using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;
using System; // for Action<T>
using Core; // register with ItemManager
using Core.Settings; // Added for IInteractionSettings

namespace Interactions
{
    // New enum describing possible states for the slotted item
    public enum ItemSlotState
    {
        None,
        Correct,
        Incorrect,
        Forbidden
    }

    /// <summary>
    /// Display behavior for slot renderers
    /// </summary>
    [Serializable]
    public enum SlotRendererDisplayType
    {
        UseConfig = 0,      // Assign sprite from slotted item's config (default)
        RevealExisting = 1  // Just make the renderer visible (sprite already on renderer)
    }

    /// <summary>
    /// Maps a sprite renderer to an optional item assignment
    /// </summary>
    [Serializable]
    public class SlotRendererMapping
    {
        public SpriteRenderer renderer;
        [Tooltip("Optional: If set, this renderer slot is dedicated to this specific item. Leave null for flexible slots.")]
        public PickupItemData assignedItem;
        [Tooltip("Display behavior: UseConfig assigns sprite from item config, RevealExisting just makes renderer visible")]
        public SlotRendererDisplayType displayType = SlotRendererDisplayType.UseConfig;
    }

    /// <summary>
    /// Saveable data for ItemSlot state
    /// </summary>
    [Serializable]
    public class ItemSlotSaveData
    {
        public ItemSlotState slotState;
        public List<string> slottedItemSaveIds = new List<string>(); // Changed to list for multi-slot support
        public List<string> slottedItemDataIds = new List<string>(); // Changed to list for multi-slot support
        public bool isLocked; // Track if slot is completed and locked
    }

    /// <summary>
    /// Interaction that allows slotting items in a slot.
    /// ItemSlot is a CONTAINER, not a Pickup itself.
    /// Items cannot be removed or swapped once slotted (except via combinations).
    /// </summary>
    public class ItemSlot : SaveableInteractable
    {
        // Slot visual data (for the slot itself, not the item in it)
        public PickupItemData itemData;
        public SpriteRenderer iconRenderer;
        
        // Multi-slot item tracking - now only stores correct items (dense arrays)
        private List<PickupItemData> slottedItemsData = new List<PickupItemData>();
        public SlotRendererMapping[] slottedItemRenderers; // Array of renderers with optional item assignments
        private List<GameObject> slottedItemObjects = new List<GameObject>();
        
        // Tracks the current state of the slotted item(s)
        private ItemSlotState currentState = ItemSlotState.None;
        
        // Lock flag to prevent removal after successful completion
        private bool isLockedAfterCompletion;

        // Settings reference
        private IInteractionSettings interactionSettings;

        /// <summary>
        /// Read-only access to the current slotted item state.
        /// </summary>
        public ItemSlotState CurrentSlottedState => currentState;
        
        /// <summary>
        /// Number of items currently slotted (all are correct in new system)
        /// </summary>
        public int CurrentSlottedCount => slottedItemObjects.Count;
        
        /// <summary>
        /// Number of CORRECT items currently slotted (all items are correct now)
        /// </summary>
        public int CurrentCorrectCount => slottedItemObjects.Count;
        
        /// <summary>
        /// Number of items required to complete this slot
        /// </summary>
        public int RequiredItemCount
        {
            get
            {
                var config = interactionSettings?.GetSlotItemConfig(itemData);
                if (config != null)
                {
                    // If requiredItemCount is set (> 0), use it; otherwise require all allowed items
                    return config.requiredItemCount > 0 ? config.requiredItemCount : (config.allowedItems?.Count ?? 0);
                }
                return 1; // Default to 1 for backward compatibility
            }
        }
        
        /// <summary>
        /// Whether this slot has all required CORRECT items
        /// </summary>
        public bool IsComplete => CurrentCorrectCount >= RequiredItemCount && RequiredItemCount > 0;
        
        /// <summary>
        /// Whether this slot has space for more items
        /// </summary>
        public bool HasSpace => slottedItemRenderers != null && CurrentSlottedCount < slottedItemRenderers.Length;
        
        /// <summary>
        /// Whether this is a multi-slot (more than one renderer)
        /// </summary>
        private bool IsMultiSlot => slottedItemRenderers != null && slottedItemRenderers.Length > 1;

        // Event dispatchers (only 3 events needed)
        public UnityEvent onItemSlotted;
        public event Action<PickupItemData, PickupItemData> OnItemSlotted; // (slotData, slottedItemData)

        public UnityEvent onCorrectItemSlotted;
        public event Action<PickupItemData, PickupItemData> OnCorrectItemSlotted; // (slotData, slottedItemData)
        
        public UnityEvent onWrongItemAttempted;
        public event Action<PickupItemData, PickupItemData> OnWrongItemAttempted; // (slotData, attemptedItem)
        
