DocumentService/DocumentService.Tests/Unit/Client/ZugferdClientTests.cs

using DocumentService.Application.Common.DTOs;
using DocumentService.Application.ExtractZugferd;
using DocumentService.Client.Clients;
using DocumentService.Client.Interfaces;
using FluentAssertions;
using Microsoft.Extensions.Logging.Abstractions;
using System.Net;
using System.Net.Http;
using System.Text.Json;

namespace DocumentService.Tests.Unit.Client;

/// <summary>
/// Unit tests for <see cref="ZugferdClient"/>.
/// All tests use a fake <see cref="MockHttpMessageHandler"/> <20> no real HTTP calls are made.
/// </summary>
public class ZugferdClientTests
{
    // ?? helpers ?????????????????????????????????????????????????????????????

    private static (ZugferdClient client, MockHttpMessageHandler handler) BuildJson<T>(T body)
    {
        var handler = MockHttpMessageHandler.ReturningJson(body);
        var httpClient = new HttpClient(handler) { BaseAddress = new Uri("http://localhost") };
        var client = new ZugferdClient(httpClient, NullLogger<ZugferdClient>.Instance);
        return (client, handler);
    }

    private static (ZugferdClient client, MockHttpMessageHandler handler) BuildBytes(byte[] bytes, string mediaType = "application/xml")
    {
        var handler = MockHttpMessageHandler.ReturningBytes(bytes, mediaType);
        var httpClient = new HttpClient(handler) { BaseAddress = new Uri("http://localhost") };
        var client = new ZugferdClient(httpClient, NullLogger<ZugferdClient>.Instance);
        return (client, handler);
    }

    private static byte[] FakePdfBytes() => "fake-pdf-content"u8.ToArray();
    private static byte[] FakeXmlBytes() => "<invoice>test</invoice>"u8.ToArray();

    // ?? CheckAsync (Stream) ?????????????????????????????????????????????

    [Fact]
    public async Task CheckAsync_Stream_WhenZugferdPresent_ReturnsTrue()
    {
        // Arrange
        var expected = new ZugferdCheckResult { HasZugferd = true, ZugferdFileName = "factur-x.xml" };
        var (client, handler) = BuildJson(expected);

        // Act
        var result = await client.CheckAsync(new MemoryStream(FakePdfBytes()));

        // Assert
        result.HasZugferd.Should().BeTrue();
        handler.LastRequest!.RequestUri!.PathAndQuery.Should().Be("/api/pdf/zugferd/has-zugferd");
        handler.LastRequest.Content.Should().BeOfType<MultipartFormDataContent>();
    }

    [Fact]
    public async Task CheckAsync_Stream_WhenNoZugferd_ReturnsFalse()
    {
        // Arrange
        var expected = new ZugferdCheckResult { HasZugferd = false };
        var (client, _) = BuildJson(expected);

        // Act
        var result = await client.CheckAsync(new MemoryStream(FakePdfBytes()));

        // Assert
        result.HasZugferd.Should().BeFalse();
        result.ZugferdFileName.Should().BeNull();
    }

    // ?? CheckAsync (byte[]) ?????????????????????????????????????????????

    [Fact]
    public async Task CheckAsync_Bytes_SendsJsonWithBase64()
    {
        // Arrange
        var expected = new ZugferdCheckResult { HasZugferd = true };
        var (client, handler) = BuildJson(expected);

        // Act
        await client.CheckAsync(FakePdfBytes());

        // Assert
        handler.LastRequest!.Content.Should().NotBeNull();
        handler.LastRequest.Content!.Headers.ContentType!.MediaType.Should().Be("application/json");
        var body = await handler.LastRequest.Content!.ReadAsStringAsync();
        var doc = JsonDocument.Parse(body);
        doc.RootElement.GetProperty("base64Pdf").GetString().Should().NotBeNullOrEmpty();
    }

    // ?? ExtractAsync (Stream) <20> raw XML stream ?????????????????????????

