using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Xunit;

namespace Wabbajack.Common.Test
{
    public class PMapTests
    {
        const int TypicalThreadCount = 6;
        const int TypicalDelayMS = 50;
        const int TimeoutSeconds = 15;

        [Fact]
        public async Task Typical_Action()
        {
            using var queue = new WorkQueue(TypicalThreadCount);
            var input = Enumerable.Range(0, TypicalThreadCount * 2).ToArray();
            var output = new List<int>();
            var workTask = Utils.PMap(Enumerable.Range(0, TypicalThreadCount * 2), queue, (item) =>
            {
                Assert.True(WorkQueue.WorkerThread);
                Thread.Sleep(TypicalDelayMS);
                lock (output)
                {
                    output.Add(item);
                }
            });
            await workTask.TimeoutButContinue(TimeSpan.FromSeconds(TimeoutSeconds), () => throw new TimeoutException());
            Assert.True(input.SequenceEqual(output.OrderBy(i => i)));
        }

        [Fact]
        public async Task Typical_Func()
        {
            using var queue = new WorkQueue(TypicalThreadCount);
            var input = Enumerable.Range(0, TypicalThreadCount * 2).ToArray();
            var workTask = Utils.PMap(Enumerable.Range(0, TypicalThreadCount * 2), queue, (item) =>
            {
                Assert.True(WorkQueue.WorkerThread);
                Thread.Sleep(TypicalDelayMS);
                return item.ToString();
            });
            var results = await workTask.TimeoutButContinue(TimeSpan.FromSeconds(TimeoutSeconds), () => throw new TimeoutException());
            Assert.True(input.Select(i => i.ToString()).SequenceEqual(results));
        }

        [Fact]
        public async Task Typical_Task()
        {
            using var queue = new WorkQueue(TypicalThreadCount);
            var input = Enumerable.Range(0, TypicalThreadCount * 2).ToArray();
            var output = new List<int>();
            var workTask = Enumerable.Range(0, TypicalThreadCount * 2)
                .PMap(queue, async (item) =>
                {
                    Assert.True(WorkQueue.WorkerThread);
                    await Task.Delay(TypicalDelayMS);
                    lock (output)
                    {
                        output.Add(item);
                    }
                });
            await workTask.TimeoutButContinue(TimeSpan.FromSeconds(TimeoutSeconds), () => throw new TimeoutException());
            Assert.True(input.SequenceEqual(output.OrderBy(i => i)));
        }

        [Fact]
        public async Task Typical_TaskReturn()
        {
            using var queue = new WorkQueue(TypicalThreadCount);
            var input = Enumerable.Range(0, TypicalThreadCount * 2).ToArray();
            var workTask = Enumerable.Range(0, TypicalThreadCount * 2)
                .PMap(queue, async (item) =>
                {
                    Assert.True(WorkQueue.WorkerThread);
                    await Task.Delay(TypicalDelayMS);
                    return item.ToString();
                });
            var results = await workTask.TimeoutButContinue(TimeSpan.FromSeconds(TimeoutSeconds), () => throw new TimeoutException());
            Assert.True(input.Select(i => i.ToString()).SequenceEqual(results));
        }

        [Fact]
        public async Task NestedAction()
        {
            using var queue = new WorkQueue(TypicalThreadCount);
            var input = Enumerable.Range(0, TypicalThreadCount * 2).ToArray();
            var inputConstructedResults = input.SelectMany(i => Enumerable.Range(i * 100, TypicalThreadCount * 2));
            var output = new List<int>();
            var workTask = Enumerable.Range(0, TypicalThreadCount * 2)
                .PMap(queue, async (item) =>
                {
                    Assert.True(WorkQueue.WorkerThread);
                    await Enumerable.Range(item * 100, TypicalThreadCount * 2)
                        .PMap(queue, async (subItem) =>
                        {
                            Assert.True(WorkQueue.WorkerThread);
                            Thread.Sleep(TypicalDelayMS);
                            lock (output)
                            {
                                output.Add(subItem);
                            }
                        });
                });
            await workTask.TimeoutButContinue(TimeSpan.FromSeconds(TimeoutSeconds), () => throw new TimeoutException());
            Assert.True(inputConstructedResults.SequenceEqual(output.OrderBy(i => i)));
        }

