Imports System.Drawing
Imports System.IO
Imports System.Security.Cryptography
Imports System.Text
Imports DevExpress.Utils.Svg
Imports EnvelopeGenerator.Domain.Constants

Public Class Helpers
    Private Shared key As String = "$xzBvyPETUS&amm8)D8x#)f;4%;?[BPd" ' Passwort-Schlüssel (16, 24, or 32 bytes)
    Private Shared iv As String = "1wN&e[zrQ6_B7X/0" ' Initialisierungsvektor (16 bytes)

    ' Entschlüsselungsfunktion
    Public Shared Function Decrypt(cipherText As String) As String
        Dim aesAlg As Aes = Aes.Create()
        aesAlg.Key = Encoding.UTF8.GetBytes(key)
        aesAlg.IV = Encoding.UTF8.GetBytes(iv)
        Dim decryptor As ICryptoTransform = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV)
        Dim cipherBytes As Byte() = Convert.FromBase64String(cipherText)
        Dim msDecrypt As New IO.MemoryStream(cipherBytes)
        Using csDecrypt As New CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read)
            Using srDecrypt As New IO.StreamReader(csDecrypt)
                Return srDecrypt.ReadToEnd()
            End Using
        End Using
    End Function

    ''' <summary>
    ''' Encodes the EnvelopeUUID and the ReceiverSignature into an EnvelopeKey
    ''' </summary>
    ''' <param name="pEnvelopeUuid"></param>
    ''' <param name="pReceiverSignature"></param>
    ''' <returns>The EnvelopeKey</returns>
    Public Shared Function EncodeEnvelopeReceiverId(pEnvelopeUuid As String, pReceiverSignature As String) As String
        Dim oString = $"{pEnvelopeUuid}::{pReceiverSignature}"
        Dim oBytes = System.Text.Encoding.UTF8.GetBytes(oString)
        Dim oBase64String = Convert.ToBase64String(oBytes)

        Return oBase64String
    End Function

    ''' <summary>
    ''' Decodes the EnvelopeKey and returns the EnvelopeUUID and the ReceiverSignature
    ''' </summary>
    ''' <param name="pEnvelopeReceiverId">The EnvelopeKey</param>
    ''' <returns>A tuple containing EnvelopeUUID and Receiver Signature</returns>
    Public Shared Function DecodeEnvelopeReceiverId(pEnvelopeReceiverId As String) As Tuple(Of String, String)
        Dim oBytes = Convert.FromBase64String(pEnvelopeReceiverId)
        Dim oString = System.Text.Encoding.UTF8.GetString(oBytes)
        Dim oSplit = oString.Split(New String() {"::"}, StringSplitOptions.None)

        Return New Tuple(Of String, String)(oSplit(0), oSplit(1))
    End Function

    Public Shared Function GetEnvelopeURL(pHost As String, pEnvelopeUuid As String, pReceiverSignature As String) As String

        Dim oEnvelopeUserReference As String = EncodeEnvelopeReceiverId(pEnvelopeUuid, pReceiverSignature)
        Dim oURL As String = String.Format("{0}/EnvelopeKey/{1}", pHost.Trim(), oEnvelopeUserReference)
        Return oURL

    End Function

    Public Shared Function GetAccessCode() As String
        Return Guid.NewGuid().ToString("d").Substring(1, 6).ToUpper()
    End Function


    Public Shared Function ColorTypeToColor(pColorType As ColorType) As Color
        Select Case pColorType
            Case ColorType.ReceiverColor1
                Return ColorTranslator.FromHtml("#22c55e")

            Case ColorType.ReceiverColor2
                Return ColorTranslator.FromHtml("#3b82f6")

            Case ColorType.ReceiverColor3
                Return ColorTranslator.FromHtml("#8b5cf6")

            Case ColorType.ReceiverColor4
                Return ColorTranslator.FromHtml("#f59e0b")

            Case ColorType.ReceiverColor5
                Return ColorTranslator.FromHtml("#ef4444")

            Case ColorType.ReceiverColor6
                Return ColorTranslator.FromHtml("#14b8a6")

            Case ColorType.ReceiverColor7
                Return ColorTranslator.FromHtml("#d946ef")

            Case ColorType.ReceiverColor8
                Return ColorTranslator.FromHtml("#06b6d4")

            Case ColorType.ReceiverColor9
                Return ColorTranslator.FromHtml("#10b981")

            Case ColorType.ReceiverColor10
                Return ColorTranslator.FromHtml("#84cc16")

        End Select
    End Function

    Public Shared Function GetColorCircle(pBaseImage As SvgImage, pColor As Color) As SvgImage
        Dim oColoredImage As SvgImage = pBaseImage.
            Clone(Sub(el As SvgElement, table As Hashtable)
                      If TypeOf el Is SvgCircle Then
                          el.Styles.Clear()
                          table("StyleName") = String.Empty
                          table("Fill") = ColorTranslator.ToHtml(pColor)
                      End If
                  End Sub)

        Return oColoredImage
    End Function

    Public Shared Function IsValidEmailAddress(pEmailAddress As String) As Boolean
        Try
            Dim oAddress = New System.Net.Mail.MailAddress(pEmailAddress)
            Return oAddress.Address = pEmailAddress
        Catch ex As Exception
            Return False
        End Try
    End Function

    Public Shared Async Function CopyFileAsync(sourceFile As String, destinationFile As String) As Task
        Dim fileOptions = IO.FileOptions.Asynchronous Or IO.FileOptions.SequentialScan
        Dim bufferSize = 4096

        Using sourceStream = New FileStream(sourceFile, FileMode.Open, FileAccess.Read, FileShare.Read, bufferSize, fileOptions)

            Using destinationStream = New FileStream(destinationFile, FileMode.CreateNew, FileAccess.Write, FileShare.None, bufferSize, fileOptions)
                Await sourceStream.CopyToAsync(destinationStream, bufferSize).ConfigureAwait(False)
            End Using
        End Using
    End Function
End Class