using UnityEngine;
using UnityEngine.InputSystem;
using System.Collections.Generic;
using System.Linq;
using Unheimlich.Data.DetectiveBoard;
using Unheimlich.Managers;
using Unheimlich.Core;

namespace Unheimlich.UI.DetectiveBoard
{
    public class DetectiveBoardCanvas : Singleton<DetectiveBoardCanvas>
    {
        [Header("References")]
        [SerializeField] private Canvas _canvas;
        [SerializeField] private RectTransform _boardArea;
        [SerializeField] private GameObject _postItNodePrefab;
        [SerializeField] private GameObject _connectionLinePrefab;
        
        [Header("World Space Setup")]
        [SerializeField] private Camera _targetCamera;
        
        [Header("Connection Settings")]
        [SerializeField] private Color _connectionColor = Color.white;
        [SerializeField] private bool _allowFreeConnections = false;
        
        [Header("Input")]
        [SerializeField] private Key _connectModeKey = Key.LeftCtrl;
        [SerializeField] private Key _eliminateKey = Key.X;
        
        private Dictionary<string, PostItNode> _activeNodes = new Dictionary<string, PostItNode>();
        private List<ConnectionLine> _activeConnections = new List<ConnectionLine>();
        private PostItNode _selectedNode;
        private bool _isConnectMode;
        private DetectiveBoardSaveData _saveData;
        
        public bool IsConnectMode => _isConnectMode;
        
        /// <summary>
        /// Called by DetectiveBoardInteraction when a node is left-clicked.
        /// Handles connection creation in connect mode, or selection in normal mode.
        /// </summary>
        public void OnNodeClicked(PostItNode node)
        {
            if (_isConnectMode)
            {
                HandleConnectionModeClick(node);
            }
            else
            {
                _selectedNode = node;
                UpdateAllNodeSelections();
            }
        }
        
        /// <summary>
        /// Called by DetectiveBoardInteraction when a node is right-clicked.
        /// Toggles the eliminated state of the node.
        /// </summary>
        public void OnNodeRightClicked(PostItNode node)
        {
            ToggleNodeEliminated(node);
        }
        
        protected override void OnAwake()
        {
            if (_canvas == null)
                _canvas = GetComponent<Canvas>();
            
            if (_canvas != null && _canvas.renderMode == RenderMode.WorldSpace)
            {
                if (_targetCamera == null)
                    _targetCamera = Camera.main;
                
                _canvas.worldCamera = _targetCamera;
            }
            
            _saveData = new DetectiveBoardSaveData();
        }
        
        private void OnEnable()
        {
            TrySubscribeToManager();
        }
        
        private void Start()
        {
            TrySubscribeToManager();
        }
        
        private void TrySubscribeToManager()
        {
            if (DetectiveBoardManager.Instance != null)
            {
                DetectiveBoardManager.Instance.OnClueUnlocked -= OnClueUnlocked;
                DetectiveBoardManager.Instance.OnClueUnlocked += OnClueUnlocked;
                
                foreach (var clue in DetectiveBoardManager.Instance.GetUnlockedClues())
                {
                    if (!_activeNodes.ContainsKey(clue.ClueID))
                    {
                        AddClueNode(clue);
                    }
                }
            }
        }
        
        private void OnDisable()
        {
            if (DetectiveBoardManager.Instance != null)
            {
                DetectiveBoardManager.Instance.OnClueUnlocked -= OnClueUnlocked;
            }
        }
        
        private void OnClueUnlocked(ClueData clueData)
        {
            AddClueNode(clueData);
        }
        
        private void Update()
        {
            HandleConnectModeInput();
            HandleEliminateInput();
        }
        
        private void HandleConnectModeInput()
        {
            if (Keyboard.current == null)
                return;
            
            bool wasConnectMode = _isConnectMode;
            _isConnectMode = Keyboard.current[_connectModeKey].isPressed;
            
            if (wasConnectMode && !_isConnectMode)
            {
                _selectedNode = null;
                UpdateAllNodeSelections();
            }
        }
        
        private void HandleEliminateInput()
        {
            if (Keyboard.current == null)
                return;
            
            if (Keyboard.current[_eliminateKey].wasPressedThisFrame && _selectedNode != null)
            {
                ToggleNodeEliminated(_selectedNode);
            }
        }
        
        public void AddClueNode(ClueData clueData)
        {
            if (_activeNodes.ContainsKey(clueData.ClueID))
                return;
            
            if (_postItNodePrefab == null)
            {
                Debug.LogError("[DetectiveBoardCanvas] _postItNodePrefab is null! Assign the prefab in the inspector.");
                return;
            }
            
            if (_boardArea == null)
            {
                Debug.LogError("[DetectiveBoardCanvas] _boardArea is null! Assign NodesContainer in the inspector.");
                return;
            }
            
            PostItNodeData nodeData = _saveData.GetNodeData(clueData.ClueID);
            if (nodeData == null)
            {
                Vector2 canvasSize = _boardArea.rect.size;
                Vector2 randomPos = new Vector2(
                    Random.Range(-canvasSize.x * 0.4f, canvasSize.x * 0.4f),
                    Random.Range(-canvasSize.y * 0.4f, canvasSize.y * 0.4f)
                );
                nodeData = new PostItNodeData(clueData.ClueID, randomPos);
                _saveData.AddOrUpdateNode(nodeData);
            }
            
            GameObject nodeObj = Instantiate(_postItNodePrefab, _boardArea);
            
            PostItNode node = nodeObj.GetComponent<PostItNode>();
            
            if (node == null)
            {
                Debug.LogError("[DetectiveBoardCanvas] PostItNode component not found on prefab");
                Destroy(nodeObj);
                return;
            }
            
            node.Initialize(clueData, nodeData);
            
