How to write a program to interact with another?

Question

Automation

I need to write a program that would interact with another program. Namely, I searched for the elements I needed in it, clicked on the input fields and entered data, in other words, some kind of bot for Windows.
The program with which you need to interact is an android emulator, I think bluestacks should be taken as the basis, although it doesn’t matter.
I see people write bots in C#. What can you get away from? Share infoy, articles - anything. I will be grateful.

Answer 1

From Winapi you will need one function - SendMessage. Find the rest on MSDN.
Also keep in mind that there are a bunch of ready-made automatizers, like autoit.

Answer 2

AutoIt

AutoIt v3 is a freeware BASIC-like scripting language designed for automating the Windows GUI and general scripting. It uses a combination of simulated keystrokes, mouse movement and window/control manipulation in order to automate tasks in a way not possible or reliable with other languages ​​(eg VBScript and SendKeys). AutoIt is also very small, self-contained and will run on all versions of Windows out-of-the-box with no annoying “runtimes” required!