using System;
using System.Collections.Generic;

namespace Global.API.Util
{
    public static class CollectionUtils
    {
        public static TV ComputeIfAbsent<TK, TV>(this Dictionary<TK, TV> self, TK key, Func<TK, TV> valueCreator)
        {
            if (self.ContainsKey(key))
                return self[key];
            var val = valueCreator(key);
            self.Add(key, val);
            return val;
        }

        public static void SetOrAdd<TK, TV>(this Dictionary<TK, TV> self, TK key, Func<TK, TV> valueCreator,
            Func<TV, TV> valueIncrement)
        {
            if (self.ContainsKey(key))
            {
                var current = self[key];
                self.Remove(key);
                self.Add(key, valueIncrement(current));
                return;
            }

            var val = valueCreator(key);
            self.Add(key, val);
        }

        public static bool TryGetElementAt<T>(this IReadOnlyList<T> self, int index, out T foundValue)
        {
            if (self.Count < index + 1)
            {
                foundValue = default;
                return false;
            }

            foundValue = self[index];
            return true;
        }

        public static T GetElementAtIndexOrElse<T>(this IReadOnlyList<T> self, int index, T defaultValue)
        {
            return self.TryGetElementAt(index, out var e) ? e : defaultValue;
        }
    }
}