Add support for Internationalization/Localization

[howdyai]

Add support for Internationalization/Localization

[RafaelCosman]

@rodrigoalviani, great point. This is important.

[peterswimm]

Created a new dev4slack channel, #botkit-localization to discuss this Feature Request. If you are interested, please join the conversation!

[znat]

For now I am doing the following (with i18n-node):

At bot initialization:

var i18n = require('i18n');
i18n.configure({...});
var bot = controller.spawn({...});
bot.i18n = i18n;

I wrote a middleware to add facebook messenger's user_profile to the message object:

{ text: 'ce soir',
  user: '123456789',
  channel: '/#QpmoHYNhZlvOzUXiAAAB', // socket id 
  timestamp: 1484084415264,
  user_profile: 
   { 
     first_name: 'Nathan',
     last_name: 'Zylbersztejn',
     locale: 'fr_CA',
     profile_pic: '<url>',
     timezone: -5,
     gender: 'male',
     is_payment_enabled: true,
     id: '123456789' },
  entities: {...} 
}

In the conversation:

 bot.createConversation(message, function (err, convo) {
        convo.setVar("user_profile",message.user_profile);
        convo.addMessage({
            text: bot.i18n.__({phrase:'reminder_confirmation',locale:convo.vars.user_profile.locale}),
            action: 'completed'
        },'set_reminder');
       // rest of convo...
}

It would make sense to have the user profile accessible in the convo (which is also semantically defined by the people who run it). This would avoid setting the variable and we could find a way to make i18n aware of it to avoid passing the locale at every translation.