//License: GPL. Copyright 2007 by Immanuel Scholz and others

//TODO: this is far from complete, but can emulate old RawGps behaviour
package org.openstreetmap.josm.io;

import static org.openstreetmap.josm.tools.I18n.tr;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedList;
import java.util.Map;
import java.util.Stack;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParserFactory;

import org.openstreetmap.josm.data.coor.LatLon;
import org.openstreetmap.josm.data.gpx.GpxData;
import org.openstreetmap.josm.data.gpx.GpxLink;
import org.openstreetmap.josm.data.gpx.GpxRoute;
import org.openstreetmap.josm.data.gpx.GpxTrack;
import org.openstreetmap.josm.data.gpx.WayPoint;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

/**
 * Read a gpx file. Bounds are not read, as we caluclate them. @see GpxData.recalculateBounds()
 * @author imi, ramack
 */
public class GpxReader {
	// TODO: implement GPX 1.0 parsing

	/**
	 * The resulting gpx data
	 */
	public GpxData data;
	public enum state { init, metadata, wpt, rte, trk, ext, author, link, trkseg }

	private class Parser extends DefaultHandler {

		private GpxData currentData;
		private GpxTrack currentTrack;
		private Collection<WayPoint> currentTrackSeg;
		private GpxRoute currentRoute;
		private WayPoint currentWayPoint;

		private state currentState = state.init;
	
		private GpxLink currentLink;
		private Stack<state> states;

		private StringBuffer accumulator = new StringBuffer();

		@Override public void startDocument() {
			accumulator = new StringBuffer();
			states = new Stack<state>();
			currentData = new GpxData();
		}		

		private double parseCoord(String s) {
			try {
				return Double.parseDouble(s);
			} catch (NumberFormatException ex) {
				return Double.NaN;
			}
		}

		private LatLon parseLatLon(Attributes atts) {
			return new LatLon(
				parseCoord(atts.getValue("lat")),
				parseCoord(atts.getValue("lon")));
		}

		@Override public void startElement(String namespaceURI, String localName, String qName, Attributes atts) throws SAXException {
			switch(currentState) {
			case init:
				if (qName.equals("metadata")) {
					states.push(currentState);
					currentState = state.metadata;
				} else if (qName.equals("wpt")) {
					states.push(currentState);
					currentState = state.wpt;
					currentWayPoint = new WayPoint(parseLatLon(atts));
				} else if (qName.equals("rte")) {
					states.push(currentState);
					currentState = state.rte;
					currentRoute = new GpxRoute();
				} else if (qName.equals("trk")) {
					states.push(currentState);
					currentState = state.trk;
					currentTrack = new GpxTrack();
				} else if (qName.equals("extensions")) {
					states.push(currentState);
					currentState = state.ext;
				}
				break;
			case author:
				if (qName.equals("link")) {
					states.push(currentState);
					currentState = state.link;
					currentLink = new GpxLink(atts.getValue("href"));
				}
				break;
			case trk:
				if (qName.equals("trkseg")) {
					states.push(currentState);
					currentState = state.trkseg;
					currentTrackSeg = new ArrayList<WayPoint>();
				} else if (qName.equals("link")) {
					states.push(currentState);
					currentState = state.link;
					currentLink = new GpxLink(atts.getValue("href"));
				} else if (qName.equals("extensions")) {
					states.push(currentState);
					currentState = state.ext;
				}
				break;
			case metadata:
				if (qName.equals("author")) {
					states.push(currentState);
					currentState = state.author;
				} else if (qName.equals("extensions")) {
					states.push(currentState);
					currentState = state.ext;
				}
				break;
			case trkseg:
				if (qName.equals("trkpt")) {
					states.push(currentState);
					currentState = state.wpt;
					currentWayPoint = new WayPoint(parseLatLon(atts));
				}
				break;
			case wpt:
				if (qName.equals("link")) {
					states.push(currentState);
					currentState = state.link;
					currentLink = new GpxLink(atts.getValue("href"));
				} else if (qName.equals("extensions")) {
					states.push(currentState);
					currentState = state.ext;
				}
				break;
			case rte:
				if (qName.equals("link")) {
					states.push(currentState);
					currentState = state.link;
					currentLink = new GpxLink(atts.getValue("href"));
				} else if (qName.equals("rtept")) {
					states.push(currentState);
					currentState = state.wpt;
					currentWayPoint = new WayPoint(parseLatLon(atts));
				} else if (qName.equals("extensions")) {
					states.push(currentState);
					currentState = state.ext;
				}
				break;
			default:
			}
			accumulator.setLength(0);
		}

