using System.Collections.Generic;

using UnityEngine;

namespace Colosseum.Passives
{
    /// <summary>
    /// 패시브 트리 전체 데이터를 정의합니다.
    /// </summary>
    [CreateAssetMenu(fileName = "PassiveTree", menuName = "Colosseum/Passives/Passive Tree")]
    public class PassiveTreeData : ScriptableObject
    {
        [Header("기본 정보")]
        [SerializeField] private string treeId;
        [SerializeField] private string treeName;
        [TextArea(2, 4)]
        [SerializeField] private string description;
        [Min(0)] [SerializeField] private int initialPoints = 0;

        [Header("노드")]
        [SerializeField] private List<PassiveNodeData> nodes = new List<PassiveNodeData>();

        public string TreeId => treeId;
        public string TreeName => treeName;
        public string Description => description;
        public int InitialPoints => initialPoints;
        public IReadOnlyList<PassiveNodeData> Nodes => nodes;

        public PassiveNodeData GetNodeById(string nodeId)
        {
            if (string.IsNullOrWhiteSpace(nodeId))
                return null;

            for (int i = 0; i < nodes.Count; i++)
            {
                PassiveNodeData node = nodes[i];
                if (node != null && string.Equals(node.NodeId, nodeId, System.StringComparison.Ordinal))
                    return node;
            }

            return null;
        }

        /// <summary>
        /// 선택된 노드 구성이 유효한지 검사합니다.
        /// </summary>
        public bool TryResolveSelection(IReadOnlyList<string> selectedNodeIds, out List<PassiveNodeData> resolvedNodes, out string reason)
        {
            resolvedNodes = new List<PassiveNodeData>();
            reason = string.Empty;

            HashSet<string> uniqueIds = new HashSet<string>();
            int totalCost = 0;

            if (selectedNodeIds == null)
                return true;

            for (int i = 0; i < selectedNodeIds.Count; i++)
            {
                string nodeId = selectedNodeIds[i];
                if (string.IsNullOrWhiteSpace(nodeId))
                    continue;

                if (!uniqueIds.Add(nodeId))
                {
                    reason = $"중복 노드가 포함되어 있습니다: {nodeId}";
                    return false;
                }

                PassiveNodeData node = GetNodeById(nodeId);
                if (node == null)
                {
                    reason = $"트리에 없는 노드입니다: {nodeId}";
                    return false;
                }

                resolvedNodes.Add(node);
                totalCost += node.Cost;
            }

            for (int i = 0; i < resolvedNodes.Count; i++)
            {
                PassiveNodeData node = resolvedNodes[i];
                IReadOnlyList<PassiveNodeData> prerequisiteNodes = node.PrerequisiteNodes;
                if (prerequisiteNodes == null)
                    continue;

                for (int j = 0; j < prerequisiteNodes.Count; j++)
                {
                    PassiveNodeData prerequisiteNode = prerequisiteNodes[j];
                    if (prerequisiteNode == null)
                        continue;

                    if (!uniqueIds.Contains(prerequisiteNode.NodeId))
                    {
                        reason = $"{node.DisplayName} 선택에는 선행 노드 {prerequisiteNode.DisplayName} 이(가) 필요합니다.";
                        return false;
                    }
                }
            }

            if (totalCost > initialPoints)
            {
                reason = $"선택한 노드 비용이 보유 포인트를 초과합니다. Used={totalCost}, Max={initialPoints}";
                return false;
            }

            return true;
        }

        public int CalculateUsedPoints(IReadOnlyList<PassiveNodeData> selectedNodes)
        {
            if (selectedNodes == null)
                return 0;

            int totalCost = 0;
            for (int i = 0; i < selectedNodes.Count; i++)
            {
                PassiveNodeData node = selectedNodes[i];
                if (node == null)
                    continue;

                totalCost += Mathf.Max(0, node.Cost);
            }

            return totalCost;
        }
    }
}