// License: GPL. Copyright 2007 by Immanuel Scholz and others
package org.openstreetmap.josm.io;

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

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.text.ParseException;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Map;
import java.util.Map.Entry;

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

import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.data.Bounds;
import org.openstreetmap.josm.data.coor.LatLon;
import org.openstreetmap.josm.data.osm.DataSet;
import org.openstreetmap.josm.data.osm.DataSource;
import org.openstreetmap.josm.data.osm.Relation;
import org.openstreetmap.josm.data.osm.RelationMember;
import org.openstreetmap.josm.data.osm.Node;
import org.openstreetmap.josm.data.osm.OsmPrimitive;
import org.openstreetmap.josm.data.osm.User;
import org.openstreetmap.josm.data.osm.Way;
import org.openstreetmap.josm.data.osm.visitor.AddVisitor;
import org.openstreetmap.josm.data.osm.visitor.Visitor;
import org.openstreetmap.josm.gui.PleaseWaitDialog;
import org.openstreetmap.josm.tools.DateParser;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

/**
 * Parser for the Osm Api. Read from an input stream and construct a dataset out of it.
 *
 * Reading process takes place in three phases. During the first phase (including xml parse),
 * all nodes are read and stored. Other information than nodes are stored in a raw list
 *
 * The second phase read all ways out of the remaining objects in the raw list.
 *
 * @author Imi
 */
public class OsmReader {

	/**
	 * This is used as (readonly) source for finding missing references when not transferred in the
	 * file.
	 */
	private DataSet references;

	/**
	 * The dataset to add parsed objects to.
	 */
	private DataSet ds = new DataSet();

	/**
	 * The visitor to use to add the data to the set.
	 */
	private AddVisitor adder = new AddVisitor(ds);

	/**
	 * All read nodes after phase 1.
	 */
	private Map<Long, Node> nodes = new HashMap<Long, Node>();

	// TODO: What the hack? Is this really from me? Please, clean this up!
	private static class OsmPrimitiveData extends OsmPrimitive {
		@Override public void visit(Visitor visitor) {}
		public int compareTo(OsmPrimitive o) {return 0;}

		public void copyTo(OsmPrimitive osm) {
			osm.id = id;
			osm.keys = keys;
			osm.modified = modified;
			osm.selected = selected;
			osm.deleted = deleted;
			osm.timestamp = timestamp;
			osm.user = user;
			osm.visible = visible;
		}
	}

	/**
	 * Used as a temporary storage for relation members, before they
	 * are resolved into pointers to real objects.
	 */
	private static class RelationMemberData {
		public String type;
		public long id;
		public RelationMember relationMember;
	}

	/**
	 * Data structure for the remaining way objects
	 */
	private Map<OsmPrimitiveData, Collection<Long>> ways = new HashMap<OsmPrimitiveData, Collection<Long>>();

	/** 
	 * Data structure for relation objects
	 */
	private Map<OsmPrimitiveData, Collection<RelationMemberData>> relations = new HashMap<OsmPrimitiveData, Collection<RelationMemberData>>();

	/** 
	 * List of protocol versions that will be accepted on reading
	 */
	private HashSet<String> allowedVersions = new HashSet<String>();

	private class Parser extends DefaultHandler {
		/**
		 * The current osm primitive to be read.
		 */
		private OsmPrimitive current;

		@Override public void startElement(String namespaceURI, String localName, String qName, Attributes atts) throws SAXException {
			try {
				if (qName.equals("osm")) {
					if (atts == null)
						throw new SAXException(tr("Unknown version"));
					if (!allowedVersions.contains(atts.getValue("version")))
						throw new SAXException(tr("Unknown version")+": "+atts.getValue("version"));
				} else if (qName.equals("bound")) {
					String bbox = atts.getValue("box");
					String origin = atts.getValue("origin");
					if (bbox != null) {
						String[] b = bbox.split(",");
						Bounds bounds = null;
						if (b.length == 4)
							bounds = new Bounds(
									new LatLon(Double.parseDouble(b[0]),Double.parseDouble(b[1])),
									new LatLon(Double.parseDouble(b[2]),Double.parseDouble(b[3])));
						DataSource src = new DataSource(bounds, origin);
						ds.dataSources.add(src);
					}
					
