// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Runtime.InteropServices;

namespace Microsoft.AspNetCore.Testing
{
    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Class | AttributeTargets.Assembly, AllowMultiple = true)]
    public class OSSkipConditionAttribute : Attribute, ITestCondition
    {
        private readonly OperatingSystems _excludedOperatingSystem;
        private readonly OperatingSystems _osPlatform;

        public OSSkipConditionAttribute(OperatingSystems operatingSystem) :
            this(operatingSystem, GetCurrentOS())
        {
        }

        [Obsolete("Use the Minimum/MaximumOSVersionAttribute for version checks.", error: true)]
        public OSSkipConditionAttribute(OperatingSystems operatingSystem, params string[] versions) :
            this(operatingSystem, GetCurrentOS())
        {
        }

        // to enable unit testing
        internal OSSkipConditionAttribute(OperatingSystems operatingSystem, OperatingSystems osPlatform)
        {
            _excludedOperatingSystem = operatingSystem;
            _osPlatform = osPlatform;
        }

        public bool IsMet
        {
            get
            {
                var skip = (_excludedOperatingSystem & _osPlatform) == _osPlatform;
                // Since a test would be excuted only if 'IsMet' is true, return false if we want to skip
                return !skip;
            }
        }

        public string SkipReason { get; set; } = "Test cannot run on this operating system.";

        static private OperatingSystems GetCurrentOS()
        {
            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
            {
                return OperatingSystems.Windows;
            }
            else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
            {
                return OperatingSystems.Linux;
            }
            else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
            {
                return OperatingSystems.MacOSX;
            }
            throw new PlatformNotSupportedException();
        }
    }
}