Imports System.IO
Imports System.Net
Imports System.Security.Cryptography.X509Certificates
Imports System.Text
Imports DigitalData.Modules.Logging
Imports Newtonsoft.Json

Public Class GraphQLInterface
    Private _logConfig As LogConfig
    Private _logger As Logger
    Private _baseUrl As String
    Private _userEmail As String
    Private _userPassword As String
    Private _certificate As X509Certificate2
    Private _cookieJar As CookieContainer
    Private _Encoding As New UTF8Encoding

    Private Const MAX_COOKIE_SIZE As Integer = 32768
    Private Const MAX_COOKIE_COUNT As Integer = 300
    Private Const MAX_COOKIE_COUNT_PER_DOMAIN As Integer = 20

    Public Property Proxy As WebProxy
    Public Property Credentials As NetworkCredential

    Public Event LogRequested As EventHandler(Of String)

    Public ReadOnly Property Certificate As X509Certificate2
        Get
            Return _certificate
        End Get
    End Property


    Public Sub New(LogConfig As LogConfig, BaseUrl As String, Email As String, Password As String, CertificateFingerprint As String)
        Try
            _logConfig = LogConfig
            _logger = LogConfig.GetLogger()
            _baseUrl = BaseUrl
            _userEmail = Email
            _userPassword = Password

            Dim oStoreNames As New List(Of StoreName) From {StoreName.Root, StoreName.My}
            Dim oStoreLocations As New List(Of StoreLocation) From {StoreLocation.CurrentUser, StoreLocation.LocalMachine}

            Dim oCertificate As X509Certificate2 = Nothing

            For Each oStoreLocation In oStoreLocations
                _logger.Debug("Checking Stores in Location [{0}]", oStoreLocation.ToString)

                For Each oStoreName In oStoreNames
                    oCertificate = FindCertificateByFingerprint(oStoreLocation, oStoreName, CertificateFingerprint, False)

                    If oCertificate IsNot Nothing Then
                        _logger.Info("Certificate found in Store [{0}]/[{1}]!", oStoreName.ToString, oStoreLocation.ToString)
                        Exit For
                    End If
                Next

                If oCertificate IsNot Nothing Then
                    Exit For
                End If
            Next


            If oCertificate Is Nothing Then
                _logger.Warn("Certificate could not be found! Exiting.")
                Exit Sub
            End If

            _certificate = oCertificate

        Catch ex As Exception
            _logger.Error(ex)
        End Try
    End Sub

    Private Function FindCertificateByFingerprint(pLocation As StoreLocation, pStoreName As StoreName, pFingerprint As String, pValidOnly As Boolean) As X509Certificate2
        Try
            Dim oStore As New X509Store(pStoreName, pLocation)
            Dim oLocation As String = pLocation.ToString

            _logger.Info("Opening Store [{0}]/[{1}]..", oLocation, oStore.Name)
            oStore.Open(OpenFlags.ReadOnly)

            _logger.Info("Available Certificates in Store [{0}]/[{1}]: [{2}]", oLocation, oStore.Name, oStore.Certificates.Count)

            For Each oCert In oStore.Certificates
                _logger.Debug("FriendlyName: {0}", oCert.FriendlyName)
                _logger.Debug("IssuerName: {0}", oCert.IssuerName.Name)
                _logger.Debug("SubjectName: {0}", oCert.SubjectName.Name)
                _logger.Debug("Fingerprint: {0}", oCert.Thumbprint)
            Next

            _logger.Debug("Looking for Certificate with Fingerprint [{0}]", pFingerprint)
            Dim oFoundCerts = oStore.Certificates.Find(X509FindType.FindByThumbprint, pFingerprint, pValidOnly)

            _logger.Debug("Closing store..")
            oStore.Close()

            If oFoundCerts.Count = 0 Then
                _logger.Debug("Certificate with Fingerprint [{0}] not found in Store [{1}]/[{2}]", pFingerprint, oLocation, oStore.Name)
                Return Nothing
            End If

            Return oFoundCerts.Item(0)
        Catch ex As Exception
            _logger.Warn("Unexpected error while searching for certificate with Fingerprint [{0}].", pFingerprint)
            _logger.Error(ex)
            Return Nothing
        End Try
    End Function

    Public Sub SaveCookies(Cookie As Cookie)
        GetCookies().Add(Cookie)
    End Sub

    Public Function Login() As HttpWebResponse
        Try
            RaiseEvent LogRequested(Me, $"Login started with user: [{_userEmail}]")

            Dim oLoginData As New LoginData() With {.email = _userEmail, .token = _userPassword}
            Dim oBytes As Byte() = ToBytes(JsonConvert.SerializeObject(oLoginData))
            Dim oRequest As HttpWebRequest = GetRequest("/login", oBytes)

