Merge pull request #168 from AirQualityControl/feature/implement-get-…

…airpollution-by-geolocation

implement feature

src/AirSnitch.API/Controllers/AirQualityIndexController/AirQualityIndexController.cs

@@ -1,3 +1,4 @@
+using System.Linq;
 using System.Threading.Tasks;
 using AirSnitch.Api.Controllers.AirQualityIndexController.ViewModel;
 using AirSnitch.Api.Rest;
@@ -42,16 +43,22 @@ public AirQualityIndexController(
         [ProducesResponseType(StatusCodes.Status400BadRequest)]
         public async Task<IActionResult> GetIndexValue([FromQuery]AirQualityIndexRequestParams requestParams)
         {
-            //TODO:https://github.com/AirQualityControl/server/issues/93
-            var nearestStation =
-                await _monitoringStationRepository.GetNearestStation(requestParams.Geolocation, requestParams.Radius);
+            var nearestStations =
+                await _monitoringStationRepository.GetNearestStations(requestParams.Geolocation, numberOfStations:10);
 
-            if (nearestStation.IsEmpty)
+            if (!nearestStations.Any())
             {
                 return NotFound();
             }
-
-            var airPollution = nearestStation.GetAirPollution();
+
+            var activeStation = nearestStations.FirstOrDefault(station => station.HasActualData());
+
+            if (activeStation == null)
+            {
+                return NotFound();
+            }
+
+            var airPollution = activeStation.GetAirPollution();
 
             var usaAqi = new UsaAirQualityIndex();
 
@@ -61,12 +68,11 @@ public async Task<IActionResult> GetIndexValue([FromQuery]AirQualityIndexRequest
                 index: usaAqi,
                 indexValue:indexValue,
                 Request);
-
 
-            //aqiViewModel.SetMeasurementDateTime(airPollution.GetMeasurementsDateTime());
+            aqiViewModel.SetMeasurementDateTime(airPollution.GetMeasurementsDateTime());
+
+            aqiViewModel.SetStationId(activeStation.Id);
 
-            aqiViewModel.SetStationId("5480d666-cd1e-45ff-9e63-f283592c72e2");
-
             return new RestApiResult(
                 new RestResponseBody(
                     Request, 

src/AirSnitch.API/Controllers/AirQualityIndexController/Params/AirQualityIndexRequestParams.cs

@@ -1,5 +1,4 @@
 using AirSnitch.Domain.Models;
-using AirSnitch.Infrastructure.Abstract.Persistence.Repositories;
 using Microsoft.AspNetCore.Mvc;
 
 namespace AirSnitch.Api.Controllers.AirQualityIndexController
@@ -11,10 +10,7 @@ public class AirQualityIndexRequestParams
 
         [FromQuery(Name = "lat")] 
         public double LatitudeValue { get; set; }
-
-        [FromQuery(Name = "radius")]
-        public int Radius { get; set; }
-
+
         internal GeoCoordinates Geolocation => new() {Latitude = LatitudeValue, Longitude = LongitudeValue};
     }
 }

src/AirSnitch.Domain/Models/MonitoringStation.cs

@@ -111,5 +111,12 @@ private string GenerateId()
         {
             return Guid.NewGuid().ToString();
         }
+
+        public bool HasActualData()
+        {
+            var measurementsDateInUtc = GetAirPollution().GetMeasurementsDateTime();
+
+            return DateTime.UtcNow - measurementsDateInUtc <= TimeSpan.FromHours(2);
+        }
     }
 }

src/AirSnitch.Infrastructure.Abstract/Persistence/Repositories/IMonitoringStationRepository.cs

@@ -1,3 +1,4 @@
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using AirSnitch.Domain.Models;
 using AirSnitch.Infrastructure.Abstract.Persistence.Query;
@@ -26,7 +27,7 @@ public interface IMonitoringStationRepository
         /// 
         /// </summary>
         /// <returns></returns>
-        Task<MonitoringStation> GetNearestStation(GeoCoordinates geoCoordinates, int radius = default);
+        Task<MonitoringStation> GetNearestStation(GeoCoordinates geoCoordinates, int radius = 5, int numberOfStations = 10);
 
         /// <summary>
         ///     Search station by provider station name
@@ -35,6 +36,15 @@ public interface IMonitoringStationRepository
         /// <returns></returns>
         Task<MonitoringStation> FindByProviderNameAsync(string providerStationName);
 
