/*-
 *  Copyright 2020 Beuth Hochschule für Technik Berlin, Hochschule für Technik Stuttgart
 * 
 *  This file is part of CityDoctor2.
 *
 *  CityDoctor2 is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  CityDoctor2 is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with CityDoctor2.  If not, see <https://www.gnu.org/licenses/>.
 */
package de.hft.stuttgart.citydoctor2.edge;


import java.util.ArrayList;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Map;

import de.hft.stuttgart.citydoctor2.datastructure.Geometry;
import de.hft.stuttgart.citydoctor2.datastructure.LinearRing;
import de.hft.stuttgart.citydoctor2.datastructure.Polygon;
import de.hft.stuttgart.citydoctor2.datastructure.Vertex;

public class MeshSurface {
	
	private List<CDPolygonNs> polygons;
	
	public static MeshSurface of(Geometry geom) {
		List<CDPolygonNs> polygonList = new ArrayList<>();
		
		Map<Vertex, Coordinate3d> pointMap = new IdentityHashMap<>();
		for (Polygon p : geom.getPolygons()) {
			List<List<Coordinate3d>> loopCoordinates = new ArrayList<>();
			List<Coordinate3d> edgeExtRing = createCoordinatesFromRing(pointMap, p.getExteriorRing().getVertices());
			loopCoordinates.add(edgeExtRing);
			
			for (LinearRing innerRing : p.getInnerRings()) {
				List<Coordinate3d> edgeInnerRing = createCoordinatesFromRing(pointMap, innerRing.getVertices());
				loopCoordinates.add(edgeInnerRing);
			}
			
			List<List<HalfEdge>> halfEdges = new ArrayList<>();
			for (List<Coordinate3d> ringCoordinates : loopCoordinates) {
				List<HalfEdge> currHeList = createHalfEdgesFromCoordinates(ringCoordinates);
				halfEdges.add(currHeList);
			}
			
			CDPolygonNs newPolygon = new CDPolygonNs(halfEdges);
			polygonList.add(newPolygon);
		}
		return new MeshSurface(polygonList);
	}

	private static List<Coordinate3d> createCoordinatesFromRing(Map<Vertex, Coordinate3d> pointMap,
			List<Vertex> vertices) {
		List<Coordinate3d> edgeRing = new ArrayList<>();
		for (int i = 0; i < vertices.size() - 1; i++) {
			Vertex v = vertices.get(i);
			Coordinate3d c = pointMap.computeIfAbsent(v, key -> new Coordinate3d(key.getX(), key.getY(), key.getZ()));
			edgeRing.add(c);
		}
		return edgeRing;
	}

	private static List<HalfEdge> createHalfEdgesFromCoordinates(List<Coordinate3d> ringCoordinates) {
		List<HalfEdge> currHeList = new ArrayList<>();
		HalfEdge prevHalfEdge = null;
		for (int currCoordIndex = 1; currCoordIndex < ringCoordinates.size(); currCoordIndex++) {
			int prevCoordIndex = currCoordIndex - 1;
			Coordinate3d currCoord = ringCoordinates.get(currCoordIndex);
			Coordinate3d prevCoord = ringCoordinates.get(prevCoordIndex);
			HalfEdge e = new HalfEdge(prevCoord, currCoord);
			if (prevHalfEdge != null) {
				prevHalfEdge.setNext(e);
			}
			currHeList.add(e);
			prevHalfEdge = e;
		}
		if (prevHalfEdge == null) {
			throw new IllegalStateException("No half edges were created");
		}
		Coordinate3d start = ringCoordinates.get(0);
		Coordinate3d end = ringCoordinates.get(ringCoordinates.size() - 1);
		HalfEdge e = new HalfEdge(end, start);
		prevHalfEdge.setNext(e);
		e.setNext(currHeList.get(0));
		currHeList.add(e);
		return currHeList;
	}
	
	public MeshSurface(List<CDPolygonNs> polygons) {
		this.polygons = polygons;
	}
	
	public List<CDPolygonNs> getPolygons() {
		return polygons;
	}

}