        /// <summary>
        /// Get the first (or only) slotted object - for backward compatibility
        /// </summary>
        public GameObject GetSlottedObject()
        {
            return slottedItemObjects.Count > 0 ? slottedItemObjects[0] : null;
        }

        /// <summary>
        /// Set a slotted object - for backward compatibility, replaces first item or adds
        /// </summary>
        public void SetSlottedObject(GameObject obj)
        {
            if (obj != null)
            {
                if (slottedItemObjects.Count == 0)
                {
                    slottedItemObjects.Add(obj);
                }
                else
                {
                    slottedItemObjects[0] = obj;
                }
                obj.SetActive(false);
            }
        }

        internal override void OnManagedAwake()
        {
            base.OnManagedAwake(); // SaveableInteractable registration
            
            // Setup visuals
            if (iconRenderer == null)
                iconRenderer = GetComponent<SpriteRenderer>();
            
            ApplyItemData();
            
            // Initialize settings references
            interactionSettings = GameManager.GetSettingsObject<IInteractionSettings>();
            
            // Hide all RevealExisting renderers at start
            if (slottedItemRenderers != null)
            {
                foreach (var mapping in slottedItemRenderers)
                {
                    if (mapping != null && mapping.renderer != null && 
                        mapping.displayType == SlotRendererDisplayType.RevealExisting)
                    {
                        mapping.renderer.enabled = false;
                    }
                }
            }
        }

#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 slot (icon, name, etc).
        /// </summary>
        public void ApplyItemData()
        {
            if (itemData != null)
            {
                if (iconRenderer != null && itemData.mapSprite != null)
                {
                    iconRenderer.sprite = itemData.mapSprite;
                }
                gameObject.name = itemData.itemName + "_Slot";
            }
        }

        #region Interaction Logic

        /// <summary>
        /// Validation: Check if interaction can proceed based on held item and slot state.
        /// Now allows all items to proceed - wrong items will trigger reactions without slotting.
        /// No unslotting or swapping allowed.
        /// </summary>
        protected override (bool canProceed, string errorMessage) CanProceedWithInteraction()
        {
            var heldItem = FollowerController?.CurrentlyHeldItemData;
            
            // Check if slot is locked after completion
            if (isLockedAfterCompletion)
            {
                if (heldItem != null)
                    return (false, "This is already complete.");
                else
                    return (false, "I can't remove these items.");
            }
            
            // Scenario: Nothing held + Empty slot = Error
            if (heldItem == null && CurrentSlottedCount == 0)
                return (false, "This requires an item.");
            
            // Scenario: Nothing held + Has items = Can't remove (no unslotting)
            if (heldItem == null && CurrentSlottedCount > 0)
                return (false, "I can't remove these items.");
            
            // Scenario: Holding item + Slot full = Error (no swapping)
            if (heldItem != null && !HasSpace)
                return (false, "This slot is full.");
            
            // All other cases proceed (holding item + has space)
            return (true, null);
        }

        /// <summary>
        /// Main interaction logic: Slot correct items or trigger reactions for wrong items.
        /// No swapping, unslotting, or combinations allowed - items stay once slotted.
        /// Returns true only if correct item was slotted AND slot is now complete.
        /// </summary>
        protected override bool DoInteraction()
        {
            Logging.Debug("[ItemSlot] DoInteraction");
            
            var heldItemData = FollowerController.CurrentlyHeldItemData;
            var heldItemObj = FollowerController.GetHeldPickupObject();
            
            // Only scenario: Held item + Has space = Check if allowed, then slot or react
            if (heldItemData != null && HasSpace)
            {
                var config = interactionSettings?.GetSlotItemConfig(itemData);
                var allowed = config?.allowedItems ?? new List<PickupItemData>();
                
                // Check if item is allowed
                if (PickupItemData.ListContainsEquivalent(allowed, heldItemData))
                {
                    // CORRECT ITEM - Slot it
                    SlotItem(heldItemObj, heldItemData);
                    FollowerController.ClearHeldItem(); // Clear follower's hand after slotting
                    
                    // Check if we completed the slot
                    if (IsComplete)
                    {
                        isLockedAfterCompletion = true;
                        currentState = ItemSlotState.Correct;
                        return true; // Completed!
                    }
                    
                    return false; // Slotted but not complete yet
                }
                else
                {
                    // WRONG ITEM - Trigger reaction, don't slot, item stays in hand
                    TriggerWrongItemReaction(heldItemData);
                    return false;
                }
            }
            
