Public Class frmUsers

    Dim db As New Objects.Db
    Dim p As New Persist
    Dim user As New User

    Public closeOnly As Boolean = False

    Private Sub btnMenu_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnMenu.Click
        If Not (closeOnly) Then
            Me.Hide()
            frmMenu.Show()
            frmMenu.Focus()
        End If
    End Sub

    Private Sub frmUsers_FormClosed(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosedEventArgs) Handles Me.FormClosed
        If Not (closeOnly) Then
            frmMenu.Show()
            frmMenu.Focus()
        End If
    End Sub

    Private Sub btnUser_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnUser.Click
        ViewRecord(txtUsername.Text)
    End Sub

    Public Sub ViewRecord(Optional ByVal username As String = "")

        If (username = "") Then
            username = txtUsername.Text
        Else
            txtUsername.Text = username
        End If

        Dim tmpUser As User = p.GetObject(db.SQLSelect("Users", New Collection, "Username = '" & username & "'"), New User)

        If (tmpUser.Username <> "") Then 'record found
            txtFirstName.Text = tmpUser.FirstName
            txtSurname.Text = tmpUser.Surname
            txtPassword.Text = tmpUser.Password
            txtComments.Text = tmpUser.Comments
            cboUserLevel.SelectedIndex = tmpUser.AccessLevel - 1
            txtUsername.BackColor = Color.PaleGreen
            user = tmpUser
        Else
            MsgBox("Could not find user: ''" & txtUsername.Text & "''", MsgBoxStyle.Exclamation, "Error")
            txtUsername.Text = user.Username

            If (user.Username = "") Then 'no records in database
                txtUsername.BackColor = Color.Red
            End If
        End If

    End Sub

    Private Sub UpdateUserObject()
        user.Username = txtUsername.Text
        user.FirstName = txtFirstName.Text
        user.Surname = txtSurname.Text
        user.Password = txtPassword.Text
        user.Comments = txtComments.Text
        user.AccessLevel = cboUserLevel.SelectedIndex + 1
    End Sub

    Private Sub ClearInput()
        txtUsername.Text = ""
        txtComments.Text = ""
        txtFirstName.Text = ""
        txtSurname.Text = ""
        txtPassword.Text = ""
        cboUserLevel.Text = ""
    End Sub

    Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click

        'error checking
        If (txtUsername.Text = "") Then
            MsgBox("Username cannot be blank.", MsgBoxStyle.Exclamation, "Error")
            Exit Sub
        End If



        'update
        Dim oldUsername As String = user.Username
        UpdateUserObject()

        If (oldUsername <> txtUsername.Text) And btnAdd.Enabled = True Then
            MsgBox("Username cannot be changed. Username has been reset to: ''" & oldUsername & "''", MsgBoxStyle.Exclamation, "Error")
            user.Username = oldUsername
        End If

        If (btnCancel.Enabled = False) Then 'editing

            p.UpdateObject(user)

            If (user.Username = frmLogin.user.Username) Then 'edited current user
                frmLogin.user = user 'get updated user details
            End If
        Else
            'adding
            If (txtUsername.Text <> "") Then

                'check that username is unique
                Dim tempuser As DataTable
                tempuser = db.SQLSelect("Users", "Username", "Username = '" & txtUsername.Text & "'")

                If tempuser.Rows.Count > 0 Then
                    MsgBox("There is already a user with that username. Enter a unique username.", MsgBoxStyle.Exclamation, "Error")
                    txtUsername.Focus()
                    Exit Sub
                Else

                    UpdateUserObject()
                    p.AddObject(user)

                    'normal mode
                    btnUser.Enabled = True
                    btnDelete.Enabled = True
                    btnCancel.Enabled = False
                    btnAdd.Enabled = True
                End If
            Else
                MsgBox("Please fill in all fields. (Comments are optional).", MsgBoxStyle.Exclamation, "Error")
            End If
            End If

    End Sub

    Public Sub ShowDefault()
        Dim r As User = p.GetObject(db.SQLSelect("Users", "TOP(1) * "), New User)
        If (r.Username <> "") Then
            ViewRecord(r.Username)
        Else 'no records
            txtUsername.BackColor = Color.Red
        End If
    End Sub

    Private Sub btnDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click
        Dim username As String = user.Username
        Dim defaultUser As User = p.GetObject(db.SQLSelect("User", New Collection, "Top(1) *", "Username <> '" & user.Username & "'"), New User)
        Dim result As MsgBoxResult

        If (defaultUser.Username <> "") Then
            result = MsgBox("Are you sure you want to delete this record?" & Chr(13) & Chr(13) & "All locations that have their manager set to this user & all bookings that are related to this user will revert to the default user ''" & defaultUser.FullName & "''. This ensures application stabillity." & Chr(13) & Chr(13) & "Continue?", MsgBoxStyle.YesNo, "Caution")
        Else
            MsgBox("Cannot delete user. This is the only user registered on the system. At least one user is required to run the system.")
            Exit Sub
        End If

        Dim usersCount As DataTable = db.SQLSelect("Users", "COUNT(Username)")
        If (usersCount.Rows.Count = 1) Then
            defaultUser.AccessLevel = 2
            p.UpdateObject(defaultUser)
        End If

        If (result = MsgBoxResult.Yes) Then
            UpdateUserObject()
            p.DeleteObject(user)

            'enforce referential integerity
            db.SQLUpdate("Bookings", "StaffUsername='" & defaultUser.Username & "'", "StaffUsername='" & username & "'")
            db.SQLUpdate("Locations", "Manager='" & defaultUser.Username & "'", "Manager='" & username & "'")

            ShowDefault()
        End If

    End Sub

    Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
        ClearInput()
        btnUser.Enabled = False
        btnDelete.Enabled = False
        btnCancel.Enabled = True
        btnAdd.Enabled = False
        user = New User 'clear user data
    End Sub

    Private Sub frmUsers_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        ShowDefault()
    End Sub

    Private Sub btnCancel_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnCancel.Click
        'normal mode
        btnCancel.Enabled = False
        btnUser.Enabled = True
        btnDelete.Enabled = True
        btnAdd.Enabled = True

        Dim r As DataTable = db.SQLSelect("Users", "TOP(1) *")
        If (r.Rows.Count > 0) Then
            ViewRecord(r.Rows(0).Item("Username"))
            txtUsername.Text = r.Rows(0).Item("Username")
        End If
    End Sub

    Private Sub btnLoginAs_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLoginAs.Click
        If (user.Username <> "") Then
            frmLogin.user = user
            MsgBox("You are now logged in as ''" & user.Username & "''.")
        Else
            MsgBox("Please select a user first.")
        End If
    End Sub

End Class