using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

/// <summary>
/// Windows 的COPYDATA消息封装类。
/// </summary>
public class Messager : System.Windows.Forms.Form
{
    /// <summary>
    /// 必需的设计器变量。
    /// </summary>
    private System.ComponentModel.Container components = null;

    //消息标识
    private const int WM_COPYDATA = 0x004A;

    //消息数据类型(typeFlag以上二进制，typeFlag以下字符)
    private const uint typeFlag = 0x8000;

    /// <summary>
    /// 重载CopyDataStruct
    /// </summary>
    [StructLayout(LayoutKind.Sequential)]
    public struct COPYDATASTRUCT
    {
        public IntPtr dwData;
        public int cbData;
        public IntPtr lpData;
    }

    [DllImport("User32.dll", EntryPoint = "SendMessage")]
    private static extern int SendMessage(
            int hWnd,                    // handle to destination window
            int Msg,                     // message
            int wParam,                  // first message parameter
            ref COPYDATASTRUCT lParam    // second message parameter
            );

    [DllImport("User32.dll", EntryPoint = "FindWindow")]
    private static extern int FindWindow(string lpClassName, string lpWindowName);

    // 接收到数据委托与事件定义
    public delegate void ReceiveStringEvent(object sender, uint flag, string str);
    public delegate void ReceiveBytesEvent(object sender, uint flag, byte[] bt);
    public event ReceiveStringEvent OnReceiveString;
    public event ReceiveBytesEvent OnReceiveBytes;

    // 发送数据委托与事件定义
    public delegate void SendStringEvent(object sender, uint flag, string str);
    public delegate void SendBytesEvent(object sender, uint flag, byte[] bt);
    public event SendStringEvent OnSendString;
    public event SendBytesEvent OnSendBytes;

    public Messager()
    {
        InitializeComponent();
    }

    /// <summary>
    /// 清理所有正在使用的资源。
    /// </summary>
    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            if (components != null)
            {
                components.Dispose();
            }
        }
        base.Dispose(disposing);
    }


    #region Windows 窗体设计器生成的代码

    /// <summary>
    /// 设计器支持所需的方法 - 不要使用代码编辑器修改
    /// 此方法的内容。
    /// </summary>
    private void InitializeComponent()
    {
            this.SuspendLayout();
            // 
            // Messager
            // 
            this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
            this.ClientSize = new System.Drawing.Size(342, 242);
            this.Name = "Messager";
            this.ShowInTaskbar = false;
            this.WindowState = System.Windows.Forms.FormWindowState.Minimized;
            this.ResumeLayout(false);

    }

    #endregion

    /// <summary>
    /// 重载窗口消息处理函数
    /// </summary>
    /// <param name="m"></param>
    protected override void DefWndProc(ref System.Windows.Forms.Message m)
    {
        switch (m.Msg)
        {
            // 接收CopyData消息，读取发送过来的数据
            case WM_COPYDATA:
                COPYDATASTRUCT cds = new COPYDATASTRUCT();
                Type mytype = cds.GetType();
                cds = (COPYDATASTRUCT)m.GetLParam(mytype);
                uint flag = (uint)(cds.dwData);
                byte[] bt = new byte[cds.cbData];
                Marshal.Copy(cds.lpData, bt, 0, bt.Length);
                if (flag <= typeFlag)
                {
                    if (OnReceiveString != null)
                    {
                        OnReceiveString(this, flag, System.Text.Encoding.Default.GetString(bt));
                    }
                }
                else
                {
                    if (OnReceiveBytes != null)
                    {
                        OnReceiveBytes(this, flag, bt);
                    }
                }
                break;
            default:
                base.DefWndProc(ref m);
                break;
        }
    }

    /// <summary>
    /// 发送字符串格式数据
    /// </summary>
    /// <param name="destWindow">目标窗口标题</param>
    /// <param name="flag">数据标志</param>
    /// <param name="str">数据</param>
    /// <returns></returns>
    public bool SendString(string destWindow, uint flag, string str)
    {
        if (flag > typeFlag)
        {
            MessageBox.Show("要发送的数据不是字符格式");
            return false;
        }

        int WINDOW_HANDLER = FindWindow(null, @destWindow);
        if (WINDOW_HANDLER == 0) return false;

        try
        {
            byte[] sarr = System.Text.Encoding.Default.GetBytes(str);
            COPYDATASTRUCT cds;
            cds.dwData = (IntPtr)flag;
            cds.cbData = sarr.Length;
            cds.lpData = Marshal.AllocHGlobal(sarr.Length);
            Marshal.Copy(sarr, 0, cds.lpData, sarr.Length);
            SendMessage(WINDOW_HANDLER, WM_COPYDATA, 0, ref cds);
            if (OnSendString != null)
            {
                OnSendString(this, flag, str);
            }
            return true;
        }
        catch (Exception e)
        {
            MessageBox.Show(e.Message);
            return false;
        }
    }

    /// <summary>
    /// 发送二进制格式数据
    /// </summary>
    /// <param name="destWindow">目标窗口</param>
    /// <param name="flag">数据标志</param>
    /// <param name="data">数据</param>
    /// <returns></returns>
    public bool SendBytes(string destWindow, uint flag, byte[] data)
    {
        if (flag <= typeFlag)
        {
            MessageBox.Show("要发送的数据不是二进制格式");
            return false;
        }

        int WINDOW_HANDLER = FindWindow(null, @destWindow);
        if (WINDOW_HANDLER == 0) return false;

        try
        {
            COPYDATASTRUCT cds;
            cds.dwData = (IntPtr)flag;
            cds.cbData = data.Length;
            cds.lpData = Marshal.AllocHGlobal(data.Length);
            Marshal.Copy(data, 0, cds.lpData, data.Length);
            SendMessage(WINDOW_HANDLER, WM_COPYDATA, 0, ref cds);
            if (OnSendBytes != null)
            {
                OnSendBytes(this, flag, data);
            }
            return true;
        }

        catch (Exception e)
        {
            MessageBox.Show(e.Message);
            return false;
        }
    }
}