package com.esri.hadoop.hive;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.io.BytesWritable;
// DoubleWritable - must use hive-serde2; the other one produces struct {value:d.d}
import org.apache.hadoop.hive.serde2.io.DoubleWritable;

import com.esri.core.geometry.Geometry;
import com.esri.core.geometry.GeometryEngine;
import com.esri.core.geometry.MultiPath;
import com.esri.core.geometry.Point;


import com.esri.core.geometry.ogc.OGCGeometry;

@Description(name = "ST_GeodesicLengthWGS84",
   value = "_FUNC_(line) - returns distance along line on WGS84 spheroid, in meters, for geographic coordinates",
   extended = "Requires the geometry to be in in WGS84 spatial reference, else returns NULL\nExample:\n"
   + " SELECT _FUNC_(ST_SetSRID(ST_Linestring(0.0,0.0, 0.3,0.4), 4326)) FROM src LIMIT 1; -- 55km\n"
   + " SELECT _FUNC_(ST_GeomFromText('MultiLineString((0.0 80.0, 0.3 80.4))', 4326)) FROM src LIMIT 1; -- 45km\n"
)
//@HivePdkUnitTests(
//	cases = {
//		@HivePdkUnitTest(
//			query = "select substr(ST_GeodesicLengthWGS84(ST_GeomFromText('LineString(0 0, 0.03 0.04)', 4326)), 1, 5) from onerow",
//			result = "5542."
//			),
//		@HivePdkUnitTest(
//			query = "select substr(ST_GeodesicLengthWGS84(ST_GeomFromText('MultiLineString((0 80, 0.03 80.04))', 4326)), 1, 5) from onerow",
//			result = "4503."
//			),
//		@HivePdkUnitTest(
//			query = "select ST_Length(null) from onerow",
//			result = "null"
//			)
//	}
//)

public class ST_GeodesicLengthWGS84 extends ST_GeometryAccessor {
	final DoubleWritable resultDouble = new DoubleWritable();
	static final Log LOG = LogFactory.getLog(ST_GeodesicLengthWGS84.class.getName());

	public DoubleWritable evaluate(BytesWritable geomref) {
		if (geomref == null || geomref.getLength() == 0) {
			LogUtils.Log_ArgumentsNull(LOG);
			return null;
		}

		int WGS84 = 4326;
		if (GeometryUtils.getWKID(geomref) != WGS84) {
		    LogUtils.Log_SRIDMismatch(LOG, geomref, WGS84);
			return null;
		}

		OGCGeometry ogcGeometry = GeometryUtils.geometryFromEsriShape(geomref);
		if (ogcGeometry == null){
			LogUtils.Log_ArgumentsNull(LOG);
			return null;
		}

		Geometry esriGeom = ogcGeometry.getEsriGeometry();
		switch(esriGeom.getType()) {
		case Point:
		case MultiPoint:
			resultDouble.set(0.);
			break;
		default:
			MultiPath lines = (MultiPath)(esriGeom);
			int nPath = lines.getPathCount();
			double length = 0.;
			for (int ix = 0; ix < nPath; ix++) {
				int curPt = lines.getPathStart(ix);
				int pastPt = lines.getPathEnd(ix);
				Point fromPt = lines.getPoint(curPt);
				Point toPt = null;
				for (int vx = curPt+1; vx < pastPt; vx++) {
					toPt = lines.getPoint(vx);
					length += GeometryEngine.geodesicDistanceOnWGS84(fromPt, toPt);
					fromPt = toPt;
				}
			}
			resultDouble.set(length);
			break;
		}

		return resultDouble;
	}
}