// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System;
using System.Collections.Concurrent;

namespace Microsoft.VisualStudio.TestPlatform.Utilities;

/// <summary>
/// !!!NEVER USE A FLAG TO ENABLE FUNCTIONALITY!!!
///
/// The reasoning is:
///
/// * New version will automatically ship with the feature enabled. There is no action needed to be done just before release.
/// * Anyone interested in the new feature will get it automatically by grabbing our preview.
/// * Anyone who needs more time before using the new feature can disable it in the released package.
/// * If we remove the flag from our code, we will do it after the feature is the new default, or after the functionality was completely removed from our codebase.
/// * If there is a very outdated version of an assembly that for some reason loaded with the newest version of TP and it cannot find a feature flag, because we removed that feature flag in the meantime, it will just run with all it's newest features enabled.
///
/// Use constants so the feature name will be compiled directly into the assembly that references this, to avoid backwards compatibility issues, when the flag is removed in newer version.
/// </summary>

// !!! SDK USED FEATURE NAMES MUST BE KEPT IN SYNC IN https://github.com/dotnet/sdk/blob/main/src/Cli/dotnet/commands/dotnet-test/VSTestFeatureFlag.cs !!!
internal partial class FeatureFlag : IFeatureFlag
{
    private readonly ConcurrentDictionary<string, bool> _cache = new();

    public static IFeatureFlag Instance { get; private set; } = new FeatureFlag();

    private FeatureFlag() { }

    // Only check the env variable once, when it is not set or is set to 0, consider it unset. When it is anything else, consider it set.
    public bool IsSet(string featureFlag) => _cache.GetOrAdd(featureFlag, f => (Environment.GetEnvironmentVariable(f)?.Trim() ?? "0") != "0");

    // Added for artifact post-processing, it enable/disable the post processing.
    // Added in 17.2-preview 7.0-preview
    public const string VSTEST_DISABLE_ARTIFACTS_POSTPROCESSING = nameof(VSTEST_DISABLE_ARTIFACTS_POSTPROCESSING);

    // Added for artifact post-processing, it will show old output for dotnet sdk scenario.
    // It can be useful if we need to restore old UX in case users are parsing the console output.
    // Added in 17.2-preview 7.0-preview
    public const string VSTEST_DISABLE_ARTIFACTS_POSTPROCESSING_NEW_SDK_UX = nameof(VSTEST_DISABLE_ARTIFACTS_POSTPROCESSING_NEW_SDK_UX);

    // Faster JSON serialization relies on less internals of NewtonsoftJson, and on some additional caching.
    public const string VSTEST_DISABLE_FASTER_JSON_SERIALIZATION = nameof(VSTEST_DISABLE_FASTER_JSON_SERIALIZATION);

    // Forces vstest.consoleto run all sources using the same target framework (TFM) and architecture, instead of allowing
    // multiple different tfms and architectures to run at the same time.
    public const string VSTEST_DISABLE_MULTI_TFM_RUN = nameof(VSTEST_DISABLE_MULTI_TFM_RUN);

    // Disables setting a higher value for SetMinThreads. Setting SetMinThreads value to higher allows testhost to connect back faster
    // even though we are blocking additional threads because we don't have to wait for ThreadPool to start more threads.
    public const string VSTEST_DISABLE_THREADPOOL_SIZE_INCREASE = nameof(VSTEST_DISABLE_THREADPOOL_SIZE_INCREASE);

    // Disable the SerialTestRunDecorator
    public const string VSTEST_DISABLE_SERIALTESTRUN_DECORATOR = nameof(VSTEST_DISABLE_SERIALTESTRUN_DECORATOR);

    // Disable setting UTF8 encoding in console.
    public const string VSTEST_DISABLE_UTF8_CONSOLE_ENCODING = nameof(VSTEST_DISABLE_UTF8_CONSOLE_ENCODING);

    // VSTEST_EXPERIMENTAL_FORWARD_OUTPUT_FEATURE=1 replaced by the CAPTURING and FORWARDING flags, and was enabling
    // the same behavior as what is now the default (both capture and forward set to TRUE).
    // Because this is the new default we don't have to handle it in any special way. Setting it to 0 was not defined
    // and so it also does not need any special treatment.
    //
    // Disable capturing standard output of testhost.
    public const string VSTEST_DISABLE_STANDARD_OUTPUT_CAPTURING = nameof(VSTEST_DISABLE_STANDARD_OUTPUT_CAPTURING);

    // Disable forwarding standard output of testhost.
    public const string VSTEST_DISABLE_STANDARD_OUTPUT_FORWARDING = nameof(VSTEST_DISABLE_STANDARD_OUTPUT_FORWARDING);

    // Disable not sharing .NET Framework testhosts. Which will return behavior to sharing testhosts when they are running .NET Framework dlls, and are not disabling appdomains or running in parallel.
    public const string VSTEST_DISABLE_SHARING_NETFRAMEWORK_TESTHOST = nameof(VSTEST_DISABLE_SHARING_NETFRAMEWORK_TESTHOST);

    // Disable setting DOTNET_ROOT environment variable on non-Windows platforms. We used to set it only only on Windows when we found testhost.exe, now we set it always to allow xunit v3 to run tests in child process.
    public const string VSTEST_DISABLE_DOTNET_ROOT_ON_NONWINDOWS = nameof(VSTEST_DISABLE_DOTNET_ROOT_ON_NONWINDOWS);

    // Disable turning dynamic code coverage for native code to OFF by default. Setting this to 1 will skip adding the setting.
    public const string VSTEST_DISABLE_DYNAMICNATIVE_CODECOVERAGE_DEFAULT_SETTING = nameof(VSTEST_DISABLE_DYNAMICNATIVE_CODECOVERAGE_DEFAULT_SETTING);



    [Obsolete("Only use this in tests.")]
    internal static void Reset()
    {
        Instance = new FeatureFlag();
    }

    [Obsolete("Only use this in tests.")]
    internal void SetFlag(string key, bool value)
    {
        _cache[key] = value;
    }
}