// 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. 

<#@ 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" #>
using System.Reactive.Subjects;

namespace System.Reactive.Linq
{
    // REVIEW: Consider if these are worth retaining in the async space.

    partial class AsyncObservable
    {
<#
for (var i = 0; i <= 14; i++)
{
    var args = Enumerable.Range(1, i).Select(j => "T" + j).Concat(new[] { "IAsyncObservable<TResult>" });
    var ret = "Func<" + string.Join(", ", args) + ">";

    var genArgs = string.Join(", ", Enumerable.Range(1, i).Select(j => "T" + j).Concat(new[] { "TResult" }));
    var pars = string.Join(", ", Enumerable.Range(1, i).Select(j => "arg" + j));

    var begin = "Func<" + string.Join(", ", Enumerable.Range(1, i).Select(j => "T" + j).Concat(new[] { "AsyncCallback, object, IAsyncResult" })) + ">";
    var end = "Func<IAsyncResult, TResult>";
#>
        public static <#=ret#> FromAsyncPattern<<#=genArgs#>>(<#=begin#> begin, <#=end#> end)
        {
            if (begin == null)
                throw new ArgumentNullException(nameof(begin));
            if (end == null)
                throw new ArgumentNullException(nameof(end));

            return (<#=pars#>) =>
            {
                var subject = new SequentialAsyncAsyncSubject<TResult>();

                try
                {
                    begin(<#=pars + (i > 0 ? ", " : "")#>async iar =>
                    {
                        TResult result;

                        try
                        {
                            result = end(iar);
                        }
                        catch (Exception ex)
                        {
                            await subject.OnErrorAsync(ex).ConfigureAwait(false);
                            return;
                        }

                        await subject.OnNextAsync(result).ConfigureAwait(false);
                        await subject.OnCompletedAsync().ConfigureAwait(false);
                    }, null);
                }
                catch (Exception ex)
                {
                    return Throw<TResult>(ex);
                }

                return subject.AsAsyncObservable();
            };
        }

<#
}
#>
<#
for (var i = 0; i <= 14; i++)
{
    var args = Enumerable.Range(1, i).Select(j => "T" + j).Concat(new[] { "IAsyncObservable<Unit>" });
    var ret = "Func<" + string.Join(", ", args) + ">";

    var genArgs = string.Join(", ", Enumerable.Range(1, i).Select(j => "T" + j));
    var pars = string.Join(", ", Enumerable.Range(1, i).Select(j => "arg" + j));

    var begin = "Func<" + string.Join(", ", Enumerable.Range(1, i).Select(j => "T" + j).Concat(new[] { "AsyncCallback, object, IAsyncResult" })) + ">";
    var end = "Func<IAsyncResult, Unit>";

    if (genArgs != "")
    {
        genArgs = "<" + genArgs + ">";
    }
#>
        public static <#=ret#> FromAsyncPattern<#=genArgs#>(<#=begin#> begin, <#=end#> end)
        {
            if (begin == null)
                throw new ArgumentNullException(nameof(begin));
            if (end == null)
                throw new ArgumentNullException(nameof(end));

            return FromAsyncPattern(begin, iar =>
            {
                end(iar);
                return Unit.Default;
            });
        }

<#
}
#>
    }
}