Add endpoint to create a mission launch

src/MissionControl.Server/Endpoints/Missions/MissionLaunches/Contract.cs

@@ -0,0 +1,23 @@
+using MissionControl.Domain.Entities;
+
+namespace MissionControl.Server.Endpoints.Missions.MissionLaunches;
+
+public record MissionLaunchResponse
+{
+    public Guid Id { get; set; } = Guid.NewGuid();
+
+    public DateTimeOffset ScheduledFor { get; set; }
+
+    public MissionLaunchStatus Status { get; set; }
+
+    public DateTimeOffset CreatedAt { get; init; } = DateTimeOffset.UtcNow;
+
+    public static MissionLaunchResponse FromDomain(MissionLaunch missionLaunch) =>
+        new()
+        {
+            Id = missionLaunch.Id,
+            ScheduledFor = missionLaunch.ScheduledFor,
+            Status = missionLaunch.Status,
+            CreatedAt = missionLaunch.CreatedAt,
+        };
+}

src/MissionControl.Server/Endpoints/Missions/MissionLaunches/CreateMissionLaunch.cs

@@ -0,0 +1,53 @@
+using FastEndpoints;
+using FluentValidation;
+using Microsoft.AspNetCore.Mvc;
+using MissionControl.Data;
+using MissionControl.Domain.Entities;
+
+namespace MissionControl.Server.Endpoints.Missions.MissionLaunches;
+
+public class CreateMissionLaunch(MissionControlContext dbContext)
+    : Endpoint<CreateMissionLaunchRequest, MissionLaunchResponse>
+{
+    public override void Configure()
+    {
+        Post("/missions/{MissionId}/launch");
+    }
+
+    public override async Task HandleAsync(CreateMissionLaunchRequest req, CancellationToken ct)
+    {
+        var missionLaunch = new MissionLaunch
+        {
+            ScheduledFor = req.ScheduledFor,
+            // Validated in `CreateMissionLaunchRequestValidator`
+            Status = Enum.Parse<MissionLaunchStatus>(req.Status, true),
+            MissionId = req.MissionId,
+        };
+
+        dbContext.MissionLaunches.Add(missionLaunch);
+        await dbContext.SaveChangesAsync(ct);
+
+        await Send.OkAsync(MissionLaunchResponse.FromDomain(missionLaunch), ct);
+    }
+}
+
+public record CreateMissionLaunchRequest
+{
+    public Guid MissionId { get; init; }
+    public required DateTimeOffset ScheduledFor { get; init; }
+
+    // Define as a string here so it can be safely deserialized into its enum type, with a validation message when unable to do so
+    // Otherwise, we return a serialization error that is not assigned to a specific field
+    public required string Status { get; init; }
+}
+
+public class CreateMissionLaunchRequestValidator : Validator<CreateMissionLaunchRequest>
+{
+    public CreateMissionLaunchRequestValidator()
+    {
+        RuleFor(req => req.MissionId)
+            .NotEqual(Guid.Empty)
+            .WithMessage("Please provide a non-zero GUID.");
+        RuleFor(req => req.Status).IsEnumName(typeof(MissionLaunchStatus), false);
+    }
+}