using SharpNBT;
using SharpNBT.SNBT;
using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Numerics;
using System.Text;

namespace MCI18n.Utilities
{
    /// <summary>
    /// 提供用于将CompoundTag保存为SNBT格式文件的工具方法
    /// </summary>
    public static class SnbtWriter
    {
        /// <summary>
        /// 将CompoundTag保存为SNBT格式文件
        /// </summary>
        /// <param name="tag">要保存的CompoundTag</param>
        /// <param name="filePath">文件路径</param>
        /// <param name="prettyPrint">是否进行美化格式输出</param>
        /// <exception cref="ArgumentNullException">当tag为null时抛出</exception>
        /// <exception cref="IOException">写入文件失败时抛出</exception>
        public static void SaveToFile(CompoundTag tag, string filePath, bool prettyPrint = true)
        {
            if (tag == null)
                throw new ArgumentNullException(nameof(tag));

            try
            {
                string snbt = ConvertToSnbt(tag, prettyPrint);
                File.WriteAllText(filePath, snbt, Encoding.UTF8);
            }
            catch (Exception ex) when (ex is IOException or UnauthorizedAccessException or DirectoryNotFoundException)
            {
                throw new IOException($"保存SNBT文件失败 '{filePath}': {ex.Message}", ex);
            }
        }

        /// <summary>
        /// 将CompoundTag转换为SNBT格式字符串
        /// </summary>
        /// <param name="tag">要转换的CompoundTag</param>
        /// <param name="prettyPrint">是否美化输出格式</param>
        /// <returns>SNBT格式字符串</returns>
        public static string ConvertToSnbt(CompoundTag tag, bool prettyPrint = true)
        {
            if (prettyPrint)
                return FormatCompound(tag, 0);
            else
                return tag.Stringify(true);
        }

        private static string FormatCompound(CompoundTag tag, int indentLevel)
        {
            if (tag.Count == 0)
                return "{}";

            var sb = new StringBuilder();
            sb.AppendLine("{");

            int i = 0;
            foreach (var child in tag)
            {
                sb.Append('\t', indentLevel + 1);
                sb.Append($"{EscapeName(child.Name)}: ");
                sb.Append(FormatTag(child, indentLevel + 1));

                //if (i < tag.Count - 1)
                //    sb.AppendLine(",");
                //else
                //    sb.AppendLine();
                sb.AppendLine();
                i++;
            }

            sb.Append('\t', indentLevel);
            sb.Append("}");
            return sb.ToString();
        }

        private static string FormatTag(Tag tag, int indentLevel)
        {
            switch (tag)
            {
                case CompoundTag compoundTag:
                    return FormatCompound(compoundTag, indentLevel);
                
                case ListTag listTag:
                    return FormatList(listTag, indentLevel);
                
                case ByteArrayTag byteArrayTag:
                    return FormatArray(byteArrayTag, 'B', 'b', indentLevel);
                
                case IntArrayTag intArrayTag:
                    return FormatArray(intArrayTag, 'I', null, indentLevel);
                
                case LongArrayTag longArrayTag:
                    return FormatArray(longArrayTag, 'L', 'L', indentLevel);
                
                case StringTag stringTag:
                    return $"\"{EscapeString(stringTag.Value)}\"";
                
                case ByteTag byteTag:
                    //return $"{byteTag.Value}b";
                    return byteTag.Bool ? "true" : "false";

                case ShortTag shortTag:
                    return $"{shortTag.Value}s";
                
                case IntTag intTag:
                    return intTag.Value.ToString();
                
                case LongTag longTag:
                    return $"{longTag.Value}L";
                
                case FloatTag floatTag:
                    return $"{floatTag.Value.ToString("0.#####", CultureInfo.InvariantCulture)}f";
                
                case DoubleTag doubleTag:
                    return $"{doubleTag.Value.ToString("0.#####", CultureInfo.InvariantCulture)}d";
                
                default:
                    return tag.Stringify(false);
            }
        }

        private static string FormatList(ListTag listTag, int indentLevel)
        {
            if (listTag.Count == 0)
                return "[]";

            var sb = new StringBuilder();
            sb.AppendLine("[");

            for (int i = 0; i < listTag.Count; i++)
            {
                sb.Append('\t', indentLevel + 1);
                sb.Append(FormatTag(listTag[i], indentLevel + 1));

                //if (i < listTag.Count - 1)
                //    sb.AppendLine(",");
                //else
                //    sb.AppendLine();
                sb.AppendLine();
            }

            sb.Append('\t', indentLevel);
            sb.Append("]");
            return sb.ToString();
        }

        private static string FormatArray<T>(ArrayTag<T> arrayTag, char prefix, char? suffix, int indentLevel) 
            where T : unmanaged, INumber<T> 
        {
            if (arrayTag.Count == 0)
                return $"[{prefix};]";

            var sb = new StringBuilder();
            sb.Append($"[{prefix};");

            // 对于数组类型，我们通常不使用多行格式
            for (int i = 0; i < arrayTag.Count; i++)
            {
                if (i > 0)
                    sb.AppendLine();
                    //sb.Append("\r\n");


                sb.Append(arrayTag[i]);
                
                if (suffix != null)
                    sb.Append(suffix.Value);
            }

            sb.Append("]");
            return sb.ToString();
        }

        private static string EscapeName(string name)
        {
            // 如果名称包含特殊字符，需要用引号括起来
            if (string.IsNullOrEmpty(name) || NeedsQuotes(name))
                return $"\"{EscapeString(name)}\"";
            return name;
        }

        private static bool NeedsQuotes(string s)
        {
            foreach (char c in s)
            {
                if (!char.IsLetterOrDigit(c) && c != '_' && c != '-' && c != '.')
                    return true;
            }
            return false;
        }

        private static string EscapeString(string str)
        {
            if (string.IsNullOrEmpty(str))
                return str;

            return str.Replace("\\", "\\\\")
                     .Replace("\"", "\\\"")
                     .Replace("\n", "\\n")
                     .Replace("\r", "\\r")
                     .Replace("\t", "\\t");
        }
    }
}