using System;
using System.IO;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using Hangfire;
using MalwareMultiScan.Backends.Backends.Implementations;
using MalwareMultiScan.Shared.Data.Enums;
using MalwareMultiScan.Shared.Data.Responses;
using MalwareMultiScan.Shared.Interfaces;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;

namespace MalwareMultiScan.Worker.Jobs
{
    public class ScanJob
    {
        private readonly IScanBackend _backend;
        private readonly IHttpClientFactory _httpClientFactory;
        private readonly ILogger<ScanJob> _logger;
        private readonly int _scanTimeout;

        public ScanJob(IConfiguration configuration, ILogger<ScanJob> logger,
            IHttpClientFactory httpClientFactory)
        {
            _logger = logger;
            _httpClientFactory = httpClientFactory;
            _scanTimeout = configuration.GetValue<int>("ScanTimeout");

            _backend = configuration.GetValue<BackendType>("BackendType") switch
            {
                BackendType.Defender => new WindowsDefenderScanBackend(logger),
                BackendType.Clamav => new ClamavScanBackend(logger),
                BackendType.DrWeb => new DrWebScanBackend(logger),
                BackendType.Kes => new KesScanBackend(logger),
                _ => throw new NotImplementedException()
            };
        }

        private async Task PostResult(ResultResponse response, Uri callbackUrl, CancellationToken cancellationToken)
        {
            var serializedResponse = JsonSerializer.Serialize(
                response, typeof(ResultResponse), new JsonSerializerOptions
                {
                    WriteIndented = true
                });

            _logger.LogInformation(
                $"Sending following payload to {callbackUrl}: {serializedResponse}");

            using var httpClient = _httpClientFactory.CreateClient();

            var callbackResponse = await httpClient.PostAsync(callbackUrl,
                new StringContent(serializedResponse, Encoding.UTF8, "application/json"), cancellationToken);

            _logger.LogInformation($"Callback URL {callbackUrl} returned a status {callbackResponse.StatusCode}");
        }

        private async Task Scan(Func<CancellationToken, Task<string[]>> scanMethod, Uri callbackUrl)
        {
            var cancellationTokenSource = new CancellationTokenSource();

            cancellationTokenSource.CancelAfter(_scanTimeout * 1000);

            var cancellationToken = cancellationTokenSource.Token;

            var response = new ResultResponse
            {
                Backend = _backend.Id
            };

            try
            {
                response.Success = true;
                response.Threats = await scanMethod(cancellationToken);
                response.DatabaseLastUpdate = _backend.DatabaseLastUpdate;
            }
            catch (Exception exception)
            {
                response.Success = false;

                _logger.LogError(exception, "Scanning failed with exception");
            }

            await PostResult(response, callbackUrl, cancellationToken);
        }

        [AutomaticRetry(Attempts = 0, OnAttemptsExceeded = AttemptsExceededAction.Delete)]
        public async Task ScanUrl(Uri url, Uri callbackUrl)
        {
            await Scan(async t => await _backend.ScanAsync(url, t), callbackUrl);
        }

        [AutomaticRetry(Attempts = 0, OnAttemptsExceeded = AttemptsExceededAction.Delete)]
        public async Task ScanFile(string file, Uri callbackUrl)
        {
            try
            {
                await Scan(async t => await _backend.ScanAsync(file, t), callbackUrl);
            }
            finally
            {
                File.Delete(file);
            }
        }
    }
}