using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Bit.Core.Settings;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Quartz;
using Quartz.Impl;
using Quartz.Impl.Matchers;

namespace Bit.Core.Jobs
{
    public abstract class BaseJobsHostedService : IHostedService, IDisposable
    {
        private const int MaximumJobRetries = 10;

        private readonly IServiceProvider _serviceProvider;
        private readonly ILogger<JobListener> _listenerLogger;
        protected readonly ILogger _logger;

        private IScheduler _scheduler;
        protected GlobalSettings _globalSettings;

        public BaseJobsHostedService(
            GlobalSettings globalSettings,
            IServiceProvider serviceProvider,
            ILogger logger,
            ILogger<JobListener> listenerLogger)
        {
            _serviceProvider = serviceProvider;
            _logger = logger;
            _listenerLogger = listenerLogger;
            _globalSettings = globalSettings;
        }

        public IEnumerable<Tuple<Type, ITrigger>> Jobs { get; protected set; }

        public virtual async Task StartAsync(CancellationToken cancellationToken)
        {
            var props = new NameValueCollection
            {
                {"quartz.serializer.type", "binary"},
            };

            if (!string.IsNullOrEmpty(_globalSettings.SqlServer.JobSchedulerConnectionString))
            {
                // Ensure each project has a unique instanceName
                props.Add("quartz.scheduler.instanceName", GetType().FullName);
                props.Add("quartz.scheduler.instanceId", "AUTO");
                props.Add("quartz.jobStore.type", "Quartz.Impl.AdoJobStore.JobStoreTX");
                props.Add("quartz.jobStore.driverDelegateType", "Quartz.Impl.AdoJobStore.SqlServerDelegate");
                props.Add("quartz.jobStore.useProperties", "true");
                props.Add("quartz.jobStore.dataSource", "default");
                props.Add("quartz.jobStore.tablePrefix", "QRTZ_");
                props.Add("quartz.jobStore.clustered", "true");
                props.Add("quartz.dataSource.default.provider", "SqlServer");
                props.Add("quartz.dataSource.default.connectionString", _globalSettings.SqlServer.JobSchedulerConnectionString);
            }

            var factory = new StdSchedulerFactory(props);
            _scheduler = await factory.GetScheduler(cancellationToken);
            _scheduler.JobFactory = new JobFactory(_serviceProvider);
            _scheduler.ListenerManager.AddJobListener(new JobListener(_listenerLogger),
                GroupMatcher<JobKey>.AnyGroup());
            await _scheduler.Start(cancellationToken);
            if (Jobs != null)
            {
                foreach (var (job, trigger) in Jobs)
                {
                    for (var retry = 0; retry < MaximumJobRetries; retry++)
                    {
                        // There's a race condition when starting multiple containers simultaneously, retry until it succeeds..
                        try
                        {
                            var dupeT = await _scheduler.GetTrigger(trigger.Key);
                            if (dupeT != null)
                            {
                                await _scheduler.RescheduleJob(trigger.Key, trigger);
                            }

                            var jobDetail = JobBuilder.Create(job)
                                .WithIdentity(job.FullName)
                                .Build();

                            var dupeJ = await _scheduler.GetJobDetail(jobDetail.Key);
                            if (dupeJ != null)
                            {
                                await _scheduler.DeleteJob(jobDetail.Key);
                            }

                            await _scheduler.ScheduleJob(jobDetail, trigger);
                            break;
                        }
                        catch (Exception e)
                        {
                            if (retry == MaximumJobRetries - 1)
                            {
                                throw new Exception("Job failed to start after 10 retries.");
                            }

                            _logger.LogWarning($"Exception while trying to schedule job: {job.FullName}, {e}");
                            var random = new Random();
                            Thread.Sleep(random.Next(50, 250));
                        }
                    }
                }
            }

            // Delete old Jobs and Triggers
            var existingJobKeys = await _scheduler.GetJobKeys(GroupMatcher<JobKey>.AnyGroup());
            var jobKeys = Jobs.Select(j =>
            {
                var job = j.Item1;
                return JobBuilder.Create(job)
                    .WithIdentity(job.FullName)
                    .Build().Key;
            });

            foreach (var key in existingJobKeys)
            {
                if (jobKeys.Contains(key))
                {
                    continue;
                }

                _logger.LogInformation($"Deleting old job with key {key}");
                await _scheduler.DeleteJob(key);
            }

            var existingTriggerKeys = await _scheduler.GetTriggerKeys(GroupMatcher<TriggerKey>.AnyGroup());
            var triggerKeys = Jobs.Select(j => j.Item2.Key);

            foreach (var key in existingTriggerKeys)
            {
                if (triggerKeys.Contains(key))
                {
                    continue;
                }

                _logger.LogInformation($"Unscheduling old trigger with key {key}");
                await _scheduler.UnscheduleJob(key);
            }
        }

        public virtual async Task StopAsync(CancellationToken cancellationToken)
        {
            await _scheduler?.Shutdown(cancellationToken);
        }

        public virtual void Dispose()
        { }
    }
}