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using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace examples
{
/// <summary>
/// Example implementation of RouteGuide server.
/// </summary>
public class RouteGuideImpl : RouteGuide.IRouteGuide
{
readonly List<Feature> features;
private readonly ConcurrentDictionary<Point, List<RouteNote>> routeNotes =
new ConcurrentDictionary<Point, List<RouteNote>>();
public RouteGuideImpl(List<Feature> features)
{
this.features = features;
}
/// <summary>
/// Gets the feature at the requested point. If no feature at that location
/// exists, an unnammed feature is returned at the provided location.
/// </summary>
public Task<Feature> GetFeature(Grpc.Core.ServerCallContext context, Point request)
{
return Task.FromResult(CheckFeature(request));
}
/// <summary>
/// Gets all features contained within the given bounding rectangle.
/// </summary>
public async Task ListFeatures(Grpc.Core.ServerCallContext context, Rectangle request, Grpc.Core.IServerStreamWriter<Feature> responseStream)
{
int left = Math.Min(request.Lo.Longitude, request.Hi.Longitude);
int right = Math.Max(request.Lo.Longitude, request.Hi.Longitude);
int top = Math.Max(request.Lo.Latitude, request.Hi.Latitude);
int bottom = Math.Min(request.Lo.Latitude, request.Hi.Latitude);
foreach (var feature in features)
{
if (!RouteGuideUtil.Exists(feature))
{
continue;
}
int lat = feature.Location.Latitude;
int lon = feature.Location.Longitude;
if (lon >= left && lon <= right && lat >= bottom && lat <= top)
{
await responseStream.WriteAsync(feature);
}
}
}
/// <summary>
/// Gets a stream of points, and responds with statistics about the "trip": number of points,
/// number of known features visited, total distance traveled, and total time spent.
/// </summary>
public async Task<RouteSummary> RecordRoute(Grpc.Core.ServerCallContext context, Grpc.Core.IAsyncStreamReader<Point> requestStream)
{
int pointCount = 0;
int featureCount = 0;
int distance = 0;
Point previous = null;
var stopwatch = new Stopwatch();
stopwatch.Start();
while (await requestStream.MoveNext())
{
var point = requestStream.Current;
pointCount++;
if (RouteGuideUtil.Exists(CheckFeature(point)))
{
featureCount++;
}
if (previous != null)
{
distance += (int) CalcDistance(previous, point);
}
previous = point;
}
stopwatch.Stop();
return RouteSummary.CreateBuilder().SetPointCount(pointCount)
.SetFeatureCount(featureCount).SetDistance(distance)
.SetElapsedTime((int) (stopwatch.ElapsedMilliseconds / 1000)).Build();
}
/// <summary>
/// Receives a stream of message/location pairs, and responds with a stream of all previous
/// messages at each of those locations.
/// </summary>
public async Task RouteChat(Grpc.Core.ServerCallContext context, Grpc.Core.IAsyncStreamReader<RouteNote> requestStream, Grpc.Core.IServerStreamWriter<RouteNote> responseStream)
{
while (await requestStream.MoveNext())
{
var note = requestStream.Current;
List<RouteNote> notes = GetOrCreateNotes(note.Location);
List<RouteNote> prevNotes;
lock (notes)
{
prevNotes = new List<RouteNote>(notes);
}
foreach (var prevNote in prevNotes)
{
await responseStream.WriteAsync(prevNote);
}
lock (notes)
{
notes.Add(note);
}
}
}
/// <summary>
/// Get the notes list for the given location. If missing, create it.
/// </summary>
private List<RouteNote> GetOrCreateNotes(Point location)
{
List<RouteNote> notes = new List<RouteNote>();
routeNotes.TryAdd(location, notes);
return routeNotes[location];
}
/// <summary>
/// Gets the feature at the given point.
/// </summary>
/// <param name="location">the location to check</param>
/// <returns>The feature object at the point Note that an empty name indicates no feature.</returns>
private Feature CheckFeature(Point location)
{
foreach (var feature in features)
{
if (feature.Location.Latitude == location.Latitude
&& feature.Location.Longitude == location.Longitude)
{
return feature;
}
}
// No feature was found, return an unnamed feature.
return Feature.CreateBuilder().SetName("").SetLocation(location).Build();
}
/// <summary>
/// Calculate the distance between two points using the "haversine" formula.
/// This code was taken from http://www.movable-type.co.uk/scripts/latlong.html.
/// </summary>
/// <param name="start">the starting point</param>
/// <param name="end">the end point</param>
/// <returns>the distance between the points in meters</returns>
private static double CalcDistance(Point start, Point end)
{
double lat1 = RouteGuideUtil.GetLatitude(start);
double lat2 = RouteGuideUtil.GetLatitude(end);
double lon1 = RouteGuideUtil.GetLongitude(start);
double lon2 = RouteGuideUtil.GetLongitude(end);
int r = 6371000; // metres
double φ1 = ToRadians(lat1);
double φ2 = ToRadians(lat2);
double Δφ = ToRadians(lat2 - lat1);
double Δλ = ToRadians(lon2 - lon1);
double a = Math.Sin(Δφ / 2) * Math.Sin(Δφ / 2) + Math.Cos(φ1) * Math.Cos(φ2) * Math.Sin(Δλ / 2) * Math.Sin(Δλ / 2);
double c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
return r * c;
}
private static double ToRadians(double val)
{
return (Math.PI / 180) * val;
}
}
}
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