import { isArray,
         isBoolean,
         isDate,
         isEmpty,
         isNaN,
         isNull,
         isNumber,
         isRegExp,
         isString,
         isUndefined,
        } from "lodash"

import { ChoiceFieldValue } from "../types/values"

/**
 * Returns a boolean value indiciating whether the object is blank/empty.
 * Values of null, undefined, and NaN are considered blank and the function will return true.
 *
 * View Documentation - https://learn.fulcrumapp.com/dev/expressions/reference/isblank/
 * @param value (ChoiceFieldValue|Any, required) item to be checked for blankness or emptiness;
 * @returns boolean value
 * @example
 * ISBLANK('') // returns true
 */

export default function ISBLANK(value: ChoiceFieldValue): boolean
export default function ISBLANK(value: any): boolean
export default function ISBLANK(): boolean
export default function ISBLANK(value?: any): boolean {
  // checking for a singular, non-object value
  if (isNaN(value) || isUndefined(value) || isNull(value)) { return true }
  if (isBoolean(value) || isNumber(value) || isDate(value) || isRegExp(value)) { return false }
  if (isString(value) || isArray(value)) { return isEmpty(value) }

  // checking for value as an object, assuming the appropriate keys
  if (value && (value.choice_values ||
                isNull(value.choice_values) ||
                value.other_values ||
                isNull(value.other_values))) {
                  const choice: any[]|null|undefined = value.choice_values
                  const others: any[]|null|undefined = value.other_values

                  const hasChoice: boolean = isArray(choice) && choice.length > 0
                  const hasOthers: boolean = isArray(others) && others.length > 0

                  return !(hasChoice || hasOthers)
                }
  // return true if an empty object (no keys) is passed, otherwise false
  return Object.keys(value).length < 1
}