using System;
using System.Collections.Generic;
using System.Linq;
using Cirno.Scripts.Interactables;
using Cirno.Scripts.Resources;
using Cirno.Scripts.UI;
using Cirno.Scripts.Utils;
using Godot;

namespace Cirno.Scripts.Actors._3D;

[Tool]
public partial class VendingMachine3D : Interactable3D
{
    public sealed class RuntimeShopEntry
    {
        public RuntimeShopEntry(VendingShopEntry entry)
        {
            Entry = entry;
            RemainingQuantity = Math.Max(0, entry.StartingQuantity);
        }

        public VendingShopEntry Entry { get; }

        public LootItem Item => Entry.Item;

        public bool Unlimited => Entry.Unlimited;

        public int RemainingQuantity { get; private set; }

        public bool CanPurchase(int purchaseCount = 1)
        {
            return purchaseCount <= 0 || Unlimited || RemainingQuantity >= purchaseCount;
        }

        public bool TryConsume(int purchaseCount = 1)
        {
            if (purchaseCount <= 0 || Unlimited)
            {
                return true;
            }

            if (RemainingQuantity < purchaseCount)
            {
                return false;
            }

            RemainingQuantity -= purchaseCount;
            return true;
        }
    }

    [Signal]
    public delegate void ShopOpenedEventHandler();

    [Signal]
    public delegate void ShopClosedEventHandler();

    [Export]
    public PackedScene ShopUiScene { get; private set; } =
        ResourceLoader.Load<PackedScene>("res://Scenes/HUD/VendingMachineShopUi.tscn");

    [Export]
    public VendingShopDefinition ShopDefinition { get; private set; } =
        ResourceLoader.Load<VendingShopDefinition>("res://Resources/Shops/VendingMachine_Default.tres");

    private readonly List<RuntimeShopEntry> _runtimeEntries = [];
    private VendingMachineShopUi _activeShopUi;
    private bool _runtimeInitialized;

    public override void _Ready()
    {
        AddToGroup("Interactable");

        if (Engine.IsEditorHint())
        {
            return;
        }

        EnsureRuntimeEntries();
    }

    public override bool CanActivate()
    {
        if (Engine.IsEditorHint())
        {
            return false;
        }

        EnsureRuntimeEntries();

        return !IsShopOpen()
               && ShopUiScene != null
               && _runtimeEntries.Count > 0
               && GameStateManager.Instance?.GameState is not GameState.Shop;
    }

    public override bool Activate(ActivationType activationType = ActivationType.Toggle)
    {
        if (Engine.IsEditorHint())
        {
            return false;
        }

        var typeToUse = activationType is ActivationType.Toggle ? ActivationType.Use : activationType;
        if (typeToUse is not ActivationType.Use)
        {
            return false;
        }

        if (!MeetsRequirements() || !CanActivate())
        {
            return false;
        }

        EnsureRuntimeEntries();

        if (GameStateManager.Instance == null)
        {
            return false;
        }

        GameStateManager.Instance.ChangeState(GameState.Shop);

        _activeShopUi = ShopUiScene.Instantiate<VendingMachineShopUi>();
        _activeShopUi.Init(this);
        _activeShopUi.Closed += OnShopUiClosed;

        var parent = GetTree().CurrentScene ?? GetTree().Root;
        parent.AddChild(_activeShopUi);

        EmitSignal(SignalName.ShopOpened);
        return true;
    }

    public override void _ExitTree()
    {
        if (IsInstanceValid(_activeShopUi))
        {
            _activeShopUi.Closed -= OnShopUiClosed;
            _activeShopUi.QueueFree();
        }

        _activeShopUi = null;
    }

    public IReadOnlyList<RuntimeShopEntry> GetEntries()
    {
        EnsureRuntimeEntries();
        return _runtimeEntries;
    }

    public RuntimeShopEntry FindEntry(StringName itemKey)
    {
        EnsureRuntimeEntries();
        return _runtimeEntries.FirstOrDefault(entry => entry.Item?.ItemKey == itemKey);
    }

    public bool TryConsumeStock(StringName itemKey, int purchaseCount = 1)
    {
        var entry = FindEntry(itemKey);
        return entry?.TryConsume(purchaseCount) ?? false;
    }

    // public void _func_godot_apply_properties(Godot.Collections.Dictionary props)
    // {
    //     if (props.TryGetValue("shop_definition_path", out var shopDefinitionPath))
    //     {
    //         var path = shopDefinitionPath.AsString();
    //         if (!string.IsNullOrWhiteSpace(path))
    //         {
    //             var loadedDefinition = ResourceLoader.Load<VendingShopDefinition>(path);
    //             if (loadedDefinition != null)
    //             {
    //                 ShopDefinition = loadedDefinition;
    //                 _runtimeInitialized = false;
    //             }
    //             else
    //             {
    //                 GD.PrintErr($"Failed to load vending shop definition from '{path}'");
    //             }
    //         }
    //     }
    // }

    private void EnsureRuntimeEntries()
    {
        if (_runtimeInitialized)
        {
            return;
        }

        _runtimeInitialized = true;
        _runtimeEntries.Clear();

        if (ShopDefinition == null)
        {
            return;
        }

        foreach (var entry in ShopDefinition.Entries.Where(entry => entry?.Item != null))
        {
            _runtimeEntries.Add(new RuntimeShopEntry(entry));
        }
    }

    private bool IsShopOpen()
    {
        return IsInstanceValid(_activeShopUi);
    }

    private void OnShopUiClosed()
    {
        if (IsInstanceValid(_activeShopUi))
        {
            _activeShopUi.Closed -= OnShopUiClosed;
        }

        _activeShopUi = null;
        EmitSignal(SignalName.ShopClosed);
    }
}