				// ---- PARSING NODES AND WAYS ----
					
				} else if (qName.equals("node")) {
					current = new Node(new LatLon(getDouble(atts, "lat"), getDouble(atts, "lon")));
					readCommon(atts, current);
					nodes.put(current.id, (Node)current);
				} else if (qName.equals("way")) {
					current = new OsmPrimitiveData();
					readCommon(atts, current);
					ways.put((OsmPrimitiveData)current, new LinkedList<Long>());
				} else if (qName.equals("nd")) {
					Collection<Long> list = ways.get(current);
					if (list == null)
						throw new SAXException(tr("Found <nd> element in non-way."));
					long id = getLong(atts, "ref");
					if (id == 0)
						throw new SAXException(tr("<nd> has zero ref"));
					list.add(id);

				// ---- PARSING ENTITIES ----			

				} else if (qName.equals("relation")) {
					current = new OsmPrimitiveData();
					readCommon(atts, current);
					relations.put((OsmPrimitiveData)current, new LinkedList<RelationMemberData>());
				} else if (qName.equals("member")) {
					Collection<RelationMemberData> list = relations.get(current);
					if (list == null)
						throw new SAXException(tr("Found <member> tag on non-relation."));
					RelationMemberData emd = new RelationMemberData();
					emd.relationMember = new RelationMember();
					emd.id = getLong(atts, "ref");
					emd.type=atts.getValue("type");
					emd.relationMember.role = atts.getValue("role");
					
					if (emd.id == 0)
						throw new SAXException(tr("Incomplete <member> specification with ref=0"));
					
					list.add(emd);
					
				// ---- PARSING TAGS (applicable to all objects) ----
					
				} else if (qName.equals("tag")) {
					current.put(atts.getValue("k"), atts.getValue("v"));
				}
			} catch (NumberFormatException x) {
				x.printStackTrace(); // SAXException does not chain correctly
				throw new SAXException(x.getMessage(), x);
			} catch (NullPointerException x) {
				x.printStackTrace(); // SAXException does not chain correctly
				throw new SAXException(tr("NullPointerException, Possibly some missing tags."), x);
			}
		}

		private double getDouble(Attributes atts, String value) {
			return Double.parseDouble(atts.getValue(value));
		}
	}
	
	/** 
	 * Constructor initializes list of allowed protocol versions.
	 */
	public OsmReader() {
		// first add the main server version
		allowedVersions.add(Main.pref.get("osm-server.version", "0.5"));
		// now also add all compatible versions
		String[] additionalVersions = 
			Main.pref.get("osm-server.additional-versions", "").split("/,/");
		if (additionalVersions.length == 1 && additionalVersions[0].length() == 0)
			additionalVersions = new String[] {};
		allowedVersions.addAll(Arrays.asList(additionalVersions));	
	}

	/**
	 * Read out the common attributes from atts and put them into this.current.
	 */
	void readCommon(Attributes atts, OsmPrimitive current) throws SAXException {
		current.id = getLong(atts, "id");
		if (current.id == 0)
			throw new SAXException(tr("Illegal object with id=0"));

		String time = atts.getValue("timestamp");
		if (time != null && time.length() != 0) {
			try {
				current.timestamp = DateParser.parse(time);
			} catch (ParseException e) {
				e.printStackTrace();
				throw new SAXException(tr("Couldn't read time format \"{0}\".",time));
			}
		}
		
		// user attribute added in 0.4 API
		String user = atts.getValue("user");
		if (user != null) {
			// do not store literally; get object reference for string
			current.user = User.get(user);
		}
		
		// visible attribute added in 0.4 API
		String visible = atts.getValue("visible");
		if (visible != null) {
			current.visible = Boolean.parseBoolean(visible);
		}

		String action = atts.getValue("action");
		if (action == null)
			return;
		if (action.equals("delete"))
			current.delete(true);
		else if (action.startsWith("modify"))
			current.modified = true;
	}
	private long getLong(Attributes atts, String value) throws SAXException {
		String s = atts.getValue(value);
		if (s == null)
			throw new SAXException(tr("Missing required attribute \"{0}\".",value));
		return Long.parseLong(s);
	}

	private Node findNode(long id) {
	    Node n = nodes.get(id);
	    if (n != null)
	    	return n;
	    for (Node node : references.nodes)
	    	if (node.id == id)
	    		return node;
	    // TODO: This has to be changed to support multiple layers.
	    for (Node node : Main.ds.nodes)
	    	if (node.id == id)
	    		return new Node(node);
	    return null;
    }

	private void createWays() {
		for (Entry<OsmPrimitiveData, Collection<Long>> e : ways.entrySet()) {
			Way w = new Way();
			boolean failed = false;
			for (long id : e.getValue()) {
				Node n = findNode(id);
				if (n == null) {
					failed = true;
					break;
				}
				w.nodes.add(n);
			}
			if (failed) continue;
			e.getKey().copyTo(w);
			adder.visit(w);
		}
	}

