/*******************************************************************************
 * 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 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.search.internal.ui.text;

import org.eclipse.core.resources.IFile;
import org.eclipse.search.internal.ui.SearchPlugin;
import org.eclipse.search.ui.NewSearchUI;
import org.eclipse.search.ui.text.Match;
import org.eclipse.ui.IEditorDescriptor;
import org.eclipse.ui.IEditorPart;
import org.eclipse.ui.IEditorReference;
import org.eclipse.ui.IEditorRegistry;
import org.eclipse.ui.IFileEditorInput;
import org.eclipse.ui.IReusableEditor;
import org.eclipse.ui.IWorkbenchPage;
import org.eclipse.ui.PartInitException;
import org.eclipse.ui.ide.IDE;
import org.eclipse.ui.part.FileEditorInput;

public class EditorOpener {

	private IEditorPart fEditor;
	
	IEditorPart open(Match match, boolean activate) throws PartInitException {
		IWorkbenchPage wbPage= SearchPlugin.getActivePage();
		if (NewSearchUI.reuseEditor())
			return showWithReuse(match, wbPage, activate);
		return showWithoutReuse(match, wbPage, activate);
	}
	
	private IEditorPart showWithoutReuse(Match match, IWorkbenchPage wbPage, boolean activate) throws PartInitException {
		return IDE.openEditor(wbPage, (IFile) match.getElement(), activate);
	}

	private IEditorPart showWithReuse(Match match, IWorkbenchPage wbPage, boolean activate) throws PartInitException {
		IFile file= (IFile) match.getElement();
		String editorID= getEditorID(file);
		return showInEditor(wbPage, file, editorID, activate);
	}


	private String getEditorID(IFile file) throws PartInitException {
		IEditorDescriptor desc= IDE.getEditorDescriptor(file);
		if (desc == null)
			return SearchPlugin.getDefault().getWorkbench().getEditorRegistry().findEditor(IEditorRegistry.SYSTEM_EXTERNAL_EDITOR_ID).getId();
		return desc.getId();
	}


	private boolean isPinned(IEditorPart editor) {
		if (editor == null)
			return false;
		
		IEditorReference[] editorRefs= editor.getEditorSite().getPage().getEditorReferences();
		int i= 0;
		while (i < editorRefs.length) {
			if (editor.equals(editorRefs[i].getEditor(false)))
				return editorRefs[i].isPinned();
			i++;
		}
		return false;
	}
	
	private IEditorPart showInEditor(IWorkbenchPage page, IFile file, String editorId, boolean activate) throws PartInitException {
		IFileEditorInput input= new FileEditorInput(file);
		IEditorPart editor= page.findEditor(input);
		if (editor != null) {
			page.bringToTop(editor);
			if (activate) {
				page.activate(editor);
			}
		} else {
			boolean isOpen= false;
			if (fEditor != null) {
				IEditorReference[] parts= page.getEditorReferences();
				int i= 0;
				while (!isOpen && i < parts.length)
					isOpen= fEditor == parts[i++].getEditor(false);
			}
				
			boolean canBeReused= isOpen && !fEditor.isDirty() && !isPinned(fEditor);
			boolean showsSameInputType= fEditor != null && fEditor.getSite().getId().equals(editorId);
			if (canBeReused && !showsSameInputType) {
				page.closeEditor(fEditor, false);
				fEditor= null;
			}
			
			if (canBeReused && showsSameInputType) {
				((IReusableEditor)fEditor).setInput(input);
				page.bringToTop(fEditor);
				editor= fEditor;
				if (activate) {
					page.activate(editor);
				}
			} else {
					editor= IDE.openEditor(page, file, activate);
					if (editor instanceof IReusableEditor)
						fEditor= editor;
					else
						fEditor= null;
			}
		}
		return editor;
	}
	
}
