/*******************************************************************************
 * Copyright (c) 2008, 2018 Alexander Kurtakov.
 *
 * This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License 2.0
 * which is available at https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *    Alexander Kurtakov - initial API and implementation
 *******************************************************************************/

package org.eclipse.linuxtools.internal.rpm.ui.editor.hyperlink;

import java.util.StringTokenizer;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.eclipse.core.resources.IFile;
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.hyperlink.AbstractHyperlinkDetector;
import org.eclipse.jface.text.hyperlink.IHyperlink;
import org.eclipse.linuxtools.internal.rpm.ui.editor.ISpecfileSpecialSymbols;
import org.eclipse.linuxtools.internal.rpm.ui.editor.SpecfileEditor;
import org.eclipse.linuxtools.internal.rpm.ui.editor.parser.SpecfileSource;
import org.eclipse.linuxtools.rpm.ui.editor.parser.Specfile;
import org.eclipse.linuxtools.rpm.ui.editor.parser.SpecfileDefine;
import org.eclipse.linuxtools.rpm.ui.editor.parser.SpecfileElement;
import org.eclipse.linuxtools.rpm.ui.editor.parser.SpecfileParser;
import org.eclipse.ui.IEditorPart;
import org.eclipse.ui.IWorkbench;
import org.eclipse.ui.IWorkbenchPage;
import org.eclipse.ui.IWorkbenchWindow;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.part.FileEditorInput;

/**
 * Hyperlink detector for source, patch and defines in the spec file.
 *
 */
public class SpecfileElementHyperlinkDetector extends AbstractHyperlinkDetector {

	private static final String PATCH_IDENTIFIER = "%patch"; //$NON-NLS-1$
	private static final String SOURCE_IDENTIFIER = "%{SOURCE"; //$NON-NLS-1$
	private Specfile specfile;

	@Override
	public IHyperlink[] detectHyperlinks(ITextViewer textViewer, IRegion region, boolean canShowMultipleHyperlinks) {

		if (region == null || textViewer == null) {
			return null;
		}

		IDocument document = textViewer.getDocument();
		if (document == null) {
			return null;
		}

		// Keeps the errorHandler on the initial opening of the .spec file
		// otherwise, a new SpecfileParser does not initialize errorHandler
		// until a SpecfileEditor#editorSaved is called
		if (specfile == null) {
			SpecfileEditor a = this.getAdapter(SpecfileEditor.class);
			if (a != null && a.getSpecfile() != null) {
				specfile = a.getSpecfile();
			} else {
				SpecfileParser parser = new SpecfileParser();
				specfile = parser.parse(document);
			}
		}

		int offset = region.getOffset();

		IRegion lineInfo;
		String line;
		try {
			lineInfo = document.getLineInformationOfOffset(offset);
			line = document.get(lineInfo.getOffset(), lineInfo.getLength());
		} catch (BadLocationException ex) {
			return null;
		}

		int offsetInLine = offset - lineInfo.getOffset();

		StringTokenizer tokens = new StringTokenizer(line);
		String word = ""; //$NON-NLS-1$
		int tempLineOffset = 0;
		int wordOffsetInLine = 0;
		while (tokens.hasMoreTokens()) {
			String tempWord = tokens.nextToken();
			Pattern defineRegexp = Pattern.compile("%\\{(.*?)\\}"); //$NON-NLS-1$
			Matcher fit = defineRegexp.matcher(tempWord);
			while (fit.find()) {
				if ((fit.start() + tempLineOffset <= offsetInLine) && (offsetInLine <= fit.end() + tempLineOffset)) {
					tempWord = fit.group();
					wordOffsetInLine = fit.start();
					tempLineOffset += fit.start();
					break;
				}
			}
			tempLineOffset += tempWord.length();
			word = tempWord;
			if (tempLineOffset > offsetInLine) {
				break;
			}
		}
		if (word.startsWith(SOURCE_IDENTIFIER)) {
			int sourceNumber = Integer.valueOf(word.substring(SOURCE_IDENTIFIER.length(), word.length() - 1))
					.intValue();
			SpecfileSource source = specfile.getSource(sourceNumber);
			if (source != null) {
				return prepareHyperlink(lineInfo, line, word, source);
			}
		} else if (word.startsWith(PATCH_IDENTIFIER)) {

			int sourceNumber = Integer.valueOf(word.substring(PATCH_IDENTIFIER.length())).intValue();
			SpecfileSource source = specfile.getPatch(sourceNumber);
			if (source != null) {
				return prepareHyperlink(lineInfo, line, word, source);
			}
		} else {
			String defineName = getDefineName(word);
			SpecfileDefine define = specfile.getDefine(defineName);
			if (define != null) {
				return prepareHyperlink(lineInfo, line, defineName, define, wordOffsetInLine);
			}
		}
		return null;
	}

	private String getDefineName(String word) {
		if (word.startsWith(ISpecfileSpecialSymbols.MACRO_START_LONG)) {
			return word.substring(2, word.length() - 1);
		}
		return ""; //$NON-NLS-1$
	}

	private IHyperlink[] prepareHyperlink(IRegion lineInfo, String line, String word, SpecfileElement source,
			int lineIndex) {
		IRegion urlRegion = new Region(lineInfo.getOffset() + line.indexOf(word, lineIndex), word.length());

		// will only work with 1 active page
		// does not work with CompareEditor
		IWorkbench wb = PlatformUI.getWorkbench();
		IWorkbenchWindow win = wb.getActiveWorkbenchWindow();
		IWorkbenchPage page = win.getActivePage();
		IEditorPart editor = page.getActiveEditor();
		// A IFile cannot be retrieve from a IFileStoreEditorInput, so at this time
		// we can only provide this functionality for resources inside the workbench.
		if (editor.getEditorInput() instanceof FileEditorInput) {
			IFile original = ((FileEditorInput) editor.getEditorInput()).getFile();
			return new IHyperlink[] { new SpecfileElementHyperlink(urlRegion, source, original) };
		} else {
			return null;
		}

	}

	private IHyperlink[] prepareHyperlink(IRegion lineInfo, String line, String word, SpecfileElement source) {
		return prepareHyperlink(lineInfo, line, word, source, 0);
	}

	public void setSpecfile(Specfile specfile) {
		this.specfile = specfile;
	}
}