#Region "Uses"
Imports System.IO
Imports System.Net
Imports System.Text.RegularExpressions
#End Region

Public Class Form1

#Region "Variables"

    ReadOnly Last_User_A As String = "El último usuario registrado es <strong><a href=""/u\d+"
    ReadOnly Last_User_B As String = "\d+" 'Regex.Replace(Last_User_A, "El último usuario registrado es <strong><a href=""/u", "")
    ReadOnly User_Title_A As String = "\>Perfil - \w+"
    'ReadOnly User_Title_B As String = "^(?:\S+\s){2}(\S+)" 'Regex.Replace(User_Title_A, "\>Perfil - ", "")
    ReadOnly File_Users As String = ".\Users-" & DateTime_To_Unix(Date.Now) & ".txt"
    ReadOnly Users_Pattern As String = "ID: {0} - Nick: {1}"
    Private Foroactivo_Users As New List(Of Tuple(Of Integer, String))
    Private IndexPattern As Integer = 0
    Dim url As String

#End Region

#Region "Funciones"

    Private Function Get_URL_SourceCode(ByVal url As String) As String

        Try
            Return New StreamReader(Net.HttpWebRequest.Create(url).GetResponse().GetResponseStream()).ReadToEnd()
        Catch ex As Exception
            Throw New Exception(ex.Message)
            Return Nothing
        End Try

    End Function

    Private Function Last_User(ByVal url As String) As Long

        Dim Source As String = Get_URL_SourceCode(url)

        Return CLng(Convert.ToString(Regex.Match( _
                    Convert.ToString(Regex.Match( _
                    Source, Last_User_A).Groups(0)), _
                    Last_User_B).Groups(0) _
                    ))

    End Function

    Private Function Get_User_Nick(ByVal Id As Integer, ByVal url As String) As String

        Dim Foroactivo_Query As String = url.Replace(url.Substring(url.LastIndexOf("/") + 1), "")
        Dim SearchPattern As String = "u" & Id + 1

        Dim Source As String = Get_URL_SourceCode(String.Format("{0}{1}", Foroactivo_Query, SearchPattern))

        Return Convert.ToString(Regex.Match(Source, User_Title_A)).Replace(">Perfil - ", "")

        'Return Convert.ToString(Regex.Match(Source, User_Title_B).Groups(0))
    End Function

    Private Function DateTime_To_Unix(ByVal DateTime As DateTime) As Long
        Return DateDiff(DateInterval.Second, #1/1/1970#, DateTime)
    End Function

    Private Function Determine_Is_ForoActivo(ByVal url As String) As Boolean
        Dim Source As String = Get_URL_SourceCode(url)
        If Source.Contains("-ltr.css") Then
            Return True
        Else
            Return False
        End If
    End Function

    Public Function Count_Character(ByVal str As String, ByVal character As Char, _
                                    Optional ByVal IgnoreCase As Boolean = False) As Integer

        Return IIf(IgnoreCase, _
                   str.ToLower.Count(Function(c As Char) c = Convert.ToChar(character.ToString.ToLower)), _
                   str.Count(Function(c As Char) c = character))

    End Function

    Public Function Validate_URL(ByVal URL As String) As Boolean
        Try

            Dim Response As Net.WebResponse = Nothing
            Dim WebReq As Net.HttpWebRequest = Net.HttpWebRequest.Create(URL)
            Response = WebReq.GetResponse
            Response.Close()
            Return True
        Catch ex As Exception
            Return False
        End Try
    End Function

#End Region

    Private ReadOnly Property MyUrl
        Get
            Return TextBox1.Text
        End Get
    End Property

#Region "Subs"

    Private Sub Update_ToolStrip_Progress()

        Threading.Interlocked.Increment(IndexPattern)
        Threading.Interlocked.Increment(ProgressBar1.Value)

        Label2.Text = _
String.Format("Procesando {0} de {1} usuario(s)...", _
              IndexPattern.ToString, Last_User(TextBox1.Text))

    End Sub

    Private Sub Calcular_Users(ByVal url As String)
        Try

            ProgressBar1.Maximum = Last_User(url)

            For i As Integer = 0 To Last_User(url) - 1

                Dim User_Id = i + 1
                Dim User_Nick = Get_User_Nick(i, TextBox1.Text)

                File.AppendAllText(File_Users, String.Format(Users_Pattern, User_Id, User_Nick) & Environment.NewLine)

                Update_ToolStrip_Progress()

            Next i

            'MsgBox("¡Proceso acabado!", MsgBoxStyle.Information, "Información")
            Process.Start(File_Users)

        Catch ex As Exception When TextBox1.Text = String.Empty
            MsgBox("Debes poner algo", MsgBoxStyle.Critical, "Error")
        End Try
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        ProgressBar1.Visible = True
        Calcular_Users(TextBox1.Text)
        IndexPattern = 0
        ProgressBar1.Value = 0
        Label2.Text = "Acabado..."
        ProgressBar1.Visible = False
    End Sub

    Private Sub Label2_Click(sender As Object, e As EventArgs) Handles Label2.TextChanged
        Me.Refresh()
    End Sub

    Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
        If Count_Character(TextBox1.Text, "/") = 3 AndAlso Not MyUrl = url AndAlso Validate_URL(TextBox1.Text) = True AndAlso Determine_Is_ForoActivo(TextBox1.Text) = True Then
            Label2.Text = String.Format("Listo para obtener el nick de {0} usuarios...", Last_User(TextBox1.Text) - 1)
            url = MyUrl
        End If
    End Sub

#End Region

End Class