using System;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading;
using System.Threading.Tasks;
using Flawless.Client.Remote;
using ReactiveUI;
using Refit;

namespace Flawless.Client.Service;

public class Api : BaseService<Api>
{
    class ApiAuthenticationHandler : DelegatingHandler
    {
        public ApiAuthenticationHandler(HttpMessageHandler innerHandler) : base(innerHandler)
        {
        }

        protected override Task<HttpResponseMessage> SendAsync(
            HttpRequestMessage request,
            CancellationToken cancellationToken)
        {
            var tk = Api.C._token.Value;
            if (tk != null) request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", tk.Token);
            return base.SendAsync(request, cancellationToken);
        }

    }

    public IObservable<bool> IsLoggedIn => _isLoggedIn;
    
    public IObservable<string?> ServerUrl => _serverUrl;
    
    public IReactiveProperty<ServerStatusResponse?> Status => _status;
    
    public IObservable<TokenInfo?> Token => _token; 
    
    public IReactiveProperty<string?> Username => _username;
    
    private readonly ReactiveProperty<bool> _isLoggedIn = new(false);
    
    private readonly ReactiveProperty<string?> _serverUrl = new(string.Empty);

    private readonly ReactiveProperty<ServerStatusResponse?> _status = new(null);

    private readonly ReactiveProperty<TokenInfo?> _token = new(null);
    
    private readonly ReactiveProperty<string?> _username = new(string.Empty);

    #region GatewayConfig

    private IFlawlessServer? _gateway;
    
    public bool IsGatewayReady => _gateway != null;
    
    public IFlawlessServer Gateway => _gateway ?? throw new InvalidProgramException("Not set gateway yet!");
    
    public void ClearGateway()
    {
        _gateway = null;
        _username.Value = null;
        _isLoggedIn.Value = false;
        _status.Value = null;
        _serverUrl.Value = null;
        _token.Value = null;
    }
    
    public async ValueTask SetGatewayAsync(string host)
    {
        var setting = new RefitSettings()
        {
            HttpMessageHandlerFactory = () => new ApiAuthenticationHandler(new HttpClientHandler())
        };
        
        var tempGateway = RestService.For<IFlawlessServer>(host, setting);
        _status.Value = await tempGateway.Status();
        _serverUrl.Value = host;
        _gateway = tempGateway;
    }

    public async ValueTask LoginAsync(string username, string password)
    {
        _token.Value = await _gateway.Login(new LoginRequest
        {
            Username = username,
            Password = password
        });
        
        _username.Value = username;
        _isLoggedIn.Value = true;
        await UserService.C.DownloadUserInfoAsync(username);
    }

    #endregion

    #region TokenOperations

    public bool RequireRefreshToken()
    {
        if (_token.Value == null) return true;
        if (DateTime.UtcNow > _token.Value.Expiration!.Value.UtcDateTime.AddMinutes(-2)) return true;
        return false;
    }

    public async ValueTask<bool> TryRefreshTokenAsync()
    {
        if (_token.Value == null) return false;
        try { _token.Value = await Gateway.Refresh(_token.Value); }
        catch (Exception e)
        {
            await Console.Error.WriteLineAsync(e.ToString());
            return false;
        }

        return true;
    }

    #endregion
}