using System.Collections.ObjectModel;
using System.Reactive.Disposables;
using System.Reactive.Linq;
using Microsoft.EntityFrameworkCore;
using DynamicData;
using ReactiveUI;
using ReactiveUI.SourceGenerators;
using StarsAssistant.Services;
using Splat;
using StarsAssistant.Model;

namespace StarsAssistant.ViewModels;

public partial class PlayerPlanetViewModel : ViewModelBase
{
    private readonly Model.Planet Planet;

    private readonly Services.Game Game;

    private readonly IObservable<Change<FleetSummaryByDestination, string>> _fleetSummaryChanges;
    
    public PlayerPlanetViewModel(Model.Planet planet)
    {
        Game = Locator.Current.GetService<Services.Game>()!;

        if (planet.OwnerId != Services.Game.Player.Name)
            throw new InvalidOperationException("PlayerPlanet ViewModels can only be created for player planets.");

        Planet = planet;
        PopulationTargetPercent = planet.PopulationTargetPercent;

        _populationTargetHelper = this
            .WhenAnyValue(vm => vm.PopulationTargetPercent)
            .Select(popTgt => this.MaxPopulation * popTgt / 10000 * 100)
            .ToProperty(this, vm => vm.PopulationTarget);

        _populationToShipHelper = this
            .WhenAnyValue(vm => vm.PopulationTarget)
            .Select(popToShip => this.ComputePopulationToShip())
            .ToProperty(this, vm => vm.PopulationToShip);

        _targetFactoriesHelper = this
            .WhenAnyValue(vm => vm.PopulationTarget)
            .Select(tgtFact => GameEngine.MaxOperableFactoriesForPlayer(_populationTarget, Value))
            .ToProperty(this, vm => vm.TargetFactories);

        _remainingFactoriesHelper = this
            .WhenAnyValue(vm => vm.TargetFactories)
            .Select(factRem => Factories < _targetFactories ? _targetFactories - Factories : 0)
            .ToProperty(this, vm => vm.RemainingFactories);

        _factoryGermaniumDeltaHelper = this
            .WhenAnyValue(vm => vm.RemainingFactories)
            .Select(gerCost => ComputeFactoryGermaniumDelta())
            .ToProperty(this, vm => vm.FactoryGermaniumDelta);

        _remainingMinesHelper = this
            .WhenAnyValue(vm => vm.PopulationTarget)
            .Select(remMines => Math.Max(0, GameEngine.MaxOperableMinesForPlayer(_populationTarget, Value) - Mines))
            .ToProperty(this, vm => vm.RemainingMines);

        FleetManager fm = Locator.Current.GetService<FleetManager>()!;

        _fleetSummaryChanges = fm.FleetSummariesByDestination
            .Connect()
            .Watch(Name)
            .Log(this, "fleetSummaryChange", change => $"{Name}: {change.Reason}: {change.Previous} => {change.Current}")
        ;

        _populationEnRouteHelper = _fleetSummaryChanges
            .Select(change => change.Reason != ChangeReason.Remove ? change.Current.TotalColonists : 0)
            .Log(this, "PopulationEnRoute", pop => $"{Name}: {pop}")
            .ToProperty(this, vm => vm.PopulationEnRoute)
        ;

        this.WhenActivated((CompositeDisposable disposables) => 
        {
            disposables.Add(_populationEnRouteHelper);

            // /* handle activation */
            // Disposable
            //     .Create(() => { /* handle deactivation */ })
            //     .DisposeWith(disposables);
        });
    }
    
    #region Database Properties

    public string Name => Planet.Name;

    public string Owner => Planet.OwnerId;

    public string StarbaseType => Planet.StarbaseType;

    public int Population => Planet.Population ?? 0;

    public int Value => Planet.Value ?? 0;

    public int Mines => Planet.Mines ?? 0;

    public int Factories => Planet.Factories ?? 0;

    public decimal DefPercent => Planet.DefPercent ?? 0;

    public int SurfaceIronium => Planet.SurfaceIronium ?? 0;

    public int SurfaceBoranium => Planet.SurfaceBoranium ?? 0;

    public int SurfaceGermanium => Planet.SurfaceGermanium ?? 0;

    public int MRIronium => Planet.MRIronium ?? 0;

    public int MRBoranium => Planet.MRBoranium ?? 0;

