const {EventEmitter} = require('promise-events')
const express = require('express')
const Context = require('./context')
const logger = require('./logger')
const GitHubApi = require('./github')
/**
* The `robot` parameter available to apps
*
* @property {logger} log - A logger
*/
class Robot {
constructor ({app, cache, router, catchErrors} = {}) {
this.events = new EventEmitter()
this.app = app
this.cache = cache
this.router = router || new express.Router()
this.log = logger.wrap()
this.catchErrors = catchErrors
}
async receive (event) {
return this.events.emit('*', event).then(() => {
return this.events.emit(event.event, event)
})
}
/**
* Get an {@link http://expressjs.com|express} router that can be used to
* expose HTTP endpoints
*
* @example
* module.exports = robot => {
* // Get an express router to expose new HTTP endpoints
* const app = robot.route('/my-app');
*
* // Use any middleware
* app.use(require('express').static(__dirname + '/public'));
*
* // Add a new route
* app.get('/hello-world', (req, res) => {
* res.end('Hello World');
* });
* };
*
* @param {string} path - the prefix for the routes
* @returns {@link http://expressjs.com/en/4x/api.html#router|express.Router}
*/
route (path) {
if (path) {
const router = new express.Router()
this.router.use(path, router)
return router
} else {
return this.router
}
}
/**
* Listen for [GitHub webhooks](https://developer.github.com/webhooks/),
* which are fired for almost every significant action that users take on
* GitHub.
*
* @param {string} event - the name of the [GitHub webhook
* event](https://developer.github.com/webhooks/#events). Most events also
* include an "action". For example, the * [`issues`](
* https://developer.github.com/v3/activity/events/types/#issuesevent)
* event has actions of `assigned`, `unassigned`, `labeled`, `unlabeled`,
* `opened`, `edited`, `milestoned`, `demilestoned`, `closed`, and `reopened`.
* Often, your bot will only care about one type of action, so you can append
* it to the event name with a `.`, like `issues.closed`.
*
* @param {Robot~webhookCallback} callback - a function to call when the
* webhook is received.
*
* @example
*
* robot.on('push', context => {
* // Code was just pushed.
* });
*
* robot.on('issues.opened', context => {
* // An issue was just opened.
* });
*/
on (event, callback) {
if (event.constructor === Array) {
event.forEach(e => this.on(e, callback))
return
}
const [name, action] = event.split('.')
return this.events.on(name, async event => {
if (!action || action === event.payload.action) {
const log = this.log.child({name: 'event', id: event.id})
try {
const github = await this.auth(event.payload.installation.id, log)
const context = new Context(event, github, log)
await callback(context)
} catch (err) {
log.error({err, event})
if (!this.catchErrors) {
throw err
}
}
}
})
}
/**
* Authenticate and get a GitHub client that can be used to make API calls.
*
* You'll probably want to use `context.github` instead.
*
* **Note**: `robot.auth` is asynchronous, so it needs to be prefixed with a
* [`await`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/await)
* to wait for the magic to happen.
*
* @example
*
* module.exports = function(robot) {
* robot.on('issues.opened', async context => {
* const github = await robot.auth();
* });
* };
*
* @param {number} [id] - ID of the installation, which can be extracted from
* `context.payload.installation.id`. If called without this parameter, the
* client wil authenticate [as the app](https://developer.github.com/apps/building-integrations/setting-up-and-registering-github-apps/about-authentication-options-for-github-apps/#authenticating-as-a-github-app)
* instead of as a specific installation, which means it can only be used for
* [app APIs](https://developer.github.com/v3/apps/).
*
* @returns {Promise<github>} - An authenticated GitHub API client
* @private
*/
async auth (id, log = this.log) {
const github = new GitHubApi({
debug: process.env.LOG_LEVEL === 'trace',
host: process.env.GHE_HOST || 'api.github.com',
pathPrefix: process.env.GHE_HOST ? '/api/v3' : '',
logger: log.child({name: 'github', installation: id})
})
if (id) {
const res = await this.cache.wrap(`app:${id}:token`, () => {
log.trace(`creating token for installation`)
github.authenticate({type: 'integration', token: this.app()})
return github.apps.createInstallationToken({installation_id: id})
}, {ttl: 60 * 59}) // Cache for 1 minute less than GitHub expiry
github.authenticate({type: 'token', token: res.data.token})
} else {
github.authenticate({type: 'integration', token: this.app()})
}
return github
}
}
module.exports = (...args) => new Robot(...args)
/**
* Do the thing
* @callback Robot~webhookCallback
* @param {Context} context - the context of the event that was triggered,
* including `context.payload`, and helpers for extracting information from
* the payload, which can be passed to GitHub API calls.
*
* ```js
* module.exports = robot => {
* robot.on('push', context => {
* // Code was pushed to the repo, what should we do with it?
* robot.log(context);
* });
* };
* ```
*/
/**
* A [GitHub webhook event](https://developer.github.com/webhooks/#events) payload
*
* @typedef payload
*/