Imports System.Reflection
Imports Microsoft.VisualBasic.ComponentModel
Imports Microsoft.VisualBasic.Net.Tcp
Imports Microsoft.VisualBasic.Parallel
Imports Microsoft.VisualBasic.Serialization.JSON

Public Class TaskBuilder : Implements ITaskDriver

    ReadOnly masterPort As Integer

    Sub New(port As Integer)
        masterPort = port
    End Sub

    Public Function Run() As Integer Implements ITaskDriver.Run
        Dim task As IDelegate = GetMethod()
        Dim n As Integer = GetArgumentValueNumber()
        Dim args As New List(Of Object)

        For i As Integer = 0 To n - 1
            args.Add(GetArgumentValue(i))
        Next

        Dim api As MethodInfo = task.GetMethod
        Dim params As ParameterInfo() = api.GetParameters

        For i As Integer = n To params.Length - 1
            If Not params(i).IsOptional Then
                Return PostError(New Exception($"missing parameter value for [{i}]{params(i).Name}!"))
            Else
                args.Add(params(i).DefaultValue)
            End If
        Next

        Call PostFinished(api.Invoke(Nothing, args.ToArray))

        Return 0
    End Function

    Private Function GetArgumentValueNumber() As Integer
        Dim resp = New TcpRequest(masterPort).SendMessage(New RequestStream(IPCSocket.Protocol, Protocols.GetArgumentNumber))
        Dim n As Integer = BitConverter.ToInt32(resp.ChunkBuffer, Scan0)

        Return n
    End Function

    Private Function GetMethod() As IDelegate
        Dim resp = New TcpRequest(masterPort).SendMessage(New RequestStream(IPCSocket.Protocol, Protocols.GetTask))
        Dim json As String = resp.GetUTF8String
        Dim target As IDelegate = json.LoadJSON(Of IDelegate)

        Return target
    End Function

    Private Function GetArgumentValue(i As Integer) As Object
        Dim resp = New TcpRequest(masterPort).SendMessage(New RequestStream(IPCSocket.Protocol, Protocols.GetArgumentByIndex, BitConverter.GetBytes(i)))
        Dim stream As New ObjectStream(resp.ChunkBuffer)

        If stream.method = StreamMethods.BSON Then

        Else
            Throw New NotImplementedException
        End If
    End Function

    Private Function PostError(err As Exception) As Integer


        Return 500
    End Function

    Private Sub PostFinished(result As Object)

    End Sub
End Class