feat(api): implement endpoint for creating link tokens

src/FiscalOS.API/Institutions/Link/Endpoint.cs

@@ -0,0 +1,31 @@
+namespace FiscalOS.API.Institutions.Link;
+
+internal static class Endpoint
+{
+  private const string Route = "/link";
+
+  public static RouteHandlerBuilder MapLinkEndpoint(this RouteGroupBuilder groupBuilder)
+  {
+    return groupBuilder.MapPost(Route, HandleAsync);
+  }
+
+  private static async Task<IResult> HandleAsync(
+    HttpContext httpContext,
+    [FromServices] AppDbContext appDbContext,
+    [FromServices] PlaidService plaidService
+  )
+  {
+    var userId = httpContext.GetUserId();
+
+    var user = await appDbContext.Users.SingleOrDefaultAsync(u => u.Id == userId);
+
+    if (user is null)
+    {
+      return Results.Unauthorized();
+    }
+
+    var linkToken = await plaidService.CreateLinkTokenAsync(user.Id.ToString());
+
+    return Results.Ok(Response.From(linkToken));
+  }
+}

src/FiscalOS.API/Institutions/Link/Response.cs

@@ -0,0 +1,19 @@
+namespace FiscalOS.API.Institutions.Link;
+
+public sealed record Response
+{
+  public string LinkToken { get; init; } = string.Empty;
+
+  [JsonConstructor]
+  private Response()
+  {
+  }
+
+  public static Response From(string linkToken)
+  {
+    return new()
+    {
+      LinkToken = linkToken,
+    };
+  }
+}