using System;
using Splat;

namespace StarsAssistant.Services;

public class GameEngine
{
    /// <summary>
    /// Helper reference to the Game, populated during service registration for the
    /// loaded game.
    /// </summary>
    // TODO: check for better options here.
    public static Game Game { get; set; } = null!;

    /// <summary>
    /// Minimum effective value of a planet for purposes of maximum population etc.
    /// </summary>
    public const int MinEffectiveValue = 5;

    /// <summary>
    /// Normalize a planet value for minimum effetive value.
    /// </summary>
    /// <param name="value">Real planet value</param>
    /// <returns>Effective plante value</returns>
    public static int EffectivePlanetValue(int value) => (value < MinEffectiveValue) ? MinEffectiveValue : value;

    /// <summary>
    /// Compute the maximum regular (non-overcrowded) population on a planet for the active player.
    /// </summary>
    /// <param name="value">Real planet value</param>
    /// <returns>effective maximum population</returns>
    public static int MaxPopOnPlanetForPlayer(int value) => Game.Player.MaxPopOnPlanet * EffectivePlanetValue(value) / 100;

    /// <summary>
    /// Compute population growth for player planets.
    /// </summary>
    /// <param name="currentPop">Current population on planet</param>
    /// <param name="value">Real planet value</param>
    /// <returns>population growth per turn</returns>
    public static int PlanetPopGrowthForPlayer(int currentPop, int value) 
    {
        int maxPop = MaxPopOnPlanetForPlayer(value);
        int growth;

        if (value < 0)
        {
            growth = currentPop * value / 1000;
        } 
        else 
        {
            double popRatio = (double) currentPop / maxPop;
            if (popRatio <= 0.25) 
            {
                growth = currentPop 
                    * Game.Player.GrowthRatePercent / 100
                    * value / 100;
            }
            else if (popRatio < 1) 
            {
                double factor = Math.Pow(1.0 - popRatio, 2);
                growth = currentPop 
                    * Game.Player.GrowthRatePercent / 100
                    * value / 100
                    * 16 / 9;
                growth = (int) ((double) growth * factor);
            }
            else 
            {
                double factor = 0.04 * (popRatio - 1);
                growth = (int) ((double) currentPop * factor);
            }
        }

        // round down by 100
        return growth / 100 * 100;
    }

    /// <summary>
    /// Returns the maximum operable factories on a given player planet for a given value.
    /// </summary>
    /// <param name="currentPop">Population on planet</param>
    /// <param name="value">Real planet value</param>
    /// <returns>Maximum operable factories for currentPop</returns>
    public static int MaxOperableFactoriesForPlayer(int currentPop, int value)
    {
        int effectivePop = Math.Min(currentPop, MaxPopOnPlanetForPlayer(value));
        double tmp = (double) effectivePop / 10000 * Game.Player.FactoryNumberPer10k;
        return (int) tmp;
    }

    /// <summary>
    /// Maximum buildable factories on a player planet with a given value.
    /// </summary>
    /// <param name="value">Real Planet Value</param>
    /// <returns>Maximum buildable factories</returns>
    public static int MaxBuildableFactoriesForPlayer(int value)
    {
        double tmp = (double) MaxPopOnPlanetForPlayer(value) / 10000 * Game.Player.FactoryNumberPer10k;
        return (int) tmp;
    }

    /// <summary>
    /// Returns the maximum operable mines on a given player planet for a given value.
    /// </summary>
    /// <param name="currentPop">Population on planet</param>
    /// <param name="value">Real planet value</param>
    /// <returns>Maximum operable mines for currentPop</returns>
    public static int MaxOperableMinesForPlayer(int currentPop, int value)
    {
        int effectivePop = Math.Min(currentPop, MaxPopOnPlanetForPlayer(value));
        double tmp = (double) effectivePop / 10000 * Game.Player.MineNumberPer10k;
        return (int) tmp;
    } 

    /// <summary>
    /// Maximum buildable factories on a player planet with a given value.
    /// </summary>
    /// <param name="value">Real Planet Value</param>
    /// <returns>Maximum buildable factories</returns>
    public static int MaxBuildableMinesForPlayer(int value)
    {
        double tmp = (double) MaxPopOnPlanetForPlayer(value) / 10000 * Game.Player.MineNumberPer10k;
        return (int) tmp;
    }

    /// <summary>
    /// Ressources produced by population on a player planet with a given value. Takes
    /// less effective overcrowding pop into account.
    /// </summary>
    /// <param name="currentPop">Current planetary population</param>
    /// <param name="value">Real planet value</param>
    /// <returns>Resources generated by populationa</returns>
    public static int ResourcesFromPopForPlayer(int currentPop, int value) 
    {
        if (Game.Player.ColonistsPerResource == 0) 
            return 0;
        
        int maxPop = MaxPopOnPlanetForPlayer(value);
        int popFullEfficiency;
        int popHalfEfficiency;
        if (currentPop <= maxPop) {
            popHalfEfficiency = 0;
            popFullEfficiency = currentPop;
        }
        else if (currentPop <= 3 * maxPop) {
            popFullEfficiency = maxPop;
            popHalfEfficiency = currentPop - maxPop;
        }
        else {
            popFullEfficiency = maxPop;
            popHalfEfficiency = 2 * maxPop;
        }
        int popEffective = popFullEfficiency + (popHalfEfficiency / 2);
        return popEffective / Services.Game.Player.ColonistsPerResource;
    }

    /// <summary>
    /// Ressources generated by factories on a player planet for a given value an
    /// population. Takes maximum operable factories into account.
    /// </summary>
    /// <param name="currentPop">Current planetary population</param>
    /// <param name="factories">Number of factories built</param>
    /// <param name="value">Real planet value</param>
    /// <returns>Resources generated by factories</returns>
    public static int ResourcesFromFactForPlayer(int currentPop, int factories, int value) 
    {
        int maxPop = MaxPopOnPlanetForPlayer(value);
        int effectivePop = Math.Min(currentPop, maxPop);
        double tmp = (double) effectivePop / 10000 * Game.Player.FactoryNumberPer10k;
        int maxOperableFactories = (int) tmp;
        int operableFactories = Math.Min(factories, maxOperableFactories);
        tmp = (double) operableFactories / 10 * Services.Game.Player.FactoryResPer10;
        return (int) tmp;
    }

}