/*=============================================================================#
 # Copyright (c) 2012, 2017 Stephan Wahlbrink and others.
 # 
 # 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, or the Apache License, Version 2.0
 # which is available at https://www.apache.org/licenses/LICENSE-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 # 
 # Contributors:
 #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.internal.r.core.pkgmanager;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;

import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.helpers.XMLReaderFactory;

import org.eclipse.statet.internal.r.core.RCorePlugin;
import org.eclipse.statet.r.core.RCore;
import org.eclipse.statet.rj.data.RCharacterStore;
import org.eclipse.statet.rj.data.RDataUtils;
import org.eclipse.statet.rj.data.UnexpectedRDataException;
import org.eclipse.statet.rj.services.FunctionCall;
import org.eclipse.statet.rj.services.RService;


class RViewTasks {
	
	
	private static class CRANViewHandler extends DefaultHandler {
		
		private static final int S_VIEW= 1;
		private static final int S_NAME= 2;
		private static final int S_TOPIC= 3;
		private static final int S_PKGLIST= 4;
		private static final int S_PKGLIST_PKG= 5;
		
		
		private final List<RView> viewList;
		
		private RView view;
		
		private final StringBuilder string= new StringBuilder();
		
		private int state= -1;
		private int depth;
		private int skipDepth;
		
		
		public CRANViewHandler(final List<RView> viewList) {
			this.viewList= viewList;
		}
		
		
		@Override
		public void startDocument() throws SAXException {
			this.state= 0;
			this.depth= 0;
			this.skipDepth= Integer.MAX_VALUE;
		}
		
		@Override
		public void endDocument() throws SAXException {
			this.state= -1;
		}
		
		private void enter(final int newState) {
			this.state= newState;
		}
		
		private void exit(final int newState) {
			this.state= newState;
		}
		
		@Override
		public void startElement(final String uri, final String localName, final String qName, final Attributes attributes)
				throws SAXException {
			this.depth++;
			
			if (this.depth < this.skipDepth) {
				switch (this.state) {
				case 0:
					if (localName.equals("CRANTaskView")) { //$NON-NLS-1$
						enter(S_VIEW);
						this.view= null;
						return;
					}
					break;
				case S_VIEW:
					if (localName.equals("name")) { //$NON-NLS-1$
						if (this.view == null) {
							enter(S_NAME);
							this.string.setLength(0);
							return;
						}
					}
					else if (localName.equals("topic")) { //$NON-NLS-1$
						if (this.view != null) {
							enter(S_TOPIC);
							this.string.setLength(0);
							return;
						}
					}
					else if (localName.equals("packagelist")) { //$NON-NLS-1$
						if (this.view != null) {
							enter(S_PKGLIST);
							return;
						}
					}
					break;
				case S_PKGLIST:
					if (localName.equals("pkg")) { //$NON-NLS-1$
						enter(S_PKGLIST_PKG);
						this.string.setLength(0);
						return;
					}
					break;
				}
				
				this.skipDepth= this.depth;
			}
		}
		
		@Override
		public void endElement(final String uri, final String localName, final String qName) throws SAXException {
			if (this.depth < this.skipDepth) {
				switch (this.state) {
				case S_VIEW:
					if (this.view != null && !this.view.getPkgList().isEmpty()) {
						this.viewList.add(this.view);
						this.view= null;
					}
					exit(0);
					break;
				case S_PKGLIST:
					exit(S_VIEW);
					break;
				case S_NAME:
					if (this.string.length() > 0) {
						this.view= new RView(this.string.toString());
					}
					exit(S_VIEW);
					break;
				case S_TOPIC:
					if (this.string.length() > 0) {
						this.view.setTopic(this.string.toString());
					}
					exit(S_VIEW);
					break;
				case S_PKGLIST_PKG:
					if (this.string.length() > 0) {
						this.view.getPkgList().add(this.string.toString().intern());
					}
					exit(S_PKGLIST);
					break;
				}
			}
			else if (this.depth == this.skipDepth) {
				this.skipDepth= Integer.MAX_VALUE;
			}
			
			this.depth--;
		}
		
		@Override
		public void characters(final char[] ch, final int start, final int length) throws SAXException {
			switch (this.state) {
			case S_NAME:
			case S_TOPIC:
			case S_PKGLIST_PKG:
				this.string.append(ch, start, length);
				break;
			}
		}
	}
	