            RaiseEvent LogRequested(Me, $"Sending HTTP request to GraphQL")
            RaiseEvent LogRequested(Me, $"Request Host: [{oRequest.Host}]")
            RaiseEvent LogRequested(Me, $"Request Address: [{oRequest.Address}]")
            RaiseEvent LogRequested(Me, $"Request Method: [{oRequest.Method}]")
            RaiseEvent LogRequested(Me, $"Request ContentType: [{oRequest.ContentType}]")

            Using oStream = oRequest.GetRequestStream()
                oStream.Write(oBytes, 0, oBytes.Length)
            End Using

            Return oRequest.GetResponse()
        Catch ex As Exception
            _logger.Error(ex)
            Throw ex
        End Try
    End Function

    Public Function Logout() As HttpWebResponse
        Try
            Dim oLogoutData As New LogoutData() With {.email = _userEmail}
            Dim oBytes As Byte() = ToBytes(JsonConvert.SerializeObject(oLogoutData))
            Dim oRequest As HttpWebRequest = GetRequest("/logout", oBytes)

            Using stream = oRequest.GetRequestStream()
                stream.Write(oBytes, 0, oBytes.Length)
            End Using

            Return oRequest.GetResponse()
        Catch ex As Exception
            _logger.Error(ex)
            Throw ex
        End Try
    End Function

    Public Function GetData(Query As String, OperationName As String) As HttpWebResponse
        Try
            Dim oQueryData As New QueryData() With {
                .operationName = OperationName,
                .query = Query,
                .variables = New Object
            }
            Dim oJson = JsonConvert.SerializeObject(oQueryData)
            Dim oBytes = ToBytes(oJson)
            Dim oRequest = GetRequest("/graphql", oBytes)

            Using stream = oRequest.GetRequestStream()
                stream.Write(oBytes, 0, oBytes.Length)
            End Using

            Return oRequest.GetResponse()
        Catch ex As Exception
            _logger.Error(ex)
            Throw ex
        End Try
    End Function

    Public Function ReadJSONPathFragmented(pObject As Linq.JObject, pJsonPath As String)
        Dim oSplitPath As List(Of String) = pJsonPath.Split(".").ToList()
        Dim oCurrentPath As String = String.Empty

        For Each oPart In oSplitPath
            If oCurrentPath = String.Empty Then
                oCurrentPath = oPart
            Else
                oCurrentPath &= "." & oPart
            End If

            _logger.Debug("Selecting Path Fragment [{0}]", oCurrentPath)

            Try
                pObject.SelectToken(oCurrentPath, errorWhenNoMatch:=True)
            Catch ex As Exception
                _logger.Warn("Path Fragment [{0}] did not return a valid token", oCurrentPath)
                Return False
            End Try
        Next

        Return True
    End Function

    Private Function GetRequest(Url As String, PostData As Byte()) As HttpWebRequest
        Try
            ' Set supported TLS versions for WebRequest
            ' Source: https://stackoverflow.com/questions/10822509/the-request-was-aborted-could-not-create-ssl-tls-secure-channel
            'SetSecurityOptions()
            'SetSecurityOptionsInsecure()
            'SetSecurityOptionsModern()

            Dim oRequest As HttpWebRequest = WebRequest.Create($"{_baseUrl}{Url}")
            oRequest.Method = "POST"
            oRequest.ContentType = "application/json"
            oRequest.ContentLength = PostData.Length
            oRequest.ClientCertificates.Add(_certificate)
            oRequest.CookieContainer = GetCookies()
            oRequest.Proxy = Nothing

            If Proxy Is Nothing Then
                oRequest.Proxy = Nothing
            Else
                oRequest.Proxy = Proxy
                oRequest.Credentials = Credentials
            End If

            Return oRequest
        Catch ex As Exception
            _logger.Error(ex)
            Throw ex
        End Try
    End Function


    Private Sub SetSecurityOptions()
        ServicePointManager.SecurityProtocol =
            SecurityProtocolType.Tls Or
            SecurityProtocolType.Tls11 Or
            SecurityProtocolType.Tls12
    End Sub

    Private Sub SetSecurityOptionsInsecure()
        ServicePointManager.SecurityProtocol =
            SecurityProtocolType.Tls Or
            SecurityProtocolType.Tls11 Or
            SecurityProtocolType.Tls12 Or
            SecurityProtocolType.Ssl3
    End Sub

    Private Sub SetSecurityOptionsModern()
        ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12
    End Sub

    Private Function GetCookies() As CookieContainer
        If _cookieJar Is Nothing Then
            _cookieJar = New CookieContainer(MAX_COOKIE_COUNT, MAX_COOKIE_COUNT_PER_DOMAIN, MAX_COOKIE_SIZE)
        End If

        Return _cookieJar
    End Function

    Private Function ToBytes(Str As String) As Byte()
        Return _Encoding.GetBytes(Str)
    End Function
End Class