/*******************************************************************************
 * Copyright (c) 2000, 2017 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.dltk.ui.text;

import java.util.ArrayList;
import java.util.Iterator;

import org.eclipse.core.runtime.Assert;
import org.eclipse.dltk.ui.DLTKUIPlugin;
import org.eclipse.dltk.ui.PreferenceConstants;
import org.eclipse.jface.internal.text.html.HTMLTextPresenter;
import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.jface.preference.PreferenceConverter;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DefaultInformationControl;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IInformationControlCreator;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.Position;
import org.eclipse.jface.text.quickassist.IQuickAssistAssistant;
import org.eclipse.jface.text.quickassist.QuickAssistAssistant;
import org.eclipse.jface.text.source.Annotation;
import org.eclipse.jface.text.source.IAnnotationModel;
import org.eclipse.jface.text.source.ISourceViewer;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.ui.IEditorPart;
import org.eclipse.ui.texteditor.IDocumentProvider;
import org.eclipse.ui.texteditor.ITextEditor;

public class ScriptCorrectionAssistant extends QuickAssistAssistant {

	private ITextViewer fViewer;
	private ITextEditor fEditor;
	private Position fPosition;
	private Annotation[] fCurrentAnnotations;

	// private TclQuickAssistLightBulbUpdater fLightBulbUpdater;

	/**
	 * Constructor for JavaCorrectionAssistant.
	 *
	 * @param editor
	 *            the editor
	 */
	public ScriptCorrectionAssistant(ITextEditor editor, IPreferenceStore store,
			IColorManager manager) {
		super();
		Assert.isNotNull(editor);
		fEditor = editor;

		ScriptCorrectionProcessor processor = new ScriptCorrectionProcessor(
				this);

		setQuickAssistProcessor(processor);

		setInformationControlCreator(getInformationControlCreator());

		Color c = getColor(store,
				PreferenceConstants.CODEASSIST_PROPOSALS_FOREGROUND, manager);
		setProposalSelectorForeground(c);

		c = getColor(store, PreferenceConstants.CODEASSIST_PROPOSALS_BACKGROUND,
				manager);
		setProposalSelectorBackground(c);
	}

	public IEditorPart getEditor() {
		return fEditor;
	}

	private IInformationControlCreator getInformationControlCreator() {
		return parent -> new DefaultInformationControl(parent,
				new HTMLTextPresenter());
	}

	private static Color getColor(IPreferenceStore store, String key,
			IColorManager manager) {
		RGB rgb = PreferenceConverter.getColor(store, key);
		return manager.getColor(rgb);
	}

	@Override
	public void install(ISourceViewer sourceViewer) {
		super.install(sourceViewer);
		fViewer = sourceViewer;

		// fLightBulbUpdater = new TclQuickAssistLightBulbUpdater(fEditor,
		// sourceViewer);
		// fLightBulbUpdater.install();
	}

	@Override
	public void uninstall() {
		// if (fLightBulbUpdater != null) {
		// fLightBulbUpdater.uninstall();
		// fLightBulbUpdater = null;
		// }
		super.uninstall();
	}

	/**
	 * Show completions at caret position. If current position does not contain
	 * quick fixes look for next quick fix on same line by moving from left to
	 * right and restarting at end of line if the beginning of the line is
	 * reached.
	 *
	 * @see IQuickAssistAssistant#showPossibleQuickAssists()
	 */
	@Override
	public String showPossibleQuickAssists() {
		fPosition = null;
		fCurrentAnnotations = null;

		if (fViewer == null || fViewer.getDocument() == null)
			// Let superclass deal with this
			return super.showPossibleQuickAssists();

		ArrayList<Annotation> resultingAnnotations = new ArrayList<Annotation>(
				20);
		try {
			Point selectedRange = fViewer.getSelectedRange();
			int currOffset = selectedRange.x;
			int currLength = selectedRange.y;
			boolean goToClosest = (currLength == 0);

			int newOffset = collectQuickFixableAnnotations(currOffset,
					goToClosest, resultingAnnotations);
			if (newOffset != currOffset) {
				storePosition(currOffset, currLength);
				fViewer.setSelectedRange(newOffset, 0);
				fViewer.revealRange(newOffset, 0);
			}
		} catch (BadLocationException e) {
			// JavaPlugin.log(e);
		}
		fCurrentAnnotations = resultingAnnotations
				.toArray(new Annotation[resultingAnnotations.size()]);

		return super.showPossibleQuickAssists();
	}

	private static IRegion getRegionOfInterest(ITextEditor editor,
			int invocationLocation) throws BadLocationException {
		IDocumentProvider documentProvider = editor.getDocumentProvider();
		if (documentProvider == null) {
			return null;
		}
		IDocument document = documentProvider
				.getDocument(editor.getEditorInput());
		if (document == null) {
			return null;
		}
		return document.getLineInformationOfOffset(invocationLocation);
	}

	public int collectQuickFixableAnnotations(int invocationLocation,
			boolean goToClosest, ArrayList<Annotation> resultingAnnotations)
			throws BadLocationException {
		IAnnotationModel model = DLTKUIPlugin.getDocumentProvider()
				.getAnnotationModel(fEditor.getEditorInput());
		if (model == null) {
			return invocationLocation;
		}

		ensureUpdatedAnnotations(fEditor);

