using System;
using System.Threading.Tasks;
using Flawless.Client.Remote;
using ReactiveUI;
using Refit;

namespace Flawless.Client.Service;

public class Api
{
    #region Instance

    private static Api? _instance;
    
    public static Api Current => _instance ??= new Api();

    #endregion

    public IObservable<bool> IsLoggedIn => _isLoggedIn;
    
    public IObservable<string?> ServerUrl => _serverUrl;
    
    public IObservable<ServerStatusResponse?> Status => _status;
    
    public IObservable<TokenInfo?> Token => _token; 
    
    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);

    #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;
        _isLoggedIn.Value = false;
        _status.Value = null;
        _serverUrl.Value = null;
        _token.Value = null;
    }
    
    public async Task SetGatewayAsync(string host)
    {
        var setting = new RefitSettings
        {
            AuthorizationHeaderValueGetter = (req, ct) => _token.Value != null ? 
                Task.FromResult<string>($"Bearer {_token}") : Task.FromResult(string.Empty)
        };
        
        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
        });
        
        _isLoggedIn.Value = true;
    }

    #endregion

    #region TokenOperations

    public bool RequireRefreshToken()
    {
        if (_token.Value == null) return true;
        if (DateTime.UtcNow.AddMinutes(1) > _token.Value.Expiration) 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
}