Basic plugin management tool

[geezee]

The point of this pull request is to make a system where everyone can control the rendered note. Presently I'm forcing asciinema and mathjax down users' throats, maybe someone doesn't want these.

Introducing the plugin system

A plugin is an anonymous function that takes the note of a body (string), and the note (object) and must return a promise of HTML (string). For example, here's the code for the markdown plugin:

function (body) {
    return loadScript('showdown', 'js/showdown.min.js')
    .then(() => {
        return new showdown.Converter().makeHtml(body);
    });
}

It makes use of loadScript(name, url) common function which returns a promise which will get resolved right after loading the script at the provided URL.

A plugin should be registered in the repository located in resources/note-format/repository.json under the format:

{
    "name": "plugin name",
    "description": "a small description",
    "src": "src\/plugin-source.js",
}

Here's how to use the plugin manager:

> php artisan note-format:list
  1. markdown             - Renders the note in markdown
  2. mathjax              - Render LaTeX equations inside the note
  3. markdown             - Renders the note in markdown

will list the installed plugins in order of execution.

> php artisan note-format:list --all
5 available formatters

* markdown             - Renders the note in markdown
  iframe               - Play around with iframe attributes or block them
* mathjax              - Render LaTeX equations inside the note
  asciinema            - Use $asciinema(attachment_url) to include an asciinema cast
  js-eval              - Evaluate javascript code and display output in an <iframe>

will list all the plugins in the repository.

> php artisan note-format:install markdown asciinema --after=2
> php artisan note-format:list
  1. markdown             - Renders the note in markdown
  2. mathjax              - Render LaTeX equations inside the note
  3. markdown             - Renders the note in markdown
  4. asciinema            - Use $asciinema(attachment_url) to include an asciinema cast
  5. markdown             - Renders the note in markdown

will install the markdown and asciinema plugins after the second plugin.

> php artisan note-format:remove 3
> php artisan note-format:list
  1. markdown             - Renders the note in markdown
  2. mathjax              - Render LaTeX equations inside the note
  3. asciinema            - Use $asciinema(attachment_url) to include an asciinema cast
  4. markdown             - Renders the note in markdown

will remove the third plugin. Unfortunately it does not support multiple indeces, unlike the install rule.

php artisan note-format:compile

will produce the output javascript file.

What it actually does

It generates a file in resources/note-format/note-format.out.js which is an array of the formatters to be applied in order.

bundle-js should be executed after every compilation

Available formatters

markdown

Will load Showdown and render the body to HTML.

mathjax

Will load MathJax and will render equations.

asciinema

Will replace all instances of $asciinema(attachement-name.cast) with an asciinema player

iframe

Will set a sandbox around all iframes. The set value is "allow-scripts allow-same-origin allow-forms"

js-eval

Evaluates all the javascript code that starts with !eval on its first line. The output is displayed inside a sandboxed iframe with only allow-scripts. For example if the note contains the code:

```js
!eval
for (var i=0; i < 10; i++) {
    document.write('hello world!<br>');
}
```

Then this javascript is executed in an iframe that will show "hello world!" 10 times, each on a line.