	
	static List<RView> loadRViews(final RService r, final IProgressMonitor monitor) {
		final Exception error= null;
		monitor.subTask("Loading R task views...");
		try {
			final String dir;
			{	final FunctionCall call= r.createFunctionCall("system.file"); //$NON-NLS-1$
				call.addChar("ctv"); //$NON-NLS-1$
				call.addChar("package", "ctv"); //$NON-NLS-1$ //$NON-NLS-2$
				dir= RDataUtils.checkSingleChar(call.evalData(monitor));
			}
			if (dir == null || dir.equals("")) { //$NON-NLS-1$
				return null;
			}
			
			final String[] files ;
			{	final FunctionCall call= r.createFunctionCall("dir"); //$NON-NLS-1$
				call.addChar("path", dir); //$NON-NLS-1$
				final RCharacterStore data= RDataUtils.checkRCharVector(call.evalData(monitor)).getData();
				files= data.toArray();
			}
			
			final List<RView> views= new ArrayList<>(files.length);
			{	final String sep= r.getPlatform().getFileSep();
				final CRANViewHandler handler= new CRANViewHandler(views);
				final XMLReader reader= XMLReaderFactory.createXMLReader();
				reader.setContentHandler(handler);
				for (int i= 0; i < files.length; i++) {
					if (files[i].endsWith(".ctv")) { //$NON-NLS-1$
						final byte[] file= r.downloadFile(dir + sep + files[i], 0, monitor);
						if (file.length > 0) {
							reader.parse(new InputSource(new ByteArrayInputStream(file)));
						}
					}
				}
			}
			
			return views;
		}
		catch (final UnexpectedRDataException | IOException | SAXException | CoreException e) {
			RCorePlugin.log(new Status(IStatus.ERROR, RCore.BUNDLE_ID,
					"An error occurred when loading R task views.", error));
		}
		return null;
	}
	
	//	private void loadBioCViews(final RService r, final ISelectedRepos repoSettings,
	//	final AvailableRPkgs pkgs, final Change event,
	//	final IProgressMonitor monitor) throws CoreException, UnexpectedRDataException, IOException {
	//	final IRPkgInfo pkg= getInstalled(pkgs, "biocViews"); //$NON-NLS-1$
	//	if (pkg == null || (pkg.getVersion().equals(this.biocViewsVersion)
	//				&& Math.abs(event.stamp - biocViewsStamp) < MIRROR_CHECK ) ) {
	//		return;
	//	}
	//	
	//	Collection<RRepo> repos= repoSettings.getRepos();
	//	r.evalVoid("data(biocViewsVocab, package= 'biocViews', envir= rj::.rj.tmp)", monitor);
	//	for (RRepo repo : repos) {
	//		if (repo.getId().startsWith(RRepo.BIOC_ID_PREFIX)) {
	//			try {
	//				RObject data= r.evalData("biocViews:::getBiocViews('" + repo.getURL() + "', " +
	//						"rj::.rj.tmp$biocViewsVocab, 'NoViewProvided')", monitor );
	//				System.out.println(data);
	//			}
	//			catch (CoreException e) {
	//				e.printStackTrace();
	//			}
	//		}
	//	}
	//	final String dir;
	//	{	final FunctionCall call= r.createFunctionCall("system.file"); //$NON-NLS-1$
	//		call.addChar("ctv"); //$NON-NLS-1$
	//		call.addChar("package", "ctv"); //$NON-NLS-1$
	//		dir= RDataUtils.checkSingleChar(call.evalData(monitor));
	//	}
	//	if (dir == null || dir.equals("")) { //$NON-NLS-1$
	//		return;
	//	}
	//	
	//	final String[] files ;
	//	{	final FunctionCall call= r.createFunctionCall("dir"); //$NON-NLS-1$
	//		call.addChar("path", dir); //$NON-NLS-1$
	//		final RCharacterStore data= RDataUtils.checkRCharVector(call.evalData(monitor)).getData();
	//		files= data.toArray();
	//	}
	//	
	//	this.biocViews= views;
	//	this.biocViewsVersion= pkg.getVersion();
	//	this.biocViewsStamp= event.stamp;
	//	event.views= true;
	//}
	
}