using System;
using System.Collections.Generic;
using JetBrains.Annotations;
using Robust.Client.Graphics;
using Robust.Client.ResourceManagement;
using Robust.Client.Utility;
using Robust.Shared.GameObjects;
using Robust.Shared.IoC;
using Robust.Shared.Log;
using Robust.Shared.Map;
using Robust.Shared.Prototypes;
using Robust.Shared.Utility;

namespace Robust.Client.GameObjects;

public sealed partial class SpriteSystem
{
    [Dependency] private readonly IPrototypeManager _proto = default!;
    [Dependency] private readonly IResourceCache _resourceCache = default!;

    private readonly Dictionary<string, IRsiStateLike> _cachedPrototypeIcons = new();

    public Texture Frame0(SpriteSpecifier specifier)
    {
        return RsiStateLike(specifier).Default;
    }

    public IRsiStateLike RsiStateLike(SpriteSpecifier specifier)
    {
        switch (specifier)
        {
            case SpriteSpecifier.Texture tex:
                return tex.GetTexture(_resourceCache);

            case SpriteSpecifier.Rsi rsi:
                return GetState(rsi);

            case SpriteSpecifier.EntityPrototype prototypeIcon:
                return GetPrototypeIcon(prototypeIcon.EntityPrototypeId);

            default:
                throw new NotSupportedException();
        }
    }

    /// <summary>
    ///     Returns an icon for a given <see cref="EntityPrototype"/> ID, or a fallback in case of an error.
    ///     This method caches the result based on the prototype identifier.
    /// </summary>
    public IRsiStateLike GetPrototypeIcon(string prototype)
    {
        // Check if this prototype has been cached before, and if so return the result.
        if (_cachedPrototypeIcons.TryGetValue(prototype, out var cachedResult))
            return cachedResult;

        if (!_proto.TryIndex<EntityPrototype>(prototype, out var entityPrototype))
        {
            // The specified prototype doesn't exist, return the fallback "error" sprite.
            Logger.Error("Failed to load PrototypeIcon {0}", prototype);
            return GetFallbackState();
        }

        // Generate the icon and cache it in case it's ever needed again.
        var result = GetPrototypeIcon(entityPrototype);
        _cachedPrototypeIcons[prototype] = result;

        return result;
    }

    /// <summary>
    ///     Returns an icon for a given <see cref="EntityPrototype"/> ID, or a fallback in case of an error.
    ///     This method does NOT cache the result.
    /// </summary>
    public IRsiStateLike GetPrototypeIcon(EntityPrototype prototype)
    {
        // IconComponent takes precedence. If it has a valid icon, return that. Otherwise, continue as normal.
        if (prototype.Components.TryGetValue("Icon", out var compData)
            && compData is IconComponent {Icon: {} icon})
        {
            return icon.Default;
        }

        // If the prototype doesn't have a SpriteComponent, then there's nothing we can do but return the fallback.
        if (!prototype.Components.ContainsKey("Sprite"))
        {
            return GetFallbackState();
        }

        // Finally, we use spawn a dummy entity to get its icon.
        var dummy = Spawn(prototype.ID, MapCoordinates.Nullspace);
        var spriteComponent = EnsureComp<SpriteComponent>(dummy);
        var result = spriteComponent.Icon ?? GetFallbackState();
        Del(dummy);

        return result;
    }

    [Pure]
    public RSI.State GetFallbackState()
    {
        return _resourceCache.GetFallback<RSIResource>().RSI["error"];
    }

    [Pure]
    public RSI.State GetState(SpriteSpecifier.Rsi rsiSpecifier)
    {
        if (_resourceCache.TryGetResource<RSIResource>(
                SharedSpriteComponent.TextureRoot / rsiSpecifier.RsiPath,
                out var theRsi) &&
            theRsi.RSI.TryGetState(rsiSpecifier.RsiState, out var state))
        {
            return state;
        }

        Logger.Error("Failed to load RSI {0}", rsiSpecifier.RsiPath);
        return GetFallbackState();
    }

    private void OnPrototypesReloaded(PrototypesReloadedEventArgs protoReloaded)
    {
        // Check if any EntityPrototype has been changed.
        if (!protoReloaded.ByType.TryGetValue(typeof(EntityPrototype), out var changedSet))
            return;

        // Remove all changed prototypes from the cache, if they're there.
        foreach (var (prototype, _) in changedSet.Modified)
        {
            // Let's be lazy and not regenerate them until something needs them again.
            _cachedPrototypeIcons.Remove(prototype);
        }
    }
}