import { Calendar, mapHash } from '@fullcalendar/core'
import { ResourceAction } from './resources'
import { ResourceHash, ResourceInput, parseResource } from '../structs/resource'
import { ResourceSource } from '../structs/resource-source'

export default function(store: ResourceHash | undefined, action: ResourceAction, source: ResourceSource, calendar: Calendar): ResourceHash {
  switch (action.type) {

    case 'INIT':
      return {}

    case 'RECEIVE_RESOURCES':
      return receiveRawResources(store, action.rawResources, action.fetchId, source, calendar)

    case 'ADD_RESOURCE':
      return addResource(store, action.resourceHash)

    case 'REMOVE_RESOURCE':
      return removeResource(store, action.resourceId)

    case 'SET_RESOURCE_PROP':
      return setResourceProp(store, action.resourceId, action.propName, action.propValue)

    case 'RESET_RESOURCES':
      // must make the calendar think each resource is a new object :/
      return mapHash(store, function(resource) {
        return { ...resource }
      })

    default:
      return store
  }
}

function receiveRawResources(existingStore: ResourceHash, inputs: ResourceInput[], fetchId: string, source: ResourceSource, calendar: Calendar): ResourceHash {
  if (source.latestFetchId === fetchId) {
    let nextStore: ResourceHash = {}

    for (let input of inputs) {
      parseResource(input, '', nextStore, calendar)
    }

    return nextStore
  } else {
    return existingStore
  }
}

function addResource(existingStore: ResourceHash, additions: ResourceHash) {
  // TODO: warn about duplicate IDs

  return { ...existingStore, ...additions }
}

function removeResource(existingStore: ResourceHash, resourceId: string) {
  let newStore = { ...existingStore } as ResourceHash

  delete newStore[resourceId]

  // promote children
  for (let childResourceId in newStore) { // a child, *maybe* but probably not

    if (newStore[childResourceId].parentId === resourceId) {

      newStore[childResourceId] = {
        ...newStore[childResourceId],
        parentId: ''
      }
    }
  }

  return newStore
}

function setResourceProp(existingStore: ResourceHash, resourceId: string, name: string, value: any): ResourceHash {
  let existingResource = existingStore[resourceId]

  // TODO: sanitization

  if (existingResource) {
    return {
      ...existingStore,
      [resourceId]: {
        ...existingResource,
        [name]: value
      }
    }
  } else {
    return existingStore
  }
}