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 ChatSystemlUI : MonoBehaviour
    {
        [Header("ChatPanelUI")] public ScrollRect scrollRect;
        [Tooltip("Nền/fullscreen block — bật/tắt cùng lúc với chatPanelUIGO (có thể để null).")]
        public GameObject BgGameObject;
        public GameObject chatPanelUIGO;
        public RectTransform content;
        public ChatMessageView messagePrefab;
        public Button closeChatPanelButton;
        public Button closeBGChatPanelButton;
        public Button emojiButton;
        public Button sendButton;

        [Header("EmojiPanelUI")]
        public GameObject EmojiPanelUI;
        public Button closeEmojiPanelButton;

        [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 List<ChatMessageData> _filteredMessagesCache = new();
        private ObjectPool<ChatMessageView> _pool;

        private bool _userAtBottom = true;
        private ChatChannel _currentFilterChannel = ChatChannel.GP_CHAT_LOCAL;

        ChatInputHandler _chatInput;

        void Awake()
        {
            ClearChat();
            _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<OnEventClearChat>(OnChatMessageClear);
            EventBus.Subscribe<GameSession.ChatMessageEvent>(OnChatMessageReceived);
            EventBus.Subscribe<ChatChannelFilterChangedEvent>(OnChannelFilterChanged);
            EventBus.Subscribe<OpenChatPanelRequestedEvent>(OnOpenChatPanelRequested);
            _pool = new ObjectPool<ChatMessageView>(
                CreateItem,
                OnGetItem,
                OnReleaseItem,
                OnDestroyItem,
                false,
                10,
                100
            );

            scrollRect.onValueChanged.AddListener(OnScrollChanged);

            SetChatPanelAndBgVisible(false);
        }

        /// <summary>Bật/tắt panel chat và BG cùng trạng thái (2 GO tách nhưng luồng giống nhau).</summary>
        void SetChatPanelAndBgVisible(bool visible)
        {
            if (chatPanelUIGO != null)
                chatPanelUIGO.SetActive(visible);
            if (BgGameObject != null)
                BgGameObject.SetActive(visible);
        }

        void OnEnable()
        {
            if (chatPanelUIGO == null || !chatPanelUIGO.activeSelf || _pool == null || content == null)
                return;

            RefreshVisible();
        }

        void Start()
        {
            _chatInput = GetComponent<ChatInputHandler>();
            WireUiButtons();
        }

        void WireUiButtons()
        {
            if (closeChatPanelButton != null)
                closeChatPanelButton.onClick.AddListener(CloseChatPanel);
            if (closeBGChatPanelButton != null)
                closeBGChatPanelButton.onClick.AddListener(CloseChatPanel);
            if (emojiButton != null)
                emojiButton.onClick.AddListener(ToggleEmojiPanel);
            if (closeEmojiPanelButton != null)
                closeEmojiPanelButton.onClick.AddListener(CloseEmojiPanel);
            if (sendButton != null)
                sendButton.onClick.AddListener(OnSendButtonClicked);
        }

        private void OnDestroy()
        {
            if (closeChatPanelButton != null)
                closeChatPanelButton.onClick.RemoveListener(CloseChatPanel);
            if (closeBGChatPanelButton != null)
                closeBGChatPanelButton.onClick.RemoveListener(CloseChatPanel);
            if (emojiButton != null)
                emojiButton.onClick.RemoveListener(ToggleEmojiPanel);
            if (closeEmojiPanelButton != null)
                closeEmojiPanelButton.onClick.RemoveListener(CloseEmojiPanel);
            if (sendButton != null)
                sendButton.onClick.RemoveListener(OnSendButtonClicked);

            EventBus.Unsubscribe<OnEventClearChat>(OnChatMessageClear);
            EventBus.Unsubscribe<GameSession.ChatMessageEvent>(OnChatMessageReceived);
            EventBus.Unsubscribe<ChatChannelFilterChangedEvent>(OnChannelFilterChanged);
            EventBus.Unsubscribe<OpenChatPanelRequestedEvent>(OnOpenChatPanelRequested);

            if (scrollRect != null)
                scrollRect.onValueChanged.RemoveListener(OnScrollChanged);

            if (_pool != null)
            {
                _pool.Clear();
                _pool.Dispose();
            }
        }

        private void OnChannelFilterChanged(ChatChannelFilterChangedEvent e)
        {
            if (this == null) return;
            _currentFilterChannel = e.channel;
            if (chatPanelUIGO != null && chatPanelUIGO.activeSelf)
                RefreshVisible();
        }

        void OnOpenChatPanelRequested(OpenChatPanelRequestedEvent _)
        {
            if (this == null) return;
            OpenChatPanel(_.focusInputOnOpen);
        }

        private bool ShouldShowMessage(ChatMessageData data)
        {
            if (_currentFilterChannel == ChatChannel.GP_CHAT_LOCAL) return true;
            if (data.channel == (byte)ChatChannel.GP_CHAT_MISC) return true;
            return data.channel == (byte)_currentFilterChannel;
        }

