Optimize Transport Connection Selection with Enhanced Timing Logic (#24)

* Initial plan

* Implement enhanced transport connection optimization logic

Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>

* Add configuration for new transport optimization parameters and complete implementation

Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>

* Address PR feedback: remove comments, old logic, and unnecessary tests

Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>

* Fix looking for connection

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>
Co-authored-by: clayschaad <c.schaad@pog.ch>

Server/appsettings.json

@@ -12,7 +12,9 @@
     "EndStation": "Basel",
     "ApiBaseUrl": "http://transport.opendata.ch/v1",
     "SafetyBufferMinutes": 30,
-    "MinBreakMinutes": 60
+    "MinBreakMinutes": 60,
+    "MaxEarlyArrivalMinutes": 60,
+    "MaxLateArrivalMinutes": 15
   },
 
   "Shifts": [

Services/TransportConnectionCalculator.cs

@@ -4,9 +4,19 @@ namespace ShiftScheduler.Services;
 
 public static class TransportConnectionCalculator
 {
-    public static TransportConnection? FindBestConnection(IReadOnlyList<TransportConnection> connections, DateTime latestArrivalTime)
+    public static TransportConnection? FindBestConnection(
+        IReadOnlyList<TransportConnection> connections, 
+        DateTime shiftStartTime, 
+        int safetyBufferMinutes, 
+        int maxEarlyArrivalMinutes, 
+        int maxLateArrivalMinutes)
     {
+        var latestArrivalTime = shiftStartTime.AddMinutes(-safetyBufferMinutes);
+        var earliestAcceptableTime = shiftStartTime.AddMinutes(-maxEarlyArrivalMinutes);
+        var latestAcceptableTime = shiftStartTime.AddMinutes(maxLateArrivalMinutes);
+
         var validConnections = new List<TransportConnection>();
+        var lateValidConnections = new List<TransportConnection>();
 
         foreach (var connection in connections)
         {
@@ -16,21 +26,48 @@ public static class TransportConnectionCalculator
                 {
                     validConnections.Add(connection);
                 }
+                else if (arrivalTime <= latestAcceptableTime)
+                {
+                    lateValidConnections.Add(connection);
+                }
             }
         }
 
+        // If we have valid connections (arriving before latest arrival time)
         if (validConnections.Count > 0)
         {
             var sortedValid = validConnections
                 .OrderBy(c => DateTime.Parse(c.ArrivalTime ?? "00:00"))
                 .ToList();
 
-            return sortedValid.Last();
+            var bestValidConnection = sortedValid.Last();
+            var bestValidArrivalTime = DateTime.Parse(bestValidConnection.ArrivalTime!);
+
+            // Check if the best valid connection arrives too early (more than maxEarlyArrivalMinutes before shift)
+            if (bestValidArrivalTime < earliestAcceptableTime && lateValidConnections.Count > 0)
+            {
+                // Return the earliest connection that arrives after latest arrival time but within acceptable range
+                var sortedLateValid = lateValidConnections
+                    .OrderBy(c => DateTime.Parse(c.ArrivalTime ?? "23:59"))
+                    .ToList();
+                
+                return sortedLateValid.First();
             }
 
-        // If no valid connections, return the earliest available
+            return bestValidConnection;
-        return connections
+        }
+
+        // If no connections arrive before latest arrival time, check if any arrive within acceptable late range
+        if (lateValidConnections.Count > 0)
+        {
+            var sortedLateValid = lateValidConnections
                 .OrderBy(c => DateTime.Parse(c.ArrivalTime ?? "23:59"))
-            .FirstOrDefault();
+                .ToList();
+            
+            return sortedLateValid.First();
+        }
+
+        // No suitable connections found
+        return null;
     }
 }

Services/TransportService.cs

@@ -9,7 +9,10 @@ namespace ShiftScheduler.Services
         {
             var latestArrivalTime = shiftStartTime.AddMinutes(-config.SafetyBufferMinutes);
             var searchDate = shiftStartTime.ToString("yyyy-MM-dd");
-            var searchTime = shiftStartTime.ToString("HH:mm");
+            
+            // To allow connections that arrive after shift starts, we search from earlier time
+            // and request more connections to cover the full range
+            var searchTime = shiftStartTime.AddMinutes(config.MaxLateArrivalMinutes).ToString("HH:mm");
 
