/**
 * Checks if two items are equal by value rather than reference
 * 
 * @param {*} item1 - The item in question
 * @param {*} item2 - An item to compare against
 * @returns {boolean}
 */
export function areEqual (item1: any, item2: any): boolean {
  const type1: string = typeof item1,
        type2: string = typeof item2;
  
  if (type1 !== type2) {
    return false;
  }

  switch (type1) {
    case 'object':
      return areObjectsEqual(item1, item2);
    default:
      return item1 === item2;
  }

  /**
   * Since the typeof an object and an array are 'object' in Javascript,
   * additional type checking is needed to determine if an object is an 
   * array or not.
   * 
   * @param item1 
   * @param item2 
   * @returns {boolean}
   */
  function areObjectsEqual (item1, item2): boolean {
    // typeof null === 'object', so we have to check for null with the object 
    // checks rather than with the other primitives
    if (item1 === null && item2 === null) {
      return true;
    }

    let isArray1: boolean = item1 instanceof Array,
        isArray2: boolean = item2 instanceof Array;

    if (isArray1 && isArray2) {
      return areArraysEqual(item1, item2)
    } else if (!isArray1 && !isArray2) {
      return areNonArrayObjectsEqual(item1, item2);
    } else {
      return false;
    }
  }

  /**
   * Checks if two arrays are equal
   * 
   * @param {*} array1 
   * @param {*} array2 
   * 
   * @returns {boolean}
   */
  function areArraysEqual (array1, array2): boolean {
    const len1: number = array1.length,
          len2: number = array2.length;
    
    if (len1 !== len2) {
      return false;
    } else {
      for (let i = 0; i < len1; i++) {
        const item1 = array1[i];
        const item2 = array2[i];

        if (!areEqual(item1, item2)) {
          return false;
        }
      }
      return true;
    }
  }

  /**
   * Check if two non-array objects are equal
   * 
   * @param {*} array1 
   * @param {*} array2 
   * 
   * @returns {boolean}
   */
  function areNonArrayObjectsEqual (obj1, obj2): boolean {
    const keys1 = Object.keys(obj1),
          keys2 = Object.keys(obj2),
          length = keys1.length;
    
    if (length !== keys2.length) {
      return false;
    }

    for (let i = 0; i < length; i++) {
      const item1 = obj1[keys1[i]];
      const item2 = obj2[keys2[i]];

      if (!areEqual(item1, item2)) {
        return false;
      }
    }

    return true;
  }
}