            // No other scenarios
            return false;
        }
        

        
        /// <summary>
        /// Triggers a "wrong item" reaction without slotting.
        /// Integrates with DialogueComponent for NPC feedback.
        /// Item stays in player's hand.
        /// </summary>
        private void TriggerWrongItemReaction(PickupItemData wrongItem)
        {
            DebugUIMessage.Show($"{wrongItem.itemName} doesn't belong here.", Color.yellow);
            
            // Fire event for DialogueComponent integration
            onWrongItemAttempted?.Invoke();
            OnWrongItemAttempted?.Invoke(itemData, wrongItem);
            
            // Item stays in player's hand - no state change
        }
        

        #endregion
        
        #region Visual Updates

        /// <summary>
        /// Determines the best slot index for an item based on assignments and availability.
        /// Returns -1 if no mappings are configured (uses append behavior).
        /// Simplified for dense arrays.
        /// </summary>
        private int GetTargetSlotIndexForItem(PickupItemData itemData)
        {
            if (slottedItemRenderers == null || slottedItemRenderers.Length == 0)
                return -1; // Append behavior
            
            // Check if any renderer has assignments configured
            bool hasAnyAssignments = false;
            for (int i = 0; i < slottedItemRenderers.Length; i++)
            {
                if (slottedItemRenderers[i]?.assignedItem != null)
                {
                    hasAnyAssignments = true;
                    break;
                }
            }
            
            // If no assignments configured, use append behavior (backward compatible)
            if (!hasAnyAssignments)
                return -1;
            
            // Check if this item has a dedicated assigned slot
            for (int i = 0; i < slottedItemRenderers.Length; i++)
            {
                var mapping = slottedItemRenderers[i];
                if (mapping?.assignedItem != null && PickupItemData.AreEquivalent(mapping.assignedItem, itemData))
                {
                    // This is the assigned slot for this item
                    return i;
                }
            }
            
            // Item is not assigned to a specific slot - return next available index
            // Dense arrays: just return current count if there's space
            return slottedItemObjects.Count < slottedItemRenderers.Length 
                ? slottedItemObjects.Count 
                : -1; // No space, use append (will trigger swap logic)
        }

        /// <summary>
        /// Updates the sprite and scale for all slotted items.
        /// Handles both UseConfig (assign sprite) and RevealExisting (just enable renderer) display modes.
        /// </summary>
        private void UpdateSlottedSprite()
        {
            if (slottedItemRenderers == null || slottedItemRenderers.Length == 0)
                return;
            
            // Update each renderer based on slotted items
            for (int i = 0; i < slottedItemRenderers.Length; i++)
            {
                var mapping = slottedItemRenderers[i];
                if (mapping == null || mapping.renderer == null)
                    continue;
                
                var slotRenderer = mapping.renderer;
                
                // If we have an item at this index, show it
                if (i < slottedItemsData.Count && slottedItemsData[i] != null)
                {
                    var slottedData = slottedItemsData[i];
                    
                    // Handle display mode
                    if (mapping.displayType == SlotRendererDisplayType.RevealExisting)
                    {
                        // RevealExisting: Just make the renderer visible
                        slotRenderer.enabled = true;
                    }
                    else // UseConfig (default)
                    {
                        // UseConfig: Assign sprite from item config
                        if (slottedData.mapSprite != null)
                        {
                            slotRenderer.sprite = slottedData.mapSprite;
                            
                            // Scale sprite to desired height, preserve aspect ratio, compensate for parent scale
                            var configs = GameManager.GetSettingsObject<IPlayerMovementConfigs>();
                            float desiredHeight = configs?.FollowerMovement?.HeldIconDisplayHeight ?? 2.0f;
                            var sprite = slottedData.mapSprite;
                            float spriteHeight = sprite.bounds.size.y;
                            Vector3 parentScale = slotRenderer.transform.parent != null
                                ? slotRenderer.transform.parent.localScale
                                : Vector3.one;
                            
                            if (spriteHeight > 0f)
                            {
                                float uniformScale = desiredHeight / spriteHeight;
                                float scale = uniformScale / Mathf.Max(parentScale.x, parentScale.y);
                                slotRenderer.transform.localScale = new Vector3(scale, scale, 1f);
                            }
                        }
                    }
                }
                else
                {
                    // No item at this index - clear/hide renderer
                    if (mapping.displayType == SlotRendererDisplayType.RevealExisting)
                    {
                        // RevealExisting: Hide the renderer
                        slotRenderer.enabled = false;
                    }
                    else // UseConfig (default)
                    {
                        // UseConfig: Clear sprite
                        slotRenderer.sprite = null;
                    }
                }
            }
        }
        
