using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;

namespace StardewModdingAPI.Framework
{
    /// <summary>A thread-safe command queue optimized for infrequent changes.</summary>
    internal class CommandQueue
    {
        /********
        ** Fields
        ********/
        /// <summary>The underlying list of queued commands to parse and execute.</summary>
        private readonly List<string> RawCommandQueue = new();


        /********
        ** Public methods
        ********/
        /// <summary>Add a command to the queue.</summary>
        /// <param name="command">The command to add.</param>
        public void Add(string command)
        {
            lock (this.RawCommandQueue)
                this.RawCommandQueue.Add(command);
        }

        /// <summary>Remove and return all queued commands, if any.</summary>
        /// <param name="queued">The commands that were dequeued, in the order they were originally queued.</param>
        /// <returns>Returns whether any values were dequeued.</returns>
        [SuppressMessage("ReSharper", "InconsistentlySynchronizedField", Justification = "Deliberately check if it's empty before locking unnecessarily.")]
        public bool TryDequeue([NotNullWhen(true)] out string[]? queued)
        {
            if (this.RawCommandQueue.Count is 0)
            {
                queued = null;
                return false;
            }

            lock (this.RawCommandQueue)
            {
                queued = this.RawCommandQueue.ToArray();
                this.RawCommandQueue.Clear();
                return queued.Length > 0;
            }
        }
    }
}