// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

#nullable disable

using System.Security;
using Microsoft.Win32;

namespace Microsoft.DotNet.Cli.Telemetry;

internal class DockerContainerDetectorForTelemetry : IDockerContainerDetector
{
    public IsDockerContainer IsDockerContainer()
    {
        if (OperatingSystem.IsWindows())
        {
            try
            {
                using (RegistryKey subkey
                    = Registry.LocalMachine.OpenSubKey("System\\CurrentControlSet\\Control"))
                {
                    return subkey?.GetValue("ContainerType") != null
                        ? Cli.Telemetry.IsDockerContainer.True
                        : Cli.Telemetry.IsDockerContainer.False;
                }
            }
            catch (SecurityException)
            {
                return Cli.Telemetry.IsDockerContainer.Unknown;
            }
        }
        else if (OperatingSystem.IsLinux())
        {
            try
            {
                bool isDocker = File
                    .ReadAllText("/proc/1/cgroup")
                    .Contains("/docker/");

                return isDocker
                    ? Cli.Telemetry.IsDockerContainer.True
                    : Cli.Telemetry.IsDockerContainer.False;
            }
            catch (Exception ex) when (ex is IOException || ex.InnerException is IOException)
            {
                // in some environments (restricted docker container, shared hosting etc.),
                // procfs is not accessible and we get UnauthorizedAccessException while the
                // inner exception is set to IOException. Ignore and continue when that happens.
            }
        }
        else if (OperatingSystem.IsMacOS())
        {
            return Cli.Telemetry.IsDockerContainer.False;
        }

        return Cli.Telemetry.IsDockerContainer.Unknown;
    }
}

internal enum IsDockerContainer
{
    True,
    False,
    Unknown
}