In this video, I am going to make a bot

and I am going to make an image bot

and I'm very excited about this project

because it pulls together a whole lot of different things.

I am going to use processing to generate an image.

I am going to use node to call processing

to generate the image and I'm going to use node

to talk to an API and the API is Mastodon.

So one thing you might want to do

is I'll refer you to all of my,

a tutorial series about the basics of making

a Mastodon bot, I will start largely from scratch here,

but I am going, I've already gotten my API keys

and I already have imported and installed

this node package called mastodon.api

and this .env package that loads my API keys for me.

So that is stuff that I've done in another video.

If you want to see that, I'll link to that

in the video description but I'm just going to get started.

So what is the first thing that I want to do?

Okay, actually, let's go to, so this is my inspiration.

Tree bot, made by Alix Novosi for National Bot Making Month

and I am going to try to recreate this.

My trees won't be nearly as nice.

So the first thing I want to do is I want to use processing.

I don't have to, I could find some node package

that does drawing or generates an image,

svg, whatever, but I love processing, it's my happy place

and I'm pretty sure I could get processing

to generate a tree, in fact, I don't even have to write

the code for this because I have before.

I'm just going to go to examples, right,

isn't it in here somewhere?

Topics, simulate,

no, no, no?

Okay, I'll be back in a second.

Oh yeah, I'm back, I found it under fractals

and L-systems tree.

Well look, recursive tree by Daniel Shiffman.

This is my, this is a recursive tree

and as I move the mouse, it changes the angle.

So let's alter this code a little bit.

Let's say that, we don't care about a frame rate.

And let's not, let's have the angle be random

between 0 and two pi.

Oh and it's converting it to radians,

so okay, between 0 and 360.

Whoa and it's doing it over and over again in draw,

that's exciting, I'm going to say no loop

so it's done each time I run this.

I get a random tree.

There's so much more that I could do to the design

of the tree and I'm so tempted to recode the tree

but I'm going to just leave it as is, ya know maybe I want

to not have so many large angles and there we go,

beautiful tree, okay.

So now, now that I've done that, what do I want?

I want my processing sketch to also save

and I'm just going to call it tree.png.

So when it's done drawing, it's going to save an image.

I've got my code here.

This is the code that will talk to the Mastodon service

and what I want is for this code to actually run

a processing sketch but this is node, this is JavaScript.

Processing is java and it's a desktop environment

where I hit the play button, how can I possibly do this?

Well the first thing I'm going to do is actually go

and save this processing sketch in where my bot is

and I'm actually working in this folder,

Mastodon bot 3, you can see node modules, bot.js,

so I'm going to save it there and I'm going to call it treegen.

So I'm going to save it treegen, I'm going to make sure

it still runs, it still runs.

And now, what I'm going to do,

I'm going to show you a little trick.

Now wouldn't it be nice if I could just execute

a command like processing run.

Of course, in terminal, in the shell,

it's not going to know what that is

but a little known fact about processing,

which I have done this in other videos before

but just to start anew again, processing command line.

There is actually a way to run a processing sketch

command line by saying processing-java,

the path to the sketch and then --run

but the only way you can do that is by installing first

processing.java to your system so this is installing

a command line command to run a processing sketch.

So I'm going to do this, install processing java,

I'm going to say yes for all users.

It's going to want to use my password.

So I'm going to enter my password 'cause it needs

to be able to put that where it needs to go

and now I can actually say processing-java

and you can see, I get all sorts of stuff.

It doesn't know what I want to do but watch this,

I can say, let me just look in here,

there is the treegen processing sketch.

So I can say processing-java, sketch=,

is that what it was?

Let's go look at the, sketch=, now I need the full path

so the full path and I'm going to show you a way around this

in a second, is this, treegen, right,

this is the full path to that processing sketch.

Then I can say --run, here we go.

Magic.

It ran it, look, there's the processing sketch.

This is really cool, now watch.

What's exciting about this and it's bothering me

that the background isn't 51 which is very important.

I can actually quit processing completely.

I don't need to have processing open and still do this.

Look at that, there it is.

There's my tree, ah, but I actually do want

to have processing open 'cause I've got

a little bit of a problem here and we can see here,

look, that image is there, it's now saved.

