﻿/*
MIT License

Copyright(c) 2019 Mitchel Thompson
www.angryarugula.com

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/


/*
        void Usage()
        {
            float meters = 7.5f;

            float yards = meters.ConvertUnits(Unit.Meters, Unit.Yards);

            Debug.Log(yards.ToString(Unit.Yards));
        }
*/

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

namespace Arugula.Math
{
    public enum Unit
    {
        //length
        Millimeters,
        Centimeters,
        Decimeters,
        Meters,
        Kilometers,
        Inches,
        Feet,
        Yards,
        Miles,
        //angle
        Degrees,
        Radians,
        //temperature
        Fahrenheit,
        Celsius,
        Kelvin,
        //speed
        MPH,
        FeetPerSecond,
        KPH,
        MetersPerSecond,
        Knots,
        //mass
        MetricTon,
        Kilograms,
        Grams,
        Milligrams,
        Micrograms,
        ImperialTon,
        Stone,
        USTon,
        Pound,
        Ounce,
        //pressure
        Bar,
        Pascal,
        PSI,
        StandardAtmosphere,
        Torr
    }


    public static class UnitConversion
    {
        delegate float Conversion(float input);
        delegate string UnitPrinter(float input, string formatter = "");

        static Dictionary<Tuple<Unit, Unit>, Conversion> conversions = new Dictionary<Tuple<Unit, Unit>, Conversion>();
        static Dictionary<Unit, UnitPrinter> printers = new Dictionary<Unit, UnitPrinter>();

        static UnitConversion()
        {
            //lengths
            Map(Unit.Millimeters, Unit.Centimeters, 0.1f);
            Map(Unit.Millimeters, Unit.Decimeters, 0.01f);
            Map(Unit.Millimeters, Unit.Meters, 0.001f);
            Map(Unit.Millimeters, Unit.Kilometers, 0.000001f);
            Map(Unit.Millimeters, Unit.Inches, 0.0393701f);
            Map(Unit.Millimeters, Unit.Feet, 0.00328084f);
            Map(Unit.Millimeters, Unit.Yards, 0.00109361f);
            Map(Unit.Millimeters, Unit.Miles, 6.2137e-7f);

            Map(Unit.Centimeters, Unit.Decimeters, 0.1f);
            Map(Unit.Centimeters, Unit.Meters, 0.01f);
            Map(Unit.Centimeters, Unit.Kilometers, 0.00001f);
            Map(Unit.Centimeters, Unit.Inches, 0.393701f);
            Map(Unit.Centimeters, Unit.Feet, 0.0328084f);
            Map(Unit.Centimeters, Unit.Yards, 0.0109361f);
            Map(Unit.Centimeters, Unit.Miles, 6.2137e-6f);

            Map(Unit.Decimeters, Unit.Meters, 0.1f);
            Map(Unit.Decimeters, Unit.Kilometers, 0.0001f);
            Map(Unit.Decimeters, Unit.Inches, 3.93701f);
            Map(Unit.Decimeters, Unit.Feet, 0.328084f);
            Map(Unit.Decimeters, Unit.Yards, 0.109361f);
            Map(Unit.Decimeters, Unit.Miles, 6.2137e-5f);

            Map(Unit.Meters, Unit.Kilometers, 0.001f);
            Map(Unit.Meters, Unit.Inches, 39.3701f);
            Map(Unit.Meters, Unit.Feet, 3.28084f);
            Map(Unit.Meters, Unit.Yards, 1.09361f);
            Map(Unit.Meters, Unit.Miles, 6.2137e-4f);

            Map(Unit.Kilometers, Unit.Inches, 393.701f);
            Map(Unit.Kilometers, Unit.Feet, 32.8084f);
            Map(Unit.Kilometers, Unit.Yards, 10.9361f);
            Map(Unit.Kilometers, Unit.Miles, 6.2137e-3f);

            Map(Unit.Feet, Unit.Inches, 12f);
            Map(Unit.Inches, Unit.Yards, 0.0277778f);
            Map(Unit.Inches, Unit.Miles, 1.5783e-5f);

            Map(Unit.Yards, Unit.Feet, 3f);
            Map(Unit.Miles, Unit.Feet, 5280f);

            Map(Unit.Miles, Unit.Yards, 1760f);

