using System;
using System.Collections.Generic;
using AppConv.General;

namespace AppConv.Utils {
	static class SI {
		private static readonly List<Tuple<string, string, int>> Factors = new List<Tuple<string, string, int>> {
			new Tuple<string, string, int>("yotta", "Y", 24),
			new Tuple<string, string, int>("zetta", "Z", 21),
			new Tuple<string, string, int>("exa", "E", 18),
			new Tuple<string, string, int>("peta", "P", 15),
			new Tuple<string, string, int>("tera", "T", 12),
			new Tuple<string, string, int>("giga", "G", 9),
			new Tuple<string, string, int>("mega", "M", 6),
			new Tuple<string, string, int>("kilo", "k", 3),
			new Tuple<string, string, int>("hecto", "h", 2),
			new Tuple<string, string, int>("deca", "da", 1),
			new Tuple<string, string, int>("deci", "d", -1),
			new Tuple<string, string, int>("centi", "c", -2),
			new Tuple<string, string, int>("milli", "m", -3),
			new Tuple<string, string, int>("micro", "μ", -6),
			new Tuple<string, string, int>("nano", "n", -9),
			new Tuple<string, string, int>("pico", "p", -12),
			new Tuple<string, string, int>("femto", "f", -15),
			new Tuple<string, string, int>("atto", "a", -18),
			new Tuple<string, string, int>("zepto", "z", -21),
			new Tuple<string, string, int>("yocto", "y", -24)
		};

		public static void AddSupport<T>(Type enumType, T unitObject, string[] unitShortNames, string[] unitLongNames, DecimalUnitConverterBase<T>.DecimalFuncMap funcFrom, DecimalUnitConverterBase<T>.DecimalFuncMap funcTo, DecimalUnitConverterBase<T>.NameMap nameMap) where T : struct {
			int enumCounter = 1000 + Factors.Count * (int) (object) unitObject;

			Func<decimal, decimal> convertFrom = funcFrom[unitObject];
			Func<decimal, decimal> convertTo = funcTo[unitObject];

			foreach (Tuple<string, string, int> factor in Factors) {
				T enumObject = (T) (object) enumCounter++;
				int exponent = factor.Item3;

				foreach (string unitShortName in unitShortNames) {
					nameMap.Add(factor.Item2 + unitShortName, enumObject);
				}

				foreach (string unitLongName in unitLongNames) {
					nameMap.Add(factor.Item1 + unitLongName, enumObject);
				}

				funcFrom.Add(enumObject, val => convertFrom(val) * (decimal) Math.Pow(10, -exponent));
				funcTo.Add(enumObject, val => convertTo(val) * (decimal) Math.Pow(10, exponent));
			}
		}

		public static void AddSupportCustom<T>(Type enumType, T unitObject, string[] unitShortNames, string[] unitLongNames, DecimalUnitConverterBase<T>.DecimalFuncMap funcFrom, DecimalUnitConverterBase<T>.DecimalFuncMap funcTo, DecimalUnitConverterBase<T>.NameMap nameMap, ExtededProperties extendedProps) where T : struct {
			int enumCounter = 1000 + Factors.Count * (int) (object) unitObject;

			Func<decimal, decimal> convertFrom = funcFrom[unitObject];
			Func<decimal, decimal> convertTo = funcTo[unitObject];

			foreach (Tuple<string, string, int> factor in Factors) {
				if (extendedProps.FactorPredicate != null && !extendedProps.FactorPredicate(factor.Item3)) {
					continue;
				}

				T enumObject = (T) (object) enumCounter++;
				int exponent = factor.Item3;

				foreach (string unitShortName in unitShortNames) {
					nameMap.Add(factor.Item2 + unitShortName, enumObject);
				}

				foreach (string unitLongName in unitLongNames) {
					nameMap.Add(factor.Item1 + unitLongName, enumObject);
				}

				Func<decimal> genFrom = extendedProps.FromFunctionGenerator(exponent);
				Func<decimal> genTo = extendedProps.ToFunctionGenerator(exponent);

				funcFrom.Add(enumObject, val => convertFrom(val) * genFrom());
				funcTo.Add(enumObject, val => convertTo(val) * genTo());
			}
		}

		internal class ExtededProperties {
			public Predicate<int> FactorPredicate { get; set; }
			public Func<int, Func<decimal>> FromFunctionGenerator { get; set; }
			public Func<int, Func<decimal>> ToFunctionGenerator { get; set; }
		}
	}
}