YouTube-Manager/Manager.YouTube/YouTubeClient.cs

using System.Net;
using System.Net.Mime;
using System.Text;
using System.Text.Json;
using System.Text.Json.Nodes;
using DotBased.Monads;
using Manager.YouTube.Models.Innertube;
using Manager.YouTube.Parsers;
using Manager.YouTube.Parsers.Json;

namespace Manager.YouTube;

public sealed class YouTubeClient : IDisposable
{
    public string Id { get; private set; } = "";
    public string? UserAgent { get; set; }
    public bool IsAnonymous { get; }
    public CookieContainer CookieContainer { get; } = new() { PerDomainCapacity = 50 };
    public ClientState? State { get; private set; }
    public List<string> DatasyncIds { get; } = [];
    public Cookie? SapisidCookie => CookieContainer.GetAllCookies()["SAPISID"];
    public HttpClient HttpClient { get; }
    
    private YouTubeClient(CookieCollection cookies, string userAgent)
    {
        if (string.IsNullOrWhiteSpace(userAgent))
        {
            throw new ArgumentNullException(nameof(userAgent));
        }
        UserAgent = userAgent;
        if (cookies.Count == 0)
        {
            Id = $"anon_{Guid.NewGuid()}";
            IsAnonymous = true;
        }

        CookieContainer.Add(cookies);
        HttpClient = new HttpClient(GetHttpClientHandler());
    }

    /// <summary>
    /// Loads the given cookies and fetch client state.
    /// </summary>
    /// <param name="cookies">The cookies to use for making requests. Empty collection for anonymous requests.</param>
    /// <param name="userAgent">The user agent to use for the requests. Only WEB client is supported.</param>
    /// <returns></returns>
    public static async Task<Result<YouTubeClient>> CreateAsync(CookieCollection cookies, string userAgent)
    {
        var client = new YouTubeClient(cookies, userAgent);
        var clientInitializeResult = await client.FetchClientDataAsync();
        if (!clientInitializeResult.IsSuccess)
        {
            return clientInitializeResult.Error ?? ResultError.Fail("Failed to initialize YouTube client!");
        }

        return client;
    }

    private HttpClientHandler GetHttpClientHandler()
    {
        var clientHandler = new HttpClientHandler
        {
            AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip,
            UseCookies = true,
            CookieContainer = CookieContainer
        };
        return clientHandler;
    }

    internal async Task<Result> FetchClientDataAsync()
    {
        if (State is not { LoggedIn: true })
        {
            var state = await GetClientStateAsync();
            if (!state.IsSuccess)
            {
                return state;
            }
        }

        if (string.IsNullOrWhiteSpace(State?.WebPlayerContextConfig?.WebPlayerContext?.DatasyncId))
        {
            var datasyncResult = await GetDatasyncIds();
            if (!datasyncResult.IsSuccess)
            {
                return datasyncResult;
            }

            foreach (var id in datasyncResult.Value)
            {
                if (DatasyncIds.Contains(id))
                    continue;
                DatasyncIds.Add(id);
            }
        }

        if (string.IsNullOrWhiteSpace(Id))
        {
            var accountInfoResult = await GetCurrentAccountIdAsync();
            if (!accountInfoResult.IsSuccess)
            {
                return accountInfoResult;
            }

            Id = accountInfoResult.Value;
        }

        return Result.Success();
    }
    
    private async Task<Result> GetClientStateAsync()
    {
        var httpRequest = new HttpRequestMessage
        {
            Method = HttpMethod.Get,
            RequestUri = new Uri(NetworkService.Origin)
        };
        
        var result = await NetworkService.MakeRequestAsync(httpRequest, this, true);
        if (!result.IsSuccess)
        {
            return result.Error ?? ResultError.Fail("Request failed!");
        }

        var clientStateResult = HtmlParser.GetStateJson(result.Value);
        if (clientStateResult is { IsSuccess: false, Error: not null })
        {
            return clientStateResult.Error;
        }

        try
        {
            State = JsonSerializer.Deserialize<ClientState>(clientStateResult.Value.Item1);
        }
        catch (Exception e)
        {
            return ResultError.Error(e, "Error while parsing JSON!");
        }


        if (State == null)
        {
            return ResultError.Fail("Unable to parse client state!");
        }