What I want to do is go back and open this again,

open, open, open, open, open and I want to add one thing.

I want it to go away so I actually want to say

after I save it, exit, and I'm also,

this is going to be helpful for me later,

I want to say println("Tree generated");

We'll see where this comes up later.

Okay, now, quit processing.

And now I'm going to run this.

See it, there it is, oh, finished, tree generated, finished.

One more time.

There it is, oh, finished.

Okay, this is really exciting

'cause there's so much stuff you could do.

Now, here's the thing.

I am executing this command via the shell

but I want node to execute it.

How can I execute it in node and it turns out

there is a way to execute any generic shell command

from node and it is with the child process package.

So if I go to child process, you'll see here

that there is a method called exec.

Child_process.exec spawns a shell

and runs a command within that shell.

Truth of the matter is it might useful to use

this execSync because I'm going to want to,

sync means synchronous, meaning wait until it's done

to go on to the next thing but I've got a crazy plan here.

I want to do asynchronous stuff with es8,

this await and async function,

you may or may not have heard about.

So I'm going to use this one, exec.

So what I need to do is in my node code,

I need to say const exec = require('')

and where was this, it is in child process.exec,

child_process, no there's no, yeah, that's right, huh,

oh .exec, yes I'm confused.

So this is me requiring the child process package

and I don't have to mpm install this.

You'll notice that I'm on the node.js documentation page.

I'm not in some separate third party mpm package,

this is built into node, but, just like file system is.

But I've got to say that I want to use it.

So require child process and all I want

is that exec function.

So now, there's no reason why I can't just say

exec and then pass in what?

Exactly this.

Oh let me make, this is so unwieldy.

So a nice little trick that I can do

is I can actually always get the current path.

If I want to get the current, I just type pwd,

print working directory.

Well guess what?

I can actually have pwd executed within this command

by using these back ticks.

I'm pretty sure this is how I do it.

So now I'm saying run and I think I don't actually even need

this first slash, right, run sketch =

print working directory, then treegen run.

Let's see if this works.

It is done, okay.

So now, so great so I can grab this, this is my command.

We're going to get to the Mastodon stuff in a second.

Uh (clicking tongue).

Constant command = let's just put this

in a variable like this.

Then I could say exec command and then that's going to have

a callback, oh, I don't want the,

let me just run this, let's just run this,

let's see what happens.

Node bot.js.

Hey, look what happened, it made it happen.

Now here's the thing, the next thing I was going to do

was add a callback but I'm a new,

I'm turning over a new leaf, I'm turning a new page

in the book of JavaScript and I'm a kind of person

who uses promises and I'm not only a kind of person

uses promises, I even use the async and await keyword

to really make my life full of just (sighs) ease.

Eh, it's not full of ease but I'm doing my best.

So what does that mean?

The thing is, this particular node package,

child process.exec, and I have a feeling if I bother

to look at the chat (laughs) which I'm going to open up

for a second, someone's going to tell me I could just use

something else now that natively supports promises.

Oh I'm being told that node.js has underscore

directory names so there are other ways,

people are telling me other ways I could get

the directory name but what I'm going to do

is I'm going to promisify, which is a word apparently,

promisify, I'm going to, oh look at this,

I must have googled this another time,

unless it's just very common, by using java,

not java, sorry, the node package util.

So node package util, if I go look at util

and I actually just want to be here,

there is a promisify,

util.promisify.

So what I can actually do is I can say

const util = require('util') and then I can say

util.promisify, what a weird word,

what happens if I promisify myself, uh, this.

So now, this require child process exec function

no longer uses a callback, now it uses a promise

and what does that mean?

That means I can say .then and whatever

the result, the response is.

I can console log that response.

And then I can also catch any error

and I console.error that error.

Now, this might be and there's no semicolon there,

there's a semicolon there.

This might look completely insane to you

if you haven't seen promises used before in JavaScript.

It's very similar to a callback but instead of saying

a callback, I basically have this callback

that happens in .then.

I'm also using the arrow syntax.

The arrow syntax is a nice way of sort of shorthanding this.

I'm getting the response as the argument to the callback

and I'm console logging it.

So if you want to know about those things,