    public int MRGermanium => Planet.MRGermanium ?? 0;

    public int MCIronium => Planet.MCIronium ?? 0;

    public int MCBoranium => Planet.MCBoranium ?? 0;

    public int MCGermanium => Planet.MCGermanium ?? 0;
 
    public int Resources => Planet.Resources ?? 0;

    public decimal Gravity => Planet.Gravity ?? 0;

    public decimal Temperature => Planet.Temperature ?? 0;

    public decimal Radiation => Planet.Radiation ?? 0;

    public decimal GravityOrig => Planet.GravityOrig ?? 0;

    public decimal TemperatureOrig => Planet.TemperatureOrig ?? 0;

    public decimal RadiationOrig => Planet.RadiationOrig ?? 0;
 
    public int MaxTerraforming => Planet.MaxTerraforming ?? 0; 

    public int CapacityPercent => Planet.CapacityPercent ?? 0; 

    public int ScanRange => Planet.ScanRange ?? 0; 

    public int PenScanRange => Planet.PenScanRange ?? 0; 

    public int Driver => Planet.Driver ?? 0; 

    public int DriverWarp => Planet.DriverWarp ?? 0; 

    public string RouteTarget => Planet.RouteTarget;

    public int GateRange => Planet.GateRange ?? 0; 

    public int GateMass => Planet.GateMass ?? 0;

    public int PctDamage => Planet.PctDamage ?? 0;

    [Reactive]
    private int _populationTargetPercent;

    #endregion

    #region Derived Properties

    public int EffectiveValue => GameEngine.EffectivePlanetValue(Value);

    public int MaxPopulation => GameEngine.MaxPopOnPlanetForPlayer(Value);

    public int PopulationGrowth => GameEngine.PlanetPopGrowthForPlayer(Population, Value);

    public int PopulationT1 => Population + PopulationGrowth /* TODO + Pop En Route */;

    public int BuildableFactories => GameEngine.MaxBuildableFactoriesForPlayer(Value);

    public int BuildableMines => GameEngine.MaxBuildableMinesForPlayer(Value);

    public int OperableFactories => GameEngine.MaxOperableFactoriesForPlayer(Population, Value);

    public int OperableMines => GameEngine.MaxOperableMinesForPlayer(Population, Value);

    public int ResourcesFromPopulation => GameEngine.ResourcesFromPopForPlayer(Population, Value);

    public int ResourcesFromFactories => GameEngine.ResourcesFromFactForPlayer(Population, Factories, Value);

    public int AvailableIronium => MRIronium + SurfaceIronium;

    public int AvailableBoranium => MRBoranium + SurfaceBoranium;

    public int AvailableGermanium => MRGermanium + SurfaceGermanium;

    [ObservableAsProperty]
    private int _populationTarget;

    [ObservableAsProperty]
    private int _populationToShip;

    [ObservableAsProperty]
    private int _targetFactories;

    [ObservableAsProperty]
    private int _remainingFactories;

    [ObservableAsProperty]
    private int _factoryGermaniumDelta;

    [ObservableAsProperty]
    private int _remainingMines;

    [ObservableAsProperty]
    private int _populationEnRoute;

    #endregion

    #region Helper functions

    private int ComputePopulationToShip()
    {
        if (Population >= _populationTarget)
            return Population - _populationTarget;
        
        if (PopulationT1 < _populationTarget)
            return PopulationT1 - _populationTarget;
        
        return 0;
    }

    private int ComputeFactoryGermaniumDelta()
    {
        int gerReq = GameEngine.FactoryGermaniumCostForPlayer(_remainingFactories);
        
        if (gerReq < AvailableGermanium)
            return Math.Max(0, SurfaceGermanium - gerReq);

        return AvailableGermanium + MRGermanium - gerReq;
        // TODO: Extrapolate to T1, so that excess Germanium is visible.
        // TODO: Take shipping into account.
    }

    /*
    private int ComputePopulationEnRoute()
    {
        using var db = Locator.Current.GetService<Model.StarsDatabase>()!;

        var enRoute = from flt in db.Fleet
            where flt.OwnerFileId == Game.Player.PlayerFileId && flt.TrueDestination == Planet.Name
            select new {  Colonists = flt.Sum(f => f.Colonists) };

        return enRoute.Colonists ?? 0;
    }
    */

    #endregion

}