using AsbCloudInfrastructure.Services.Background;
using System;
using System.Threading;
using System.Threading.Tasks;
using Xunit;

namespace AsbCloudWebApi.Tests.ServicesTests
{
    public class BackgroundWorkerService_WorkQueue_Test
    {
        private readonly TimeSpan period = TimeSpan.FromSeconds(10);
        private readonly Func<string, IServiceProvider, CancellationToken, Task> somAction = (string id, IServiceProvider scope, CancellationToken token) => Task.CompletedTask;

        [Fact]
        public void Push_not_unique_id_should_throw()
        {
            var work1 = new WorkPeriodic("1", somAction, TimeSpan.FromSeconds(30));
            var work2 = new WorkBase("1", somAction);

            var queue = new WorkQueue();
            queue.Push(work1);

            Assert.Throws<ArgumentException>(
                () => queue.Push(work2));
        }

        [Fact]
        public void Pop_should_return_null()
        {            
            var work1 = new WorkPeriodic("1", somAction, TimeSpan.FromSeconds(30))
            { LastStart = DateTime.Now };

            var queue = new WorkQueue();
            queue.Push(work1);
            var workpoPoped= queue.Pop();

            Assert.Null(workpoPoped);
        }

        [Fact]
        public void Pop_primary_first()
        { 
            var work1 = new WorkBase("1", somAction);
            var work2 = new WorkPeriodic("1", somAction, period);

            var queue = new WorkQueue();
            queue.Push(work2);
            queue.Push(work1);
            var workpoPoped= queue.Pop();

            Assert.Equal(work1, workpoPoped);
        }

        [Fact]
        public void Pop_second_after_delete_first()
        {
            var work1 = new WorkPeriodic("1", somAction, period);
            var work2 = new WorkPeriodic("2", somAction, period);

            var queue = new WorkQueue();
            queue.Push(work1);
            queue.Push(work2);
            queue.Delete("1");

            var workpoPoped= queue.Pop();

            Assert.Equal(work2, workpoPoped);
        }

        [Fact]
        public void Pop_closest_to_nextStart()
        {
            var work1 = new WorkPeriodic("1", somAction, period) {
                LastStart = DateTime.Now,
            };
            var work2 = new WorkPeriodic("2", somAction, period);

            var queue = new WorkQueue();
            queue.Push(work1);
            queue.Push(work2);
            
            var workpoPoped= queue.Pop();

            Assert.Equal(work2, workpoPoped);
        }

        [Fact]
        public void Pop_closest_to_explicit_nextStart()
        {
            var baseTime = DateTime.Now - period;
            var work1 = new WorkPeriodic("1", somAction, period)
            {
                LastStart = baseTime - TimeSpan.FromSeconds(-1),
            };
            var work2 = new WorkPeriodic("2", somAction, period)
            {
                LastStart = baseTime,
            };

            var queue = new WorkQueue();
            queue.Push(work1);
            queue.Push(work2);

            var workpoPoped= queue.Pop();

            Assert.Equal(work2, workpoPoped);
        }
    }
}