        #endregion
        
        // Register with ItemManager when enabled
        private void OnEnable()
        {
            // Register as ItemSlot
            ItemManager.Instance?.RegisterItemSlot(this);
        }

        internal override void OnManagedDestroy()
        {
            // Unregister from slot manager
            ItemManager.Instance?.UnregisterItemSlot(this);
        }

        #region Save/Load Implementation

        protected override object GetSerializableState()
        {
            var saveData = new ItemSlotSaveData
            {
                slotState = currentState,
                isLocked = isLockedAfterCompletion
            };
            
            // Save all slotted items
            foreach (var itemObj in slottedItemObjects)
            {
                if (itemObj != null)
                {
                    var slottedPickup = itemObj.GetComponent<Pickup>();
                    if (slottedPickup is SaveableInteractable saveablePickup)
                    {
                        saveData.slottedItemSaveIds.Add(saveablePickup.SaveId);
                    }
                    else
                    {
                        saveData.slottedItemSaveIds.Add("");
                    }
                }
                else
                {
                    saveData.slottedItemSaveIds.Add("");
                }
            }
            
            // Save all item data IDs for verification
            foreach (var slottedData in slottedItemsData)
            {
                if (slottedData != null)
                {
                    saveData.slottedItemDataIds.Add(slottedData.itemId);
                }
                else
                {
                    saveData.slottedItemDataIds.Add("");
                }
            }

            return saveData;
        }

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

            // Restore slot state
            currentState = data.slotState;
            isLockedAfterCompletion = data.isLocked;

            // Restore all slotted items if there were any
            if (data.slottedItemSaveIds != null && data.slottedItemSaveIds.Count > 0)
            {
                for (int i = 0; i < data.slottedItemSaveIds.Count; i++)
                {
                    string saveId = data.slottedItemSaveIds[i];
                    string dataId = i < data.slottedItemDataIds.Count ? data.slottedItemDataIds[i] : "";
                    
                    if (!string.IsNullOrEmpty(saveId))
                    {
                        Logging.Debug($"[ItemSlot] Restoring slotted item {i}: {saveId} (itemId: {dataId})");
                        RestoreSlottedItem(saveId, dataId);
                    }
                }
            }
            
            // Update all renderers after restoration
            UpdateSlottedSprite();
        }

        /// <summary>
        /// Restore a slotted item from save data.
        /// This is called during load restoration and should NOT trigger events.
        /// </summary>
        private void RestoreSlottedItem(string slottedItemSaveId, string expectedItemDataId)
        {
            // Try to find the item in the scene by its save ID via ItemManager
            GameObject slottedObject = ItemManager.Instance?.FindPickupBySaveId(slottedItemSaveId);
            
            if (slottedObject == null && !string.IsNullOrEmpty(expectedItemDataId))
            {
                // Item not found in scene - it might be a dynamically spawned combined item
                // Try to spawn it from the itemDataId
                Logging.Debug($"[ItemSlot] Slotted item not found in scene: {slottedItemSaveId}, attempting to spawn from itemId: {expectedItemDataId}");
                
                GameObject prefab = interactionSettings?.FindPickupPrefabByItemId(expectedItemDataId);
                if (prefab != null)
                {
                    // Spawn the item (inactive, since it will be slotted)
                    slottedObject = Instantiate(prefab, transform.position, Quaternion.identity);
                    slottedObject.SetActive(false);
                    Logging.Debug($"[ItemSlot] Successfully spawned combined item for slot: {expectedItemDataId}");
                }
                else
                {
                    Logging.Warning($"[ItemSlot] Could not find prefab for itemId: {expectedItemDataId}");
                    return;
                }
            }
            else if (slottedObject == null)
            {
                Logging.Warning($"[ItemSlot] Could not find slotted item with save ID: {slottedItemSaveId}");
                return;
            }

            // Get the item data from the pickup component
            PickupItemData slottedData = null;
            var pickup = slottedObject.GetComponent<Pickup>();
            if (pickup != null)
            {
                slottedData = pickup.itemData;
                
