using UnityEngine;
using System.Collections.Generic;
using Unheimlich.Core;
using Unheimlich.Features.DetectiveBoard.Data;

namespace Unheimlich.Features.DetectiveBoard.UI
{
    /// <summary>
    /// Manages the clue hand fan displayed at the bottom of the screen (Screen Space canvas).
    /// Reuses the PostItNode prefab for each card — ClueHandCard is added at runtime.
    /// Hovering a card pops it up and straightens it; clicking starts a lerp-depth
    /// placement animation then hands the clue to DetectiveBoardCanvas.
    /// </summary>
    public class ClueHandUI : Singleton<ClueHandUI>
    {
        [Header("References")]
        [SerializeField] private GameObject _postItNodePrefab;
        [SerializeField] private RectTransform _handContainer;

        [Header("Fan Layout Settings")]
        [SerializeField] private float _cardSpacingPixels = 80f;
        [SerializeField] private float _fanArcRadius = 800f;
        [SerializeField] private float _cardBaseY = -120f;
        [SerializeField] private float _maxFanHalfAngle = 40f;

        [Header("Placement Settings")]
        // [SerializeField] private float _placementLerpSpeed = 5f;

        private readonly List<ClueHandCard> _handCards = new List<ClueHandCard>();
        private bool _isPlacing;        protected override void OnAwake() { }

        protected override void OnEnabled()
        {
            // With Scene Reload disabled, stale card references from the previous session
            // may point to destroyed GameObjects. Clear and rebuild from manager state.
            if (_handCards.Count > 0)
            {
                foreach (ClueHandCard card in _handCards)
                {
                    if (card != null && card.gameObject != null)
                        Destroy(card.gameObject);
                }
                _handCards.Clear();
            }

            if (DetectiveBoardManager.Instance != null)
            {
                foreach (var clue in DetectiveBoardManager.Instance.GetUnlockedClues())
                {
                    // Skip clues already placed on the board — they must not reappear in the hand
                    if (DetectiveBoardCanvas.Instance != null && DetectiveBoardCanvas.Instance.HasNodeForClue(clue.ClueID))
                        continue;

                    AddClueCard(clue);
                }
            }
        }

        private void Start()
        {
            if (DetectiveBoardManager.Instance != null)
            {
                DetectiveBoardManager.Instance.OnClueUnlocked += OnClueUnlocked;

                foreach (var clue in DetectiveBoardManager.Instance.GetUnlockedClues())
                    AddClueCard(clue);
            }

            // Start hidden — shown when the board activates
            SetHandVisible(false);
        }

        private void OnDestroy()
        {
            if (DetectiveBoardManager.Instance != null)
                DetectiveBoardManager.Instance.OnClueUnlocked -= OnClueUnlocked;
        }

        private void OnClueUnlocked(ClueData clueData)
        {
            AddClueCard(clueData);
        }

        // ──────────────────────────────────────────────────────────────────────
        // Card management
        // ──────────────────────────────────────────────────────────────────────

        /// <summary>
        /// Instantiates a PostItNode prefab, injects ClueHandCard, and adds it to the fan.
        /// </summary>
        public void AddClueCard(ClueData clueData)
        {
            if (_postItNodePrefab == null || _handContainer == null)
            {
                Debug.LogError("[ClueHandUI] Missing _postItNodePrefab or _handContainer reference.");
                return;
            }

            if (_handCards.Exists(c => c.ClueData != null && c.ClueData.ClueID == clueData.ClueID))
                return;

            // Instantiate the PostItNode prefab inside the screen-space hand container
            GameObject cardObj = Instantiate(_postItNodePrefab, _handContainer);

            // PostItNode is nested one level inside "Canvas (Environment)" wrapper in the prefab
            // — grab it directly
            PostItNode node = cardObj.GetComponentInChildren<PostItNode>(true);
            if (node == null)
            {
                Debug.LogError("[ClueHandUI] PostItNode not found on prefab.");
                Destroy(cardObj);
                return;
            }

            // Create a dummy NodeData for the hand display (position handled by fan layout)
            PostItNodeData dummyData = new PostItNodeData(clueData.ClueID, Vector2.zero);
            node.Initialize(clueData, dummyData);

            // Add ClueHandCard wrapper on the PostItNode GameObject
            ClueHandCard card = node.gameObject.AddComponent<ClueHandCard>();
            card.Initialize(node, this);

