feat(api): add validation to prevent duplicate accounts from being added

src/FiscalOS.API/Accounts/AccountsExtensions.cs

@@ -6,8 +6,10 @@ internal static class AccountsExtensions
 
   public static RouteGroupBuilder MapAccountsEndpoints(this WebApplication app)
   {
-    var accountsGroup = app.MapGroup(RouteGroupPrefix).RequireAuthorization();
+    var accountsGroup = app.MapGroup(RouteGroupPrefix)
+      .RequireAuthorization();
 
+    accountsGroup.MapAddEndpoint();
     accountsGroup.MapConnectEndpoint();
 
     return accountsGroup;

src/FiscalOS.API/Accounts/Add/Endpoint.cs

@@ -0,0 +1,41 @@
+namespace FiscalOS.API.Accounts.Add;
+
+internal static class Endpoint
+{
+  private const string Route = "/";
+
+  public static RouteHandlerBuilder MapAddEndpoint(this RouteGroupBuilder groupBuilder)
+  {
+    return groupBuilder.MapPost(Route, HandleAsync);
+  }
+
+  private static async Task<IResult> HandleAsync(
+    HttpContext httpContext,
+    [FromBody] Request request,
+    [FromServices] AppDbContext appDbContext,
+    CancellationToken ct
+  )
+  {
+    var userId = httpContext.GetUserId();
+
+    var user = await appDbContext.Users
+      .Include(u => u.Accounts.Where(a => a.Metadata is PlaidAccountMetadata && ((PlaidAccountMetadata)a.Metadata).PlaidId == request.PlaidAccountId))
+      .ThenInclude(a => a.Metadata)
+      .SingleOrDefaultAsync(u => u.Id == userId, ct);
+
+    if (user is null)
+    {
+      return Results.Unauthorized();
+    }
+
+    if (user.Accounts.Any())
+    {
+      return Results.Conflict();
+    }
+
+    // TODO: This is new account
+    // so we should add to the database
+
+    return Results.Ok();
+  }
+}

src/FiscalOS.API/Accounts/Add/Request.cs

@@ -0,0 +1,23 @@
+
+namespace FiscalOS.API.Accounts.Add;
+
+public record Request : IValidatableObject
+{
+  public string PlaidInstitutionId { get; init; } = string.Empty;
+  public string PlaidAccountId { get; init; } = string.Empty;
+
+  public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
+  {
+    if (string.IsNullOrWhiteSpace(PlaidInstitutionId))
+    {
+      var fieldName = nameof(PlaidInstitutionId);
+      yield return new($"The {fieldName} field is required.", [fieldName]);
+    }
+
+    if (string.IsNullOrWhiteSpace(PlaidAccountId))
+    {
+      var fieldName = nameof(PlaidAccountId);
+      yield return new($"The {fieldName} field is required.", [fieldName]);
+    }
+  }
+}

src/FiscalOS.API/Usings.cs

@@ -3,6 +3,7 @@ global using System.Security.Claims;
 global using System.Text.Json.Serialization;
 
 global using FiscalOS.API.Accounts;
+global using FiscalOS.API.Accounts.Add;
 global using FiscalOS.API.Accounts.Connect;
 global using FiscalOS.API.Http;
 global using FiscalOS.API.Login;