                // Verify itemId matches if we have it (safety check)
                if (slottedData != null && !string.IsNullOrEmpty(expectedItemDataId))
                {
                    if (slottedData.itemId != expectedItemDataId)
                    {
                        Logging.Warning($"[ItemSlot] ItemId mismatch! Pickup has '{slottedData.itemId}' but expected '{expectedItemDataId}'");
                    }
                }
                
                if (slottedData == null)
                {
                    Logging.Warning($"[ItemSlot] Pickup {pickup.gameObject.name} has null itemData! Expected itemId: {expectedItemDataId}");
                    if (slottedObject != null)
                        Destroy(slottedObject);
                    return;
                }
            }
            else
            {
                Logging.Warning($"[ItemSlot] Slotted object has no Pickup component: {slottedObject.name}");
                if (slottedObject != null)
                    Destroy(slottedObject);
                return;
            }

            // Add to slotted items list (no events, no interaction completion)
            // Follower state is managed separately during save/load restoration
            // All saved items are correct (wrong items never get slotted)
            slottedItemObjects.Add(slottedObject);
            slottedItemsData.Add(slottedData);
            
            // Deactivate the item and set pickup state
            slottedObject.SetActive(false);
            if (pickup != null)
            {
                pickup.IsPickedUp = true;
                pickup.OwningSlot = this;
            }
            
            Logging.Debug($"[ItemSlot] Successfully restored slotted item: {slottedData.itemName} (itemId: {slottedData.itemId})");
        }

        /// <summary>
        /// Public API for slotting items during gameplay.
        /// Adds item to the slot (multi-slot support with positional awareness).
        /// Only called for correct items - wrong items trigger reactions instead.
        /// Caller is responsible for managing follower's held item state.
        /// </summary>
        public void SlotItem(GameObject itemToSlot, PickupItemData itemToSlotData)
        {
            if (itemToSlot == null || itemToSlotData == null)
            {
                Logging.Warning($"[ItemSlot] Attempted to slot null item or data");
                return;
            }
            
            // NOTE: Only called for CORRECT items now (validation done in DoInteraction)
            
            // Determine target slot index
            int targetIndex = GetTargetSlotIndexForItem(itemToSlotData);
            
            if (targetIndex >= 0 && targetIndex < slottedItemObjects.Count)
            {
                // Insert at specific position (shifts items if needed)
                slottedItemObjects.Insert(targetIndex, itemToSlot);
                slottedItemsData.Insert(targetIndex, itemToSlotData);
            }
            else
            {
                // Append to end (backward compatible or when all slots full)
                slottedItemObjects.Add(itemToSlot);
                slottedItemsData.Add(itemToSlotData);
            }
            
            // Deactivate item and set pickup state
            itemToSlot.SetActive(false);
            itemToSlot.transform.SetParent(null);
            
            var pickup = itemToSlot.GetComponent<Pickup>();
            if (pickup != null)
            {
                pickup.IsPickedUp = true;
                pickup.OwningSlot = this;
            }
            
            // Update visuals
            UpdateSlottedSprite();
            
            // Fire success events (all items are correct now)
            DebugUIMessage.Show($"Slotted {itemToSlotData.itemName}", Color.green);
            onItemSlotted?.Invoke();
            OnItemSlotted?.Invoke(itemData, itemToSlotData);
            
            // Check if slot is complete
            if (IsComplete)
            {
                currentState = ItemSlotState.Correct;
                DebugUIMessage.Show($"Completed: {itemData.itemName}", Color.green);
                onCorrectItemSlotted?.Invoke();
                OnCorrectItemSlotted?.Invoke(itemData, itemToSlotData);
            }
        }

        /// <summary>
        /// Bilateral restoration entry point: Pickup calls this to offer itself to the Slot.
        /// Returns true if claim was successful, false if slot is full or wrong pickup.
        /// </summary>
        public bool TryClaimSlottedItem(Pickup pickup)
        {
            if (pickup == null)
                return false;

            // If slot is full, reject the claim
            if (!HasSpace)
            {
                Logging.Warning($"[ItemSlot] Slot is full, rejecting claim from {pickup.gameObject.name}");
                return false;
            }

            // Verify this pickup's SaveId matches what we expect (from our save data)
            // Note: We don't have easy access to the expected SaveId here, so we just accept it
            // The Pickup's bilateral restoration ensures it only claims the correct slot

            // Add the item to lists (all items are correct in new system)
            slottedItemObjects.Add(pickup.gameObject);
            slottedItemsData.Add(pickup.itemData);
            
            pickup.gameObject.SetActive(false);
            pickup.IsPickedUp = true;
            pickup.OwningSlot = this;
            
            Logging.Debug($"[ItemSlot] Successfully claimed slotted item: {pickup.itemData?.itemName}");
            return true;
        }

        #endregion
    }
}