import {
  isFunction,
  filter,
  map,
  uniqBy,
  keys,
  difference,
  join,
  reduce,
  find,
} from "lodash/fp"
import { compileExpression, compileCode } from "../common/compileCode"
import { $ } from "../common"
import { _executeAction } from "./execute"
import { BadRequestError, NotFoundError } from "../common/errors"

export const initialiseActions = (
  subscribe,
  behaviourSources,
  actions,
  triggers,
  apis
) => {
  validateSources(behaviourSources, actions)
  subscribeTriggers(subscribe, behaviourSources, actions, triggers, apis)
  return createActionsCollection(behaviourSources, actions)
}

const createActionsCollection = (behaviourSources, actions) =>
  $(actions, [
    reduce((all, a) => {
      all[a.name] = opts => _executeAction(behaviourSources, a, opts)
      return all
    }, {}),
  ])

const subscribeTriggers = (
  subscribe,
  behaviourSources,
  actions,
  triggers,
  apis
) => {
  const createOptions = (optionsCreator, eventContext) => {
    if (!optionsCreator) return {}
    const create = compileCode(optionsCreator)
    return create({ context: eventContext, apis })
  }

  const shouldRunTrigger = (trigger, eventContext) => {
    if (!trigger.condition) return true
    const shouldRun = compileExpression(trigger.condition)
    return shouldRun({ context: eventContext })
  }

  for (let trig of triggers) {
    subscribe(trig.eventName, async (ev, ctx) => {
      if (shouldRunTrigger(trig, ctx)) {
        await _executeAction(
          behaviourSources,
          find(a => a.name === trig.actionName)(actions),
          createOptions(trig.optionsCreator, ctx)
        )
      }
    })
  }
}

const validateSources = (behaviourSources, actions) => {
  const declaredSources = $(actions, [
    uniqBy(a => a.behaviourSource),
    map(a => a.behaviourSource),
  ])

  const suppliedSources = keys(behaviourSources)

  const missingSources = difference(declaredSources, suppliedSources)

  if (missingSources.length > 0) {
    throw new BadRequestError(
      `Declared behaviour sources are not supplied: ${join(
        ", ",
        missingSources
      )}`
    )
  }

  const missingBehaviours = $(actions, [
    filter(
      a => !isFunction(behaviourSources[a.behaviourSource][a.behaviourName])
    ),
    map(a => `Action: ${a.name} : ${a.behaviourSource}.${a.behaviourName}`),
  ])

  if (missingBehaviours.length > 0) {
    throw new NotFoundError(
      `Missing behaviours: could not find behaviour functions: ${join(
        ", ",
        missingBehaviours
      )}`
    )
  }
}