LINQ Challenges and SQL Server Compact Edition

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using TimeApp.DataAccess;

namespace TimeApp.UI {

	public partial class ProjectListForm : Form {

		public ProjectListForm() {
			InitializeComponent();
		}

		private void ProjectListForm_Load(object sender, EventArgs e) {
			LoadProjects();
		}

		/// <summary>
		/// Updates the buttons based on the state of the interface.
		/// </summary>
		private void UpdateButtons() {
			btnEdit.Enabled = (lbProjects.SelectedItem != null);
			btnDelete.Enabled = btnEdit.Enabled;
		}

		/// <summary>
		/// Loads all projects into the interface.
		/// </summary>
		private void LoadProjects() {
			using (TimeAppDataContext DataContext = new TimeAppDataContext()) {
				lbProjects.DataSource = DataContext.GetAllProjects();
				lbProjects.DisplayMember = "Name";
				lbProjects.ValueMember = "ProjectId";
			}

			UpdateButtons();
		}

		/// <summary>
		/// Opens a project form for adding a new project.
		/// </summary>
		private void AddProject() {
			// Create a new project for adding.
			Project ProjectToAdd = new Project();

			// Show the project form.
			ProjectForm frmProject = new ProjectForm();
			if (frmProject.ShowDialog(this, ProjectToAdd, true) == DialogResult.OK) {
				// Save the new project.
				using (TimeAppDataContext DataContext = new TimeAppDataContext()) {
					DataContext.Projects.InsertOnSubmit(ProjectToAdd);
					DataContext.SubmitChanges();
				}

				// Reload the projects.
				LoadProjects();
			}
		}

		/// <summary>
		/// Opens a project form for editing the currently selected project.
		/// </summary>
		private void EditProject() {
			using (TimeAppDataContext DataContext = new TimeAppDataContext()) {
				// Get the project for editing.
				ProjectSummary SelectedProject = (ProjectSummary)lbProjects.SelectedItem;
				Project ProjectToEdit = DataContext.GetProject(SelectedProject.ProjectId);

				// Show the project form.
				ProjectForm frmProject = new ProjectForm();
				if (frmProject.ShowDialog(this, ProjectToEdit) == DialogResult.OK) {
					// Set tasks that are marked for deletion to be deleted from the DB.
					var MarkedTasks = from T in ProjectToEdit.Tasks
										where T.IsMarked
										select T;
					foreach (Task TaskToDelete in MarkedTasks)
						DataContext.Tasks.DeleteOnSubmit(TaskToDelete);

					// Save the edited project/tasks.
					DataContext.SubmitChanges();

					// Update the displayed project upon successful save.
					SelectedProject.Name = ProjectToEdit.Name;
					SelectedProject.DetectAway = ProjectToEdit.DetectAway;
				}
			}
		}

		/// <summary>
		/// Deletes the currently selected project.
		/// </summary>
		private void DeleteProject() {
			if (MessageBox.Show(this, "Delete this project?", "Delete Project", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes) {
				// Delete the project.
				using (TimeAppDataContext DataContext = new TimeAppDataContext())
					DataContext.DeleteProject(((ProjectSummary)lbProjects.SelectedItem).ProjectId);

				// Reload the projects.
				LoadProjects();
			}
		}

		private void lbProjects_SelectedIndexChanged(object sender, EventArgs e) {
			UpdateButtons();
		}

		private void lbProjects_DoubleClick(object sender, EventArgs e) {
			EditProject();
		}

		private void btnAdd_Click(object sender, EventArgs e) {
			AddProject();
		}

		private void btnEdit_Click(object sender, EventArgs e) {
			EditProject();
		}

		private void btnDelete_Click(object sender, EventArgs e) {
			DeleteProject();
		}

	}

}