// Copyright (c) The Geekeey Authors
// SPDX-License-Identifier: EUPL-1.2

using System.Buffers;
using System.CommandLine;
using System.Globalization;

internal sealed class LengthCommand : Command
{
	private static readonly Option<OutputTarget> Target = new("--target") { DefaultValueFactory = _ => OutputTarget.StdOut };
	private static readonly Option<int> Buffer = new("--buffer") { DefaultValueFactory = _ => 81920 };

	public LengthCommand() : base("length")
	{
		Add(Target);
		Add(Buffer);
		SetAction(ExecuteAsync);
	}

	public async Task<int> ExecuteAsync(ParseResult result, CancellationToken cancellationToken)
	{
		using var output = Output.Connect();

		using var buffer = MemoryPool<byte>.Shared.Rent(result.GetRequiredValue(Buffer));

		var count = 0L;
		while (true)
		{
			var bytesRead = await output.Stdin.BaseStream.ReadAsync(buffer.Memory, cancellationToken);
			if (bytesRead <= 0)
			{
				break;
			}

			count += bytesRead;
		}

		foreach (var writer in output.GetWriters(result.GetRequiredValue(Target)))
		{
			await writer.WriteLineAsync(count.ToString(CultureInfo.InvariantCulture));
		}

		return 0;
	}
}