        State.IsPremiumUser = clientStateResult.Value.Item2;
        
        return Result.Success();
    }
    
    public async Task<Result<InnertubeChannel>> GetChannelByIdAsync(string channelId)
    {
        if (State == null)
        {
            return ResultError.Fail("No client state!");
        }

        if (string.IsNullOrWhiteSpace(channelId))
        {
            return ResultError.Fail("Channel id is empty!");
        }

        var serializedContext = JsonSerializer.SerializeToNode(State.InnerTubeContext);
        var payload = new JsonObject { { "context", serializedContext }, { "browseId", channelId } };
        var requestMessage = new HttpRequestMessage
        {
            Method = HttpMethod.Post,
            RequestUri = new Uri($"{NetworkService.Origin}/youtubei/v1/browse?key={State.InnertubeApiKey}"),
            Content = new StringContent(payload.ToJsonString(), Encoding.UTF8, MediaTypeNames.Application.Json)
        };
        var responseResult = await NetworkService.MakeRequestAsync(requestMessage, this);
        if (!responseResult.IsSuccess)
        {
            return responseResult.Error ?? ResultError.Fail("Request failed!");
        }

        return ChannelJsonParser.ParseJsonToChannelData(responseResult.Value);
    }

    public string GetDatasyncId()
    {
        if (!string.IsNullOrWhiteSpace(State?.WebPlayerContextConfig?.WebPlayerContext?.DatasyncId))
        {
            return State.WebPlayerContextConfig.WebPlayerContext.DatasyncId;
        }

        var tempDatasyncId = "";
        foreach (var datasyncId in DatasyncIds)
        {
            var split = datasyncId.Split("||", StringSplitOptions.RemoveEmptyEntries);
            switch (split.Length)
            {
                case 0:
                case 2 when tempDatasyncId.Equals(split[1]):
                    continue;
                case 2:
                    tempDatasyncId = split[1];
                    break;
            }
        }

        return tempDatasyncId;
    }

    public void Dispose()
    {
        HttpClient.Dispose();
    }
    
    private async Task<Result<string>> GetCurrentAccountIdAsync()
    {
        if (State is not { LoggedIn: true })
        {
            return ResultError.Fail("Client not logged in!");
        }

        var httpRequest = new HttpRequestMessage
        {
            Method = HttpMethod.Post,
            RequestUri = new Uri($"{NetworkService.Origin}/youtubei/v1/account/account_menu")
        };
        var serializedContext = JsonSerializer.SerializeToNode(State.InnerTubeContext);
        var payload = new JsonObject { { "context", serializedContext } };
        httpRequest.Content = new StringContent(payload.ToJsonString(), Encoding.UTF8, MediaTypeNames.Application.Json);
        var responseResult = await NetworkService.MakeRequestAsync(httpRequest, this);

        if (!responseResult.IsSuccess)
        {
            return responseResult.Error ?? ResultError.Fail("Request failed!");
        }
        
        return JsonAccountParser.ParseAccountId(responseResult.Value);
    }
    
    private async Task<Result<string[]>> GetDatasyncIds()
    {
        if (State is not { LoggedIn: true } || CookieContainer.Count == 0)
        {
            return ResultError.Fail("Client is not logged in, requires logged in client for this endpoint (/getDatasyncIdsEndpoint).");
        }

        var httpRequest = new HttpRequestMessage
        {
            Method = HttpMethod.Get,
            RequestUri = new Uri($"{NetworkService.Origin}/getDatasyncIdsEndpoint")
        };
        var responseResult = await NetworkService.MakeRequestAsync(httpRequest, this);
        if (!responseResult.IsSuccess)
        {
            return responseResult.Error ?? ResultError.Fail("Request failed!");
        }
        
        var datasyncIdsJson = JsonNode.Parse(responseResult.Value.Replace(")]}'", ""));

        var isLoggedOut = datasyncIdsJson?["responseContext"]?["mainAppWebResponseContext"]?["loggedOut"]
            .Deserialize<bool>() ?? true;
        if (!isLoggedOut)
        {
            return datasyncIdsJson?["datasyncIds"].Deserialize<string[]>() ?? [];
        }

        return ResultError.Fail("Failed to get datasyncIds! Client not logged in.");
    }
}