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


        private void OnChatMessageClear(OnEventClearChat obj)
        {
            ChatThreadDispatcher.Instance.Post(() =>
            {
                if (this == null) return;
                ClearChat();
            });
        }

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

        void OnGetItem(ChatMessageView item)
        {
            if (item != null)
                item.gameObject.SetActive(true);
        }

        void OnReleaseItem(ChatMessageView item)
        {
            if (item != null)
                item.gameObject.SetActive(false);
        }

        void OnDestroyItem(ChatMessageView item)
        {
            if (item != null)
                Destroy(item.gameObject);
        }

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

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

        public void AddMessage(string msg, byte channel)
        {
            if (this == null) return;

            var data = new ChatMessageData { message = msg, channel = channel };
            _messages.Add(data);

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

            if (chatPanelUIGO == null || !chatPanelUIGO.activeSelf)
                return;

            if (ShouldShowMessage(data))
            {
                AddMessageView(data);

                if (_userAtBottom)
                    ScrollToBottom();
            }
        }

        void AddMessageView(ChatMessageData data)
        {
            if (this == null) return;
            var view = _pool.Get();
            if (view == null) view = CreateItem();
            if (view == null) return;

            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);
                if (old != null)
                {
                    _pool.Release(old);
                }
            }

            Canvas.ForceUpdateCanvases();
        }

        void RefreshVisible()
        {
            foreach (var view in _visibleViews)
            {
                if (view != null)
                    _pool.Release(view);
            }

            _visibleViews.Clear();

            _filteredMessagesCache.Clear();
            foreach (var msg in _messages)
            {
                if (ShouldShowMessage(msg))
                {
                    _filteredMessagesCache.Add(msg);
                }
            }

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

            for (int i = start; i < _filteredMessagesCache.Count; i++)
            {
                var view = _pool.Get();
                if (view == null) view = CreateItem();
                if (view == null) continue;

                view.transform.SetParent(content, false);
                view.transform.SetAsLastSibling();

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

                _visibleViews.Add(view);
            }

            Canvas.ForceUpdateCanvases();
            ScrollToBottom();
        }

        /// <summary>Cuộn log chat xuống dòng cuối (sau khi layout xong).</summary>
        public void ScrollToBottom()
        {
            if (scrollRect == null) return;
            if (content != null)
                LayoutRebuilder.ForceRebuildLayoutImmediate(content);
            Canvas.ForceUpdateCanvases();
            scrollRect.verticalNormalizedPosition = 0f;
        }

        public void ClearChat()
        {
            foreach (var view in _visibleViews)
            {
                if (view != null)
                    _pool.Release(view);
            }

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

        public void OnHandlerChatButton()
        {
            if (chatPanelUIGO == null) return;
            bool open = !chatPanelUIGO.activeSelf;
            SetChatPanelAndBgVisible(open);

            if (open)
                RefreshVisible();
            else
                SetEmojiPanelVisible(false);
        }

        public void OpenChatPanel()
        {
            OpenChatPanel(true);
        }

        public void OpenChatPanel(bool focusInputOnOpen)
        {
            if (chatPanelUIGO == null) return;
            SetChatPanelAndBgVisible(true);
            RefreshVisible();

            _chatInput ??= GetComponent<ChatInputHandler>();
            if (focusInputOnOpen && _chatInput != null && _chatInput.inputField != null)
                _chatInput.inputField.ActivateInputField();
        }

        public void CloseChatPanel()
        {
            SetChatPanelAndBgVisible(false);
            SetEmojiPanelVisible(false);
        }

        public void ToggleEmojiPanel()
        {
            if (EmojiPanelUI == null) return;
            SetEmojiPanelVisible(!EmojiPanelUI.activeSelf);
        }

        public void CloseEmojiPanel()
        {
            SetEmojiPanelVisible(false);
        }

        void SetEmojiPanelVisible(bool visible)
        {
            if (EmojiPanelUI != null)
                EmojiPanelUI.SetActive(visible);
        }

        void OnSendButtonClicked()
        {
            _chatInput ??= GetComponent<ChatInputHandler>();
            _chatInput?.SubmitFromSendButton();
        }
    }

    public struct OnEventClearChat { }

    /// <summary>
    /// Mini chat (hoặc HUD) publish để mở panel chat đầy đủ; <see cref="ChatSystemlUI"/> subscribe.
    /// </summary>
    public struct OpenChatPanelRequestedEvent
    {
        public bool focusInputOnOpen;

        public OpenChatPanelRequestedEvent(bool focusInputOnOpen)
        {
            this.focusInputOnOpen = focusInputOnOpen;
        }
    }
}