using Input;
using UnityEngine;
using System;
using System.Linq;
using Bootstrap; // added for Action<T>
using Core; // register with ItemManager

namespace Interactions
{
    /// <summary>
    /// Saveable data for Pickup state
    /// </summary>
    [System.Serializable]
    public class PickupSaveData
    {
        public bool isPickedUp;
        public bool wasHeldByFollower;  // Track if held by follower for bilateral restoration
        public Vector3 worldPosition;
        public Quaternion worldRotation;
        public bool isActive;
    }

    public class Pickup : SaveableInteractable
    {
        public PickupItemData itemData;
        public SpriteRenderer iconRenderer;
        
        // Track if the item has been picked up
        public bool IsPickedUp { get; internal set; }

        // Event: invoked when the item was picked up successfully
        public event Action<PickupItemData> OnItemPickedUp;
        
        // Event: invoked when this item is successfully combined with another
        public event Action<PickupItemData, PickupItemData, PickupItemData> OnItemsCombined;
        
        /// <summary>
        /// Unity Awake callback. Sets up icon and applies item data.
        /// </summary>
        protected override void Awake()
        {
            base.Awake(); // Register with save system

            if (iconRenderer == null)
                iconRenderer = GetComponent<SpriteRenderer>();

            ApplyItemData();
        }

        /// <summary>
        /// Register with ItemManager on Start
        /// </summary>
        protected override void Start()
        {
            base.Start(); // Register with save system
            
            // Always register with ItemManager, even if picked up
            // This allows the save/load system to find held items when restoring state
            BootCompletionService.RegisterInitAction(() => 
            {
                ItemManager.Instance?.RegisterPickup(this);
            });
            
        }

        /// <summary>
        /// Unity OnDestroy callback. Unregisters from ItemManager.
        /// </summary>
        protected override void OnDestroy()
        {
            base.OnDestroy(); // Unregister from save system
            
            // Unregister from ItemManager
            ItemManager.Instance?.UnregisterPickup(this);
        }

#if UNITY_EDITOR
        /// <summary>
        /// Unity OnValidate callback. Ensures icon and data are up to date in editor.
        /// </summary>
        void OnValidate()
        {
            if (iconRenderer == null)
                iconRenderer = GetComponent<SpriteRenderer>();
            ApplyItemData();
        }
#endif


        /// <summary>
        /// Applies the item data to the pickup (icon, name, etc).
        /// </summary>
        public void ApplyItemData()
        {
            if (itemData != null)
            {
                if (iconRenderer != null && itemData.mapSprite != null)
                {
                    iconRenderer.sprite = itemData.mapSprite;
                }

                gameObject.name = itemData.itemName;
            }
        }

        /// <summary>
        /// Override: Called when character arrives at the interaction point.
        /// Handles item pickup and combination logic.
        /// </summary>
        protected override void OnCharacterArrived()
        {
            Logging.Debug("[Pickup] OnCharacterArrived");
            
            var combinationResult = _followerController.TryCombineItems(this, out var combinationResultItem);
            if (combinationResultItem != null)
            {
                CompleteInteraction(true);
                
                // Fire the combination event when items are successfully combined
                if (combinationResult == FollowerController.CombinationResult.Successful)
                {
                    var resultPickup = combinationResultItem.GetComponent<Pickup>();
                    if (resultPickup != null && resultPickup.itemData != null)
                    {
                        // Get the combined item data
                        var resultItemData = resultPickup.itemData;
                        var heldItem = _followerController.GetHeldPickupObject();
                        
                        if (heldItem != null)
                        {
                            var heldPickup = heldItem.GetComponent<Pickup>();
                            if (heldPickup != null && heldPickup.itemData != null)
                            {
                                // Trigger the combination event
                                OnItemsCombined?.Invoke(itemData, heldPickup.itemData, resultItemData);
                            }
                        }
                    }
                }
                
                return;
            }
            
            _followerController?.TryPickupItem(gameObject, itemData);
            
            var step = GetComponent<PuzzleS.ObjectiveStepBehaviour>();
            if (step != null && !step.IsStepUnlocked())
            {
                CompleteInteraction(false);
                return;
            }
            
            bool wasPickedUp = (combinationResult == FollowerController.CombinationResult.NotApplicable 
                                || combinationResult == FollowerController.CombinationResult.Unsuccessful);
            CompleteInteraction(wasPickedUp);

            // Update pickup state and invoke event when the item was picked up successfully
            if (wasPickedUp)
            {
                IsPickedUp = true;
                OnItemPickedUp?.Invoke(itemData);
            }
        }

        #region Save/Load Implementation

        protected override object GetSerializableState()
        {
            // Check if this pickup is currently held by the follower
            bool isHeldByFollower = IsPickedUp && !gameObject.activeSelf && transform.parent != null;
            
            return new PickupSaveData
            {
                isPickedUp = this.IsPickedUp,
                wasHeldByFollower = isHeldByFollower,
                worldPosition = transform.position,
                worldRotation = transform.rotation,
                isActive = gameObject.activeSelf
            };
        }

        protected override void ApplySerializableState(string serializedData)
        {
            PickupSaveData data = JsonUtility.FromJson<PickupSaveData>(serializedData);
            if (data == null)
            {
                Debug.LogWarning($"[Pickup] Failed to deserialize save data for {gameObject.name}");
                return;
            }

            // Restore picked up state
            IsPickedUp = data.isPickedUp;

            if (IsPickedUp)
            {
                // Hide the pickup if it was already picked up
                gameObject.SetActive(false);
                
                // If this was held by the follower, try bilateral restoration
                if (data.wasHeldByFollower)
                {
                    // Try to give this pickup to the follower
                    // This might succeed or fail depending on timing
                    var follower = FollowerController.FindInstance();
                    if (follower != null)
                    {
                        follower.TryClaimHeldItem(this);
                    }
                }
            }
            else
            {
                // Restore position for items that haven't been picked up (they may have moved)
                transform.position = data.worldPosition;
                transform.rotation = data.worldRotation;
                gameObject.SetActive(data.isActive);
            }

            // Note: We do NOT fire OnItemPickedUp event during restoration
            // This prevents duplicate logic execution
        }

        /// <summary>
        /// Resets the pickup state when the item is dropped back into the world.
        /// Called by FollowerController when swapping items.
        /// </summary>
        public void ResetPickupState()
        {
            IsPickedUp = false;
            gameObject.SetActive(true);
            
            // Re-register with ItemManager if not already registered
            if (ItemManager.Instance != null && !ItemManager.Instance.GetAllPickups().Contains(this))
            {
                ItemManager.Instance.RegisterPickup(this);
            }
        }

        #endregion
    }
}