            //angles
            Map(Unit.Degrees, Unit.Radians, Mathf.Deg2Rad, false);
            Map(Unit.Radians, Unit.Radians, Mathf.Rad2Deg, false);

            //temperature
            Map(Unit.Fahrenheit, Unit.Celsius, (x) => (x - 32) * (5f / 9f));
            Map(Unit.Fahrenheit, Unit.Kelvin, (x) => (x - 32) * (5f / 9f) + 273.15f);
            Map(Unit.Celsius, Unit.Fahrenheit, (x) => (x * (9f / 5f)) + 32);
            Map(Unit.Celsius, Unit.Kelvin, (x) => x + 273.15f);
            Map(Unit.Kelvin, Unit.Celsius, (x) => x - 273.15f);

            //speeds
            Map(Unit.MetersPerSecond, Unit.KPH, 3.6f);
            Map(Unit.MetersPerSecond, Unit.MPH, 2.23694f);
            Map(Unit.MetersPerSecond, Unit.Knots, 1.94384f);
            Map(Unit.MetersPerSecond, Unit.FeetPerSecond, 3.28084f);

            Map(Unit.KPH, Unit.MPH, 0.621371f);
            Map(Unit.KPH, Unit.Knots, 0.539957f);
            Map(Unit.KPH, Unit.FeetPerSecond, 0.911344f);

            Map(Unit.MPH, Unit.Knots, 0.868976f);
            Map(Unit.MPH, Unit.FeetPerSecond, 1.46667f);

            Map(Unit.Knots, Unit.FeetPerSecond, 1.68781f);


            //mass
            Map(Unit.Kilograms, Unit.Micrograms, 1000000000);
            Map(Unit.Kilograms, Unit.Milligrams, 1000000);
            Map(Unit.Kilograms, Unit.Grams, 1000);
            Map(Unit.Kilograms, Unit.MetricTon, 0.001f);
            Map(Unit.Kilograms, Unit.ImperialTon, 0.000984207f);
            Map(Unit.Kilograms, Unit.USTon, 0.00110231f);
            Map(Unit.Kilograms, Unit.Stone, 0.157473f);
            Map(Unit.Kilograms, Unit.Pound, 2.20462f);
            Map(Unit.Kilograms, Unit.Ounce, 35.274f);

            DeriveFrom(Unit.Kilograms, Unit.Micrograms, Unit.Milligrams, Unit.Grams, Unit.MetricTon, Unit.ImperialTon, Unit.USTon, Unit.Stone, Unit.Pound, Unit.Ounce);

            //the ones that dont do well with float precision passing thru Metric
            Map(Unit.Pound, Unit.Ounce, 16);
            Map(Unit.USTon, Unit.Ounce, 16 * 2000);
            Map(Unit.USTon, Unit.Pound, 2000);

            //pressure
            Map(Unit.Bar, Unit.Torr, 750.062f);
            Map(Unit.Bar, Unit.StandardAtmosphere, 0.986923f);
            Map(Unit.Bar, Unit.Pascal, 100000);
            Map(Unit.Bar, Unit.PSI, 14.5038f);

            DeriveFrom(Unit.Bar, Unit.Torr, Unit.StandardAtmosphere, Unit.Pascal, Unit.PSI);


            //length
            Label(Unit.Millimeters, (x,y) => $"{x.ToString(y)}mm");
            Label(Unit.Centimeters, (x,y) => $"{x.ToString(y)}cm");
            Label(Unit.Decimeters, (x,y) => $"{x.ToString(y)}dm");
            Label(Unit.Meters, (x,y) => $"{x.ToString(y)}m");
            Label(Unit.Kilometers, (x,y) => $"{x.ToString(y)}km");

            Label(Unit.Inches, (x,y) => $"{x.ToString(y)}\"");
            Label(Unit.Feet, (x,y) =>
            {
                if (x < 1)
                    return x.ConvertUnits(Unit.Feet, Unit.Inches).ToString(Unit.Inches);

                float inches = x.ConvertUnits(Unit.Feet, Unit.Inches);
                return $"{((int)(inches / 12))}' {(inches % 12).ToString(y)}\"";
            });
            Label(Unit.Yards, (x,y) =>
            {
                if (x < 1)
                    return x.ConvertUnits(Unit.Yards, Unit.Feet).ToString(Unit.Feet);

                float feet = x.ConvertUnits(Unit.Yards, Unit.Feet);

                return $"{(int)(feet / 3)}yd{(x >= 2 ? "s" : "")} {(feet % 3).ToString(Unit.Feet)}";
            });