		Iterator<Annotation> iter = model.getAnnotationIterator();
		if (goToClosest) {
			IRegion lineInfo = getRegionOfInterest(fEditor, invocationLocation);
			if (lineInfo == null) {
				return invocationLocation;
			}
			int rangeStart = lineInfo.getOffset();
			int rangeEnd = rangeStart + lineInfo.getLength();

			ArrayList<Annotation> allAnnotations = new ArrayList<Annotation>();
			ArrayList<Position> allPositions = new ArrayList<Position>();
			int bestOffset = Integer.MAX_VALUE;
			while (iter.hasNext()) {
				Annotation annot = iter.next();
				if (ScriptAnnotationUtils.isQuickFixableType(annot)) {
					Position pos = model.getPosition(annot);
					if (pos != null
							&& isInside(pos.offset, rangeStart, rangeEnd)) {
						// inside our range?
						allAnnotations.add(annot);
						allPositions.add(pos);
						bestOffset = processAnnotation(annot, pos,
								invocationLocation, bestOffset);
					}
				}
			}
			if (bestOffset == Integer.MAX_VALUE) {
				return invocationLocation;
			}
			for (int i = 0; i < allPositions.size(); i++) {
				Position pos = allPositions.get(i);
				if (isInside(bestOffset, pos.offset, pos.offset + pos.length)) {
					resultingAnnotations.add(allAnnotations.get(i));
				}
			}
			return bestOffset;
		} else {
			while (iter.hasNext()) {
				Annotation annot = iter.next();
				if (ScriptAnnotationUtils.isQuickFixableType(annot)) {
					Position pos = model.getPosition(annot);
					if (pos != null && isInside(invocationLocation, pos.offset,
							pos.offset + pos.length)) {
						resultingAnnotations.add(annot);
					}
				}
			}
			return invocationLocation;
		}
	}

	private static void ensureUpdatedAnnotations(ITextEditor editor) {
		// Object inputElement = editor.getEditorInput().getAdapter(
		// IModelElement.class);

	}

	private int processAnnotation(Annotation annot, Position pos,
			int invocationLocation, int bestOffset) {
		int posBegin = pos.offset;
		int posEnd = posBegin + pos.length;
		if (isInside(invocationLocation, posBegin, posEnd)) { // covers
			// invocation
			// location?
			return invocationLocation;
		} else if (bestOffset != invocationLocation) {
			int newClosestPosition = computeBestOffset(posBegin,
					invocationLocation, bestOffset);
			if (newClosestPosition != -1) {
				if (newClosestPosition != bestOffset) { // new best
					if (canFix(annot)) {
						// only jump to it if there are proposals
						return newClosestPosition;
					}
				}
			}
		}
		return bestOffset;
	}

	private static boolean isInside(int offset, int start, int end) {
		return offset == start || offset == end
				|| (offset > start && offset < end); // make sure to handle
		// 0-length ranges
	}

	/**
	 * Computes and returns the invocation offset given a new position, the
	 * initial offset and the best invocation offset found so far.
	 * <p>
	 * The closest offset to the left of the initial offset is the best. If
	 * there is no offset on the left, the closest on the right is the best.
	 * </p>
	 *
	 * @param newOffset
	 *            the offset to llok at
	 * @param invocationLocation
	 *            the invocation location
	 * @param bestOffset
	 *            the current best offset
	 * @return -1 is returned if the given offset is not closer or the new best
	 *         offset
	 */
	private static int computeBestOffset(int newOffset, int invocationLocation,
			int bestOffset) {
		if (newOffset <= invocationLocation) {
			if (bestOffset > invocationLocation) {
				return newOffset; // closest was on the right, prefer on the
				// left
			} else if (bestOffset <= newOffset) {
				return newOffset; // we are closer or equal
			}
			return -1; // further away
		}

		if (newOffset <= bestOffset)
			return newOffset; // we are closer or equal

		return -1; // further away
	}

	/*
	 * @see ContentAssistant#possibleCompletionsClosed()
	 */
	@Override
	protected void possibleCompletionsClosed() {
		super.possibleCompletionsClosed();
		restorePosition();
	}

	private void storePosition(int currOffset, int currLength) {
		fPosition = new Position(currOffset, currLength);
	}

	private void restorePosition() {
		if (fPosition != null && !fPosition.isDeleted()
				&& fViewer.getDocument() != null) {
			fViewer.setSelectedRange(fPosition.offset, fPosition.length);
			fViewer.revealRange(fPosition.offset, fPosition.length);
		}
		fPosition = null;
	}

	/**
	 * Returns true if the last invoked completion was called with an updated
	 * offset.
	 *
	 * @return <code> true</code> if the last invoked completion was called with
	 *         an updated offset.
	 */
	public boolean isUpdatedOffset() {
		return fPosition != null;
	}

	/**
	 * Returns the annotations at the current offset
	 *
	 * @return the annotations at the offset
	 */
	public Annotation[] getAnnotationsAtOffset() {
		return fCurrentAnnotations;
	}
}