using System;
using System.Collections.Generic;
using CSNetwork;
using CSNetwork.GPDataType;
using UnityEngine;
using UnityEngine.Pool;
using UnityEngine.UI;

namespace BrewMonster.Scripts.ChatUI
{
    [Serializable]
    public struct ChatMessageData
    {
        public string message;
        public byte channel;
    }

    public class ChatPanelUI : MonoBehaviour
    {
        [Header("UI")] public ScrollRect scrollRect;
        public GameObject chatPanelUIGO;
        public RectTransform content;
        public ChatMessageView messagePrefab;
        //public GameObject newMessageIndicator;

        [Header("Config")] public int maxVisibleMessages = 30;
        public int maxStoredMessages = 2000;

        [Header("Chat System Data")]
        public ChatSystemSO chatSystemSO;
        private Dictionary<byte, Sprite> _iconCache;

        private List<ChatMessageData> _messages = new();
        private List<ChatMessageView> _visibleViews = new();

        private ObjectPool<ChatMessageView> _pool;

        private bool _userAtBottom = true;

        void Awake()
        {
            _iconCache = new Dictionary<byte, Sprite>();
            if (chatSystemSO != null && chatSystemSO.channelIcons != null)
            {
                foreach (var mapping in chatSystemSO.channelIcons)
                {
                    _iconCache[(byte)mapping.channel] = mapping.icon;
                }
            }

            EventBus.Subscribe<GameSession.ChatMessageEvent>(OnChatMessageReceived);
            _pool = new ObjectPool<ChatMessageView>(
                CreateItem,
                OnGetItem,
                OnReleaseItem,
                OnDestroyItem,
                false,
                10,
                100
            );

            scrollRect.onValueChanged.AddListener(OnScrollChanged);
        }

        private void OnDestroy()
        {
            EventBus.Unsubscribe<GameSession.ChatMessageEvent>(OnChatMessageReceived);
        }

        private void OnChatMessageReceived(GameSession.ChatMessageEvent x)
        {
            ChatThreadDispatcher.Instance.Post(() =>
            {
                AddMessage(x.context, x.channel);
            });
        }

        ChatMessageView CreateItem()
        {
            var item = Instantiate(messagePrefab);
            item.transform.SetParent(content, false);
            return item;
        }

        void OnGetItem(ChatMessageView item)
        {
            item.gameObject.SetActive(true);
        }

        void OnReleaseItem(ChatMessageView item)
        {
            item.gameObject.SetActive(false);
        }

        void OnDestroyItem(ChatMessageView item)
        {
            Destroy(item.gameObject);
        }

        void OnScrollChanged(Vector2 pos)
        {
            _userAtBottom = scrollRect.verticalNormalizedPosition <= 0.001f;

            if (_userAtBottom)
            {
                //newMessageIndicator.SetActive(false);
            }
        }

        bool IsAtBottom()
        {
            return scrollRect.verticalNormalizedPosition <= 0.001f;
        }

        public void AddMessage(string msg, byte channel)
        {
            var data = new ChatMessageData { message = msg, channel = channel };
            _messages.Add(data);

            if (_messages.Count > maxStoredMessages)
                _messages.RemoveAt(0);

            if (!chatPanelUIGO.activeSelf)
                return;

            AddMessageView(data);

            if (_userAtBottom)
                ScrollToBottom();
        }

        void AddMessageView(ChatMessageData data)
        {
            var view = _pool.Get();
            view.transform.SetParent(content, false);
            view.transform.SetAsLastSibling();

            Sprite icon = _iconCache.ContainsKey(data.channel) ? _iconCache[data.channel] : null;
            view.Bind(icon, data.message);

            _visibleViews.Add(view);

            if (_visibleViews.Count > maxVisibleMessages)
            {
                var old = _visibleViews[0];
                _visibleViews.RemoveAt(0);
                _pool.Release(old);
            }

            Canvas.ForceUpdateCanvases();
        }

        void RefreshVisible()
        {
            foreach (var view in _visibleViews)
                _pool.Release(view);

            _visibleViews.Clear();

            int start = Mathf.Max(0, _messages.Count - maxVisibleMessages);

            for (int i = start; i < _messages.Count; i++)
            {
                var view = _pool.Get();
                view.transform.SetParent(content, false);
                view.transform.SetAsLastSibling();

                var data = _messages[i];
                Sprite icon = _iconCache.ContainsKey(data.channel) ? _iconCache[data.channel] : null;
                view.Bind(icon, data.message);

                _visibleViews.Add(view);
            }

            Canvas.ForceUpdateCanvases();
            ScrollToBottom();
        }

        public void ScrollToBottom()
        {
            Canvas.ForceUpdateCanvases();
            scrollRect.verticalNormalizedPosition = 0f;
            //newMessageIndicator.SetActive(false);
        }

        public void ClearChat()
        {
            foreach (var view in _visibleViews)
                _pool.Release(view);

            _visibleViews.Clear();
            _messages.Clear();
        }

        public void OnHandlerChatButton()
        {
            bool open = !chatPanelUIGO.activeSelf;
            chatPanelUIGO.SetActive(open);

            if (open)
                RefreshVisible();
        }
    }
}