/*******************************************************************************
    * Copyright (c) 2015 VoyagerSearch
    * All rights reserved. This program and the accompanying materials
    * are made available under the terms of the Apache License, Version 2.0 which
    * accompanies this distribution and is available at
    *    http://www.apache.org/licenses/LICENSE-2.0.txt
    ******************************************************************************/
   
   package org.locationtech.spatial4j.io;
  
  import org.locationtech.spatial4j.context.SpatialContext;
  import org.locationtech.spatial4j.context.SpatialContextFactory;
  import org.locationtech.spatial4j.distance.DistanceUtils;
  import org.locationtech.spatial4j.shape.*;
  import org.locationtech.spatial4j.shape.impl.BufferedLine;
  import org.locationtech.spatial4j.shape.impl.BufferedLineString;
  import org.locationtech.spatial4j.shape.impl.GeoCircle;
  
  import java.io.IOException;
  import java.io.StringWriter;
  import java.io.Writer;
  import java.text.NumberFormat;
  import java.util.Iterator;
  
  import static org.locationtech.spatial4j.io.GeoJSONReader.BUFFER;
  import static org.locationtech.spatial4j.io.GeoJSONReader.BUFFER_UNITS;
  
  public class GeoJSONWriter implements ShapeWriter {
  
    public GeoJSONWriter(SpatialContext ctx, SpatialContextFactory factory) {
  
    }
  
    @Override
    public String getFormatName() {
      return ShapeIO.GeoJSON;
    }
  
    protected void write(Writer output, NumberFormat nf, double... coords) throws IOException {
      output.write('[');
      for (int i = 0; i < coords.length; i++) {
        if (Double.isNaN(coords[i])) {
          break; // empty point or no more coordinates
        }
        if (i > 0) {
          output.append(',');
        }
        output.append(nf.format(coords[i]));
      }
      output.write(']');
    }
  
    @Override
    public void write(Writer output, Shape shape) throws IOException {
      if (shape == null) {
        throw new NullPointerException("Shape can not be null");
      }
      NumberFormat nf = LegacyShapeWriter.makeNumberFormat(6);
      if (shape instanceof Point) {
        Point v = (Point) shape;
        output.append("{\"type\":\"Point\",\"coordinates\":");
        write(output, nf, v.getX(), v.getY());
        output.append('}');
        return;
      }
      if (shape instanceof Rectangle) {
        Rectangle v = (Rectangle) shape;
        output.append("{\"type\":\"Polygon\",\"coordinates\":[[");
        write(output, nf, v.getMinX(), v.getMinY());
        output.append(',');
        write(output, nf, v.getMinX(), v.getMaxY());
        output.append(',');
        write(output, nf, v.getMaxX(), v.getMaxY());
        output.append(',');
        write(output, nf, v.getMaxX(), v.getMinY());
        output.append(',');
        write(output, nf, v.getMinX(), v.getMinY());
        output.append("]]}");
        return;
      }
      if (shape instanceof BufferedLine) {
        BufferedLine v = (BufferedLine) shape;
        output.append("{\"type\":\"LineString\",\"coordinates\":[");
        write(output, nf, v.getA().getX(), v.getA().getY());
        output.append(',');
        write(output, nf, v.getB().getX(), v.getB().getY());
        output.append(',');
        output.append("]");
        if (v.getBuf() > 0) {
          output.append(',');
          output.append("\"buffer\":");
          output.append(nf.format(v.getBuf()));
        }
        output.append('}');
        return;
      }
      if (shape instanceof BufferedLineString) {
        BufferedLineString v = (BufferedLineString) shape;
        output.append("{\"type\":\"LineString\",\"coordinates\":[");
       BufferedLine last = null;
       Iterator<BufferedLine> iter = v.getSegments().iterator();
       while (iter.hasNext()) {
         BufferedLine seg = iter.next();
         if (last != null) {
           output.append(',');
         }
         write(output, nf, seg.getA().getX(), seg.getA().getY());
         last = seg;
       }
       if (last != null) {
         output.append(',');
         write(output, nf, last.getB().getX(), last.getB().getY());
       }
       output.append("]");
       if (v.getBuf() > 0) {
         writeDistance(output, nf, v.getBuf(), shape.getContext().isGeo(), BUFFER, BUFFER_UNITS);
       }
       output.append('}');
       return;
     }
     if (shape instanceof Circle) {
       // See: https://github.com/geojson/geojson-spec/wiki/Proposal---Circles-and-Ellipses-Geoms
       Circle v = (Circle) shape;
       Point center = v.getCenter();
       output.append("{\"type\":\"Circle\",\"coordinates\":");
       write(output, nf, center.getX(), center.getY());
       writeDistance(output, nf, v.getRadius(), v instanceof GeoCircle, "radius", "radius_units");
       output.append("}");
       return;
     }
     if (shape instanceof ShapeCollection) {
       ShapeCollection v = (ShapeCollection) shape;
       output.append("{\"type\":\"GeometryCollection\",\"geometries\":[");
       for (int i = 0; i < v.size(); i++) {
         if (i > 0) {
           output.append(',');
         }
         write(output, v.get(i));
       }
       output.append("]}");
       return;
     }
     output.append("{\"type\":\"Unknown\",\"wkt\":\"");
     output.append(LegacyShapeWriter.writeShape(shape));
     output.append("\"}");
   }
 
   /**
    * Helper method to encode a distance property (with optional unit). 
    * <p>
    *  The distance unit is only encoded when <tt>isGeo</tt> is true, and it is converted to km. 
    * </p>
    * <p>
    *  The distance unit is encoded within a properties object.
    * </p>
    * @param output The writer.
    * @param nf The number format.
    * @param dist The distance value to encode.
    * @param isGeo The flag determining 
    * @param distProperty The distance property name.
    * @param distUnitsProperty The distance unit property name.
    */
   void writeDistance(Writer output, NumberFormat nf, double dist, boolean isGeo, String distProperty, String distUnitsProperty) 
       throws IOException {
     output.append(",\"").append(distProperty).append("\":");
     if (isGeo) {
       double distKm =
           DistanceUtils.degrees2Dist(dist, DistanceUtils.EARTH_MEAN_RADIUS_KM);
       output.append(nf.format(distKm));
       output.append(",\"properties\":{");
       output.append("\"").append(distUnitsProperty).append("\":\"km\"}");
     } else {
       output.append(nf.format(dist));
     }
   }
 
   @Override
   public String toString(Shape shape) {
     try {
       StringWriter buffer = new StringWriter();
       write(buffer, shape);
       return buffer.toString();
     } catch (IOException ex) {
       throw new RuntimeException(ex);
     }
   }
 }