using System;
using NLog;
using NzbDrone.Common.Cloud;
using NzbDrone.Common.EnvironmentInfo;
using NzbDrone.Common.Http;
using NzbDrone.Common.Serializer;
using NzbDrone.Core.Localization;

namespace NzbDrone.Core.HealthCheck.Checks
{
    public class SystemTimeCheck : HealthCheckBase
    {
        private readonly IHttpClient _client;
        private readonly IHttpRequestBuilderFactory _cloudRequestBuilder;
        private readonly Logger _logger;

        public SystemTimeCheck(IHttpClient client, IProwlarrCloudRequestBuilder cloudRequestBuilder, Logger logger, ILocalizationService localizationService)
            : base(localizationService)
        {
            _client = client;
            _cloudRequestBuilder = cloudRequestBuilder.Services;
            _logger = logger;
        }

        public override HealthCheck Check()
        {
            if (BuildInfo.IsDebug)
            {
                return new HealthCheck(GetType());
            }

            try
            {
                var request = _cloudRequestBuilder.Create()
                    .Resource("/time")
                    .Build();

                var response = _client.Execute(request);
                var result = Json.Deserialize<ServiceTimeResponse>(response.Content);
                var systemTime = DateTime.UtcNow;

                // +/- more than 1 day
                if (Math.Abs(result.DateTimeUtc.Subtract(systemTime).TotalDays) >= 1)
                {
                    _logger.Error("System time mismatch. SystemTime: {0} Expected Time: {1}. Update system time", systemTime, result.DateTimeUtc);
                    return new HealthCheck(GetType(), HealthCheckResult.Error, _localizationService.GetLocalizedString("SystemTimeHealthCheckMessage"), "#system-time-off");
                }
            }
            catch (Exception e)
            {
                _logger.Warn(e, "Unable to verify system time");
            }

            return new HealthCheck(GetType());
        }
    }

    public class ServiceTimeResponse
    {
        public DateTime DateTimeUtc { get; set; }
    }
}