Authentication implementation

WebApp/Authentication/AuthenticationService.cs

@@ -0,0 +1,72 @@
+using Microsoft.Extensions.Configuration;
+
+namespace WebApp.Authentication;
+
+public class AuthenticationService
+{
+    private readonly IConfiguration _configuration;
+    private readonly ILogger<AuthenticationService> _logger;
+
+    public AuthenticationService(IConfiguration configuration, ILogger<AuthenticationService> logger)
+    {
+        _configuration = configuration;
+        _logger = logger;
+    }
+
+    public AuthenticationResult ValidateCredentials(string email, string password)
+    {
+        try
+        {
+            // Bind User Secrets to AuthenticationSettings
+            var authSettings = new AuthenticationSettings();
+            _configuration.GetSection("Authentication").Bind(authSettings);
+
+            if (authSettings.Users == null || !authSettings.Users.Any())
+            {
+                _logger.LogWarning("No users configured in authentication settings");
+                return AuthenticationResult.Failed("Authentication system not configured");
+            }
+
+            // Find user by email (case-insensitive)
+            var user = authSettings.Users
+                .FirstOrDefault(u => u.Email.Equals(email, StringComparison.OrdinalIgnoreCase));
+
+            if (user == null)
+            {
+                _logger.LogDebug("User not found: {Email}", email);
+                return AuthenticationResult.Failed("Invalid email or password");
+            }
+
+            // Verify password using BCrypt
+            if (!BCrypt.Net.BCrypt.Verify(password, user.PasswordHash))
+            {
+                _logger.LogDebug("Invalid password for user: {Email}", email);
+                return AuthenticationResult.Failed("Invalid email or password");
+            }
+
+            // Success
+            _logger.LogDebug("Successful credential validation for {Email}", email);
+            return AuthenticationResult.Success(user.Email, user.DisplayName, user.Role);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Error during credential validation");
+            return AuthenticationResult.Failed("An error occurred during authentication");
+        }
+    }
+}
+
+public class AuthenticationResult
+{
+    public bool IsSuccess { get; set; }
+    public string? Email { get; set; }
+    public string? DisplayName { get; set; }
+    public string? Role { get; set; }
+    public string? ErrorMessage { get; set; }
+
+    public static AuthenticationResult Success(string email, string displayName, string role)
+        => new() { IsSuccess = true, Email = email, DisplayName = displayName, Role = role };
+
+    public static AuthenticationResult Failed(string error)
+        => new() { IsSuccess = false, ErrorMessage = error };
+}