Imports System
Imports System.IO
Imports System.Net.Http
Imports System.Text
Imports System.Windows.Forms.VisualStyles.VisualStyleElement.StartPanel
Imports Newtonsoft.Json
Imports sun.security.util
Imports VERAG_PROG_ALLGEMEIN.cRelayHub

Public Class cRelayHubToken

    Private Shared ReadOnly TOKEN_ENDPOINT_PROD As String = "https://login.singlewindow.io/auth/realms/agsw/protocol/openid-connect/token"
    Private Shared ReadOnly TOKEN_ENDPOINT_TEST As String = "https://dev-kc.singlewindow.io/auth/realms/agsw/protocol/openid-connect/token"

    Private Shared ReadOnly CLIENT_ID As String = "agsw-admin"

    Private Shared ReadOnly USERNAME_PROD As String = "dhub@verag.ag"
    Private Shared ReadOnly PASSWORD_PROD As String = "Dhub1234*"

    Private Shared ReadOnly USERNAME_TEST As String = "andreas.test@test.com"
    Private Shared ReadOnly PASSWORD_TEST As String = "Atez123."

    Private Const ExpirySkewSeconds As Integer = 60

    '======================================================================
    ' KONFIGURATION
    '======================================================================
    Private Shared Function GetTokenEndpoint(environment As cRelayHubEnvironment) As String
        Select Case environment
            Case cRelayHubEnvironment.TEST
                Return TOKEN_ENDPOINT_TEST
            Case cRelayHubEnvironment.PROD
                Return TOKEN_ENDPOINT_PROD
            Case Else
                Throw New ApplicationException("Unbekannte RelayHub-Umgebung.")
        End Select
    End Function

    Private Shared Function GetUsername(environment As cRelayHubEnvironment) As String
        Select Case environment
            Case cRelayHubEnvironment.TEST
                Return USERNAME_TEST
            Case cRelayHubEnvironment.PROD
                Return USERNAME_PROD
            Case Else
                Throw New ApplicationException("Unbekannte RelayHub-Umgebung.")
        End Select
    End Function

    Private Shared Function GetPassword(environment As cRelayHubEnvironment) As String
        Select Case environment
            Case cRelayHubEnvironment.TEST
                Return PASSWORD_TEST
            Case cRelayHubEnvironment.PROD
                Return PASSWORD_PROD
            Case Else
                Throw New ApplicationException("Unbekannte RelayHub-Umgebung.")
        End Select
    End Function

    Private Shared Function GetStorePath(environment As cRelayHubEnvironment) As String
        Dim fileName As String = If(environment = cRelayHubEnvironment.TEST, "token_test.json", "token_prod.json")
        Return Path.Combine(System.Environment.GetFolderPath(System.Environment.SpecialFolder.ApplicationData), "RelayHub", fileName)
    End Function

    '======================================================================
    ' ACCESS TOKEN
    '======================================================================
    Public Shared Function GetAccessToken(environment As cRelayHubEnvironment) As String
        Dim store = LoadStore(environment)

        If store IsNot Nothing AndAlso Not String.IsNullOrWhiteSpace(store.AccessToken) Then
            If store.ExpiresAtUtc > DateTimeOffset.UtcNow.AddSeconds(ExpirySkewSeconds) Then Return store.AccessToken
        End If

        If store IsNot Nothing AndAlso Not String.IsNullOrWhiteSpace(store.RefreshToken) Then store = TryRefresh(store.RefreshToken, environment)

        If store Is Nothing OrElse String.IsNullOrWhiteSpace(store.AccessToken) Then store = PasswordLogin(environment)

        If store Is Nothing OrElse String.IsNullOrWhiteSpace(store.AccessToken) Then Throw New ApplicationException("Konnte keinen gültigen Access Token erhalten (" & environment.ToString() & ").")

        SaveStore(store, environment)
        Return store.AccessToken
    End Function

    '======================================================================
    ' LOGIN
    '======================================================================
    Private Shared Function PasswordLogin(environment As cRelayHubEnvironment) As TokenStore
        Dim form = New Dictionary(Of String, String) From {
            {"grant_type", "password"},
            {"username", GetUsername(environment)},
            {"password", GetPassword(environment)},
            {"client_id", CLIENT_ID}
        }

        Dim resp = PostForm(form, environment)
        Return ParseTokenResponse(resp, environment)
    End Function

    '======================================================================
    ' REFRESH
    '======================================================================
    Private Shared Function TryRefresh(refreshToken As String, environment As cRelayHubEnvironment) As TokenStore
        Try
            Dim form = New Dictionary(Of String, String) From {
                {"grant_type", "refresh_token"},
                {"refresh_token", refreshToken},
                {"client_id", CLIENT_ID}
            }

            Dim resp = PostForm(form, environment)
            Dim token = ParseTokenResponse(resp, environment)

            If Not String.IsNullOrWhiteSpace(token.AccessToken) Then
                SaveStore(token, environment)
                Return token
            End If
        Catch ex As Exception
            Console.WriteLine("Token Refresh fehlgeschlagen (" & environment.ToString() & "): " & ex.Message)
        End Try

        Return Nothing
    End Function

    '======================================================================
    ' HTTP
    '======================================================================
    Private Shared Function PostForm(formFields As Dictionary(Of String, String), environment As cRelayHubEnvironment) As String
        Using client As New HttpClient()
            Using content As New FormUrlEncodedContent(formFields)
                Dim tokenEndpoint As String = GetTokenEndpoint(environment)

