using Microsoft.Extensions.DependencyInjection;

using MongoDB.Entities;

using PrivaPub.Federation.Outbox;
using PrivaPub.Infrastructure.Jobs;
using PrivaPub.Models.Jobs;

using System.Linq.Expressions;
using System.Text.Json;
using System.Text.Json.Nodes;

namespace PrivaPub.Tests.Support.Host
{
	public static class Jobs
	{
		public static async Task<int> Run(this PrivaPubHost host, Expression<Func<Job, bool>> which, CancellationToken token = default)
		{
			var handlers = host.Services.GetServices<IJobHandler>().ToDictionary(h => h.Kind);
			var queue = host.Get<IJobQueue>();
			var ran = 0;
			for (var round = 0; round < 50; round++)
			{
				var pending = await DB.Default.Find<Job>().Match(which).Match(j => j.State == JobState.Pending).ExecuteAsync(token);
				if (pending.Count == 0)
					return ran;
				foreach (var candidate in pending)
				{
					var job = await DB.Default.UpdateAndGet<Job>()
						.Match(j => j.ID == candidate.ID && j.State == JobState.Pending)
						.Modify(j => j.State, JobState.Running)
						.Modify(j => j.LeasedUntil, DateTime.UtcNow + JobQueue.LeaseTime)
						.Modify(b => b.Inc(j => j.Attempts, 1))
						.ExecuteAsync(token);
					if (job == default)
						continue;
					var handler = handlers[job.Kind];
					JobOutcome outcome;
					try
					{
						outcome = await handler.Handle(job, token);
					}
					catch (Exception ex)
					{
						outcome = JobOutcome.Dead(ex.GetType().Name + ": " + ex.Message);
					}
					await queue.Finish(job, outcome, handler.MaxAttempts, token);
					ran++;
				}
			}
			return ran;
		}

		public static Task<int> RunInbox(this PrivaPubHost host, string activityId, CancellationToken token = default) =>
			host.Run(j => j.Kind == JobKind.ProcessInbox && j.DedupeKey == "inbox|" + activityId, token);

		public static async Task<List<JsonObject>> Deliveries(string inbox, DateTime since, CancellationToken token = default) =>
			(await DB.Default.Find<Job>().Match(j => j.Kind == JobKind.Deliver && j.CreatedAt >= since).ExecuteAsync(token))
				.Select(j => JsonSerializer.Deserialize<DeliveryPayload>(j.Payload))
				.Where(p => p.Inbox == inbox)
				.Select(p => JsonNode.Parse(p.Body)!.AsObject())
				.ToList();
	}
}