package org.insa.graph.io;

import java.io.DataInputStream;
import java.io.IOException;
import java.util.ArrayList;

import org.insa.graph.Arc;
import org.insa.graph.Graph;
import org.insa.graph.Node;
import org.insa.graph.Point;
import org.insa.graph.RoadInformation;
import org.insa.graph.RoadInformation.RoadType;

public class BinaryGraphReader extends BinaryReader implements AbstractGraphReader {
	
	// Map version and magic number targeted for this reader.
	private static final int VERSION = 4;
	private static final int MAGIC_NUMBER = 0xbacaff;

	/**
	 * Convert a character to its corresponding road type.
	 * 
	 * @param ch Character to convert.
	 * 
	 * @return Road type corresponding to ch.
	 * 
	 * @see http://wiki.openstreetmap.org/wiki/Highway_tag_usage.
	 */
	public static RoadType toRoadType(char ch) {
		switch (ch) {
			case 'a': return RoadType.MOTORWAY;
			case 'b': return RoadType.TRUNK;
			case 'c': return RoadType.PRIMARY;
			case 'd': return RoadType.SECONDARY;
			case 'e': return RoadType.MOTORWAY_LINK;
			case 'f': return RoadType.TRUNK_LINK;
			case 'g': return RoadType.PRIMARY_LINK;
			case 'h': return RoadType.SECONDARY_LINK;
			case 'i': return RoadType.TERTIARY;
			case 'j': return RoadType.RESIDENTIAL;
			case 'k': return RoadType.UNCLASSIFIED;
			case 'l': return RoadType.ROAD;
			case 'm': return RoadType.LIVING_STREET;
			case 'n': return RoadType.SERVICE;
			case 'o': return RoadType.ROUNDABOUT;
			case 'z': return RoadType.COASTLINE;
		}
		return RoadType.UNCLASSIFIED;
	}

	/**
	 * Create a new BinaryGraphReader using the given DataInputStream.
	 * 
	 * @param dis
	 */
	public BinaryGraphReader(DataInputStream dis) {
		super(MAGIC_NUMBER, VERSION, dis);
	}

	@Override
	public Graph read() throws IOException {
		
		// Read and check magic number and file version.
		checkMagicNumberOrThrow(dis.readInt());
		checkVersionOrThrow(dis.readInt());
		
		// Read map id.
		int mapId = dis.readInt();
		
		// Read zone.
		int graphZone = dis.readInt();

		// Number of descriptors and nodes.
		int nbDesc = dis.readInt();
		int nbNodes = dis.readInt();
		
		// Number of successors for each nodes.
		int[] nbSuccessors = new int[nbNodes];

		// Construct an array list with initial capacity of nbNodes.
		ArrayList<Node> nodes = new ArrayList<Node>(nbNodes);
		
		// Read nodes.
		for (int node = 0; node < nbNodes; ++node) {
			float longitude = ((float)dis.readInt ()) / 1E6f;
			float latitude = ((float)dis.readInt ()) / 1E6f;
			nbSuccessors[node] = dis.readUnsignedByte();
			nodes.add(new Node(node, new Point(longitude, latitude)));
		}
		
		// Check format.
		checkByteOrThrow(255);
		
		// Read descriptors.
		RoadInformation[] descs = new RoadInformation[nbDesc];
		
		// Read
		for (int descr = 0; descr < nbDesc; ++descr) {
			descs[descr] = readRoadInformation();
		}
		
		// Check format.
		checkByteOrThrow(254);
		
		// Read successors and convert to arcs.
		for (int node = 0; node < nbNodes; ++node) {
			for (int succ = 0; succ < nbSuccessors[node]; ++succ) {
				
				// Read destination zone.
				int destZone = dis.readUnsignedByte();
				
				// Read target node number.
				int destNode = this.read24bits();
				
				// Read information number.
				int descrNum = this.read24bits();
				
				// Length of the arc.
				int length = dis.readUnsignedShort();
				
				// Number of segments.
				int nbSegments = dis.readUnsignedShort();

				// Chain of points corresponding to the segments.
				ArrayList<Point> points = new ArrayList<Point>(nbSegments + 2);
				points.add(nodes.get(node).getPoint());
				
				for (int seg = 0; seg < nbSegments; ++seg) {
					Point lastPoint = points.get(points.size() - 1);
							
					float dlon = (dis.readShort()) / 2.0e5f;
					float dlat = (dis.readShort()) / 2.0e5f;
					
					points.add(new Point(lastPoint.getLongitude() + dlon,
										lastPoint.getLatitude() + dlat));
				}
				
				points.add(nodes.get(destNode).getPoint());
				
				if (graphZone == destZone) {
					
					RoadInformation info = descs[descrNum];
					Node orig = nodes.get(node);
					Node dest = nodes.get(destNode);
	
					// Add successor to initial arc.
					orig.addSuccessor(new Arc(dest, length, info, points));
					
					// And reverse arc if its a two-way road.
					if (!info.isOneWay()) {
						// Add without segments.
						dest.addSuccessor(new Arc(orig, length, info));
					}
					
				}
			}
		}
		
		// Check format.
		checkByteOrThrow(253);
		
		return new Graph(mapId, nodes);
	}
		
	/**
	 * Read the next road information from the stream.
	 * 
	 * @throws IOException
	 */
	private RoadInformation readRoadInformation() throws IOException {
		char type = (char)dis.readUnsignedByte();
		int x = dis.readUnsignedByte() ;
		return new RoadInformation(toRoadType(type), (x & 0x80) > 0, (x & 0x7F) * 5, dis.readUTF());
	}
	
}