Coding in Tiers - Part II

using System;
using System.Collections;

using Dao;
using Services;
using Utility;

namespace Lib
{
	#region -- AccountManager --
	/// <summary>
	/// A <code>class</code> that provides account registration and authentication
	/// services.
	/// </summary>
	/// <remarks>
	/// This class resides in the Business tier and provides implementation of
	/// the account related services offered by the application. This class is
	/// used by the UI via the services offered through the Service tier.
	/// </remarks>
	public sealed class AccountManager : IRegistrationService, IAuthenticationService
	{
		#region -- Constructors --
		/// <summary>
		/// Constructor used by the Service tier
		/// </summary>
		internal AccountManager() {}
		#endregion

		#region -- Methods --
		/// <summary>
		/// Register a new user into the system
		/// </summary>
		/// <remarks>
		/// The Username and Password on the account should not be <code>null</code>
		/// or empty faliure on which the corresponding errors will be reported.
		/// </remarks>
		/// <param name="registration">The registration information</param>
		/// <exception cref="ValidationException">If the Username and Password on the account is
		/// <code>null</code> or empty</exception>
		public void Authenticate(IAccount acct)
		{
			// Place holder for error information
			Hashtable errors = new Hashtable(2);

			// Check if username is valid
			if(!ValidationHelper.ValidateRequired(acct.Username))
			{
				// Store the error message
				errors["Username"] = "Username is required.";
			}

			// Check if password is valid
			if(!ValidationHelper.ValidateRequired(acct.Password))
			{
				// Store the error message
				errors["Password"] = "Password is required.";
			}

			// Additional checks to verify if user exists and passwords match etc.

			if(errors.Count > 0)
			{
				// Throw exception for errors to be reported
				throw new ValidationException("Validation Error.", errors);
			}
		}

		/// <summary>
		/// Register a new user into the system
		/// </summary>
		/// <remarks>
		/// The Username and Password on the account should not be <code>null</code>
		/// or empty faliure on which the corresponding errors will be reported. The
		/// username on the registration information is checked for duplication. If
		/// the username does not currently exist in the database, the account is
		/// created and registration is successful. If the username already exists,
		/// an error message is reported back to the caller.
		/// </remarks>
		/// <param name="registration">The registration information</param>
		/// <exception cref="ValidationException">If an error occurs during processing.</exception>
		public void Register(IRegistration registration)
		{
			// Place holder for error information
			Hashtable errors = new Hashtable(3);

			// Check if username is valid
			if(!ValidationHelper.ValidateRequired(registration.Username))
			{
				// Store the error message
				errors["Username"] = "Username is required.";
			}

			// Check if password is valid
			if(!ValidationHelper.ValidateRequired(registration.Password))
			{
				// Store the error message
				errors["Password"] = "Password is required.";
			}

			// Create the Data Access Object
			RegistrationDAO dao = new RegistrationDAO();

			// Check if an account exists for the username supplied
			if(dao.AccountExists(registration.Username))
			{
				// Store the error message
				errors["Username"] = "An account with the username entered already exists.";
			}

			// Check if there are any errors
			if(errors.Count > 0)
			{
				// Throw exception for errors to be reported
				throw new ValidationException("Validation Error.", errors);
			}

			// Register the user
			dao.Register(registration);
		}
		#endregion
	}
	#endregion
}