// 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.Concurrency;
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 <= 16; 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 type = "Func<" + string.Join(", ", Enumerable.Range(1, i).Select(j => "T" + j).Concat(new[] { "TResult" })) + ">";
#>
        public static <#=ret#> ToAsync<<#=genArgs#>>(<#=type#> function)
        {
            if (function == null)
                throw new ArgumentNullException(nameof(function));

            return ToAsync(function, TaskPoolAsyncScheduler.Default);
        }

        public static <#=ret#> ToAsync<<#=genArgs#>>(<#=type#> function, IAsyncScheduler scheduler)
        {
            if (function == null)
                throw new ArgumentNullException(nameof(function));
            if (scheduler == null)
                throw new ArgumentNullException(nameof(scheduler));

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

                // NB: We don't do anything with the result of scheduling the action; it can't be cancelled.

                scheduler.ScheduleAsync(async ct =>
                {
                    TResult res;
                    try
                    {
                        res = function(<#=pars#>);
                    }
                    catch (Exception ex)
                    {
                        await subject.OnErrorAsync(ex).RendezVous(scheduler);
                        return;
                    }

                    await subject.OnNextAsync(res).RendezVous(scheduler);
                    await subject.OnCompletedAsync().RendezVous(scheduler);
                });

                return subject.AsAsyncObservable();
            };
        }

<#
}
#>
<#
for (var i = 0; i <= 16; 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 type = "Action";

    if (genArgs != "")
    {
        genArgs = "<" + genArgs + ">";
        type += genArgs;
    }
#>
        public static <#=ret#> ToAsync<#=genArgs#>(<#=type#> action)
        {
            if (action == null)
                throw new ArgumentNullException(nameof(action));

            return ToAsync(action, TaskPoolAsyncScheduler.Default);
        }

        public static <#=ret#> ToAsync<#=genArgs#>(<#=type#> action, IAsyncScheduler scheduler)
        {
            if (action == null)
                throw new ArgumentNullException(nameof(action));
            if (scheduler == null)
                throw new ArgumentNullException(nameof(scheduler));

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

                // NB: We don't do anything with the result of scheduling the action; it can't be cancelled.

                scheduler.ScheduleAsync(async ct =>
                {
                    try
                    {
                        action(<#=pars#>);
                    }
                    catch (Exception ex)
                    {
                        await subject.OnErrorAsync(ex).RendezVous(scheduler);
                        return;
                    }

                    await subject.OnNextAsync(Unit.Default).RendezVous(scheduler);
                    await subject.OnCompletedAsync().RendezVous(scheduler);
                });

                return subject.AsAsyncObservable();
            };
        }

<#
}
#>
    }
}