DocumentService/DocumentService.Tests/Unit/Application/Features/AddAnnotation/AddAnnotationHandlerTests.cs

using DocumentService.Application.AddAnnotation;
using DocumentService.Application.Common.Interfaces;
using DocumentService.Domain.Common.Exceptions;
using DocumentService.Domain.Models.ValueObjects;
using FluentAssertions;
using Moq;
using Xunit;

namespace DocumentService.Tests.Unit.Application.Features.AddAnnotation;

public class AddAnnotationHandlerTests
{
    private readonly Mock<IPdfProcessor> _mockProcessor;
    private readonly AddAnnotationHandler _handler;
    private static readonly byte[] FakePdfBytes = "%PDF"u8.ToArray();

    public AddAnnotationHandlerTests()
    {
        _mockProcessor = new Mock<IPdfProcessor>();
        _handler = new AddAnnotationHandler(_mockProcessor.Object);
    }

    [Fact]
    public async Task Handle_TextMarkupAnnotation_ReturnsAnnotatedBytes()
    {
        // Arrange
        var command = new AddAnnotationCommand
        {
            PdfStream = new MemoryStream(FakePdfBytes),
            AnnotationType = AnnotationType.TextMarkup,
            PageNumber = 1,
            Rectangle = (10, 20, 200, 50),
            TextMarkupStyle = TextMarkupStyle.Highlight,
            Author = "TestUser",
            Color = "FFFF00"
        };
        var expected = new byte[] { 0x25, 0x50, 0x44, 0x46, 0x01 };
        _mockProcessor.Setup(x => x.AddAnnotationAsync(
                It.IsAny<Stream>(), AnnotationType.TextMarkup, 1,
                It.IsAny<(double, double, double, double)>(),
                null, "TestUser", "FFFF00", TextMarkupStyle.Highlight, AnnotationOrigin.BottomLeft))
            .ReturnsAsync(expected);

        // Act
        var result = await _handler.Handle(command, CancellationToken.None);

        // Assert
        result.Should().BeEquivalentTo(expected);
        _mockProcessor.Verify(x => x.AddAnnotationAsync(
            It.IsAny<Stream>(), AnnotationType.TextMarkup, 1,
            It.IsAny<(double, double, double, double)>(),
            null, "TestUser", "FFFF00", TextMarkupStyle.Highlight, AnnotationOrigin.BottomLeft), Times.Once);
    }

    [Fact]
    public async Task Handle_FreeTextAnnotation_PassesContentToProcessor()
    {
        // Arrange
        var command = new AddAnnotationCommand
        {
            PdfStream = new MemoryStream(FakePdfBytes),
            AnnotationType = AnnotationType.FreeText,
            PageNumber = 2,
            Rectangle = (50, 100, 300, 150),
            Content = "Review this section"
        };
        var expected = new byte[] { 0x25, 0x50, 0x44, 0x46, 0x02 };
        _mockProcessor.Setup(x => x.AddAnnotationAsync(
                It.IsAny<Stream>(), AnnotationType.FreeText, 2,
                It.IsAny<(double, double, double, double)>(),
                "Review this section", null, null, null, AnnotationOrigin.BottomLeft))
            .ReturnsAsync(expected);

        // Act
        var result = await _handler.Handle(command, CancellationToken.None);

        // Assert
        result.Should().BeEquivalentTo(expected);
    }

    [Fact]
    public async Task Handle_ProcessorThrowsBadRequest_PropagatesException()
    {
        // Arrange
        var command = new AddAnnotationCommand
        {
            PdfStream = new MemoryStream(FakePdfBytes),
            AnnotationType = AnnotationType.Circle,
            PageNumber = 99,
            Rectangle = (0, 0, 100, 100)
        };
        _mockProcessor.Setup(x => x.AddAnnotationAsync(
                It.IsAny<Stream>(), It.IsAny<AnnotationType>(), It.IsAny<int>(),
                It.IsAny<(double, double, double, double)>(),
                It.IsAny<string?>(), It.IsAny<string?>(), It.IsAny<string?>(),
                It.IsAny<TextMarkupStyle?>(), It.IsAny<AnnotationOrigin>()))
            .ThrowsAsync(new BadRequestException("Page number 99 exceeds document page count"));

        // Act & Assert
        var ex = await Assert.ThrowsAsync<BadRequestException>(
            () => _handler.Handle(command, CancellationToken.None));
        ex.Message.Should().Contain("Page number 99");
    }

    [Fact]
    public async Task Handle_ProcessorThrowsGenericException_PropagatesException()
    {
        // Arrange
        var command = new AddAnnotationCommand
        {
            PdfStream = new MemoryStream(FakePdfBytes),
            AnnotationType = AnnotationType.Square,
            PageNumber = 1,
            Rectangle = (0, 0, 100, 100)
        };
        _mockProcessor.Setup(x => x.AddAnnotationAsync(
                It.IsAny<Stream>(), It.IsAny<AnnotationType>(), It.IsAny<int>(),
                It.IsAny<(double, double, double, double)>(),
                It.IsAny<string?>(), It.IsAny<string?>(), It.IsAny<string?>(),
                It.IsAny<TextMarkupStyle?>(), It.IsAny<AnnotationOrigin>()))
            .ThrowsAsync(new Exception("Unexpected error"));

        // Act & Assert
        await Assert.ThrowsAsync<Exception>(() => _handler.Handle(command, CancellationToken.None));
    }
}