    [Fact]
    public async Task ExtractAsync_Stream_SendsMultipartWithAsFileTrue()
    {
        // Arrange
        var (client, handler) = BuildBytes(FakeXmlBytes());

        // Act
        using var result = await client.ExtractAsync(new MemoryStream(FakePdfBytes()));

        // Assert
        result.Should().NotBeNull();
        handler.LastRequest!.RequestUri!.PathAndQuery.Should().Be("/api/pdf/zugferd/extract?asFile=true");
        handler.LastRequest.Content.Should().BeOfType<MultipartFormDataContent>();
    }

    [Fact]
    public async Task ExtractAsync_Stream_ReturnsXmlContent()
    {
        // Arrange
        var xmlBytes = "<root><invoice/></root>"u8.ToArray();
        var (client, _) = BuildBytes(xmlBytes);

        // Act
        using var result = await client.ExtractAsync(new MemoryStream(FakePdfBytes()));
        var content = await new StreamReader(result).ReadToEndAsync();

        // Assert
        content.Should().Be("<root><invoice/></root>");
    }

    // ?? ExtractAsync (byte[]) ?????????????????????????????????????????

    [Fact]
    public async Task ExtractAsync_Bytes_SendsJsonWithFormatFile()
    {
        // Arrange
        var (client, handler) = BuildBytes(FakeXmlBytes());

        // Act
        using var result = await client.ExtractAsync(FakePdfBytes());

        // Assert
        handler.LastRequest!.RequestUri!.PathAndQuery.Should().Be("/api/pdf/zugferd/extract?format=file");
        handler.LastRequest.Content.Should().NotBeNull();
        handler.LastRequest.Content!.Headers.ContentType!.MediaType.Should().Be("application/json");
    }

    // ?? ExtractAsResultAsync (Stream) ?????????????????????????????????

    [Fact]
    public async Task ExtractAsResultAsync_Stream_ReturnsStructuredResult()
    {
        // Arrange
        var expected = new ZugferdExtractionResult
        {
            FileName   = "factur-x.xml",
            XmlContent = "<invoice/>",
        };
        var (client, handler) = BuildJson(expected);

        // Act
        var result = await client.ExtractAsResultAsync(new MemoryStream(FakePdfBytes()));

        // Assert
        result.FileName.Should().Be("factur-x.xml");
        result.XmlContent.Should().Be("<invoice/>");
        handler.LastRequest!.RequestUri!.PathAndQuery.Should().Be("/api/pdf/zugferd/extract?asFile=false");
    }

    // ?? ExtractAsResultAsync (byte[]) ?????????????????????????????????

    [Fact]
    public async Task ExtractAsResultAsync_Bytes_SendsJsonWithFormatJson()
    {
        // Arrange
        var expected = new ZugferdExtractionResult { FileName = "zugferd.xml", XmlContent = "<x/>" };
        var (client, handler) = BuildJson(expected);

        // Act
        await client.ExtractAsResultAsync(FakePdfBytes());

        // Assert
        handler.LastRequest!.RequestUri!.PathAndQuery.Should().Be("/api/pdf/zugferd/extract?format=json");
        handler.LastRequest.Content.Should().NotBeNull();
        handler.LastRequest.Content!.Headers.ContentType!.MediaType.Should().Be("application/json");
    }

    // ?? HTTP error propagation ???????????????????????????????????????????????

    [Fact]
    public async Task CheckAsync_WhenApiReturns400_ThrowsHttpRequestException()
    {
        // Arrange
        var handler = MockHttpMessageHandler.ReturningStatus(HttpStatusCode.BadRequest);
        var httpClient = new HttpClient(handler) { BaseAddress = new Uri("http://localhost") };
        var client = new ZugferdClient(httpClient, NullLogger<ZugferdClient>.Instance);

        // Act & Assert
        await client.Invoking(c => c.CheckAsync(new MemoryStream(FakePdfBytes())))
            .Should().ThrowAsync<HttpRequestException>();
    }
}