<#@ template debug="false" hostspecific="false" language="C#" #>
<#@ assembly name="System.Core" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Text" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ output extension=".cs" #>
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the Apache 2.0 License.
// See the LICENSE file in the project root for more information. 

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

namespace System.Linq
{
    public static partial class AsyncEnumerable
    {
<#
var os = new[]
{
    new { type = "int", zero = "0", @checked = true },
    new { type = "long", zero = "0L", @checked = true },
    new { type = "float", zero = "0.0f", @checked = false },
    new { type = "double", zero = "0.0", @checked = false },
    new { type = "decimal", zero = "0m", @checked = false },
    new { type = "int?", zero = "0", @checked = true },
    new { type = "long?", zero = "0L", @checked = true },
    new { type = "float?", zero = "0.0f", @checked = false },
    new { type = "double?", zero = "0.0", @checked = false },
    new { type = "decimal?", zero = "0m", @checked = false },
};

foreach (var o in os)
{
    var n = o.type.EndsWith("?") ? ".GetValueOrDefault()" : "";
#>
        public static Task<<#=o.type#>> SumAsync(this IAsyncEnumerable<<#=o.type#>> source, CancellationToken cancellationToken = default)
        {
            if (source == null)
                throw Error.ArgumentNull(nameof(source));

            return Core(source, cancellationToken);

            async Task<<#=o.type#>> Core(IAsyncEnumerable<<#=o.type#>> _source, CancellationToken _cancellationToken)
            {
                var sum = <#=o.zero#>;

#if CSHARP8 && AETOR_HAS_CT // CS0656 Missing compiler required member 'System.Collections.Generic.IAsyncEnumerable`1.GetAsyncEnumerator'
                await foreach (<#=o.type#> value in _source.WithCancellation(_cancellationToken).ConfigureAwait(false))
                {
<#
if (o.@checked)
{
#>
                    checked
                    {
                        sum += value<#=n#>;
                    }
<#
}
else
{
#>
                    sum += value<#=n#>;
<#
}
#>
                }
#else
                var e = _source.GetAsyncEnumerator(_cancellationToken);

                try
                {
                    while (await e.MoveNextAsync().ConfigureAwait(false))
                    {
<#
if (o.@checked)
{
#>
                        checked
                        {
                            sum += e.Current<#=n#>;
                        }
<#
}
else
{
#>
                        sum += e.Current<#=n#>;
<#
}
#>
                    }
                }
                finally
                {
                    await e.DisposeAsync().ConfigureAwait(false);
                }
#endif

                return sum;
            }
        }

        public static Task<<#=o.type#>> SumAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, <#=o.type#>> selector, CancellationToken cancellationToken = default)
        {
            if (source == null)
                throw Error.ArgumentNull(nameof(source));
            if (selector == null)
                throw Error.ArgumentNull(nameof(selector));

            return Core(source, selector, cancellationToken);

            async Task<<#=o.type#>> Core(IAsyncEnumerable<TSource> _source, Func<TSource, <#=o.type#>> _selector, CancellationToken _cancellationToken)
            {
                var sum = <#=o.zero#>;

#if CSHARP8 && AETOR_HAS_CT // CS0656 Missing compiler required member 'System.Collections.Generic.IAsyncEnumerable`1.GetAsyncEnumerator'
                await foreach (TSource item in _source.WithCancellation(_cancellationToken).ConfigureAwait(false))
                {
                    var value = _selector(item);

<#
if (o.@checked)
{
#>
                    checked
                    {
                        sum += value<#=n#>;
                    }
<#
}
else
{
#>
                    sum += value<#=n#>;
<#
}
#>
                }
#else
                var e = _source.GetAsyncEnumerator(_cancellationToken);

                try
                {
                    while (await e.MoveNextAsync().ConfigureAwait(false))
                    {
                        var value = _selector(e.Current);