+        /// <summary>
+        /// Returns n nearest stations by geolocation
+        /// </summary>
+        /// <param name="geoCoordinates"></param>
+        /// <param name="numberOfStations"></param>
+        /// <returns></returns>
+        Task<ICollection<MonitoringStation>> GetNearestStations(GeoCoordinates geoCoordinates,
+            int numberOfStations = 10);
+
         Task AddAsync(MonitoringStation monitoringStation);
         Task UpdateAsync(MonitoringStation monitoringStation);
     }

src/AirSnitch.Infrastructure/Persistence/Repositories/MonitoringStationRepository.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using System.Threading.Tasks;
 using AirSnitch.Domain.Models;
@@ -9,15 +11,17 @@
 using AirSnitch.Infrastructure.Persistence.Repositories.Common;
 using AirSnitch.Infrastructure.Persistence.StorageModels;
 using MongoDB.Bson;
+using MongoDB.Driver;
 
 namespace AirSnitch.Infrastructure.Persistence.Repositories
 {
     public class MonitoringStationRepository : IMonitoringStationRepository
     {
         private readonly IGenericRepository<MonitoringStationStorageModel> _genericRepository;
-
+        private readonly MongoDbClient _client;
         public MonitoringStationRepository(MongoDbClient client)
         {
+            _client = client;
             _genericRepository = new MongoDbGenericRepository<MonitoringStationStorageModel>(client, "airMonitoringStation");
         }
 
@@ -91,10 +95,30 @@ public async Task<MonitoringStation> FindByProviderNameAsync(string providerStat
             return MonitoringStation.Empty;
         }
 
-        public Task<MonitoringStation> GetNearestStation(GeoCoordinates geoCoordinates, int radius = default)
+        public async Task<MonitoringStation> GetNearestStation(GeoCoordinates geoCoordinates, int radius = default, int numberOfStations = 10)
+        {
+            throw new NotImplementedException();
+        }
+
+        public async Task<ICollection<MonitoringStation>> GetNearestStations(GeoCoordinates geoCoordinates,
+            int numberOfStations = 10)
         {
-            var monitoringStation = new MonitoringStation();
-            return Task.FromResult(monitoringStation);
+            var monitoringStations = new List<MonitoringStation>(numberOfStations);
+
+            var pipeline = NearestStationsAggregationPipeline.Create(geoCoordinates, numberOfStations);
+
+            var collection = _client.Db.GetCollection<MonitoringStationStorageModel>("airMonitoringStation");
+
+            var cursor = collection.Aggregate<MonitoringStationStorageModel>(pipeline);
+
+            Action<MonitoringStationStorageModel> cursorAction = st =>
+            {
+                monitoringStations.Add(st.MapToDomainModel());
+            };
+
+            await cursor.ForEachAsync(cursorAction);
+
+            return monitoringStations;
         }
 
         public async Task AddAsync(MonitoringStation monitoringStation)

src/AirSnitch.Infrastructure/Persistence/Repositories/NearestStationsAggregationPipeline.cs

@@ -0,0 +1,39 @@
+using System.Collections.Generic;
+using AirSnitch.Domain.Models;
+using MongoDB.Bson;
+
+namespace AirSnitch.Infrastructure.Persistence.Repositories;
+
+internal static class NearestStationsAggregationPipeline
+{
+    public static List<BsonDocument> Create(GeoCoordinates geoLocation, int numberOfNearestStation)
+    {
+        int numOfPipelineStages = 2;
+
+        var geoNearOptions = new BsonDocument
+        {
+            {
+                "near", new BsonDocument
+                {
+                    {"type", "Point"},
+                    {"coordinates", new BsonArray {geoLocation.Longitude, geoLocation.Latitude}},
+                }
+            },
+            {"key", "geoLocation"},
+            {"distanceField", "dist.calculated"},
+        };
+
+        var limitOptions = new BsonDocument()
+        {
+            {"$limit", numberOfNearestStation}
+        };
+
+        var pipeline = new List<BsonDocument>(numOfPipelineStages)
+        {
+            new BsonDocument {{"$geoNear", geoNearOptions}},
+            limitOptions
+        };
+
+        return pipeline;
+    }
+}