            _activeNodes.Add(clueData.ClueID, node);
            
            RestoreConnectionsForNode(node);
        }
        
        public void RemoveClueNode(string clueID)
        {
            if (!_activeNodes.TryGetValue(clueID, out PostItNode node))
                return;
            
            RemoveConnectionsForNode(node);
            
            _activeNodes.Remove(clueID);
            Destroy(node.gameObject);
        }
        
        private void HandleConnectionModeClick(PostItNode clickedNode)
        {
            if (_selectedNode == null)
            {
                _selectedNode = clickedNode;
                UpdateAllNodeSelections();
            }
            else if (_selectedNode == clickedNode)
            {
                _selectedNode = null;
                UpdateAllNodeSelections();
            }
            else
            {
                ToggleConnection(_selectedNode, clickedNode);
                _selectedNode = null;
                UpdateAllNodeSelections();
            }
        }
        
        private void ToggleConnection(PostItNode nodeA, PostItNode nodeB)
        {
            if (!CanConnect(nodeA, nodeB))
                return;
            
            ConnectionLine existingConnection = _activeConnections.Find(c => c.ConnectsNodes(nodeA, nodeB));
            
            if (existingConnection != null)
            {
                RemoveConnection(existingConnection);
            }
            else
            {
                CreateConnection(nodeA, nodeB);
            }
        }
        
        private bool CanConnect(PostItNode nodeA, PostItNode nodeB)
        {
            if (nodeA == null || nodeB == null)
                return false;
            
            if (_allowFreeConnections)
                return true;
            
            if (nodeA.ClueData.PossibleConnections == null || nodeA.ClueData.PossibleConnections.Length == 0)
                return true;
            
            return nodeA.ClueData.PossibleConnections.Contains(nodeB.NodeID);
        }
        
        private void CreateConnection(PostItNode startNode, PostItNode endNode)
        {
            GameObject lineObj = Instantiate(_connectionLinePrefab, _boardArea);
            lineObj.transform.SetAsFirstSibling();
            
            ConnectionLine line = lineObj.GetComponent<ConnectionLine>();
            if (line == null)
            {
                Debug.LogError("[DetectiveBoardCanvas] ConnectionLine component not found on prefab");
                Destroy(lineObj);
                return;
            }
            
            line.Initialize(startNode, endNode, _connectionColor);
            _activeConnections.Add(line);
            
            if (!startNode.NodeData.ConnectedNodeIDs.Contains(endNode.NodeID))
                startNode.NodeData.ConnectedNodeIDs.Add(endNode.NodeID);
            
            if (!endNode.NodeData.ConnectedNodeIDs.Contains(startNode.NodeID))
                endNode.NodeData.ConnectedNodeIDs.Add(startNode.NodeID);
        }
        
        private void RemoveConnection(ConnectionLine connection)
        {
            if (connection.StartNode != null && connection.EndNode != null)
            {
                connection.StartNode.NodeData.ConnectedNodeIDs.Remove(connection.EndNode.NodeID);
                connection.EndNode.NodeData.ConnectedNodeIDs.Remove(connection.StartNode.NodeID);
            }
            
            _activeConnections.Remove(connection);
            Destroy(connection.gameObject);
        }
        
        private void RemoveConnectionsForNode(PostItNode node)
        {
            var connectionsToRemove = _activeConnections
                .Where(c => c.StartNode == node || c.EndNode == node)
                .ToList();
            
            foreach (var connection in connectionsToRemove)
            {
                RemoveConnection(connection);
            }
        }
        
        /// <summary>
        /// Updates all connection lines attached to the specified node.
        /// Called during node dragging to keep connections visually updated.
        /// </summary>
        public void UpdateConnectionsForNode(PostItNode node)
        {
            foreach (var connection in _activeConnections)
            {
                if (connection.StartNode == node || connection.EndNode == node)
                {
                    connection.UpdateLine();
                }
            }
        }
        
        private void RestoreConnectionsForNode(PostItNode node)
        {
            if (node.NodeData.ConnectedNodeIDs == null || node.NodeData.ConnectedNodeIDs.Count == 0)
                return;
            
            foreach (string connectedID in node.NodeData.ConnectedNodeIDs)
            {
                if (_activeNodes.TryGetValue(connectedID, out PostItNode otherNode))
                {
                    bool connectionExists = _activeConnections.Any(c => c.ConnectsNodes(node, otherNode));
                    if (!connectionExists)
                    {
                        CreateConnection(node, otherNode);
                    }
                }
            }
        }
        
        private void ToggleNodeEliminated(PostItNode node)
        {
            node.SetEliminated(!node.IsEliminated);
        }
        
        private void UpdateAllNodeSelections()
        {
            foreach (var node in _activeNodes.Values)
            {
                node.SetSelected(node == _selectedNode);
            }
        }
        
        public DetectiveBoardSaveData GetSaveData()
        {
            return _saveData;
        }
        
        public void LoadSaveData(DetectiveBoardSaveData saveData)
        {
            _saveData = saveData;
            
            foreach (var node in _activeNodes.Values)
            {
                PostItNodeData nodeData = _saveData.GetNodeData(node.NodeID);
                if (nodeData != null)
                {
                    node.SetPosition(nodeData.Position);
                    node.SetEliminated(nodeData.IsEliminated);
                }
            }
            
            _activeConnections.Clear();
            foreach (var node in _activeNodes.Values)
            {
                RestoreConnectionsForNode(node);
            }
        }
    }
}