		@Override public void characters(char[] ch, int start, int length) {
			accumulator.append(ch, start, length);
		}

		private Map<String, Object> getAttr() {
			switch (currentState) {
				case rte: return currentRoute.attr;
				case metadata: return currentData.attr;
				case wpt: return currentWayPoint.attr;
				case trk: return currentTrack.attr;
				default: return null;
			}
		}

		@Override public void endElement(String namespaceURI, String localName, String qName) {
			switch (currentState) {
			case metadata:
				if (qName.equals("name") || qName.equals("desc") ||
						qName.equals("time") || qName.equals("keywords")) {
					currentData.attr.put(qName, accumulator.toString());
				} else if (qName.equals("metadata")) {
					currentState = states.pop();
				}
				//TODO: parse copyright, bounds, extensions
				break;
			case author:
				if (qName.equals("author")) {
					currentState = states.pop();
				} else if (qName.equals("name") || qName.equals("email")) {
					currentData.attr.put("author" + qName, accumulator.toString());
				} else if (qName.equals("link")) {
					currentData.attr.put("authorlink", currentLink);
				}
				break;
			case link:
				if (qName.equals("text")) {
					currentLink.text = accumulator.toString();
				} else if (qName.equals("type")) {
					currentLink.type = accumulator.toString();
				} else if (qName.equals("link")) {
					// <link>URL</link>
					if (currentLink.uri == null)
						currentLink.uri = accumulator.toString();

					currentState = states.pop();
				}
				if (currentState == state.author) {
					currentData.attr.put("authorlink", currentLink);
				} else if (currentState != state.link) {
					Map<String, Object> attr = getAttr();
					if (!attr.containsKey("link")) {
						attr.put("link", new LinkedList<GpxLink>());
					}
					((Collection<GpxLink>) attr.get("link")).add(currentLink);
				}
				break;
			case wpt:
				if (qName.equals("ele") || qName.equals("desc")
						|| qName.equals("magvar") || qName.equals("geoidheight")
						|| qName.equals("name")	|| qName.equals("sym") 
						|| qName.equals("cmt") || qName.equals("type")) {
					currentWayPoint.attr.put(qName, accumulator.toString());
				} else if (qName.equals("time")) {
					currentWayPoint.attr.put(qName, accumulator.toString());
					currentWayPoint.setTime();					
				} else if (qName.equals("rtept")) {
					currentState = states.pop();
					currentRoute.routePoints.add(currentWayPoint);
				} else if (qName.equals("trkpt")) {
					currentState = states.pop();
					currentTrackSeg.add(currentWayPoint);
				} else if (qName.equals("wpt")) {
					currentState = states.pop();
					currentData.waypoints.add(currentWayPoint);
				}
				break;
			case trkseg:
				if (qName.equals("trkseg")) {
					currentState = states.pop();
					currentTrack.trackSegs.add(currentTrackSeg);
				}
				break;
			case trk:
				if (qName.equals("trk")) {
					currentState = states.pop();
					currentData.tracks.add(currentTrack);
				} else if (qName.equals("name") || qName.equals("cmt")
						|| qName.equals("desc") || qName.equals("src")
						|| qName.equals("type") || qName.equals("number")) {
					currentTrack.attr.put(qName, accumulator.toString());
				}
				break;
			case ext:
				if (qName.equals("extensions")) {
					currentState = states.pop();
				}
				break;
			default:
				if (qName.equals("wpt")) {
					currentState = states.pop();
				} else if (qName.equals("rte")) {
					currentState = states.pop();
					currentData.routes.add(currentRoute);
				}
			}
		}

		@Override public void endDocument() throws SAXException  {
			if (!states.empty()) {
				throw new SAXException(tr("Parse error: invalid document structure for gpx document"));
			}
			data = currentData;
		}
	}

	/**
	 * Parse the input stream and store the result in trackData and markerData
	 * 
	 * @param relativeMarkerPath The directory to use as relative path for all &lt;wpt&gt; 
	 *    marker tags. Maybe <code>null</code>, in which case no relative urls are constructed for the markers. 
	 */
	public GpxReader(InputStream source, File relativeMarkerPath) throws SAXException, IOException {
		
		Parser parser = new Parser();
		InputSource inputSource = new InputSource(new InputStreamReader(source, "UTF-8"));
		try {
			SAXParserFactory.newInstance().newSAXParser().parse(inputSource, parser);
			data.storageFile = relativeMarkerPath;
		} catch (ParserConfigurationException e) {
			e.printStackTrace(); // broken SAXException chaining
			throw new SAXException(e);
		}
	}
}