[CHANGE] WIP YouTubeClient & HTML parsing

Manager.YouTube/Parsers/HtmlParser.cs

@@ -0,0 +1,39 @@
+using System.Text.RegularExpressions;
+using DotBased.Monads;
+using HtmlAgilityPack;
+
+namespace Manager.YouTube.Parsers;
+
+public static class HtmlParser
+{
+    public static Result<string> GetJsonFromScriptFunction(string html, string functionName)
+    {
+        if (string.IsNullOrWhiteSpace(html))
+        {
+            return ResultError.Fail("html cannot be empty!");
+        }
+        
+        if (string.IsNullOrWhiteSpace(functionName))
+        {
+            return ResultError.Fail("No function names provided!");
+        }
+
+        var htmlDocument = new HtmlDocument();
+        htmlDocument.LoadHtml(html);
+        
+        var scriptNode = htmlDocument.DocumentNode.SelectSingleNode($"//script[contains(., '{functionName}')]");
+        if (string.IsNullOrWhiteSpace(scriptNode.InnerText))
+            return ResultError.Fail($"Could not find {functionName} in html script nodes!");
+        
+        var regexPattern = $@"{Regex.Escape(functionName)}\(([^)]+)\);";
+        var match = Regex.Match(scriptNode.InnerText, regexPattern);
+
+        if (match.Success)
+        {
+            var jsonString = match.Groups[1].Value.Trim();
+            return jsonString;
+        }
+
+        return ResultError.Fail($"Unable to parse {functionName} JSON!");
+    }
+}