using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;
using System.Linq;
using Newtonsoft.Json;

namespace LTEMvcApp.Models
{
    /// <summary>
    /// ASN1解析器，用于解析GSER格式的ASN1数据
    /// </summary>
    public class ASN1Parser
    {
        private static readonly Regex RegExpOpen = new Regex(@"((?! )[\w-\s]+(?<! ))?:?\s*{", RegexOptions.Compiled);
        private static readonly Regex RegExpClose = new Regex(@"}", RegexOptions.Compiled);
        private static readonly Regex RegExpValueNum = new Regex(@"([\w-]+)\s+(\d+),?$", RegexOptions.Compiled);
        private static readonly Regex RegExpValueEnumerated = new Regex(@"([\w-]+)\s+([\w-']+)\s*,?$", RegexOptions.Compiled);
        private static readonly Regex RegExpValueChoice = new Regex(@"([\w-]+) ([\w-]+):\s+([\w-']+)\s*,?$", RegexOptions.Compiled);
        private static readonly Regex RegExpValueListNum = new Regex(@"\s+(\d+),?$", RegexOptions.Compiled);
        private static readonly Regex RegExpValueListMisc = new Regex(@"\s+([\w-]+),?$", RegexOptions.Compiled);
        private static readonly Regex RegExpHexDump = new Regex(@"^[0-9A-Fa-f\s]+$", RegexOptions.Compiled);

        /// <summary>
        /// 从GSER格式的字符串数组解析ASN1数据
        /// </summary>
        /// <param name="data">GSER格式的字符串数组</param>
        /// <returns>解析后的ASN1对象</returns>
        public static Dictionary<string, object> FromGSER(string[] data)
        {
            if (data == null || data.Length == 0)
                return null;

            var root = (ASN1Node)null;
            var stack = new Stack<ASN1Node>();

            try
            {
                int i = 0;
                // 移除十六进制转储
                for (; i < data.Length; i++)
                {
                    var d = data[i];
                    if (!RegExpHexDump.IsMatch(d))
                        break;
                }

                for (; i < data.Length; i++)
                {
                    var d = data[i];

                    // 移除注释
                    for (int j = 0; j < 10; j++) // 最多10次迭代
                    {
                        var c0 = d.IndexOf("/*");
                        if (c0 < 0) break;

                        var c1 = d.IndexOf("*/");
                        if (c1 >= 0)
                        {
                            d = d.Remove(c0, c1 + 2 - c0);
                        }
                        else
                        {
                            d = d.Substring(0, c0);
                            for (i++; i < data.Length; i++)
                            {
                                var d1 = data[i];
                                var c2 = d1.IndexOf("*/");
                                if (c2 >= 0)
                                {
                                    d += d1.Substring(c2 + 2);
                                    break;
                                }
                            }
                        }
                    }

                    var match = RegExpOpen.Match(d);
                    if (match.Success)
                    {
                        var node = new ASN1Node { Name = match.Groups[1].Success ? match.Groups[1].Value.Trim() : null };
                        if (root == null) root = node;
                        stack.Push(node);
                        continue;
                    }

                    if (stack.Count == 0) continue;

                    match = RegExpClose.Match(d);
                    if (match.Success)
                    {
                        var node = stack.Pop();
                        if (stack.Count == 0) // 结束
                            break;

                        AddProperty(stack.Peek(), node.Name, node.Obj ?? new Dictionary<string, object>());
                        continue;
                    }

                    // 数值常量
                    match = RegExpValueNum.Match(d);
                    if (match.Success)
                    {
                        AddProperty(stack.Peek(), match.Groups[1].Value, int.Parse(match.Groups[2].Value));
                    }
                    // 通用字符串
                    else if ((match = RegExpValueEnumerated.Match(d)).Success)
                    {
                        var value = match.Groups[2].Value;
                        switch (value)
                        {
                            case "TRUE":
                                AddProperty(stack.Peek(), match.Groups[1].Value, true);
                                break;
                            case "FALSE":
                                AddProperty(stack.Peek(), match.Groups[1].Value, false);
                                break;
                            default:
                                AddProperty(stack.Peek(), match.Groups[1].Value, value);
                                break;
                        }
                    }
                    // 带基本值的Choice
                    else if ((match = RegExpValueChoice.Match(d)).Success)
                    {
                        AddProperty(stack.Peek(), match.Groups[1].Value, 
                            new Dictionary<string, object> 
                            { 
                                ["choice"] = match.Groups[2].Value, 
                                ["value"] = match.Groups[3].Value 
                            });
                    }
                    else if ((match = RegExpValueListNum.Match(d)).Success)
                    {
                        AddProperty(stack.Peek(), null, int.Parse(match.Groups[1].Value));
                    }
                    else if ((match = RegExpValueListMisc.Match(d)).Success)
                    {
                        AddProperty(stack.Peek(), null, match.Groups[1].Value);
                    }
                }

                // 验证解析结果
                if (root == null)
                    return null;

                if (stack.Count != 0)
                {
                    // 栈不为空说明解析不完整，返回null
                    return null;
                }