            //speed
            Label(Unit.KPH, (x,y) => $"{x.ToString(y)}km/h");
            Label(Unit.MetersPerSecond, (x,y) => $"{x.ToString(y)}m/s");
            Label(Unit.Miles, (x,y) => $"{x.ToString(y)}mi");
            Label(Unit.MPH, (x,y) => $"{x.ToString(y)}MPH");
            Label(Unit.FeetPerSecond, (x,y) => $"{x.ToString(y)}fps");
            Label(Unit.Knots, (x,y) => $"{x.ToString(y)}kt");

            //angles
            Label(Unit.Degrees, (x,y) => $"{x.ToString(y)}°");
            Label(Unit.Radians, (x,y) => $"{x.ToString(y)}rad");

            //temperature
            Label(Unit.Fahrenheit, (x,y) => $"{x.ToString(y)}°F");
            Label(Unit.Celsius, (x,y) => $"{x.ToString(y)}°C");
            Label(Unit.Kelvin, (x,y) => $"{x.ToString(y)}K");

            //mass
            Label(Unit.MetricTon, (x,y) => $"{x.ToString(y)}Mg");
            Label(Unit.Kilograms, (x,y) => $"{x.ToString(y)}kg");
            Label(Unit.Grams, (x,y) => $"{x.ToString(y)}g");
            Label(Unit.Milligrams, (x,y) => $"{x.ToString(y)}mg");
            Label(Unit.Micrograms, (x,y) => $"{x.ToString(y)}μg");
            Label(Unit.ImperialTon, (x,y) => $"{x.ToString(y)}t");
            Label(Unit.Stone, (x,y) => $"{x.ToString(y)}st");
            Label(Unit.USTon, (x,y) => $"{x.ToString(y)}t");
            Label(Unit.Pound, (x,y) => $"{x.ToString(y)}lbs");
            Label(Unit.Ounce, (x,y) => $"{x.ToString(y)}oz");

            //pressure
            Label(Unit.Bar, (x,y) => $"{x.ToString(y)}bar");
            Label(Unit.Pascal, (x,y) => $"{x.ToString(y)}Pa");
            Label(Unit.PSI, (x,y) => $"{x.ToString(y)}psi");
            Label(Unit.Torr, (x,y) => $"{x.ToString(y)}Torr");
            Label(Unit.StandardAtmosphere, (x,y) => $"{x.ToString(y)}atm");
        }

        static void Map(Unit from, Unit to, float constant, bool reciprocal = true)
        {
            conversions[new Tuple<Unit, Unit>(from, to)] = (x) => x * constant;
            if (reciprocal)
                conversions[new Tuple<Unit, Unit>(to, from)] = (x) => x * (1f / constant);
        }

        static void Map(Unit from, Unit to, Conversion conv)
        {
            conversions[new Tuple<Unit, Unit>(from, to)] = conv;
        }

        static void DeriveFrom(Unit origin, params Unit[] units)
        {
            foreach (var u in units)
            {
                DeriveMaps(u, origin);
            }
        }

        static void DeriveMaps(Unit unit, Unit from)
        {
            var relevant = conversions.Where(x => x.Key.Item1 == from && x.Key.Item2 != unit).ToList();

            foreach (var r in relevant)
            {
                Unit target = r.Key.Item2;
                Map(unit, target, (x) => x.ConvertUnits(unit, from).ConvertUnits(from, target));
            }
        }

        static void Label(Unit unit, UnitPrinter printer)
        {
            printers[unit] = printer;
        }

        public static float ConvertUnits(this float value, Unit from, Unit to)
        {
            if (from == to)
                return value;

            var key = new Tuple<Unit, Unit>(from, to);

            if (conversions.ContainsKey(key))
            {
                return conversions[key](value);
            }

            throw new Exception($"Cannot convert from {from} to {to}!");
        }

        public static string ToString(this float val, Unit unit, string formatter = "")
        {
            if (printers.ContainsKey(unit))
                return printers[unit](val, formatter);

            throw new Exception($"Cannot beautify {unit} yet!");
        }
    }
}