<#
if (o.@checked)
{
#>
                        checked
                        {
                            sum += value<#=n#>;
                        }
<#
}
else
{
#>
                        sum += value<#=n#>;
<#
}
#>
                    }
                }
                finally
                {
                    await e.DisposeAsync().ConfigureAwait(false);
                }
#endif

                return sum;
            }
        }

        public static Task<<#=o.type#>> SumAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<<#=o.type#>>> selector, CancellationToken cancellationToken = default)
        {
            if (source == null)
                throw Error.ArgumentNull(nameof(source));
            if (selector == null)
                throw Error.ArgumentNull(nameof(selector));

            return Core(source, selector, cancellationToken);

            async Task<<#=o.type#>> Core(IAsyncEnumerable<TSource> _source, Func<TSource, ValueTask<<#=o.type#>>> _selector, CancellationToken _cancellationToken)
            {
                var sum = <#=o.zero#>;

#if CSHARP8 && AETOR_HAS_CT // CS0656 Missing compiler required member 'System.Collections.Generic.IAsyncEnumerable`1.GetAsyncEnumerator'
                await foreach (TSource item in _source.WithCancellation(_cancellationToken).ConfigureAwait(false))
                {
                    var value = await _selector(item).ConfigureAwait(false);

<#
if (o.@checked)
{
#>
                    checked
                    {
                        sum += value<#=n#>;
                    }
<#
}
else
{
#>
                    sum += value<#=n#>;
<#
}
#>
                }
#else
                var e = _source.GetAsyncEnumerator(_cancellationToken);

                try
                {
                    while (await e.MoveNextAsync().ConfigureAwait(false))
                    {
                        var value = await _selector(e.Current).ConfigureAwait(false);

<#
if (o.@checked)
{
#>
                        checked
                        {
                            sum += value<#=n#>;
                        }
<#
}
else
{
#>
                        sum += value<#=n#>;
<#
}
#>
                    }
                }
                finally
                {
                    await e.DisposeAsync().ConfigureAwait(false);
                }
#endif

                return sum;
            }
        }

#if !NO_DEEP_CANCELLATION
        public static Task<<#=o.type#>> SumAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<<#=o.type#>>> selector, CancellationToken cancellationToken = default)
        {
            if (source == null)
                throw Error.ArgumentNull(nameof(source));
            if (selector == null)
                throw Error.ArgumentNull(nameof(selector));

            return Core(source, selector, cancellationToken);

            async Task<<#=o.type#>> Core(IAsyncEnumerable<TSource> _source, Func<TSource, CancellationToken, ValueTask<<#=o.type#>>> _selector, CancellationToken _cancellationToken)
            {
                var sum = <#=o.zero#>;

#if CSHARP8 && AETOR_HAS_CT // CS0656 Missing compiler required member 'System.Collections.Generic.IAsyncEnumerable`1.GetAsyncEnumerator'
                await foreach (TSource item in _source.WithCancellation(_cancellationToken).ConfigureAwait(false))
                {
                    var value = await _selector(item, _cancellationToken).ConfigureAwait(false);

<#
if (o.@checked)
{
#>
                    checked
                    {
                        sum += value<#=n#>;
                    }
<#
}
else
{
#>
                    sum += value<#=n#>;
<#
}
#>
                }
#else
                var e = _source.GetAsyncEnumerator(_cancellationToken);

                try
                {
                    while (await e.MoveNextAsync().ConfigureAwait(false))
                    {
                        var value = await _selector(e.Current, _cancellationToken).ConfigureAwait(false);

<#
if (o.@checked)
{
#>
                        checked
                        {
                            sum += value<#=n#>;
                        }
<#
}
else
{
#>
                        sum += value<#=n#>;
<#
}
#>
                    }
                }
                finally
                {
                    await e.DisposeAsync().ConfigureAwait(false);
                }
#endif

                return sum;
            }
        }
#endif

<#
}
#>
    }
}
