import forEach from 'lodash/forEach'
import * as types from './types/sdk'

const subscriptions = (function() {
  const _subscriptions: types.Subscriptions = {}

  return {
    publish(eventName: string, data: any) {
      if (!Array.isArray(_subscriptions[eventName])) {
        _subscriptions[eventName] = []
      }
      forEach(_subscriptions[eventName], (fn) => fn && fn(data))
    },
    subscribe(eventName: string, fn: types.Fn) {
      if (!eventName) {
        console.warn(
          'WARNING! You tried to set an event listener but it was not successful ' +
            'because the eventName value was invalid. The event registration was skipped.',
        )
        return this
      }
      if (!Array.isArray(_subscriptions[eventName])) {
        _subscriptions[eventName] = []
      }
      _subscriptions[eventName].push(fn)
      return this
    },
    unsubscribe(eventName: string, fn: types.Fn) {
      if (!Array.isArray(_subscriptions[eventName])) return this
      for (let i = 0; i < _subscriptions[eventName].length; i++) {
        if (_subscriptions[eventName][i] === fn) {
          _subscriptions[eventName].splice(i, 1)
          break
        }
      }
      return this
    },
  }
})()

export default subscriptions