using System;
using System.Collections.Generic;
using System.Linq;

namespace CoreAgent.ProtocolClient.Models
{
    /// <summary>
    /// TMSI匹配处理器
    /// 负责处理TMSI匹配和UE链的构建，从根节点获取IMSI并分配给整个链
    /// </summary>
    public class TmsiMatchProcessor
    {
        /// <summary>
        /// TMSI到UE ID的映射表
        /// </summary>
        private readonly Dictionary<uint, int> _tmsiToUeId;

        /// <summary>
        /// 请求TMSI到UE ID的映射表
        /// </summary>
        private readonly Dictionary<uint, int> _requestTmsiToUeId;

        /// <summary>
        /// IMSI到UE ID的映射表
        /// </summary>
        private readonly Dictionary<string, List<int>> _imsiToUeId;

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="tmsiToUeId">TMSI到UE ID的映射表</param>
        /// <param name="requestTmsiToUeId">请求TMSI到UE ID的映射表</param>
        /// <param name="imsiToUeId">IMSI到UE ID的映射表</param>
        public TmsiMatchProcessor(
            Dictionary<uint, int> tmsiToUeId,
            Dictionary<uint, int> requestTmsiToUeId,
            Dictionary<string, List<int>> imsiToUeId)
        {
            _tmsiToUeId = tmsiToUeId ?? new Dictionary<uint, int>();
            _requestTmsiToUeId = requestTmsiToUeId ?? new Dictionary<uint, int>();
            _imsiToUeId = imsiToUeId ?? new Dictionary<string, List<int>>();
        }

        /// <summary>
        /// 生成TMSI匹配结果
        /// 先构建树形结构，从根节点获取IMSI，然后平铺成列表
        /// </summary>
        /// <returns>TMSI匹配结果列表</returns>
        public List<TmsiMatchResult> GenerateTmsiMatches()
        {
            var matches = new List<TmsiMatchResult>();

            // 构建UE链的树形结构
            var ueChains = BuildUeChains();

            // 遍历RequestTmsiToUeId，查找在TmsiToUeId中是否有相同的TMSI
            foreach (var requestKvp in _requestTmsiToUeId)
            {
                uint tmsi = requestKvp.Key;
                int requestUeId = requestKvp.Value;

                // 检查TmsiToUeId中是否存在相同的TMSI
                if (_tmsiToUeId.TryGetValue(tmsi, out int receiveUeId))
                {
                    // 从UE链中获取IMSI
                    string imsi = GetImsiFromUeChain(receiveUeId, ueChains);

                    // 创建匹配结果
                    var matchResult = new TmsiMatchResult(tmsi, requestUeId, receiveUeId, imsi);
                    matches.Add(matchResult);
                }
            }

            return matches;
        }

        /// <summary>
        /// 构建UE链的树形结构
        /// 根据RequestTmsiToUeId和TmsiToUeId的映射关系构建链式结构
        /// </summary>
        /// <returns>UE链的字典，键为链的根节点UE ID，值为链中的所有UE ID</returns>
        private Dictionary<int, List<int>> BuildUeChains()
        {
            var ueChains = new Dictionary<int, List<int>>();
            var processedUeIds = new HashSet<int>();

            // 遍历所有TMSI匹配关系，构建链式结构
            foreach (var requestKvp in _tmsiToUeId)
            {
                uint tmsi = requestKvp.Key;
                int requestUeId = requestKvp.Value;

                if (_requestTmsiToUeId.TryGetValue(tmsi, out int receiveUeId))
                {
                    // 如果这个UE ID还没有被处理过
                    if (!processedUeIds.Contains(requestUeId) && !processedUeIds.Contains(receiveUeId))
                    {
                        var chain = BuildChainFromUe(requestUeId, receiveUeId);
                        if (chain.Count > 0)
                        {
                            // 使用链的根节点（最外层节点）作为键
                            int rootUeId = chain[0];
                            ueChains[rootUeId] = chain;

                            // 标记所有UE ID为已处理
                            foreach (int ueId in chain)
                            {
                                processedUeIds.Add(ueId);
                            }
                        }
                    }
                }
            }

            return ueChains;
        }

        /// <summary>
        /// 从指定的UE ID开始构建链式结构
        /// </summary>
        /// <param name="requestUeId">请求UE ID</param>
        /// <param name="receiveUeId">接收UE ID</param>
        /// <returns>链中的所有UE ID列表</returns>
        private List<int> BuildChainFromUe(int requestUeId, int receiveUeId)
        {
            var chain = new List<int>();
            var visited = new HashSet<int>();

            // 从requestUeId开始，沿着链式关系查找
            int currentUeId = requestUeId;
            while (currentUeId > 0 && !visited.Contains(currentUeId))
            {
                chain.Add(currentUeId);
                visited.Add(currentUeId);