        [Fact]
        public async Task Nested_Func()
        {
            using var queue = new WorkQueue(TypicalThreadCount);
            var input = Enumerable.Range(0, TypicalThreadCount * 2).ToArray();
            var inputConstructedResults = input.SelectMany(i => Enumerable.Range(i * 100, TypicalThreadCount * 2));
            var workTask = Enumerable.Range(0, TypicalThreadCount * 2)
                .PMap(queue, async (item) =>
                {
                    Assert.True(WorkQueue.WorkerThread);
                    return await Utils.PMap(Enumerable.Range(item * 100, TypicalThreadCount * 2), queue, (subItem) =>
                    {
                        Assert.True(WorkQueue.WorkerThread);
                        Thread.Sleep(TypicalDelayMS);
                        return subItem;
                    });
                });
            var results = await workTask.TimeoutButContinue(TimeSpan.FromSeconds(TimeoutSeconds), () => throw new TimeoutException());
            Assert.True(inputConstructedResults.SequenceEqual(results.SelectMany(i => i)));
        }

        [Fact]
        public async Task Nested_Task()
        {
            using var queue = new WorkQueue(TypicalThreadCount);
            var input = Enumerable.Range(0, TypicalThreadCount * 2).ToArray();
            var inputConstructedResults = input.SelectMany(i => Enumerable.Range(i * 100, TypicalThreadCount * 2));
            var output = new List<int>();
            var workTask = Enumerable.Range(0, TypicalThreadCount * 2)
                .PMap(queue, async (item) =>
                {
                    Assert.True(WorkQueue.WorkerThread);
                    await Enumerable.Range(item * 100, TypicalThreadCount * 2)
                        .PMap(queue, async (subItem) =>
                        {
                            Assert.True(WorkQueue.WorkerThread);
                            await Task.Delay(TypicalDelayMS);
                            lock (output)
                            {
                                output.Add(subItem);
                            }
                        });
                });
            await workTask.TimeoutButContinue(TimeSpan.FromSeconds(TimeoutSeconds), () => throw new TimeoutException());
            Assert.True(inputConstructedResults.SequenceEqual(output.OrderBy(i => i)));
        }

        [Fact]
        public async Task Nested_TaskReturn()
        {
            using var queue = new WorkQueue(TypicalThreadCount);
            var input = Enumerable.Range(0, TypicalThreadCount * 2).ToArray();
            var inputConstructedResults = input.SelectMany(i => Enumerable.Range(i * 100, TypicalThreadCount * 2));
            var workTask = Enumerable.Range(0, TypicalThreadCount * 2)
                .PMap(queue, async (item) =>
                {
                    Assert.True(WorkQueue.WorkerThread);
                    return await Enumerable.Range(item * 100, TypicalThreadCount * 2)
                        .PMap(queue, async (subItem) =>
                        {
                            Assert.True(WorkQueue.WorkerThread);
                            await Task.Delay(TypicalDelayMS);
                            return subItem;
                        });
                });
            var results = await workTask.TimeoutButContinue(TimeSpan.FromSeconds(TimeoutSeconds), () => throw new TimeoutException());
            Assert.True(inputConstructedResults.SequenceEqual(results.SelectMany(i => i)));
        }

        [Fact]
        public async Task Nested_BackgroundThreadsInvolved()
        {
            using var queue = new WorkQueue(TypicalThreadCount);
            var input = Enumerable.Range(0, TypicalThreadCount * 2).ToArray();
            var inputConstructedResults = input.SelectMany(i => Enumerable.Range(i * 100, TypicalThreadCount * 2));
            var workTask = Enumerable.Range(0, TypicalThreadCount * 2)
                .PMap(queue, async (item) =>
                {
                    Assert.True(WorkQueue.WorkerThread);
                    return await Enumerable.Range(item * 100, TypicalThreadCount * 2)
                        .PMap(queue, async (subItem) =>
                        {
                            return await Task.Run(async () =>
                            {
                                Assert.True(WorkQueue.WorkerThread);
                                await Task.Delay(TypicalDelayMS);
                                return subItem;
                            });
                        });
                });
            var results = await workTask.TimeoutButContinue(TimeSpan.FromSeconds(TimeoutSeconds), () => throw new TimeoutException());
            Assert.True(inputConstructedResults.SequenceEqual(results.SelectMany(i => i)));
        }
    }
}