Open notepad and then auto-typing a message on it

a-letter-to-you.cpp

#define EMBED_MESSAGE
#define DEBUG_MODE

#define WINVER 0x0500
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <windows.h>

#ifdef EMBED_MESSAGE
#define SWEET_TITLE         "My Sweetest Message"
#define SWEET_MESSAGE       "If water were kisses, I'd send you the sea\nIf leaves were hugs, I'd send you a tree\nIf nite was love ,I'd send you the stars\nBut I can't send you my heart cause that where you are"
#else
#define MESSAGE_FILE_NAME   "message.txt"
#endif // EMBED_MESSAGE
#define AUDIO_FILE_NAME     "typing.mp3"
#define TEXT_EDITOR_PATH    "c:\\windows\\notepad.exe"
#define MAX_TRY             5

struct HandleData
{
    DWORD processId;
    HWND betsHandle;
};

BOOL is_main_window(HWND handle);
BOOL CALLBACK enum_windows_callback(HWND handle, LPARAM lParam);
HWND find_main_window(DWORD processId);
VOID release_process(PPROCESS_INFORMATION processInfo);
VOID wait_until_exit(PPROCESS_INFORMATION processInfo);
VOID start_story(HWND handle);
VOID send_key(HWND handle, CHAR key);
VOID send_key(INPUT ip, SHORT vKeyCode);
#ifndef EMBED_MESSAGE
BOOL load_message_file(CONST PCHAR fileName, PCHAR content);
PCHAR get_title(CONST PCHAR content, PCHAR title);
#endif // EMBED_MESSAGE

INT main()
{
#ifndef DEBUG_MODE
    ShowWindow( GetConsoleWindow(), SW_HIDE );
#endif // DEBUG_MODE

    STARTUPINFO info;
    PROCESS_INFORMATION processInfo;

    ZeroMemory(&info, sizeof(info));

    if (CreateProcess(TEXT_EDITOR_PATH, "", NULL, NULL, TRUE, 0, NULL, NULL, &info, &processInfo))
    {
        for (INT i = 0; i < MAX_TRY; i++)
        {
            HWND handle = find_main_window(processInfo.dwProcessId);
            if (handle != NULL)
            {
                start_story(handle);
                wait_until_exit(&processInfo);
                break;
            }

            Sleep(1000);
        }

        release_process(&processInfo);
    }
}

BOOL is_main_window(HWND handle)
{
    return GetWindow(handle, GW_OWNER) == (HWND)0 && IsWindowVisible(handle);
}

BOOL CALLBACK enum_windows_callback(HWND handle, LPARAM lParam)
{
    HandleData& data = *(HandleData*) lParam;
    DWORD processId = 0;
    GetWindowThreadProcessId(handle, &processId);
    if (data.processId != processId || !is_main_window(handle))
        return TRUE;
    data.betsHandle = handle;
    return FALSE;
}

HWND find_main_window(DWORD processId)
{
    HandleData data;
    data.processId = processId;
    data.betsHandle = NULL;
    EnumWindows(enum_windows_callback, (LPARAM)&data);
    return data.betsHandle;
}

VOID release_process(PPROCESS_INFORMATION processInfo)
{
    CloseHandle((*processInfo).hProcess);
    CloseHandle((*processInfo).hThread);
}

VOID wait_until_exit(PPROCESS_INFORMATION processInfo)
{
    WaitForSingleObject((*processInfo).hProcess, INFINITE);
}

VOID start_story(HWND handle)
{
#ifdef EMBED_MESSAGE
    PCHAR message = SWEET_MESSAGE;
    SetWindowText(handle, SWEET_TITLE);
#else
    CHAR content[1000];
    if (!load_message_file(MESSAGE_FILE_NAME, content))
    {
        printf("%s not found!", MESSAGE_FILE_NAME);
        return;
    }

    CHAR title[255];
    PCHAR message = get_title(content, title);
    if (message == NULL)
    {
        printf("Message file does not have any content!");
        return;
    }
    SetWindowText(handle, title);
#endif // EMBED_MESSAGE
    INT length = strlen(message);
    srand(time(NULL));

    CHAR mciString[255];
    strcpy(mciString, "open \"");
    strcat(mciString, AUDIO_FILE_NAME);
    strcat(mciString, "\" type mpegvideo alias mp3");

    mciSendString(mciString, NULL, 0, NULL);
    mciSendString("play mp3 repeat", NULL, 0, NULL);

    for (INT i = 0 ; i < length; i++)
    {
        CHAR key = message[i];
        INT millis = rand() % 400 + 100;

        send_key(handle, key);
        printf("send[%dms]: %c\n", millis, key);
        Sleep(millis);
    }

    mciSendString("stop mp3", NULL, 0, NULL);
}

VOID send_key(HWND handle, CHAR key)
{
    if (GetForegroundWindow() != handle)
        SetForegroundWindow(handle);

    INPUT ip;

    ZeroMemory(&ip, sizeof(ip));

    ip.type = INPUT_KEYBOARD;

    SHORT vKeyCode = VkKeyScan(key);

    if ((vKeyCode & 0xFF00) != 256)
    {
        send_key(ip, vKeyCode);
    }
    else
    {
        ip.ki.dwFlags = 0;
        ip.ki.wVk = VK_LSHIFT;
        SendInput(1, &ip, sizeof(INPUT));

        send_key(ip, vKeyCode);

        ip.ki.dwFlags = KEYEVENTF_KEYUP;
        ip.ki.wVk   = VK_LSHIFT;
        SendInput(1, &ip, sizeof(INPUT));
    }
}

VOID send_key(INPUT ip, SHORT vKeyCode)
{
    ip.ki.dwFlags = 0;
    ip.ki.wVk = vKeyCode & 0x00FF;
    SendInput(1, &ip, sizeof(INPUT));

    ip.ki.dwFlags = KEYEVENTF_KEYUP;
    SendInput(1, &ip, sizeof(INPUT));
}

#ifndef EMBED_MESSAGE
BOOL load_message_file(CONST PCHAR fileName, PCHAR content)
{
    FILE * pFile = fopen(fileName, "r");
    if (pFile == NULL)
        return FALSE;

    content[0] = '\0';

    CHAR buff[255];
    while (fgets(buff, sizeof(buff), pFile) != NULL)
    {
        strcat(content, buff);
    }

    fclose(pFile);

    return TRUE;
}

PCHAR get_title(CONST PCHAR content, PCHAR title)
{
    INT length = strlen(content);
    for (INT i = 0, j = 0; i < length; i++)
    {
        if (content[i] != '\n')
        {
            title[j++] = content[i];
        }
        else
        {
            title[j] = '\0';
            return &content[i + 1];
        }
    }

    return NULL;
}
#endif // EMBED_MESSAGE