[CHANGE] WIP YouTubeClient & HTML parsing

Manager.YouTube/NetworkService.cs

@@ -0,0 +1,59 @@
+using System.Text.Json;
+using DotBased.Monads;
+using Manager.YouTube.Models.Innertube;
+using Manager.YouTube.Parsers;
+using Manager.YouTube.Util;
+
+namespace Manager.YouTube;
+
+public static class NetworkService
+{
+    public static async Task<Result<ClientState>> GetClientStateAsync(YouTubeClient client)
+    {
+        var origin = "https://www.youtube.com/";
+        var httpRequest = new HttpRequestMessage
+        {
+            Method = HttpMethod.Get,
+            RequestUri = new Uri(origin)
+        };
+        httpRequest.Headers.IfModifiedSince = new DateTimeOffset(DateTime.UtcNow);
+        httpRequest.Headers.UserAgent.ParseAdd(client.UserAgent);
+        
+        if (client.SapisidCookie != null)
+        {
+            httpRequest.Headers.Authorization = AuthenticationUtilities.GetSapisidHashHeader(client.SapisidCookie.Value, origin);
+            httpRequest.Headers.Add("Origin", origin);
+        }
+        
+        var http = client.GetHttpClient();
+        if (http == null)
+        {
+            return ResultError.Fail("Unable to get http client!");
+        }
+        
+        var response = await http.SendAsync(httpRequest);
+        if (!response.IsSuccessStatusCode)
+        {
+            var responseResult = await response.Content.ReadAsStringAsync();
+            return Result<ClientState>.Fail(ResultError.Fail(responseResult));
+        }
+        var responseHtml = await response.Content.ReadAsStringAsync();
+        var clientStateResult = HtmlParser.GetJsonFromScriptFunction(responseHtml, "ytcfg.set");
+        if (clientStateResult is { IsSuccess: false, Error: not null })
+        {
+            return clientStateResult.Error;
+        }
+
+        ClientState? clientState;
+        try
+        {
+            clientState = JsonSerializer.Deserialize<ClientState>(clientStateResult.Value);
+        }
+        catch (Exception e)
+        {
+            return ResultError.Error(e, "Error while parsing JSON!");
+        }
+        
+        return clientState == null ? ResultError.Fail("Unable to parse client state!") : clientState;
+    }
+}