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

namespace SpellProbability
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //SpellbookToIndependent();
            IndependentToSpellbook();
        }

        /// <summary>
        /// Converts a monster spellbook to a list of independent probabilities
        /// </summary>
        public static void SpellbookToIndependent()
        {
            var chances = new List<float>() { 0.5f, 0.5f };

            Console.WriteLine($"Spellbook probabilities: {string.Join(", ", chances.Select(i => PercentFormat(i)))}\n");

            var castChance = GetProbabilityAny(chances);

            Console.WriteLine($"Total casting chance: {PercentFormat(castChance)}\n");

            for (var i = 0; i < chances.Count; i++)
            {
                var prevChanceNone = i > 0 ? GetProbabilityNone(chances.GetRange(0, i)) : 1.0f;

                Console.WriteLine($"Chance of casting spell #{i + 1}: {PercentFormat(chances[i] * prevChanceNone)}");
            }
        }

        /// <summary>
        /// Converts a list of independent probabilities to monster spellbook format
        /// </summary>
        public static void IndependentToSpellbook()
        {
            var chances = new List<float>() { 0.25f, 0.25f, 0.25f, 0.25f };

            Console.WriteLine($"Independent probabilities (cannot go above 100% additive): {string.Join(", ", chances.Select(i => PercentFormat(i)))}\n");

            var spellbook = new List<float>();

            for (var i = 0; i < chances.Count; i++)
            {
                var prevChanceNone = i > 0 ? GetProbabilityNone(spellbook) : 1.0f;

                spellbook.Add(chances[i] / prevChanceNone);
            }

            Console.WriteLine($"Spellbook format: {string.Join(", ", spellbook.Select(i => PercentFormat(i)))}\n");
        }

        /// <summary>
        /// Returns the probability of none of the events occurring
        /// from a list of chances
        /// </summary>
        public static float GetProbabilityNone(List<float> chances)
        {
            var probability = 1.0f;

            foreach (var chance in chances)
                probability *= 1.0f - chance;

            return probability;
        }

        /// <summary>
        /// Returns the probability of any of the events occurring
        /// from a list of chances
        /// </summary>
        public static float GetProbabilityAny(List<float> chances)
        {
            return 1.0f - GetProbabilityNone(chances);
        }

        public static string PercentFormat(float percent)
        {
            return $"{Math.Round(percent * 100, 2)}%";
        }
    }
}