                // 查找下一个UE ID（在TmsiToUeId中查找当前UE ID作为receiveUeId的情况）
                currentUeId = FindNextUeIdInChain(currentUeId);
            }

            return chain;
        }

        /// <summary>
        /// 在链中查找下一个UE ID
        /// </summary>
        /// <param name="currentUeId">当前UE ID</param>
        /// <returns>下一个UE ID，如果没有找到则返回-1</returns>
        private int FindNextUeIdInChain(int currentUeId)
        {
            // 在RequestTmsiToUeId中查找当前UE ID作为receiveUeId的情况
            foreach (var kvp in _requestTmsiToUeId)
            {
                if (_tmsiToUeId.TryGetValue(kvp.Key, out int receiveUeId) && receiveUeId == currentUeId)
                {
                    return kvp.Value; // 返回对应的requestUeId
                }
            }

            return -1; // 没有找到下一个UE ID
        }

        /// <summary>
        /// 从UE链中获取IMSI
        /// 优先从链的根节点（最外层节点）获取IMSI
        /// </summary>
        /// <param name="ueId">当前UE ID</param>
        /// <param name="ueChains">UE链字典</param>
        /// <returns>对应的IMSI，如果未找到则返回空字符串</returns>
        private string GetImsiFromUeChain(int ueId, Dictionary<int, List<int>> ueChains)
        {
            // 查找当前UE ID所在的链
            foreach (var chain in ueChains.Values)
            {
                if (chain.Contains(ueId))
                {
                    // 从链的根节点（最外层节点）开始查找IMSI
                    foreach (int chainUeId in chain)
                    {
                        string imsi = GetImsiForUeId(chainUeId);
                        if (!string.IsNullOrEmpty(imsi))
                        {
                            return imsi;
                        }
                    }
                    break;
                }
            }

            return string.Empty;
        }

        /// <summary>
        /// 根据UE ID获取对应的IMSI
        /// 优先查找当前UE ID，如果未找到则查找整个UE链中的IMSI
        /// </summary>
        /// <param name="ueId">UE ID</param>
        /// <returns>对应的IMSI，如果未找到则返回空字符串</returns>
        private string GetImsiForUeId(int ueId)
        {
            // 1. 首先查找当前UE ID对应的IMSI
            foreach (var imsiMapping in _imsiToUeId)
            {
                if (imsiMapping.Value.Contains(ueId))
                {
                    return imsiMapping.Key;
                }
            }

            // 2. 如果当前UE ID没有IMSI，查找整个UE链中的IMSI
            // 遍历所有IMSI映射，查找是否有任何UE ID对应的IMSI
            foreach (var imsiMapping in _imsiToUeId)
            {
                if (!string.IsNullOrEmpty(imsiMapping.Key))
                {
                    return imsiMapping.Key;
                }
            }

            return string.Empty;
        }

        /// <summary>
        /// 获取UE链的统计信息
        /// </summary>
        /// <returns>UE链统计信息</returns>
        public UeChainStats GetUeChainStats()
        {
            var ueChains = BuildUeChains();

            return new UeChainStats
            {
                TotalChains = ueChains.Count,
                TotalUeIds = ueChains.Values.Sum(chain => chain.Count),
                AverageChainLength = ueChains.Count > 0 ? (double)ueChains.Values.Sum(chain => chain.Count) / ueChains.Count : 0,
                MaxChainLength = ueChains.Count > 0 ? ueChains.Values.Max(chain => chain.Count) : 0,
                MinChainLength = ueChains.Count > 0 ? ueChains.Values.Min(chain => chain.Count) : 0
            };
        }

        /// <summary>
        /// 获取所有UE链的详细信息
        /// </summary>
        /// <returns>UE链详细信息列表</returns>
        public List<UeChainInfo> GetUeChainDetails()
        {
            var ueChains = BuildUeChains();
            var chainInfos = new List<UeChainInfo>();

            foreach (var kvp in ueChains)
            {
                int rootUeId = kvp.Key;
                var chain = kvp.Value;
                string imsi = GetImsiFromUeChain(rootUeId, ueChains);

                chainInfos.Add(new UeChainInfo
                {
                    RootUeId = rootUeId,
                    ChainLength = chain.Count,
                    UeIds = chain.ToList(),
                    Imsi = imsi
                });
            }

            return chainInfos;
        }
    }

    /// <summary>
    /// UE链统计信息
    /// </summary>
    public class UeChainStats
    {
        /// <summary>
        /// 总链数
        /// </summary>
        public int TotalChains { get; set; }

        /// <summary>
        /// 总UE ID数
        /// </summary>
        public int TotalUeIds { get; set; }

        /// <summary>
        /// 平均链长度
        /// </summary>
        public double AverageChainLength { get; set; }

        /// <summary>
        /// 最大链长度
        /// </summary>
        public int MaxChainLength { get; set; }

        /// <summary>
        /// 最小链长度
        /// </summary>
        public int MinChainLength { get; set; }
    }

    /// <summary>
    /// UE链详细信息
    /// </summary>
    public class UeChainInfo
    {
        /// <summary>
        /// 根节点UE ID
        /// </summary>
        public int RootUeId { get; set; }

        /// <summary>
        /// 链长度
        /// </summary>
        public int ChainLength { get; set; }

        /// <summary>
        /// 链中的所有UE ID
        /// </summary>
        public List<int> UeIds { get; set; } = new List<int>();

        /// <summary>
        /// 对应的IMSI
        /// </summary>
        public string Imsi { get; set; } = string.Empty;
    }
}