using System;
using System.Collections.Generic;
using System.Text.Json;
using static System.Runtime.InteropServices.JavaScript.JSType;

namespace VideoAnalysisCore.Common
{
    public static class JsonExtractor
    {
        /// <summary>
        /// 提取json字符串
        /// </summary>
        /// <param name="input"></param>
        /// <returns></returns>
    public static List<string> ExtractJsonStrings(this string input)
    {
        var results = new List<string>();
        if (string.IsNullOrWhiteSpace(input)) return results;

        int braceCount = 0;
        int bracketCount = 0;
        int startIndex = -1;
        bool inString = false;
        bool isEscaped = false;

        for (int i = 0; i<input.Length; i++)
        {
            char c = input[i];

            // 1. 处理转义字符 (例如 \")
            if (isEscaped)
            {
                isEscaped = false;
                continue;
            }

            if (c == '\\')
            {
                isEscaped = true;
                continue;
            }

// 2. 处理字符串边界
if (c == '"')
{
    inString = !inString;
    continue;
}

// 3. 如果在字符串内，忽略括号逻辑
if (inString) continue;

// 4. 处理 JSON 对象和数组的开始
if (c == '{' || c == '[')
{
    if (braceCount == 0 && bracketCount == 0)
    {
        startIndex = i;
    }
    if (c == '{') braceCount++;
    else bracketCount++;
}
// 5. 处理 JSON 对象和数组的结束
else if (c == '}' || c == ']')
{
    if (c == '}') braceCount--;
    else bracketCount--;

    if (braceCount == 0 && bracketCount == 0 && startIndex != -1)
    {
        string potentialJson = input.Substring(startIndex, i - startIndex + 1);
        if (IsValidJson(potentialJson))
        {
            results.Add(potentialJson);
        }
        startIndex = -1;
    }
}
        }
        return results;
    }

        public static bool IsValidJson(string candidate)
        {
            if (string.IsNullOrEmpty(candidate))
                return false;
            try
            {
                JsonDocument.Parse(candidate);
                return true;
            }
            catch 
            {
                return false;
            }
        }
    }
}