microsoft-visualbasic-runtime/Net/Protocol/Reflection/ProtocolHandler.vb

#Region "Microsoft.VisualBasic::d883b5e7df0927d02a228167bb2da654, Microsoft.VisualBasic.Core\Net\Protocol\Reflection\ProtocolHandler.vb"

    ' Author:
    ' 
    '       asuka (amethyst.asuka@gcmodeller.org)
    '       xie (genetics@smrucc.org)
    '       xieguigang (xie.guigang@live.com)
    ' 
    ' Copyright (c) 2018 GPL3 Licensed
    ' 
    ' 
    ' GNU GENERAL PUBLIC LICENSE (GPL3)
    ' 
    ' 
    ' This program is free software: you can redistribute it and/or modify
    ' it under the terms of the GNU General Public License as published by
    ' the Free Software Foundation, either version 3 of the License, or
    ' (at your option) any later version.
    ' 
    ' This program is distributed in the hope that it will be useful,
    ' but WITHOUT ANY WARRANTY; without even the implied warranty of
    ' MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    ' GNU General Public License for more details.
    ' 
    ' You should have received a copy of the GNU General Public License
    ' along with this program. If not, see <http://www.gnu.org/licenses/>.



    ' /********************************************************************************/

    ' Summaries:

    '     Class ProtocolHandler
    ' 
    '         Properties: DeclaringType, ProtocolEntry
    ' 
    '         Constructor: (+1 Overloads) Sub New
    '         Function: GetMethod, HandlePush, HandleRequest, method1, method2
    '                   (+2 Overloads) SafelyCreateObject, ToString
    ' 
    ' 
    ' /********************************************************************************/

#End Region

Imports System.Reflection
Imports System.Runtime.CompilerServices
Imports Microsoft.VisualBasic.Net.Abstract
Imports Microsoft.VisualBasic.Net.Http
Imports Microsoft.VisualBasic.Net.Tcp
Imports TcpEndPoint = System.Net.IPEndPoint

Namespace Net.Protocols.Reflection

    ''' <summary>
    ''' 这个模块只处理<see cref="DataRequestHandler"/>类型的接口
    ''' 
    ''' ```vbnet
    ''' <see cref="System.Delegate"/> Function(request As <see cref="RequestStream"/>, RemoteAddress As <see cref="TcpEndPoint"/>) As <see cref="RequestStream"/>
    ''' ```
    ''' </summary>
    Public Class ProtocolHandler : Inherits IProtocolHandler

        Protected Protocols As Dictionary(Of Long, DataRequestHandler)
        ''' <summary>
        ''' 这个类型建议一般为某种枚举类型
        ''' </summary>
        ''' <returns></returns>
        Public ReadOnly Property DeclaringType As Type
        Public Overrides ReadOnly Property ProtocolEntry As Long

        Public Overrides Function ToString() As String
            Return $"*{ProtocolEntry}   ---> {DeclaringType.FullName}  //{Protocols.Count} Protocols."
        End Function

        Const AllInstanceMethod As BindingFlags =
            BindingFlags.Public Or
            BindingFlags.NonPublic Or
            BindingFlags.Instance

        ''' <summary>
        ''' 请注意，假若没有在目标的类型定义之中查找出入口点的定义，则这个构造函数会报错，
        ''' 假若需要安全的创建对象，可以使用<see cref="ProtocolHandler.SafelyCreateObject(Of T)(T)"/>函数
        ''' </summary>
        ''' <param name="obj">Protocol的实例</param>
        Sub New(obj As Object)
            Dim type As Type = obj.GetType
            Dim entry As Protocol = Protocol.GetProtocolCategory(type)

            Me.DeclaringType = entry?.DeclaringType
            Me.ProtocolEntry = entry?.EntryPoint

            ' 解析出所有符合 WrapperClassTools.Net.DataRequestHandler 接口类型的函数方法
            Dim Methods = type.GetMethods(bindingAttr:=AllInstanceMethod)
            Dim LQuery = (From entryPoint As MethodInfo
                          In Methods
                          Let Protocol As Protocol = Protocol.GetEntryPoint(entryPoint)
                          Let method As DataRequestHandler = GetMethod(obj, entryPoint)
                          Where Not (Protocol Is Nothing) AndAlso
                              Not method Is Nothing
                          Select Protocol, entryPoint, method)

