Imports System.Net.Http.Headers
Imports System.Security.Claims
Imports System.Text.Encodings.Web
Imports System.Threading.Tasks
Imports Microsoft.AspNetCore.Authentication
Imports Microsoft.Extensions.Logging
Imports Microsoft.Extensions.Options
Imports Microsoft.AspNetCore.Http.Abstractions


Public Class BasicAuthentificationHandler
    Inherits AuthenticationHandler(Of AuthenticationSchemeOptions)

    ReadOnly _userService As IUserService


    Public Sub New(userService As IUserService, options As Microsoft.Extensions.Options.IOptionsMonitor(Of AuthenticationSchemeOptions), logger As ILoggerFactory, encoder As UrlEncoder, clock As ISystemClock)

        MyBase.New(options, logger, encoder, clock)
        _userService = userService


    End Sub

    Protected Overrides Function HandleChallengeAsync(properties As AuthenticationProperties) As Task
        GetResponse().Headers("WWW-Authenticate") = "Basic"
        Return MyBase.HandleChallengeAsync(properties)
    End Function

    Private Function GetResponse() As Object
        Return Response
    End Function

    Protected Overrides Function HandleAuthenticateAsync() As Task(Of AuthenticateResult)

        Dim username As String = ""

        Try

            Dim authHeader = AuthenticationHeaderValue.Parse(GetResponse().Headers("Authorization"))
            Dim credentials = Encoding.UTF8.GetString(Convert.FromBase64String(authHeader.Parameter)).Split(":")
            username = credentials.FirstOrDefault
            Dim password = credentials.LastOrDefault

            If Not _userService.CheckUser(username, password) Then
                Throw New NotImplementedException("Invalid Username or password")
            End If



        Catch ex As Exception

            Return Task.FromResult(AuthenticateResult.Fail(ex.Message))

        End Try

        Dim claims = {New Claim(ClaimTypes.Name, username)}
        Dim idendity = New ClaimsIdentity(claims, Scheme.Name)
        Dim principal = New ClaimsPrincipal(idendity)
        Dim ticket = New AuthenticationTicket(principal, Scheme.Name)

        Return Task.FromResult(AuthenticateResult.Success(ticket))




    End Function
End Class