using System;
using System.Globalization;
using System.Linq;
using System.Reflection;
using System.Threading;
using Xunit.Sdk;

// Copied from https://github.com/xunit/samples.xunit/blob/master/UseCulture/UseCultureAttribute.cs

/// <summary>
/// Apply this attribute to your test method to replace the
/// <see cref="Thread.CurrentThread" /> <see cref="CultureInfo.CurrentCulture" /> and
/// <see cref="CultureInfo.CurrentUICulture" /> with another culture.
/// </summary>
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
public class UseCultureAttribute : BeforeAfterTestAttribute
{
    readonly Lazy<CultureInfo> culture;
    readonly Lazy<CultureInfo> uiCulture;

    CultureInfo originalCulture;
    CultureInfo originalUICulture;

    /// <summary>
    /// Replaces the culture and UI culture of the current thread with
    /// <paramref name="culture" />
    /// </summary>
    /// <param name="culture">The name of the culture.</param>
    /// <remarks>
    /// <para>
    /// This constructor overload uses <paramref name="culture" /> for both
    /// <see cref="Culture" /> and <see cref="UICulture" />.
    /// </para>
    /// </remarks>
    public UseCultureAttribute(string culture)
        : this(culture, culture) { }

    /// <summary>
    /// Replaces the culture and UI culture of the current thread with
    /// <paramref name="culture" /> and <paramref name="uiCulture" />
    /// </summary>
    /// <param name="culture">The name of the culture.</param>
    /// <param name="uiCulture">The name of the UI culture.</param>
    public UseCultureAttribute(string culture, string uiCulture)
    {
        this.culture = new Lazy<CultureInfo>(() => new CultureInfo(culture, false));
        this.uiCulture = new Lazy<CultureInfo>(() => new CultureInfo(uiCulture, false));
    }

    /// <summary>
    /// Gets the culture.
    /// </summary>
    public CultureInfo Culture { get { return culture.Value; } }

    /// <summary>
    /// Gets the UI culture.
    /// </summary>
    public CultureInfo UICulture { get { return uiCulture.Value; } }

    /// <summary>
    /// Stores the current <see cref="Thread.CurrentPrincipal" />
    /// <see cref="CultureInfo.CurrentCulture" /> and <see cref="CultureInfo.CurrentUICulture" />
    /// and replaces them with the new cultures defined in the constructor.
    /// </summary>
    /// <param name="methodUnderTest">The method under test</param>
    public override void Before(MethodInfo methodUnderTest)
    {
        originalCulture = Thread.CurrentThread.CurrentCulture;
        originalUICulture = Thread.CurrentThread.CurrentUICulture;

        Thread.CurrentThread.CurrentCulture = Culture;
        Thread.CurrentThread.CurrentUICulture = UICulture;

        CultureInfo.CurrentCulture.ClearCachedData();
        CultureInfo.CurrentUICulture.ClearCachedData();
    }

    /// <summary>
    /// Restores the original <see cref="CultureInfo.CurrentCulture" /> and
    /// <see cref="CultureInfo.CurrentUICulture" /> to <see cref="Thread.CurrentPrincipal" />
    /// </summary>
    /// <param name="methodUnderTest">The method under test</param>
    public override void After(MethodInfo methodUnderTest)
    {
        Thread.CurrentThread.CurrentCulture = originalCulture;
        Thread.CurrentThread.CurrentUICulture = originalUICulture;

        CultureInfo.CurrentCulture.ClearCachedData();
        CultureInfo.CurrentUICulture.ClearCachedData();
    }
}