refactor(auth): cleanup auth module and streamline the registration flow

backend/Modules/Identity/Services/EmailVerificationService.cs

@@ -0,0 +1,61 @@
+using System.Web;
+using Hutopy.Infrastructure.Configuration;
+using Hutopy.Infrastructure.Emailer.Contracts;
+using Hutopy.Modules.Identity.Data;
+using Microsoft.Extensions.Options;
+
+namespace Hutopy.Modules.Identity.Services;
+
+[PublicAPI]
+public sealed class EmailVerificationService(
+    IOptionsSnapshot<WebsiteOptions> options,
+    UserManager userManager,
+    IEmailSender emailSender)
+{
+    public async Task SendVerificationEmailAsync(
+        User user)
+    {
+        // Generate email confirmation token
+        string token = await userManager.GenerateEmailConfirmationTokenAsync(user);
+        string encodedToken = HttpUtility.UrlEncode(token);
+        string verificationLink = $"{options.Value.FrontendBaseUrl}/verify-email?userId={user.Id}&token={encodedToken}";
+
+        // Send verification email
+        await emailSender.SendEmailAsync(
+            user.Email!,
+            "Verify your email address",
+            $"""
+             <div style="font-family: Arial, sans-serif; max-width: 600px; margin: 0 auto; padding: 20px; color: #333;">
+               <h1 style="color: #2c3e50; margin-bottom: 20px;">Welcome to Hutopy!</h1>
+               
+               <p style="font-size: 16px; line-height: 1.5; margin-bottom: 25px;">
+                 Please verify your email address by clicking the button below:
+               </p>
+               
+               <div style="text-align: center; margin: 30px 0;">
+                 <a href='{verificationLink}' 
+                    style="background-color: #3498db; 
+                           color: white; 
+                           text-decoration: none; 
+                           padding: 12px 24px; 
+                           border-radius: 4px; 
+                           font-weight: bold; 
+                           display: inline-block; 
+                           box-shadow: 0 2px 5px rgba(0,0,0,0.1);">
+                   Verify Email Address
+                 </a>
+               </div>
+               
+               <p style="font-size: 14px; color: #7f8c8d; margin-top: 30px;">
+                 If you did not request this, please ignore this email.
+               </p>
+               
+               <p style="font-size: 14px; color: #7f8c8d; margin-top: 20px;">
+                 If the button doesn't work, you can copy and paste this link into your browser:
+                 <br>
+                 <a href='{verificationLink}' style="color: #3498db; word-break: break-all;">{verificationLink}</a>
+               </p>
+             </div>
+             """);
+    }
+}