                Dim username As String = GetUsername(environment)
                Dim password As String = GetPassword(environment)

                Console.WriteLine("")
                Console.WriteLine("==================================================")
                Console.WriteLine(" RELAYHUB TOKEN REQUEST")
                Console.WriteLine("==================================================")
                Console.WriteLine("Environment    : " & environment.ToString())
                Console.WriteLine("Token Endpoint : " & tokenEndpoint)
                Console.WriteLine("Client ID      : " & CLIENT_ID)
                'Console.WriteLine("Username       : " & username)
                'Console.WriteLine("Password       : " & password)
                'Console.WriteLine("Password Länge : " & If(password Is Nothing, 0, password.Length))
                'Console.WriteLine("Grant Type     : " & If(formFields.ContainsKey("grant_type"), formFields("grant_type"), "<nicht gesetzt>"))
                'Console.WriteLine("Token Store    : " & GetStorePath(environment))
                'Console.WriteLine("==================================================")


                Dim response = client.PostAsync(tokenEndpoint, content).Result
                Dim body = response.Content.ReadAsStringAsync().Result

                If Not response.IsSuccessStatusCode Then Throw New ApplicationException("Token-Endpoint Fehler (" & environment.ToString() & " / " & CInt(response.StatusCode) & "): " & body)

                Return body
            End Using
        End Using
    End Function

    '======================================================================
    ' TOKEN RESPONSE
    '======================================================================
    Private Shared Function ParseTokenResponse(json As String, environment As cRelayHubEnvironment) As TokenStore
        Dim r = JsonConvert.DeserializeObject(Of TokenResponse)(json)

        If r Is Nothing OrElse String.IsNullOrWhiteSpace(r.access_token) Then Throw New ApplicationException("Token-Antwort ungültig oder ohne access_token.")

        Dim now = DateTimeOffset.UtcNow
        Dim expiresIn = If(r.expires_in <= 0, 3600, r.expires_in)

        Dim store = New TokenStore With {
            .AccessToken = r.access_token.Trim(),
            .RefreshToken = If(r.refresh_token, String.Empty),
            .ExpiresAtUtc = now.AddSeconds(expiresIn)
        }

        Console.WriteLine("== Neuer RelayHub Token ==")
        Console.WriteLine("Environment: " & environment.ToString())
        Console.WriteLine("Gültig bis UTC: " & store.ExpiresAtUtc.ToString("yyyy-MM-dd HH:mm:ss"))

        Return store
    End Function

    '======================================================================
    ' TOKEN LADEN
    '======================================================================
    Private Shared Function LoadStore(environment As cRelayHubEnvironment) As TokenStore
        Try
            Dim storePath As String = GetStorePath(environment)

            If File.Exists(storePath) Then
                Dim json = File.ReadAllText(storePath, Encoding.UTF8)
                Dim s = JsonConvert.DeserializeObject(Of TokenStore)(json)

                If s IsNot Nothing Then
                    Console.WriteLine("== Token aus Datei geladen ==")
                    Console.WriteLine("Environment: " & environment.ToString())
                    Console.WriteLine("Gültig bis UTC: " & s.ExpiresAtUtc.ToString("yyyy-MM-dd HH:mm:ss"))
                End If

                Return s
            Else
                Console.WriteLine("Keine Token-Datei für " & environment.ToString() & " vorhanden.")
            End If
        Catch ex As Exception
            Console.WriteLine("Fehler beim Laden der Token-Datei: " & ex.Message)
        End Try

        Return Nothing
    End Function

    '======================================================================
    ' TOKEN SPEICHERN
    '======================================================================
    Private Shared Sub SaveStore(store As TokenStore, environment As cRelayHubEnvironment)
        Try
            Dim storePath As String = GetStorePath(environment)
            Dim dir = Path.GetDirectoryName(storePath)

            If Not Directory.Exists(dir) Then Directory.CreateDirectory(dir)

            Dim json = JsonConvert.SerializeObject(store, Formatting.Indented)
            File.WriteAllText(storePath, json, Encoding.UTF8)

            Console.WriteLine("Token-Datei gespeichert: " & storePath)
        Catch ex As Exception
            Console.WriteLine("Fehler beim Speichern der Token-Datei: " & ex.Message)
        End Try
    End Sub

    '======================================================================
    ' TOKEN LÖSCHEN
    '======================================================================
    Private Shared Sub Delete_Store(Optional environment As cRelayHubEnvironment = cRelayHubEnvironment.PROD)
        Try
            Dim storePath As String = GetStorePath(environment)
            If File.Exists(storePath) Then File.Delete(storePath)
            Console.WriteLine("Token-Datei gelöscht: " & storePath)
        Catch ex As Exception
            Console.WriteLine("Fehler beim Löschen der Token-Datei: " & ex.Message)
        End Try
    End Sub
    Public Shared Sub DeleteAllStores()
        Delete_Store(cRelayHubEnvironment.TEST)
        Delete_Store(cRelayHubEnvironment.PROD)
    End Sub

    '======================================================================
    ' DTOs
    '======================================================================
    Private Class TokenResponse
        Public Property access_token As String
        Public Property expires_in As Integer
        Public Property refresh_expires_in As Integer
        Public Property refresh_token As String
        Public Property token_type As String
        Public Property scope As String
    End Class

    Private Class TokenStore
        Public Property AccessToken As String
        Public Property RefreshToken As String
        Public Property ExpiresAtUtc As DateTimeOffset
    End Class

End Class