                // 确保返回的是Dictionary<string, object>类型
                if (root.Obj is Dictionary<string, object> dict)
                {
                    return dict;
                }
                else if (root.Obj is List<object> list)
                {
                    // 如果是列表，包装成字典
                    return new Dictionary<string, object> { ["items"] = list };
                }
                else if (root.Obj != null)
                {
                    // 如果是其他类型，包装成字典
                    return new Dictionary<string, object> { ["value"] = root.Obj };
                }
                else
                {
                    // 如果root.Obj为null，返回空字典
                    return new Dictionary<string, object>();
                }
            }
            catch (Exception ex)
            {
                // 记录异常信息（在实际应用中可以使用日志框架）
                throw new InvalidOperationException($"解析GSER数据时发生错误: {ex.Message}", ex);
            }
        }

        /// <summary>
        /// 添加属性到节点
        /// </summary>
        private static void AddProperty(ASN1Node node, string name, object value)
        {
            if (string.IsNullOrEmpty(name))
            {
                if (node.Obj == null) node.Obj = new List<object>();
                ((List<object>)node.Obj).Add(value);
            }
            else
            {
                if (node.Obj == null) node.Obj = new Dictionary<string, object>();

                var dict = (Dictionary<string, object>)node.Obj;
                if (!dict.ContainsKey(name))
                {
                    dict[name] = value;
                }
                else
                {
                    var cur = dict[name];
                    if (cur is List<object> list)
                    {
                        list.Add(value);
                    }
                    else
                    {
                        dict[name] = new List<object> { cur, value };
                    }
                }
            }
        }

        /// <summary>
        /// 深度访问ASN1对象
        /// </summary>
        /// <param name="asn1">ASN1对象</param>
        /// <param name="path">访问路径</param>
        /// <returns>访问到的值</returns>
        public static object Dig(Dictionary<string, object> asn1, params object[] path)
        {
            if (asn1 == null)
                return null;

            var current = (object)asn1;
            var count = 1;

            for (int i = 0; i < path.Length;)
            {
                var arg = path[i];
                if (arg is int intArg)
                {
                    count = intArg;
                    i++;
                }
                else
                {
                    if (current is Dictionary<string, object> dict)
                    {
                        var key = arg.ToString();
                        if (!dict.ContainsKey(key))
                            return null;
                        current = dict[key];
                    }
                    else if (current is List<object> list)
                    {
                        var index = int.Parse(arg.ToString());
                        if (index >= list.Count)
                            return null;
                        current = list[index];
                    }
                    else
                    {
                        return null;
                    }

                    if (--count == 0)
                    {
                        i++;
                        count = 1;
                    }
                }
            }

            return current;
        }

        /// <summary>
        /// 映射ASN1数组
        /// </summary>
        /// <typeparam name="T">返回类型</typeparam>
        /// <param name="asn1">ASN1对象</param>
        /// <param name="callback">映射函数</param>
        /// <returns>映射结果</returns>
        public static List<T> Map<T>(object asn1, Func<object, T> callback)
        {
            // 参数验证
            if (callback == null)
                throw new ArgumentNullException(nameof(callback), "回调函数不能为空");

            // 如果asn1为null，返回空列表
            if (asn1 == null)
                return new List<T>();

            try
            {
                if (asn1 is List<object> list)
                {
                    // 处理列表类型，过滤掉null值并应用映射
                    return list.Where(item => item != null)
                              .Select(callback)
                              .ToList<T>();
                }
                else
                {
                    // 处理单个对象
                    return new List<T> { callback(asn1) };
                }
            }
            catch (Exception ex)
            {
                // 记录异常信息（在实际应用中可以使用日志框架）
                throw new InvalidOperationException($"映射ASN1数据时发生错误: {ex.Message}", ex);
            }
        }

        /// <summary>
        /// 映射ASN1数组（带索引）
        /// </summary>
        /// <typeparam name="T">返回类型</typeparam>
        /// <param name="asn1">ASN1对象</param>
        /// <param name="callback">带索引的映射函数</param>
        /// <returns>映射结果</returns>
        public static List<T> Map<T>(object asn1, Func<object, int, T> callback)
        {
            // 参数验证
            if (callback == null)
                throw new ArgumentNullException(nameof(callback), "回调函数不能为空");

            // 如果asn1为null，返回空列表
            if (asn1 == null)
                return new List<T>();

            try
            {
                if (asn1 is List<object> list)
                {
                    // 处理列表类型，过滤掉null值并应用带索引的映射
                    var result = new List<T>();
                    int index = 0;
                    foreach (var item in list)
                    {
                        if (item != null)
                        {
                            result.Add(callback(item, index));
                        }
                        index++;
                    }
                    return result;
                }
                else
                {
                    // 处理单个对象
                    return new List<T> { callback(asn1, 0) };
                }
            }
            catch (Exception ex)
            {
                // 记录异常信息（在实际应用中可以使用日志框架）
                throw new InvalidOperationException($"映射ASN1数据时发生错误: {ex.Message}", ex);
            }
        }
    }

    /// <summary>
    /// ASN1节点
    /// </summary>
    public class ASN1Node
    {
        public string Name { get; set; }
        public object Obj { get; set; }
    }
}