using UnityEngine;
using System.Collections.Generic;
using DG.Tweening;
using Ashwild.Inventory;
using Ashwild.Player;

namespace Ashwild.UI
{
    public class NotificationUI : MonoBehaviour
    {
        [Header("References")]
        [SerializeField] private RectTransform container;
        [SerializeField] private GameObject notificationPrefab;

        [Header("Layout")]
        [SerializeField] private float notificationHeight = 40f;
        [SerializeField] private float spacing = 6f;
        [SerializeField] private float startOffsetY = 20f;

        [Header("Timing")]
        [SerializeField] private float displayDuration = 4f;

        [Header("Animation")]
        [SerializeField] private float slideInDuration = 0.35f;
        [SerializeField] private Ease slideInEase = Ease.OutBack;
        [SerializeField] private float stackSlideDuration = 0.25f;
        [SerializeField] private Ease stackSlideEase = Ease.OutQuad;

        [Header("Colors")]
        [SerializeField] private Color gainColor = new Color(0.45f, 1f, 0.45f); // picked up / added
        [SerializeField] private Color lossColor = new Color(1f, 0.45f, 0.45f); // dropped / consumed

        private readonly List<NotificationItemUI> activeNotifications = new List<NotificationItemUI>();

        private void OnEnable()
        {
            PlayerEvents.ItemAdded += OnItemAdded;
            PlayerEvents.ItemDropped += OnItemDropped;
            PlayerEvents.ItemConsumed += OnItemConsumed;
            PlayerEvents.FoodPlacedToCook += OnItemSpent;
            PlayerEvents.FuelAdded += OnItemSpent;
        }

        private void OnDisable()
        {
            PlayerEvents.ItemAdded -= OnItemAdded;
            PlayerEvents.ItemDropped -= OnItemDropped;
            PlayerEvents.ItemConsumed -= OnItemConsumed;
            PlayerEvents.FoodPlacedToCook -= OnItemSpent;
            PlayerEvents.FuelAdded -= OnItemSpent;
        }

        private void OnItemAdded(ItemData item, int quantity)   => Push(item, quantity);
        private void OnItemDropped(ItemData item, int quantity) => Push(item, -quantity);
        private void OnItemConsumed(ItemData item)              => Push(item, -1);

        // Food placed on a cooking station or fuel fed to it both leave the inventory by one.
        private void OnItemSpent(ItemData item)                 => Push(item, -1);

        private void Push(ItemData item, int signedQuantity)
        {
            if (item == null || signedQuantity == 0) return;

            // Clean up destroyed notifications
            activeNotifications.RemoveAll(n => n == null);

            bool gain = signedQuantity > 0;

            // Merge only with a notification for the same item AND same direction
            for (int i = 0; i < activeNotifications.Count; i++)
            {
                if (activeNotifications[i] != null && activeNotifications[i].ItemData == item
                    && activeNotifications[i].IsGain == gain)
                {
                    activeNotifications[i].AddQuantity(signedQuantity, displayDuration);
                    return;
                }
            }

            // Create new notification
            GameObject go = Instantiate(notificationPrefab, container);
            NotificationItemUI notification = go.GetComponent<NotificationItemUI>();

            float targetY = startOffsetY + activeNotifications.Count * (notificationHeight + spacing);

            RectTransform rt = notification.RectTransform;
            rt.anchoredPosition = new Vector2(0f, targetY - 30f);

            notification.Initialize(item, signedQuantity, gain ? gainColor : lossColor, displayDuration, slideInDuration, slideInEase);

            // Slide in from below
            rt.DOAnchorPosY(targetY, slideInDuration).SetEase(slideInEase);

            activeNotifications.Add(notification);
        }

        private void LateUpdate()
        {
            // Clean up destroyed notifications and reposition remaining ones
            int removed = activeNotifications.RemoveAll(n => n == null);
            if (removed > 0)
                RepositionAll();
        }

        private void RepositionAll()
        {
            for (int i = 0; i < activeNotifications.Count; i++)
            {
                if (activeNotifications[i] == null) continue;

                float targetY = startOffsetY + i * (notificationHeight + spacing);
                activeNotifications[i].RectTransform
                    .DOAnchorPosY(targetY, stackSlideDuration)
                    .SetEase(stackSlideEase);
            }
        }
    }
}