using System;

using System.Collections.Generic;

​

namespace DropCalc

{

    class Program

    {

        public class DropTable<T>

        {

            private Random _random = new Random();

            private List<DropTableEntry<T>> _entries = new List<DropTableEntry<T>>();

​

            /// <summary>

            /// Adds an item to the drop table.

            /// </summary>

            /// <param name="item">

            /// The item to add.

            /// </param>

            /// <param name="chance">

            /// The chance of the item (0..10000].

            /// </param>

            public void AddDrop(T item, int chance)

            {

                if (item == null)

                    throw new ArgumentNullException(nameof(item));

                if (chance <= 0 || chance > 10000)

                    throw new ArgumentOutOfRangeException(nameof(item));

​

                _entries.Add(new DropTableEntry<T>(item, chance, 1, 1));

            }

​

            /// <summary>

            /// Adds an item to the drop table allowing t

            /// </summary>

            /// <param name="item">

            /// The item to add.

            /// </param>

            /// <param name="chance">

            /// The chance of the item (0..10000].

            /// </param>

            /// <param name="min">

            /// The minimum amount that will drop.

            /// </param>

            /// <param name="max">

            /// The maximum amout that will drop. This may be the same as <paramref name="min"/>.

            /// </param>

            public void AddRangedDrop(T item, int chance, int min, int max)

            {

                if (item == null)

                    throw new ArgumentNullException(nameof(item));

                if (chance < 0 || chance > 10000)

                    throw new ArgumentOutOfRangeException(nameof(item));

​

                _entries.Add(new DropTableEntry<T>(item, chance, min, max));

            }

​

            /// <summary>

            /// Returns a list of the dropped items.

            /// </summary>

            /// <returns>

            /// A list of the dropped items.

            /// </returns>

            public List<Drop<T>> CalculateDrops()

            {

                List<Drop<T>> drops = new List<Drop<T>>(_entries.Count);

                foreach (var item in _entries)

                {

                    int roll = _random.Next(10000);

                    if (roll < item.Chance)

                    {

                        int count = _random.Next(item.Min, item.Max);

                        if (roll > 0)

                        {

                            drops.Add(new Drop<T>(item.Item, count));

                        }

                    }

                }

                return drops;

            }

        }

​

        internal class DropTableEntry<T>

        {

            internal DropTableEntry(T item, int chance, int min, int max)

            {

                Item = item;

                Chance = chance;

                Min = min;

                Max = max;

            }

​

            /// <summary>

            /// The dropped item.

            /// </summary>

            public T Item { get; }

​

            /// <summary>

            /// The chance of the item to drop in [0..10000].

            /// </summary>

            public int Chance { get; }

​

            /// <summary>

            /// The minimum stack size [0..N].

            /// </summary>

            public int Min { get; }

​

            /// <summary>

            /// The maximum stack size [minimum..N].

            /// </summary>

            public int Max { get; }

        }

​

        public class Drop<T>

        {

            internal Drop(T item, int count = 1)

            {

                Item = item;

                Count = count;

            }

​

            /// <summary>

            /// The dropped item.

            /// </summary>

            public T Item { get; }

​

            /// <summary>

            /// The number / stack size of the dropped item.

            /// </summary>

            public int Count { get; }

        }

​

        static void Main(string[] args)

        {

            DropTable<string> table = new DropTable<string>();

            table.AddDrop("Sword", 2500);                   // 25% chance to drop 1 sword

            table.AddDrop("Mushroom", 7500);                // 75% chance to drop a mushroom

            table.AddDrop("Mushroom", 7500);                // 75% chance to drop another mushroom

            table.AddRangedDrop("Dirt", 8500, 100, 100);    // 85% chance to drop 100 drirt

            table.AddRangedDrop("Gold", 10000, 100, 200);   // 100% chance to drop 100-200 gold

​

            for (int i = 0; i < 5; i++)

            {

                var drops = table.CalculateDrops();

​

                Console.WriteLine($"Drop {i + 1}");

                foreach (var drop in drops)

                {

                    Console.WriteLine($"{drop.Item} x{drop.Count}");

                }

​

                Console.WriteLine();

            }

        }

    }

}

​