using System;
using UnityEngine;

/// <summary>
/// Types of equipment slots available.
/// </summary>
public enum EquipmentSlotType
{
    MainHand,
    OffHand,
    Head,
    Body,
    Back,
    Accessory
}

/// <summary>
/// Represents a single equipment slot that can hold an equipped item.
/// </summary>
[Serializable]
public class EquipmentSlot
{
    /// <summary>
    /// Type of this equipment slot.
    /// </summary>
    public EquipmentSlotType SlotType;

    /// <summary>
    /// Transform where equipment is attached.
    /// </summary>
    public Transform AttachPoint;

    /// <summary>
    /// Currently spawned equipment instance.
    /// </summary>
    [NonSerialized]
    public GameObject CurrentEquipment;

    /// <summary>
    /// Currently equipped item data.
    /// </summary>
    [NonSerialized]
    public ItemData EquippedItem;

    /// <summary>
    /// Event fired when equipment changes.
    /// </summary>
    public event Action<EquipmentSlot, ItemData> OnEquipmentChanged;

    /// <summary>
    /// Equip an item to this slot.
    /// </summary>
    /// <param name="item">Item to equip (or null to unequip)</param>
    public void Equip(ItemData item)
    {
        // Remove current equipment
        Unequip();

        if (item == null) return;

        // Check if item can be equipped
        if (!item.CanBeEquipped) return;

        EquippedItem = item;

        // Spawn equipment visual
        var prefab = item.GetEquipmentPrefab();
        if (prefab != null && AttachPoint != null)
        {
            CurrentEquipment = UnityEngine.Object.Instantiate(prefab, AttachPoint);
            CurrentEquipment.transform.localPosition = item.GetPositionOffset();
            CurrentEquipment.transform.localRotation = Quaternion.Euler(item.GetRotationOffset());
        }

        OnEquipmentChanged?.Invoke(this, item);
    }

    /// <summary>
    /// Equip using IEquippableItem interface (more generic).
    /// </summary>
    /// <param name="equippable">Equippable item</param>
    /// <param name="user">The user equipping the item</param>
    public void Equip(IEquippableItem equippable, GameObject user)
    {
        Unequip();

        if (equippable == null) return;

        var prefab = equippable.GetEquipmentPrefab();
        if (prefab == null) return;

        // Find or use the configured attach point
        Transform attachTo = AttachPoint;
        if (attachTo == null && user != null)
        {
            attachTo = equippable.FindAttachmentPoint(user);
        }

        if (attachTo != null)
        {
            CurrentEquipment = UnityEngine.Object.Instantiate(prefab, attachTo);
            CurrentEquipment.transform.localPosition = equippable.GetPositionOffset();
            CurrentEquipment.transform.localRotation = Quaternion.Euler(equippable.GetRotationOffset());
        }

        OnEquipmentChanged?.Invoke(this, EquippedItem);
    }

    /// <summary>
    /// Unequip the current item.
    /// </summary>
    public void Unequip()
    {
        if (CurrentEquipment != null)
        {
            UnityEngine.Object.Destroy(CurrentEquipment);
            CurrentEquipment = null;
        }

        var previousItem = EquippedItem;
        EquippedItem = null;

        if (previousItem != null)
        {
            OnEquipmentChanged?.Invoke(this, null);
        }
    }

    /// <summary>
    /// Check if this slot has equipment.
    /// </summary>
    public bool HasEquipment => CurrentEquipment != null || EquippedItem != null;

    /// <summary>
    /// Check if a specific item can be equipped in this slot.
    /// </summary>
    public bool CanEquip(ItemData item)
    {
        if (item == null) return true; // Can always "unequip"
        return item.CanBeEquipped;
    }
}

/// <summary>
/// Manages multiple equipment slots for a character.
/// </summary>
[Serializable]
public class EquipmentManager
{
    [SerializeField]
    private EquipmentSlot[] _slots;

    /// <summary>
    /// All equipment slots.
    /// </summary>
    public EquipmentSlot[] Slots => _slots;

    /// <summary>
    /// Get a slot by type.
    /// </summary>
    public EquipmentSlot GetSlot(EquipmentSlotType type)
    {
        if (_slots == null) return null;

        foreach (var slot in _slots)
        {
            if (slot.SlotType == type)
                return slot;
        }
        return null;
    }

    /// <summary>
    /// Equip an item to the appropriate slot.
    /// </summary>
    public bool TryEquip(ItemData item, EquipmentSlotType preferredSlot = EquipmentSlotType.MainHand)
    {
        var slot = GetSlot(preferredSlot);
        if (slot != null && slot.CanEquip(item))
        {
            slot.Equip(item);
            return true;
        }
        return false;
    }

    /// <summary>
    /// Unequip all slots.
    /// </summary>
    public void UnequipAll()
    {
        if (_slots == null) return;

        foreach (var slot in _slots)
        {
            slot.Unequip();
        }
    }

    /// <summary>
    /// Initialize slots with attach points found on the character.
    /// </summary>
    public void Initialize(GameObject character, params (EquipmentSlotType type, string attachPointName)[] slotConfigs)
    {
        _slots = new EquipmentSlot[slotConfigs.Length];

        for (int i = 0; i < slotConfigs.Length; i++)
        {
            var config = slotConfigs[i];
            Transform attachPoint = null;

            // Find attach point
            var transforms = character.GetComponentsInChildren<Transform>();
            foreach (var t in transforms)
            {
                if (t.name == config.attachPointName)
                {
                    attachPoint = t;
                    break;
                }
            }

            _slots[i] = new EquipmentSlot
            {
                SlotType = config.type,
                AttachPoint = attachPoint
            };
        }
    }
}