using System.Diagnostics;
using System.Runtime.CompilerServices;

internal static class Shellify
{
	[Flags]
	private enum ShellSplitState
	{
		None = 0,
		InSingleQuote = 1 << 0,
		InDoubleQuote = 1 << 1,
		Escape = 1 << 2
	}

	/// <summary>
	/// Splits a shell-escaped string into arguments, handling quotes and escapes.
	/// </summary>
	public static List<string> ShellSplit(string input)
	{
		var args = new List<string>();
		if (string.IsNullOrEmpty(input)) return args;
		var current = new System.Text.StringBuilder();
		var state = ShellSplitState.None;
		foreach (char c in input)
		{
			if (state.HasFlag(ShellSplitState.Escape))
			{
				current.Append(c);
				state &= ~ShellSplitState.Escape;
			}
			else if (c == '\\')
			{
				state |= ShellSplitState.Escape;
			}
			else if (c == '\'' && !state.HasFlag(ShellSplitState.InDoubleQuote))
			{
				state ^= ShellSplitState.InSingleQuote;
			}
			else if (c == '"' && !state.HasFlag(ShellSplitState.InSingleQuote))
			{
				state ^= ShellSplitState.InDoubleQuote;
			}
			else if (char.IsWhiteSpace(c) && !state.HasFlag(ShellSplitState.InSingleQuote) && !state.HasFlag(ShellSplitState.InDoubleQuote))
			{
				if (current.Length > 0)
				{
					args.Add(current.ToString());
					current.Clear();
				}
			}
			else
			{
				current.Append(c);
			}
		}

		if (current.Length > 0)
			args.Add(current.ToString());
		return args;
	}

	public static TaskAwaiter<string> GetAwaiter(this string command)
	{
		return RunProcessAsync(command).GetAwaiter();
	}

	private static async Task<string> RunProcessAsync(string command)
	{
		var strings = ShellSplit(command);
		var psi = new ProcessStartInfo
		{
			FileName = strings.First(),
			ArgumentList =
			{
				strings.Skip(1)
			},
			RedirectStandardOutput = true,
			RedirectStandardError = true,
			UseShellExecute = false,
			CreateNoWindow = true,
		};
		using var process = Process.Start(psi);
		string output = await process.StandardOutput.ReadToEndAsync();
		string error = await process.StandardError.ReadToEndAsync();
		await process.WaitForExitAsync();
		if (process.ExitCode != 0)
			throw new System.Exception($"Process exited with code {process.ExitCode}: {error}");
		return output;
	}
}