            // Move the PostItNode GameObject up to be a direct child of _handContainer
            // so its RectTransform is in screen space
            node.transform.SetParent(_handContainer, false);

            // Destroy the now-empty prefab root (the "Canvas (Environment)" wrapper)
            if (cardObj != node.gameObject)
                Destroy(cardObj);

            // Normalize scale — PostItNode prefab uses 0.5 scale for world space, reset for screen space
            node.RectTransform.localScale = Vector3.one;

            _handCards.Add(card);
            RebuildFanLayout();
        }

        /// <summary>
        /// Recomputes fan arc positions and rotations for all non-placed cards.
        /// Uses fixed pixel spacing between cards, capped by a max half-angle.
        /// </summary>
        private void RebuildFanLayout()
        {
            List<ClueHandCard> visible = _handCards.FindAll(c => !c.IsPlaced);
            int count = visible.Count;

            if (count == 0)
                return;

            // Derive the angle step from pixel spacing on the arc
            float angleStepDeg = (_cardSpacingPixels / _fanArcRadius) * Mathf.Rad2Deg;

            // Total spread is (count-1) steps, capped so it never exceeds _maxFanHalfAngle on each side
            float totalHalfAngle = angleStepDeg * (count - 1) * 0.5f;
            float clampedHalfAngle = Mathf.Min(totalHalfAngle, _maxFanHalfAngle);

            for (int i = 0; i < count; i++)
            {
                float t = count == 1 ? 0.5f : (float)i / (count - 1);
                float angle = Mathf.Lerp(-clampedHalfAngle, clampedHalfAngle, t);
                float angleRad = angle * Mathf.Deg2Rad;

                float x = _fanArcRadius * Mathf.Sin(angleRad);
                float y = _cardBaseY - _fanArcRadius * (1f - Mathf.Cos(angleRad));

                visible[i].SetFanSlot(new Vector2(x, y), -angle);
            }
        }

        // ──────────────────────────────────────────────────────────────────────
        // Hover callbacks
        // ──────────────────────────────────────────────────────────────────────

        /// <summary>Brings the hovered card in front of its siblings.</summary>
        public void OnCardHovered(ClueHandCard card)
        {
            card.transform.SetAsLastSibling();
        }

        /// <summary>Restores natural sibling order after hover ends.</summary>
        public void OnCardUnhovered(ClueHandCard card)
        {
            RebuildSiblingOrder();
        }

        private void RebuildSiblingOrder()
        {
            int index = 0;
            foreach (ClueHandCard c in _handCards)
            {
                if (!c.IsPlaced)
                    c.transform.SetSiblingIndex(index++);
            }
        }

        // ──────────────────────────────────────────────────────────────────────
        // Selection & placement
        // ──────────────────────────────────────────────────────────────────────

        /// <summary>
        /// Called when the player clicks a card. Creates the node on the board
        /// directly under the mouse cursor and immediately starts drag mode.
        /// </summary>
        public void OnCardSelected(ClueHandCard card)
        {
            if (_isPlacing)
                return;

            DetectiveBoardCanvas boardCanvas = DetectiveBoardCanvas.Instance;
            if (boardCanvas == null)
            {
                Debug.LogWarning("[ClueHandUI] DetectiveBoardCanvas not found.");
                return;
            }

            DetectiveBoardInteraction interaction = DetectiveBoardInteraction.Instance;
            if (interaction == null)
            {
                Debug.LogWarning("[ClueHandUI] DetectiveBoardInteraction not found.");
                return;
            }

            boardCanvas.AddClueNode(card.ClueData);

            PostItNode boardNode = boardCanvas.GetNodeForClue(card.ClueData.ClueID);
            if (boardNode == null)
            {
                Debug.LogWarning("[ClueHandUI] Node not found on board after AddClueNode.");
                return;
            }

            // Position node under the mouse on the board canvas plane, then start drag
            interaction.SpawnNodeUnderMouseAndDrag(boardNode);

            card.MarkAsPlaced();
            RebuildFanLayout();
        }

        // ──────────────────────────────────────────────────────────────────────
        // Visibility
        // ──────────────────────────────────────────────────────────────────────

        /// <summary>
        /// Shows or hides the fan hand. Called by DetectiveBoardController.
        /// </summary>
        public void SetHandVisible(bool visible)
        {
            if (_handContainer != null)
                _handContainer.gameObject.SetActive(visible);
        }
    }
}