Add user avatar and profile feature, consolidate Auth and UserManagement features (#257)

web/backend/Features/Features.Users/Commands/Account/UpdateEmail/UpdateEmailHandler.cs

@@ -0,0 +1,41 @@
+using Domain.Exceptions;
+using Features.Auth.Dtos;
+using Features.Auth.Identity;
+using MediatR;
+using Microsoft.AspNetCore.Identity;
+
+namespace Features.Auth.Commands.Account.UpdateEmail;
+
+/// <summary>
+///     Handles <see cref="UpdateEmailCommand" /> via <see cref="UserManager{TUser}" />.
+///     <see cref="UserManager{TUser}.SetEmailAsync" /> also resets <c>EmailConfirmed</c> to
+///     <see langword="false" />, so the user must re-confirm the new address (see
+///     <c>Features.Users.Commands.ResendConfirmationEmail</c>).
+/// </summary>
+public class UpdateEmailHandler(UserManager<ApplicationUser> userManager)
+    : IRequestHandler<UpdateEmailCommand, UpdateEmailPayload>
+{
+    /// <exception cref="NotFoundException">Thrown when the account does not exist.</exception>
+    /// <exception cref="ConflictException">Thrown when the requested email address is already in use.</exception>
+    public async Task<UpdateEmailPayload> Handle(
+        UpdateEmailCommand request,
+        CancellationToken cancellationToken
+    )
+    {
+        ApplicationUser user =
+            await userManager.FindByIdAsync(request.UserAccountId.ToString())
+            ?? throw new NotFoundException("User account not found");
+
+        IdentityResult result = await userManager.SetEmailAsync(user, request.NewEmail);
+        if (!result.Succeeded)
+        {
+            if (result.Errors.Any(e => e.Code == "DuplicateEmail"))
+                throw new ConflictException("Email address already exists");
+            throw new ConflictException(
+                string.Join("; ", result.Errors.Select(e => e.Description))
+            );
+        }
+
+        return new UpdateEmailPayload(user.Id, user.Email, user.EmailConfirmed);
+    }
+}