             var url = $"{config.ApiBaseUrl}/connections?from={Uri.EscapeDataString(config.StartStation)}&to={Uri.EscapeDataString(config.EndStation)}&date={searchDate}&time={searchTime}&isArrivalTime=1&limit=5";
             var response = await httpClient.GetStringAsync(url);
@@ -21,7 +24,12 @@ namespace ShiftScheduler.Services
             if (apiResponse?.Connections.Count > 0)
             {
                 var allConnections = apiResponse.Connections.Select(MapToTransportConnection).ToList();
-                return TransportConnectionCalculator.FindBestConnection(allConnections, latestArrivalTime);
+                return TransportConnectionCalculator.FindBestConnection(
+                    allConnections, 
+                    shiftStartTime, 
+                    config.SafetyBufferMinutes, 
+                    config.MaxEarlyArrivalMinutes, 
+                    config.MaxLateArrivalMinutes);
             }
 
             return null;

Shared/TransportModels.cs

@@ -7,6 +7,8 @@ namespace ShiftScheduler.Shared
         public string ApiBaseUrl { get; set; } = string.Empty;
         public int SafetyBufferMinutes { get; set; } = 30;
         public int MinBreakMinutes { get; set; } = 60;
+        public int MaxEarlyArrivalMinutes { get; set; } = 60;
+        public int MaxLateArrivalMinutes { get; set; } = 15;
     }
 
