using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace VECV_WebApi.Models.Util
{
    public class DistanceCalc
    {
        /// <summary>
        /// take lat/long in double datatype and return decimal list of x,y,z, coordinates respectively 
        /// </summary>
        /// <param name="latitude"></param>
        /// <param name="longitude"></param>
        /// <returns></returns>
        public Dictionary<string, double> GetCoordinates(double latitude, double longitude)
        {
            //Dictionary<string, decimal> Coordinates= new Dictionary<string,decimal>();
            Dictionary<string, double> Coordinates = new Dictionary<string, double>();
            //decimal XCoordinate,YCoordinate,ZCoordinate;
            //XCoordinate = Convert.ToDecimal(6371000 * Convert.ToDouble((Math.Cos(latitude)) * (Math.Cos(longitude))));
            //YCoordinate = Convert.ToDecimal(6371000 * Convert.ToDouble((Math.Cos(latitude)) * (Math.Sin(longitude))));
            //ZCoordinate = Convert.ToDecimal(6371000 * Convert.ToDouble((Math.Sin(latitude))));
            latitude = Math.PI * latitude / 180;
            longitude = Math.PI * longitude / 180;
            double xCoordinate = 6371000d * Convert.ToDouble((Math.Cos(latitude)) * (Math.Cos(longitude)));
            double yCoordinate = 6371000d * Convert.ToDouble((Math.Cos(latitude)) * (Math.Sin(longitude)));
            double zCoordinate = 6371000d * Convert.ToDouble((Math.Sin(latitude)));

            Coordinates.Add("XCoordinate", xCoordinate);
            Coordinates.Add("YCoordinate", yCoordinate);
            Coordinates.Add("ZCoordinate", zCoordinate);
            return Coordinates;
        }

        /// <summary>
        /// This method simply return unit distance of the vehicle's current position from geofence boundry
        /// 
        /// </summary>
        /// <param name="IXCoordinate">I point X coordinate </param>
        /// <param name="IYCoordinate">I point Y coordinate</param>
        /// <param name="JXCoordinate">J point X coordinate</param>
        /// <param name="JYCoordinate">J point Y coordinate</param>
        /// <param name="XCoordinate">Current position X coordinate</param>
        /// <param name="YCoordinate">Current position Y coordinate</param>
        /// <returns></returns>
        public decimal CalcDistance(double IXCoordinate, double IYCoordinate, double JXCoordinate, double JYCoordinate, double XCoordinate, double YCoordinate)
        {
            try
            {
                double _constantA, _constantB;
                double _slopA, _slopB;
                double _tempexprA, _tempexprB;
                double _intersectX, _intersectY;
                _slopA = (JYCoordinate - IYCoordinate) / (JXCoordinate - IXCoordinate);
                _constantA = IYCoordinate - (_slopA * IXCoordinate);
                _slopB = -(1 / _slopA);
                _constantB = YCoordinate - (_slopB * XCoordinate);
                _tempexprA = (_slopA) - (_slopB);
                _tempexprB = _constantA - (_constantB);
                if (_tempexprB == 0)
                {
                    _intersectX = 0;
                }
                else
                {
                    _intersectX = -(_tempexprA / _tempexprB);
                }
                _intersectY = (_slopB * _intersectX) + (_constantB);
                return Convert.ToDecimal(Math.Sqrt(Math.Pow(Convert.ToDouble(_intersectX - XCoordinate), 2) + Math.Pow(Convert.ToDouble(_intersectY - YCoordinate), 2)));
            }
            catch (Exception ex) { throw new Exception(ex.Message); }
        }
        /// <summary>
        /// This fun use to get distance between two lat and long.
        /// </summary>
        /// <param name="latitude">location latitude</param>
        /// <param name="longitude">location longitude</param>
        /// <returns>distance</returns>
        public double DistanceInKM(double[] latitude, double[] longitude)
        {
            try
            {
                double distance = 0.0F;
                double lat1, lng1, lat2, lng2;
                double Radius = 6371;
                double LatDistance, LngDistance;
                for (int i = 0; i < latitude.Length - 1; i++)
                {
                    lat1 = latitude[i] * Math.PI / 180;
                    lat2 = latitude[i + 1] * Math.PI / 180;
                    lng1 = longitude[i] * Math.PI / 180;
                    lng2 = longitude[i + 1] * Math.PI / 180;
                    LatDistance = lat2 - lat1;
                    LngDistance = lng2 - lng1;
                    var a = Math.Sin(LatDistance / 2) * Math.Sin(LatDistance / 2) + Math.Cos(lat1) * Math.Cos(lat2) * Math.Sin(LngDistance / 2) * Math.Sin(LngDistance / 2);
                    var c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
                    distance = distance + Radius * c;
                }
                return distance;
            }
            catch (Exception ex) { throw new Exception(ex.Message); }
        }
    }

}