hrynco-notification-service/HrynCo.NotificationService.Services.Tests/EmailProcessing/EmailTemplateServiceTests.cs

namespace HrynCo.NotificationService.Services.Tests.EmailProcessing;

using HrynCo.NotificationService.DAL.Abstract.Repositories;
using HrynCo.NotificationService.DAL.Abstract.Templates;
using HrynCo.NotificationService.Worker.Services.EmailProcessing;
using NSubstitute;

public sealed class EmailTemplateServiceTests
{
    [Theory]
    [InlineData("RU")]
    [InlineData(" ru ")]
    [InlineData(" RU ")]
    public async Task GetAsync_WhenExactVersionIsMissing_RetriesLegacyTrimmedLowercaseCode(string requestedCode)
    {
        IEmailTemplateRepository repository = Substitute.For<IEmailTemplateRepository>();
        var expected = Template("ru");
        repository.GetAsync("TestService", "Welcome", "ru", Arg.Any<CancellationToken>()).Returns(expected);
        var service = new EmailTemplateService(repository);

        Assert.Same(expected, await service.GetAsync("TestService", "Welcome", requestedCode, default));
        Assert.Equal(new[] { requestedCode, "ru" }, RequestedCodes(repository));
    }

    [Fact]
    public async Task GetAsync_WhenBothExactAndLowercaseVersionsExist_PrefersExactVersion()
    {
        IEmailTemplateRepository repository = Substitute.For<IEmailTemplateRepository>();
        var expected = Template("RU");
        repository.GetAsync("TestService", "Welcome", "RU", Arg.Any<CancellationToken>()).Returns(expected);
        repository.GetAsync("TestService", "Welcome", "ru", Arg.Any<CancellationToken>()).Returns(Template("ru"));
        var service = new EmailTemplateService(repository);

        Assert.Same(expected, await service.GetAsync("TestService", "Welcome", "RU", default));
        Assert.Equal(new[] { "RU" }, RequestedCodes(repository));
    }

    [Fact]
    public async Task GetAsync_WhenExactRegionalVersionExists_DoesNotNormalizeIt()
    {
        IEmailTemplateRepository repository = Substitute.For<IEmailTemplateRepository>();
        var expected = Template("ru-RU");
        repository.GetAsync("TestService", "Welcome", "ru-RU", Arg.Any<CancellationToken>()).Returns(expected);
        var service = new EmailTemplateService(repository);

        Assert.Same(expected, await service.GetAsync("TestService", "Welcome", "ru-RU", default));
        Assert.Equal(new[] { "ru-RU" }, RequestedCodes(repository));
    }

    [Fact]
    public async Task GetAsync_WhenMissingCodeIsAlreadyCanonical_QueriesOnlyOnce()
    {
        IEmailTemplateRepository repository = Substitute.For<IEmailTemplateRepository>();
        var service = new EmailTemplateService(repository);

        var error = await Assert.ThrowsAsync<InvalidOperationException>(() => service.GetAsync("TestService", "Welcome", "zz", default));

        Assert.Contains("language='zz'", error.Message);
        Assert.Equal(new[] { "zz" }, RequestedCodes(repository));
    }

    [Fact]
    public async Task GetAsync_WhenRegionalLookupMisses_DoesNotScanOtherCaseOrRegionalVariants()
    {
        IEmailTemplateRepository repository = Substitute.For<IEmailTemplateRepository>();
        repository.GetAsync("TestService", "Welcome", "ru-RU", Arg.Any<CancellationToken>()).Returns(Template("ru-RU"));
        repository.GetAsync("TestService", "Welcome", "ru", Arg.Any<CancellationToken>()).Returns(Template("ru"));
        var service = new EmailTemplateService(repository);

        await Assert.ThrowsAsync<InvalidOperationException>(() => service.GetAsync("TestService", "Welcome", "RU-ru", default));

        Assert.Equal(new[] { "RU-ru", "ru-ru" }, RequestedCodes(repository));
    }

    [Theory]
    [InlineData(null)]
    [InlineData("")]
    [InlineData("   ")]
    public async Task GetAsync_WhenCodeIsBlank_RejectsBeforeRepositoryLookup(string? code)
    {
        IEmailTemplateRepository repository = Substitute.For<IEmailTemplateRepository>();
        var service = new EmailTemplateService(repository);

        await Assert.ThrowsAsync<InvalidDataException>(() => service.GetAsync("TestService", "Welcome", code, default));

        Assert.Empty(repository.ReceivedCalls());
    }

    private static EmailTemplate Template(string code) => new()
    {
        ServiceName = "TestService", Key = "Welcome", LanguageCode = code, Subject = "Subject " + code,
        HtmlBody = "<p>Hello</p>", TextBody = "Hello"
    };

    private static string[] RequestedCodes(IEmailTemplateRepository repository) => repository.ReceivedCalls()
        .Select(call => (string)call.GetArguments()[2]!).ToArray();
}