     public class TransportConnection

ShiftScheduler.Services.Tests/TransportConnectionCalculatorTests.cs

@@ -0,0 +1,148 @@
+using ShiftScheduler.Services;
+using ShiftScheduler.Shared;
+using Shouldly;
+
+namespace ShiftScheduler.Services.Tests;
+
+public class TransportConnectionCalculatorTests
+{
+    // Tests for new enhanced logic
+    [Fact]
+    public void FindBestConnectionEnhanced_WithGoodTimingConnection_ShouldReturnLatestValidConnection()
+    {
+        // Arrange - Shift starts at 8:00, safety buffer 30 min, so latest arrival is 7:30
+        var connections = new List<TransportConnection>
+        {
+            new TransportConnection { ArrivalTime = "2023-12-15T07:15:00" },
+            new TransportConnection { ArrivalTime = "2023-12-15T07:25:00" }, // Should be selected (latest valid)
+            new TransportConnection { ArrivalTime = "2023-12-15T08:05:00" }  // Too late
+        };
+        var shiftStartTime = new DateTime(2023, 12, 15, 8, 0, 0);
+
+        // Act
+        var result = TransportConnectionCalculator.FindBestConnection(
+            connections, shiftStartTime, 30, 60, 15);
+
+        // Assert
+        result.ShouldNotBeNull();
+        result.ArrivalTime.ShouldBe("2023-12-15T07:25:00");
+    }
+
+    [Fact]
+    public void FindBestConnectionEnhanced_WithTooEarlyConnection_ShouldPreferLaterConnection()
+    {
+        // Arrange - Shift starts at 8:00, max early arrival 60 min, so earliest acceptable is 7:00
+        var connections = new List<TransportConnection>
+        {
+            new TransportConnection { ArrivalTime = "2023-12-15T06:45:00" }, // Too early (more than 60 min before 8:00)
+            new TransportConnection { ArrivalTime = "2023-12-15T08:05:00" }  // Within acceptable late range (15 min after 8:00)
+        };
+        var shiftStartTime = new DateTime(2023, 12, 15, 8, 0, 0);
+
+        // Act
+        var result = TransportConnectionCalculator.FindBestConnection(
+            connections, shiftStartTime, 30, 60, 15);
+
+        // Assert
+        result.ShouldNotBeNull();
+        result.ArrivalTime.ShouldBe("2023-12-15T08:05:00");
+    }
+
+    [Fact]
+    public void FindBestConnectionEnhanced_WithMultipleLateConnections_ShouldReturnEarliest()
+    {
+        // Arrange - Shift starts at 8:00, no valid early connections
+        var connections = new List<TransportConnection>
+        {
+            new TransportConnection { ArrivalTime = "2023-12-15T08:10:00" },
+            new TransportConnection { ArrivalTime = "2023-12-15T08:05:00" }, // Should be selected (earliest late)
+            new TransportConnection { ArrivalTime = "2023-12-15T08:12:00" }
+        };
+        var shiftStartTime = new DateTime(2023, 12, 15, 8, 0, 0);
+
+        // Act
+        var result = TransportConnectionCalculator.FindBestConnection(
+            connections, shiftStartTime, 30, 60, 15);
+
+        // Assert
+        result.ShouldNotBeNull();
+        result.ArrivalTime.ShouldBe("2023-12-15T08:05:00");
+    }
+
+    [Fact]
+    public void FindBestConnectionEnhanced_WithConnectionsBeyondAcceptableRange_ShouldReturnNull()
+    {
+        // Arrange - All connections are too late (beyond max late arrival)
+        var connections = new List<TransportConnection>
+        {
+            new TransportConnection { ArrivalTime = "2023-12-15T08:20:00" },
+            new TransportConnection { ArrivalTime = "2023-12-15T08:25:00" },
+            new TransportConnection { ArrivalTime = "2023-12-15T08:30:00" }
+        };
+        var shiftStartTime = new DateTime(2023, 12, 15, 8, 0, 0);
+
+        // Act
+        var result = TransportConnectionCalculator.FindBestConnection(
+            connections, shiftStartTime, 30, 60, 15);
+
+        // Assert
+        result.ShouldBeNull();
+    }
+
+    [Fact]
+    public void FindBestConnectionEnhanced_WithAcceptableEarlyConnection_ShouldNotPreferLate()
+    {
+        // Arrange - Early connection is acceptable (not too early), should prefer it over late
+        var connections = new List<TransportConnection>
+        {
+            new TransportConnection { ArrivalTime = "2023-12-15T07:20:00" }, // 40 min before shift - acceptable
+            new TransportConnection { ArrivalTime = "2023-12-15T08:05:00" }  // 5 min after shift
+        };
+        var shiftStartTime = new DateTime(2023, 12, 15, 8, 0, 0);
+
+        // Act
+        var result = TransportConnectionCalculator.FindBestConnection(
+            connections, shiftStartTime, 30, 60, 15);
+
+        // Assert
+        result.ShouldNotBeNull();
+        result.ArrivalTime.ShouldBe("2023-12-15T07:20:00");
+    }
+
+    [Fact]
+    public void FindBestConnectionEnhanced_WithEmptyConnections_ShouldReturnNull()
+    {
+        // Arrange
+        var connections = new List<TransportConnection>();
+        var shiftStartTime = new DateTime(2023, 12, 15, 8, 0, 0);
+
+        // Act
+        var result = TransportConnectionCalculator.FindBestConnection(
+            connections, shiftStartTime, 30, 60, 15);
+
+        // Assert
+        result.ShouldBeNull();
+    }
+
+    [Fact]
+    public void FindBestConnectionEnhanced_WithMixedValidAndLateConnections_ShouldChooseBasedOnTiming()
+    {
+        // Arrange - Test scenario where both valid and late connections exist
+        var connections = new List<TransportConnection>
+        {
+            new TransportConnection { ArrivalTime = "2023-12-15T06:30:00" }, // Too early (90 min before shift)
+            new TransportConnection { ArrivalTime = "2023-12-15T07:25:00" }, // Valid but would be considered too early
+            new TransportConnection { ArrivalTime = "2023-12-15T08:05:00" }, // Late but acceptable
+            new TransportConnection { ArrivalTime = "2023-12-15T08:20:00" }  // Too late
+        };
+        var shiftStartTime = new DateTime(2023, 12, 15, 8, 0, 0);
+
+        // Act - MaxEarlyArrivalMinutes = 30, so earliest acceptable is 7:30
+        var result = TransportConnectionCalculator.FindBestConnection(
+            connections, shiftStartTime, 30, 30, 15);
+
+        // Assert - 7:25 arrives at 7:25, which is 35 min before shift (more than 30 min), so should prefer late connection
+        result.ShouldNotBeNull();
+        result.ArrivalTime.ShouldBe("2023-12-15T08:05:00");
+    }
+}

ShiftScheduler.Services.Tests/TransportServiceTests.cs

@@ -25,7 +25,9 @@ public class TransportServiceTests
             EndStation = "Bern",
             ApiBaseUrl = "https://transport.opendata.ch/v1",
             SafetyBufferMinutes = 30,
-            MinBreakMinutes = 60
+            MinBreakMinutes = 60,
+            MaxEarlyArrivalMinutes = 60,
+            MaxLateArrivalMinutes = 15
         };
         
         _transportService = new TransportService(_httpClient, config);