.
 */
public class PositionBasedCompletionProposal implements ICompletionProposal,
		ICompletionProposalExtension, ICompletionProposalExtension2 {

	/** The string to be displayed in the completion proposal popup */
	private String fDisplayString;

	/** The replacement string */
	private String fReplacementString;

	/** The replacement position. */
	private Position fReplacementPosition;

	/** The cursor position after this proposal has been applied */
	private int fCursorPosition;

	/** The image to be displayed in the completion proposal popup */
	private Image fImage;

	/** The context information of this proposal */
	private IContextInformation fContextInformation;

	/** The additional info of this proposal */
	private String fAdditionalProposalInfo;

	/**
	 * Creates a new completion proposal based on the provided information. The
	 * replacement string is considered being the display string too. All
	 * remaining fields are set to <code>null</code>.
	 * 
	 * @param replacementString
	 *            the actual string to be inserted into the document
	 * @param replacementPosition
	 *            the position of the text to be replaced
	 * @param cursorPosition
	 *            the position of the cursor following the insert relative to
	 *            replacementOffset
	 */
	public PositionBasedCompletionProposal(String replacementString,
			Position replacementPosition, int cursorPosition) {
		this(replacementString, replacementPosition, cursorPosition, null,
				null, null, null);
	}

	/**
	 * Creates a new completion proposal. All fields are initialized based on
	 * the provided information.
	 * 
	 * @param replacementString
	 *            the actual string to be inserted into the document
	 * @param replacementPosition
	 *            the position of the text to be replaced
	 * @param cursorPosition
	 *            the position of the cursor following the insert relative to
	 *            replacementOffset
	 * @param image
	 *            the image to display for this proposal
	 * @param displayString
	 *            the string to be displayed for the proposal
	 * @param contextInformation
	 *            the context information associated with this proposal
	 * @param additionalProposalInfo
	 *            the additional information associated with this proposal
	 */
	public PositionBasedCompletionProposal(String replacementString,
			Position replacementPosition, int cursorPosition, Image image,
			String displayString, IContextInformation contextInformation,
			String additionalProposalInfo) {
		Assert.isNotNull(replacementString);
		Assert.isTrue(replacementPosition != null);

		fReplacementString = replacementString;
		fReplacementPosition = replacementPosition;
		fCursorPosition = cursorPosition;
		fImage = image;
		fDisplayString = displayString;
		fContextInformation = contextInformation;
		fAdditionalProposalInfo = additionalProposalInfo;
	}

	/*
	 * @see ICompletionProposal#apply(IDocument)
	 */
	public void apply(IDocument document) {
		try {
			document.replace(fReplacementPosition.getOffset(),
					fReplacementPosition.getLength(), fReplacementString);
		} catch (BadLocationException x) {
			// ignore
		}
	}

	/*
	 * @see ICompletionProposal#getSelection(IDocument)
	 */
	public Point getSelection(IDocument document) {
		return new Point(fReplacementPosition.getOffset() + fCursorPosition, 0);
	}

	/*
	 * @see ICompletionProposal#getContextInformation()
	 */
	public IContextInformation getContextInformation() {
		return fContextInformation;
	}

	/*
	 * @see ICompletionProposal#getImage()
	 */
	public Image getImage() {
		return fImage;
	}

	/*
	 * @see org.eclipse.jface.text.contentassist.ICompletionProposal#getDisplayString()
	 */
	public String getDisplayString() {
		if (fDisplayString != null)
			return fDisplayString;
		return fReplacementString;
	}

	/*
	 * @see ICompletionProposal#getAdditionalProposalInfo()
	 */
	public String getAdditionalProposalInfo() {
		return fAdditionalProposalInfo;
	}

	/*
	 * @see org.eclipse.jface.text.contentassist.ICompletionProposalExtension2#apply(org.eclipse.jface.text.ITextViewer,
	 *      char, int, int)
	 */
	public void apply(ITextViewer viewer, char trigger, int stateMask,
			int offset) {
		apply(viewer.getDocument());
	}

	/*
	 * @see org.eclipse.jface.text.contentassist.ICompletionProposalExtension2#selected(org.eclipse.jface.text.ITextViewer,
	 *      boolean)
	 */
	public void selected(ITextViewer viewer, boolean smartToggle) {
	}

	/*
	 * @see org.eclipse.jface.text.contentassist.ICompletionProposalExtension2#unselected(org.eclipse.jface.text.ITextViewer)
	 */
	public void unselected(ITextViewer viewer) {
	}

	/*
	 * @see org.eclipse.jface.text.contentassist.ICompletionProposalExtension2#validate(org.eclipse.jface.text.IDocument,
	 *      int, org.eclipse.jface.text.DocumentEvent)
	 */
	public boolean validate(IDocument document, int offset, DocumentEvent event) {
		try {
			String content = document.get(fReplacementPosition.getOffset(),
					fReplacementPosition.getLength());
			if (content.startsWith(fReplacementString))
				return true;
		} catch (BadLocationException e) {
			// ignore concurrently modified document
		}
		return false;
	}

	/*
	 * @see org.eclipse.jface.text.contentassist.ICompletionProposalExtension#apply(org.eclipse.jface.text.IDocument,
	 *      char, int)
	 */
	public void apply(IDocument document, char trigger, int offset) {
		// not called any more
	}

	/*
	 * @see org.eclipse.jface.text.contentassist.ICompletionProposalExtension#isValidFor(org.eclipse.jface.text.IDocument,
	 *      int)
	 */
	public boolean isValidFor(IDocument document, int offset) {
		// not called any more
		return false;
	}

	/*
	 * @see org.eclipse.jface.text.contentassist.ICompletionProposalExtension#getTriggerCharacters()
	 */
	public char[] getTriggerCharacters() {
		return null;
	}

	/*
	 * @see org.eclipse.jface.text.contentassist.ICompletionProposalExtension#getContextInformationPosition()
	 */
	public int getContextInformationPosition() {
		return fReplacementPosition.getOffset();
	}

}
