using System;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;

namespace InspectorToolkit {
    public static class MyCollections {
        /// <summary>
        /// Returns new array with inserted empty element at index
        /// </summary>
        public static T[] InsertAt<T>(this T[] array, int index) {
            if(index < 0) {
                Debug.LogError("Index is less than zero. Array is not modified");
                return array;
            }

            if(index > array.Length) {
                Debug.LogError("Index exceeds array length. Array is not modified");
                return array;
            }

            T[] newArray = new T[array.Length + 1];
            int index1 = 0;
            for(int index2 = 0; index2 < newArray.Length; ++index2) {
                if(index2 == index) continue;

                newArray[index2] = array[index1];
                ++index1;
            }

            return newArray;
        }

        #region IsNullOrEmpty and NotNullOrEmpty

        /// <summary>
        /// Is array null or empty
        /// </summary>
        public static bool IsNullOrEmpty<T>(this T[] collection) => collection == null || collection.Length == 0;

        /// <summary>
        /// Is list null or empty
        /// </summary>
        public static bool IsNullOrEmpty<T>(this IList<T> collection) => collection == null || collection.Count == 0;

        /// <summary>
        /// Is collection null or empty. IEnumerable is relatively slow. Use Array or List implementation if possible
        /// </summary>
        public static bool IsNullOrEmpty<T>(this IEnumerable<T> collection) => collection == null || !collection.Any();

        public static bool NotNullOrEmpty<T>(this IEnumerable<T> collection) => !collection.IsNullOrEmpty();

        #endregion


        /// <summary>
        /// Performs a function on each element of a collection.
        /// </summary>
        public static IEnumerable<T> ForEach<T, R>(this IEnumerable<T> source, Func<T, R> func) {
            foreach(T element in source) func(element);
            return source;
        }
    }
}