using System;
using System.Collections.Generic;

namespace DeukBot4.Utilities
{
    public class EnglishNumberParser
    {
        private static readonly Dictionary<string, int> OneValues = new Dictionary<string, int>()
        {
            {"zero", 0}, {"a", 1}, {"an", 1}, {"one", 1}, {"two", 2}, {"three", 3}, {"four",4}, {"five", 5}, {"six", 6}, {"seven", 7},
            {"eight", 8}, {"nine", 9}
        };
        private static readonly Dictionary<string, int> TenValues = new Dictionary<string, int>()
        {
            {"ten", 10}, {"eleven", 11}, {"twelve", 12}, {"thirteen", 13}, {"fourteen", 14}, {"fifteen", 15},
            {"sixteen", 16}, {"seventeen", 17}, {"eighteen", 18}, {"nineteen", 19},

            {"twenty", 20}, {"thirty", 30}, {"forty",40}, {"fifty", 50}, {"sixty", 60}, {"seventy", 70},
            {"eighty", 80}, {"ninety", 90}
        };
        private static readonly Dictionary<string, int> HundredsValues = new Dictionary<string, int>()
        {
            {"hundred", 100}, {"thousand",1000}, {"million", 1_000_000}
        };


        public static bool ConvertNumberString(string numberString, out double number)
        {
            numberString = numberString.Replace("-", "").Replace(" ", "");
            var i = 0;
            while (numberString.Length > 0)
            {
                var next = ConvertNextNumber(ref numberString);
                if (!next.HasValue)
                {
                    number = 0;
                    return false;
                }
                i += next.Value;
            }
            number = i;
            return true;
        }

        private static int? ConvertNextNumber(ref string numberString)
        {
            foreach (var oneValue in OneValues)
            {
                if (numberString.EndsWith(oneValue.Key, StringComparison.InvariantCultureIgnoreCase))
                {
                    numberString =  numberString.Substring(0, numberString.Length - oneValue.Key.Length);
                    return oneValue.Value;
                }
            }
            foreach (var oneValue in TenValues)
            {
                if (numberString.EndsWith(oneValue.Key, StringComparison.InvariantCultureIgnoreCase))
                {
                    numberString =  numberString.Substring(0, numberString.Length - oneValue.Key.Length);
                    return oneValue.Value;
                }
            }
            foreach (var oneValue in HundredsValues)
            {
                if (numberString.EndsWith(oneValue.Key, StringComparison.InvariantCultureIgnoreCase))
                {
                    numberString =  numberString.Substring(0, numberString.Length - oneValue.Key.Length);
                    var value = oneValue.Value;
                    var next = ConvertNextNumber(ref numberString);
                    if (next.HasValue)
                    {
                        if ((int)Math.Log10(next.Value) <= (int)Math.Log10(value))
                            value *= next.Value;
                        else
                        {
                            value += next.Value;
                        }
                    }
                    return value;
                }
            }

            return null;
        }


        public static string GetShortOrdinalNumber(int number)
        {
            var tensDigit = number % 100 / 10;
            if (tensDigit == 1) return $"{number}th";
            switch (number % 10)
            {
                case 1: 
                    return $"{number}st";
                case 2: 
                    return $"{number}nd";
                case 3:
                    return $"{number}rd";
                default:
                    return $"{number}th";
            }

        }
    }
}