	/**
	 * Return the Way object with the given id, or null if it doesn't
	 * exist yet. This method only looks at ways stored in the data set.
	 * 
	 * @param id
	 * @return way object or null
	 */
	private Way findWay(long id) {
		for (Way wy : ds.ways)
			if (wy.id == id)
				return wy;
		for (Way wy : Main.ds.ways)
			if (wy.id == id)
				return wy;
		return null;
	}

	/**
	 * Return the Relation object with the given id, or null if it doesn't
	 * exist yet. This method only looks at relations stored in the data set.
	 * 
	 * @param id
	 * @return relation object or null
	 */
	private Relation findRelation(long id) {
		for (Relation e : ds.relations)
			if (e.id == id)
				return e;
		for (Relation e : Main.ds.relations)
			if (e.id == id)
				return e;
		return null;
	}

	/**
	 * Create relations. This is slightly different than n/s/w because 
	 * unlike other objects, relations may reference other relations; it
	 * is not guaranteed that a referenced relation will have been created
	 * before it is referenced. So we have to create all relations first,
	 * and populate them later.
	 */
	private void createRelations() {
		
		// pass 1 - create all relations
		for (Entry<OsmPrimitiveData, Collection<RelationMemberData>> e : relations.entrySet()) {
			Relation en = new Relation();
			e.getKey().copyTo(en);
			adder.visit(en);
		}

		// pass 2 - sort out members
		for (Entry<OsmPrimitiveData, Collection<RelationMemberData>> e : relations.entrySet()) {
			Relation en = findRelation(e.getKey().id);
			if (en == null) throw new Error("Failed to create relation " + e.getKey().id);
			
			for (RelationMemberData emd : e.getValue()) {
				RelationMember em = emd.relationMember;
				if (emd.type.equals("node")) {
					em.member = findNode(emd.id);
					if (em.member == null) {
						em.member = new Node(emd.id);
						adder.visit((Node)em.member);
					}
				} else if (emd.type.equals("way")) {
					em.member = findWay(emd.id);
					if (em.member == null) {
						em.member = new Way(emd.id);
						adder.visit((Way)em.member);
					}
				} else if (emd.type.equals("relation")) {
					em.member = findRelation(emd.id);
					if (em.member == null) {
						em.member = new Relation(emd.id);
						adder.visit((Relation)em.member);
					}
				} else {
					// this is an error.
				}
				en.members.add(em);
			}
		}
	}

	/**
	 * Parse the given input source and return the dataset.
	 * @param ref The dataset that is search in for references first. If
	 * 	the Reference is not found here, Main.ds is searched and a copy of the
	 *  elemet found there is returned.
	 */
	public static DataSet parseDataSet(InputStream source, DataSet ref, PleaseWaitDialog pleaseWaitDlg) throws SAXException, IOException {
		OsmReader osm = new OsmReader();
		osm.references = ref == null ? new DataSet() : ref;

		// phase 1: Parse nodes and read in raw ways
		InputSource inputSource = new InputSource(new InputStreamReader(source, "UTF-8"));
		try {
	        SAXParserFactory.newInstance().newSAXParser().parse(inputSource, osm.new Parser());
        } catch (ParserConfigurationException e1) {
        	e1.printStackTrace(); // broken SAXException chaining
        	throw new SAXException(e1);
        }
		if (pleaseWaitDlg != null) {
			pleaseWaitDlg.progress.setValue(0);
			pleaseWaitDlg.currentAction.setText(tr("Preparing data..."));
		}
		for (Node n : osm.nodes.values())
			osm.adder.visit(n);

		try {
			osm.createWays();
			osm.createRelations();
		} catch (NumberFormatException e) {
			e.printStackTrace();
			throw new SAXException(tr("Illformed Node id"));
		}

		// clear all negative ids (new to this file)
		for (OsmPrimitive o : osm.ds.allPrimitives())
			if (o.id < 0)
				o.id = 0;

		return osm.ds;
	}
}