const map = new Map([['a', 1], ['b', 2]])
const set = new Set([1, 2])
const arr = [1,2]
const obj = {a: 1, b: 2}
const str = "asdf" as string;
const num = 1 as number;
const bool = true as boolean;
const fn = () => {};
class Clazz { static staticProp = 1; instanceProp = 2; }
const classInstance = new Clazz();

const mapArr = [...map] // === [['a', 1], ['b', 2]]
const mapObj = {...map} // === {}

const setArr = [...set] // === [1, 2]
const setObj = {...set} // === {}

const arrArr = [...arr] // === [1, 2]
const arrObj = {...arr} // === {0: 1, 1: 2}

const objArr = [...obj] // compile time error: Type '{ a: number; b: number; }' must have a '[Symbol.iterator]()' method that returns an iterator.
                        // runtime error     : Uncaught TypeError: object is not iterable (cannot read property Symbol(Symbol.iterator))
const objObj = {...obj} // === {a: 1, b: 2}

const strArr = [...str]; // === ['a', 's', 'd', 'f']
const strObj = {...str}; // === {0: 'a', 1: 'b', 2: 'd', 3: 'f'}
                         // compile time error: Spread types may only be created from object types.
                         
const numArr = [...num]; // compile time error: Type 'number' must have a '[Symbol.iterator]()' method that returns an iterator.
                         // runtime error     : Uncaught TypeError: 1 is not iterable
const numObj = {...num}; // === {}
                         // compile time error: Spread types may only be created from object types.
                         
const boolArr = [...bool]; // compile time error: Type 'boolean' must have a '[Symbol.iterator]()' method that returns an iterator.
                           // runtime error     : Uncaught TypeError: true is not iterable
const boolObj = {...bool}; // === {}
                           // compile time error: Spread types may only be created from object types.

const fnArr = [...fn]; // compile time error: Type '() => void' must have a '[Symbol.iterator]()' method that returns an iterator.
                       // runtime error     : Uncaught TypeError: fn is not iterable
const fnObj = {...fn}; // === {}
                       // generally undesirable though

const classDeclArr = [...Clazz]; // compile time error: Type 'typeof Clazz' must have a '[Symbol.iterator]()' method that returns an iterator.
                                 // runtime error     : Uncaught TypeError: Clazz is not iterable
const classDeclObj = {...Clazz}; // === {staticProp: 1}

const classInstanceArr = [...classInstance]; // compile time error: Type 'Clazz' must have a '[Symbol.iterator]()' method that returns an iterator.
                                             // runtime error     : Uncaught TypeError: classInstance is not iterable
const classInstanceObj = {...classInstance}; // === {instanceProp: 2}

import { ESLintUtils, TSESLint, TSESTree } from '@typescript-eslint/utils';

import { ruleCreator } from '../utils';

export const noSpreadFunction = ruleCreator({
  defaultOptions: [],
  meta: {
    docs: {
      description: '',
      recommended: false,
    },
    messages: {
      forbidden: 'Spreading a function is almost always a mistake.',
    },
    schema: [],
    type: 'problem',
  },
  create: (context): TSESLint.RuleListener => {
    const listener = (node: TSESTree.SpreadElement): void => {
      const svc = ESLintUtils.getParserServices(context);
      const tc = svc.program.getTypeChecker();

      const tsNode = svc.esTreeNodeToTSNodeMap.get(node.argument);
      const type = tc.getTypeAtLocation(tsNode);

      if (type.getCallSignatures().length > 0) {
        context.report({
          node,
          messageId: 'forbidden',
        });
      }
    };
    return {
      SpreadElement: listener,
    };
  },
});