import * as express from "express"
import * as _ from "lodash"
import * as isPromise from "is-promise"

import { UserError } from "./errors"

export class Server {

  app = express()
  controllers = {}

  endpoint(route, controllerName) {

    const [method, path] = route.split(' ')

    this.app[method.toLowerCase()](path, (req, res) => {

      const params = _.assign({}, req.body, req.params)

      const succeed = (data) => {
        res.json(data)
      }

      const fail = (e) => {
        if (e instanceof UserError) {
          res.status(e.statusCode || 500).json(e.data)
        } else {
          res.status(500).end()
        }
      }

      let result
      try {
        result = this.controllers[controllerName](params)
      } catch(e) {
        fail(e)
      }

      if (isPromise(result)) 
        result
          .then(succeed)
          .catch(fail)
      else
        succeed(result)
    })

    return this
  }

  hasController(name) {
    return this.controllers[name] !== undefined
  }

  controller(name, callback) {
    if (this.controllers[name] !== undefined)
      throw new Error(`controller ${name} already exists`)
    this.controllers[name] = callback
    return this
  }

  listen(port) {
    return new Promise((accept, reject) => {
      const http = this.app.listen(port, () => {
        accept(http)
      })
    })
  }

}

export default Server