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

namespace HrynCo.NotificationService.Services.Tests.EmailProcessing;

using HrynCo.NotificationService.Contracts.Messages;
using HrynCo.NotificationService.DAL.Abstract.Templates;
using HrynCo.NotificationService.Worker.Services.EmailProcessing;

public sealed class EmailTemplateRenderingServiceTests
{
    private readonly EmailTemplateRenderingService _service = new();

    [Fact]
    public void Render_InterpolatesItemTrackerVariables()
    {
        EmailTemplate template = CreateTemplate();
        SendEmailMessageData data = CreateData(new Dictionary<string, string>
        {
            ["AppName"] = "StoreMate",
            ["VerificationUrl"] = "https://example.invalid/verify"
        });

        RenderedEmail result = _service.Render(template, data);

        Assert.Equal("Verify StoreMate", result.Subject);
        Assert.Equal("<a href=\"https://example.invalid/verify\">Verify</a>", result.HtmlBody);
        Assert.Equal("Verify at https://example.invalid/verify", result.TextBody);
    }

    [Fact]
    public void Render_WhenRequiredVariableIsMissing_ThrowsObservableFailure()
    {
        EmailTemplate template = CreateTemplate();
        SendEmailMessageData data = CreateData(new Dictionary<string, string>
        {
            ["AppName"] = "StoreMate"
        });

        InvalidDataException exception = Assert.Throws<InvalidDataException>(
            () => _service.Render(template, data));

        Assert.Equal("Required template variables are missing: VerificationUrl.", exception.Message);
    }

    [Fact]
    public void Render_HtmlEncodesVariablesWithoutChangingSubjectOrTextBody()
    {
        EmailTemplate template = CreateTemplate();
        SendEmailMessageData data = CreateData(new Dictionary<string, string>
        {
            ["AppName"] = "Invemory <script>alert('xss')</script>",
            ["VerificationUrl"] = "https://example.invalid/verify?next=\" onclick=\"alert('xss')"
        });

        RenderedEmail result = _service.Render(template, data);

        Assert.Equal("Verify Invemory <script>alert('xss')</script>", result.Subject);
        Assert.Equal(
            "<a href=\"https://example.invalid/verify?next=&quot; onclick=&quot;alert(&#39;xss&#39;)\">Verify</a>",
            result.HtmlBody);
        Assert.Equal(
            "Verify at https://example.invalid/verify?next=\" onclick=\"alert('xss')",
            result.TextBody);
    }

    private static EmailTemplate CreateTemplate() => new()
    {
        ServiceName = "StoreMate-Prod",
        Key = "EmailVerification",
        LanguageCode = "uk",
        Subject = "Verify {{AppName}}",
        HtmlBody = "<a href=\"{{VerificationUrl}}\">Verify</a>",
        TextBody = "Verify at {{VerificationUrl}}",
        Variables =
        [
            new EmailTemplateVariable { Name = "AppName", Required = true },
            new EmailTemplateVariable { Name = "VerificationUrl", Required = true }
        ]
    };

    private static SendEmailMessageData CreateData(IReadOnlyDictionary<string, string> variables) => new()
    {
        ServiceName = "StoreMate-Prod",
        TemplateKey = "EmailVerification",
        RecipientEmail = "owner@example.com",
        RecipientName = "Owner",
        LanguageCode = "uk",
        Variables = variables
    };
}