Update how bots register handlers

[byrnereese]

I would like to find a simpler way for bots to register handlers for different events. Right now, a bot consists mainly of a generic event handler. For example:

const botHandler = async event => {
    console.log(`Received ${event.type} event`)
    switch (event.type) {
    case 'Message4Bot':
        await handleBotMessage(event)
        break
    case 'Message4Others':
        await handleMessage(event)
        break
    default:
        console.log('Unknown event type: ' + event.type)
        break
    }
}

In your main index.js file you then register this handler like so:

const app = express();
var skills = []
var botOptions = {}
extendApp(app, skills, botHandler, botOptions);

Express registers handlers like so:

app.get('/zendesk/oauth', async (req, res) => {
    // do something
})

I would love it if bots could register event handlers in a similar fashion. The events I think bots can register handlers for are:

• Processing any URLs/links found in a post
• Processing commands transmitted to a bot, e.g. @botName command param
• Processing interactive messaging events, e.g. submitting adaptive card forms
• Processing messaging events, e.g. Message4Bot, PostAdded, BotDeleted, etc.

And I would love the registration of these handlers to be similar to express. Here is some pseudocode:

const app = express();
extendApp( app )
app.onUrl( function ( url, bot, response ) {
    // some logic
    response.postCard( adaptiveCard )
})
app.onCardSubmit( "action_name", function ( data, response ) {
    let variable = data.form_element_id
    // some logic
    response.postDialog( dialog )
})
app.onMessage4Bot( function ( event, response ) {
    response.postMessage( "hello" )
})
app.onBotCommand( 'command name', function ( args, response ) {
    let name = args[1]
    if (something_went_wrong) {
          throw BotError("this message will be displayed in a dialog")
    }
    response.postMessage( "hello " + name )
})

A few things I would like to point out:

• The developer need only register callbacks/handlers for all the events we support.
• Events handlers all receive a response object of some kind, and the developer uses this response object to perform common actions, e.g. posting messages/dialogs/cards as a response to the event/user
• There is a consistent way to transmit errors and for those errors to be communicated to the user