using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xunit;
using FluentAssertions;
using MontoyaTech.Parallel.Net;

namespace MontoyaTech.Parallel.Net.Tests
{
    public class ParallelTests
    {
        [Fact]
        public void Parallel_NoMaxTasks_Should_Work()
        {
            var inputs = new List<int>() { 0, 1, 2, 3, 4 };

            var results = inputs.ForEachParallel(input => input * 5);

            results.Count.Should().Be(inputs.Count);

            results.Should().Contain(0);
            results.Should().Contain(5);
            results.Should().Contain(10);
            results.Should().Contain(15);
            results.Should().Contain(20);
        }

        [Fact]
        public void Parallel_MaxTasks_Should_Work()
        {
            var inputs = new List<int>() { 0, 1, 2, 3, 4 };

            var results = inputs.ForEachParallel(input => input * 5, maxTasks: 2);

            results.Count.Should().Be(inputs.Count);

            results.Should().Contain(0);
            results.Should().Contain(5);
            results.Should().Contain(10);
            results.Should().Contain(15);
            results.Should().Contain(20);
        }

        [Fact]
        public void Parallel_MaxTasks_Zero_Ignore_Should_Work()
        {
            var inputs = new List<int>() { 0, 1, 2, 3, 4 };

            var results = inputs.ForEachParallel(input => input * 5, maxTasks: 0);

            results.Count.Should().Be(inputs.Count);

            results.Should().Contain(0);
            results.Should().Contain(5);
            results.Should().Contain(10);
            results.Should().Contain(15);
            results.Should().Contain(20);
        }

        [Fact]
        public void Parallel_Timeout_Should_Work()
        {
            var inputs = new List<int>() { 0, 1, 2, 3, 4 };

            var action = new Action(() => inputs.ForEachParallel(input => input * 5, timeout: TimeSpan.FromSeconds(0)));

            action.Should().Throw<Exception>();
        }

        [Fact]
        public void Parallel_Timeout_NoException_Should_Work()
        {
            var inputs = new List<int>() { 0, 1, 2, 3, 4 };

            var action = new Action(() => inputs.ForEachParallel(input => input * 5, timeout: TimeSpan.FromSeconds(0), throwOnTimeout: false));

            action.Should().NotThrow<Exception>();
        }

        [Fact]
        public void Parallel_NoTimeout_Exception_Should_Work()
        {
            var inputs = new List<int>() { 0, 1, 2, 3, 4 };

            var action = new Action(() => inputs.ForEachParallel(input => input * 5));

            action.Should().NotThrow<Exception>();
        }

        [Fact]
        public void Parallel_Exception_Should_Bubble()
        {
            var inputs = new List<int>() { 0, 1, 2, 3, 4 };

            var results = new List<int>();

            var action = new Action(() => results = inputs.ForEachParallel(input => {
                if (input == 0)
                    throw new Exception("Testing");

                return input * 5;
            }));

            action.Should().Throw<Exception>();

            results.Count.Should().Be(0);

            inputs.RemoveAt(0);

            action.Should().NotThrow<Exception>();

            results.Count.Should().BeGreaterThan(0);
        }

        [Fact]
        public void Parallel_Exception_NoBubble_Should_Work()
        {
            var inputs = new List<int>() { 0, 1, 2, 3, 4 };

            var results = new List<int>();

            var action = new Action(() => results = inputs.ForEachParallel(input => {
                if (input == 0)
                    throw new Exception("Testing");

                return input * 5;
            }, bubbleExceptions: false));

            action.Should().NotThrow<Exception>();

            results.Count.Should().BeGreaterThan(0);
        }

        [Fact]
        public void Parallel_Inputs_Only_Should_Work()
        {
            var inputs = new List<int>() { 0, 1, 2, 3, 4 };

            int results = 0;

            inputs.ForEachParallel(input =>
            {
                results++;
            });

            results.Should().Be(5);
        }

        [Fact]
        public void Parallel_For_Odd_Should_Work()
        {
            var indexes = new List<long>();

            ParallelTask.For(0, 3, index =>
            {
                lock (indexes)
                    indexes.Add(index);
            }, 2);

            indexes.Count.Should().Be(3);

            for (long i = 0; i < 3; i++)
                if (!indexes.Contains(i))
                    throw new Exception($"Test failed, missing index: {i}");
        }

        [Fact]
        public void Parallel_For_Even_Should_Work()
        {
            var indexes = new List<long>();

            ParallelTask.For(0, 4, index =>
            {
                lock (indexes)
                    indexes.Add(index);
            }, 2);

            indexes.Count.Should().Be(4);

            for (long i = 0; i < 4; i++)
                if (!indexes.Contains(i))
                    throw new Exception($"Test failed, missing index: {i}");
        }
    }
}