            Me.Protocols = LQuery.ToDictionary(Function(element)
                                                   Return element.Protocol.EntryPoint
                                               End Function,
                                               Function(element) element.method)
        End Sub

        ''' <summary>
        ''' 失败会返回空值
        ''' </summary>
        ''' <typeparam name="T"></typeparam>
        ''' <param name="App"></param>
        ''' <returns></returns>
        Public Shared Function SafelyCreateObject(Of T As Class)(App As T) As ProtocolHandler
            Try
                Return New ProtocolHandler(App)
            Catch ex As Exception
                Return Nothing
            End Try
        End Function

        Public Shared Function SafelyCreateObject(App As Object) As ProtocolHandler
            Try
                Return New ProtocolHandler(App)
            Catch ex As Exception
                Return Nothing
            End Try
        End Function

        <MethodImpl(MethodImplOptions.AggressiveInlining)>
        Public Function HandlePush(uid As Long, request As RequestStream) As RequestStream
            Return HandleRequest(request, Nothing)
        End Function

        ''' <summary>
        ''' Handle the data request from the client for socket events: <see cref="TcpServicesSocket.ResponseHandler"/>.
        ''' </summary>
        ''' <param name="request">The request stream object which contains the commands from the client</param>
        ''' <param name="remoteDevcie">The IPAddress of the target incoming client data request.</param>
        ''' <returns></returns>
        Public Overrides Function HandleRequest(request As RequestStream, remoteDevcie As TcpEndPoint) As RequestStream
            If request.ProtocolCategory <> Me.ProtocolEntry Then
#If DEBUG Then
                Call $"Protocol_entry:={request.ProtocolCategory} was not found!".__DEBUG_ECHO
#End If
                Return NetResponse.RFC_VERSION_NOT_SUPPORTED
            End If

            If Not Me.Protocols.ContainsKey(request.Protocol) Then
#If DEBUG Then
                Call $"Protocol:={request.Protocol} was not found!".__DEBUG_ECHO
#End If
                ' 没有找到相对应的协议处理逻辑，则没有实现相对应的数据协议处理方法
                Return NetResponse.RFC_NOT_IMPLEMENTED
            End If

            Dim EntryPoint As DataRequestHandler = Me.Protocols(request.Protocol)
            Dim value As RequestStream = EntryPoint(request, remoteDevcie)
            Return value
        End Function

        Private Shared Function GetMethod(obj As Object, entryPoint As MethodInfo) As DataRequestHandler
            Dim parameters As ParameterInfo() = entryPoint.GetParameters

            If Not entryPoint.ReturnType.Equals(GetType(RequestStream)) Then
                Return Nothing
            ElseIf parameters.Length > 2 Then
                Return Nothing
            End If

            If parameters.Length = 0 Then
                Return AddressOf New ProtocolInvoker(obj, entryPoint).InvokeProtocol0
            ElseIf parameters.Length = 1 Then
                Return method1(obj, entryPoint, parameters)
            ElseIf parameters.Length = 2 Then
                Return method2(obj, entryPoint, parameters)
            End If

            Return Nothing
        End Function

        Private Shared Function method2(obj As Object, entryPoint As MethodInfo, parameters As ParameterInfo()) As DataRequestHandler
            If (Not parameters.First.ParameterType.Equals(GetType(RequestStream)) OrElse
                Not parameters.Last.ParameterType.Equals(GetType(TcpEndPoint))) Then
                Return Nothing
            Else
                Return AddressOf New ProtocolInvoker(obj, entryPoint).InvokeProtocol2
            End If
        End Function

        Private Shared Function method1(obj As Object, entryPoint As MethodInfo, parameters As ParameterInfo()) As DataRequestHandler
            If Not parameters.First.ParameterType.Equals(GetType(RequestStream)) Then
                Return Nothing
            Else
                Return AddressOf New ProtocolInvoker(obj, entryPoint).InvokeProtocol1
            End If
        End Function

        <MethodImpl(MethodImplOptions.AggressiveInlining)>
        Public Shared Narrowing Operator CType(handler As ProtocolHandler) As DataRequestHandler
            Return AddressOf handler.HandleRequest
        End Operator
    End Class
End Namespace