using System.Diagnostics.CodeAnalysis;
using Robust.Shared.Containers;
using Robust.Shared.GameObjects;
using Robust.Shared.GameStates;
using Robust.Shared.IoC;

namespace Robust.Server.GameObjects;

public sealed partial class PointLightSystem : SharedPointLightSystem
{
    [Dependency] private readonly SharedContainerSystem _container = default!;
    [Dependency] private MetaDataSystem _metadata = default!;

    public override void Initialize()
    {
        base.Initialize();
        SubscribeLocalEvent<PointLightComponent, ComponentGetState>(OnLightGetState);
        //SubscribeLocalEvent<PointLightComponent, EntInsertedIntoContainerMessage>(OnInserted);
        SubscribeLocalEvent<PointLightComponent, EntGotInsertedIntoContainerMessage>(OnInserted);
        SubscribeLocalEvent<PointLightComponent, EntGotRemovedFromContainerMessage>(OnRemoved);
        SubscribeLocalEvent<PointLightComponent, ComponentStartup>(OnLightStartup);
        SubscribeLocalEvent<PointLightComponent, ComponentShutdown>(OnLightShutdown);
        SubscribeLocalEvent<PointLightComponent, MetaFlagRemoveAttemptEvent>(OnFlagRemoveAttempt);
    }

    private void OnLightStartup(Entity<PointLightComponent> ent, ref ComponentStartup args)
    {
        UpdatePriority(ent.Owner, ent.Comp, MetaData(ent.Owner));
        SetContainerOccluded(ent.Owner, IsCurrentContainerOrParentOccluder(ent.Owner), ent.Comp);
        _lightTree.QueueTreeUpdate(ent.Owner, ent.Comp);
    }

    private void OnLightShutdown(Entity<PointLightComponent> ent, ref ComponentShutdown args)
    {
        UpdatePriority(ent.Owner, ent.Comp, MetaData(ent.Owner));
        _lightTree.QueueTreeUpdate(ent.Owner, ent.Comp);
    }

    private void OnFlagRemoveAttempt(Entity<PointLightComponent> ent, ref MetaFlagRemoveAttemptEvent args)
    {
        if (IsHighPriority(ent.Comp))
            args.ToRemove &= ~MetaDataFlags.PvsPriority;
    }


    private bool IsHighPriority(SharedPointLightComponent comp)
    {
        return comp is { Enabled: true, CastShadows: true, Radius: > 7, LifeStage: <= ComponentLifeStage.Running };
    }

    private void OnInserted(EntityUid uid, PointLightComponent component, EntGotInsertedIntoContainerMessage args)
    {
        SetContainerOccluded(uid, IsContainerOrParentOccluder(args.Container), component);
    }

    private void OnRemoved(EntityUid uid, PointLightComponent component, EntGotRemovedFromContainerMessage args)
    {
        SetContainerOccluded(uid, IsCurrentContainerOrParentOccluder(uid), component);
    }

    private void OnLightGetState(EntityUid uid, PointLightComponent component, ref ComponentGetState args)
    {
        args.State = new PointLightComponentState()
        {
            Color = component.Color,
            Enabled = component.Enabled,
            Energy = component.Energy,
            Offset = component.Offset,
            Radius = component.Radius,
            Softness = component.Softness,
            Falloff = component.Falloff,
            CurveFactor = component.CurveFactor,
            CastShadows = component.CastShadows,
            ContainerOccluded = component.ContainerOccluded,
        };
    }
    protected override void UpdatePriority(EntityUid uid, SharedPointLightComponent comp, MetaDataComponent meta)
    {
        _metadata.SetFlag((uid, meta), MetaDataFlags.PvsPriority, IsHighPriority(comp));
    }

    public override SharedPointLightComponent EnsureLight(EntityUid uid)
    {
        return EnsureComp<PointLightComponent>(uid);
    }

    public override bool ResolveLight(EntityUid uid, [NotNullWhen(true)] ref SharedPointLightComponent? component)
    {
        if (component is not null)
            return true;

        TryComp<PointLightComponent>(uid, out var comp);
        component = comp;
        return component != null;
    }

    public override bool TryGetLight(EntityUid uid, [NotNullWhen(true)] out SharedPointLightComponent? component)
    {
        if (TryComp<PointLightComponent>(uid, out var comp))
        {
            component = comp;
            return true;
        }

        component = null;
        return false;
    }

    public override bool RemoveLightDeferred(EntityUid uid)
    {
        return RemCompDeferred<PointLightComponent>(uid);
    }

    /// <summary>
    /// Recursively check if a container or any parent container occludes light.
    /// This is probably a terribly unoptimized way to get the occlusion right
    /// </summary>
    /// <returns>True if any container should block light.</returns>
    private bool IsContainerOrParentOccluder(BaseContainer container)
    {
        if (container.OccludesLight)
            return true;

        if (!_container.TryGetContainingContainer(container.Owner, out var nextContainer))
            return false;

        return IsContainerOrParentOccluder(nextContainer);
    }

    private bool IsCurrentContainerOrParentOccluder(EntityUid uid)
    {
        return _container.TryGetContainingContainer(uid, out var container) && IsContainerOrParentOccluder(container);
    }
}