// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System.Threading;

using Microsoft.VisualStudio.TestPlatform.ObjectModel;

namespace Microsoft.VisualStudio.TestPlatform.Common.Utilities;

/// <summary>
/// Wrapper class around a job used to send additional information to the background thread.
/// </summary>
/// <typeparam name="TPayload">The type of the job.</typeparam>
internal class Job<TPayload>
{
    /// <summary>
    /// Initializes a new instance of the <see cref="Job{TPayload}"/> class.
    /// </summary>
    /// <param name="job">
    /// Job to be processed.
    /// </param>
    /// <param name="size">
    /// Size of payload.
    /// </param>
    public Job(TPayload job, int size)
    {
        Payload = job;
        Size = size;
    }

    /// <summary>
    /// Prevents a default instance of the <see cref="Job{TPayload}"/> class from being created.
    /// </summary>
    private Job()
    {
        Size = 0;
    }

    /// <summary>
    /// Gets a special job that indicates the queue should shutdown.
    /// </summary>
    public static Job<TPayload> ShutdownJob
    {
        get
        {
            var shutdownJob = new Job<TPayload>();
            shutdownJob.Shutdown = true;

            return shutdownJob;
        }
    }

    /// <summary>
    /// Gets the job to be processed.
    /// </summary>
    public TPayload? Payload { get; private set; }

    /// <summary>
    /// Gets a value indicating whether the background thread should shutdown.
    /// </summary>
    public bool Shutdown { get; private set; }

    /// <summary>
    /// Gets the signal that this job is being processed.
    /// </summary>
    public ManualResetEvent? WaitManualResetEvent { get; private set; }

    /// <summary>
    /// Gets the size of this job instance. This is used to manage the total size of Job Queue.
    /// </summary>
    public int Size { get; private set; }

    /// <summary>
    /// Creates a job with a manual reset event that will be set when the job is processed.
    /// </summary>
    /// <param name="waitEvent"> The wait Event. </param>
    /// <returns> The wait job. </returns>
    public static Job<TPayload> CreateWaitJob(ManualResetEvent waitEvent)
    {
        ValidateArg.NotNull(waitEvent, nameof(waitEvent));

        var waitJob = new Job<TPayload>();
        waitJob.WaitManualResetEvent = waitEvent;

        return waitJob;
    }

}