Search multiple files in a word and replace it to single word on a click event

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C#

I need to search the words in a log file like "INFO", "ERROR", "WARN" "FATAL" in a file and need to replace it to the word "DEBUG" on the check box click. If I uncheck the box, the words from "DEBUG" should replaced to the original state like "INFO", "ERROR" e.t.c.


I am not sure how to handle it Array or something. Also, how to hold the previous state of the file?

private void ToggleforDebugMode(bool IsDebug)
    {
        string text = @"C:\Program Files (x86)\Hi.config";
        string filePath = Path.GetDirectoryName("Hi.config") + fileName;
        text = File.ReadAllText(@"C:\Program Files (x86)\Hi.config");
        if (IsDebug)
        {
            _previousState = text.Contains("WARN") ? "WARN" : "INFO";

            if(text.Contains("WARN"))
            {
                text = text.Replace("WARN", "DEBUG");
            }
            else if (text.Contains("DEBUG"))
            {
                text = text.Replace("INFO", "DEBUG");
            }               

        }
        else
        {
             text = text.Replace("DEBUG", _previousState);
        }
        File.WriteAllText(@"C:\Program Files (x86)\Galileo Print Manager .NET\GPM_Service.exe.config", text);
    }

What I have tried:

I tried to use File.Replace() method. But it is helpful for searching & replacing only one word.