DocumentService/DocumentService.Tests/Unit/Client/PdfAttachmentClientTests.cs

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

namespace DocumentService.Tests.Unit.Client;

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

    private static (PdfAttachmentClient 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 PdfAttachmentClient(httpClient, NullLogger<PdfAttachmentClient>.Instance);
        return (client, handler);
    }

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

    private static byte[] FakePdfBytes() => "fake-pdf-content"u8.ToArray();

    /// <summary>Builds a minimal valid ZIP containing the given entries.</summary>
    private static byte[] BuildZip(Dictionary<string, string> entries)
    {
        using var ms = new MemoryStream();
        using (var archive = new ZipArchive(ms, ZipArchiveMode.Create, leaveOpen: true))
        {
            foreach (var (name, content) in entries)
            {
                var entry = archive.CreateEntry(name);
                using var writer = new StreamWriter(entry.Open());
                writer.Write(content);
            }
        }
        return ms.ToArray();
    }

    // ?? CheckAttachmentsAsync (Stream) ???????????????????????????????????????

    [Fact]
    public async Task CheckAttachmentsAsync_Stream_SendsMultipartPost()
    {
        // Arrange
        var expected = new AttachmentCheckResult
        {
            HasAttachments = true,
            AttachmentCount = 1,
            Attachments = new List<AttachmentDto>
            {
                new() { FileName = "factur-x.xml", MimeType = "application/xml", Size = 512 }
            }
        };
        var (client, handler) = BuildJson(expected);

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

        // Assert
        result.HasAttachments.Should().BeTrue();
        result.AttachmentCount.Should().Be(1);
        result.Attachments[0].FileName.Should().Be("factur-x.xml");
        handler.LastRequest!.RequestUri!.PathAndQuery.Should().Be("/api/pdf/attachments/check");
        handler.LastRequest.Content.Should().BeOfType<MultipartFormDataContent>();
    }

    [Fact]
    public async Task CheckAttachmentsAsync_Stream_PdfWithNoAttachments_ReturnsFalse()
    {
        // Arrange
        var expected = new AttachmentCheckResult { HasAttachments = false, AttachmentCount = 0, Attachments = [] };
        var (client, _) = BuildJson(expected);

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

        // Assert
        result.HasAttachments.Should().BeFalse();
        result.AttachmentCount.Should().Be(0);
        result.Attachments.Should().BeEmpty();
    }

    // ?? CheckAttachmentsAsync (byte[]) ???????????????????????????????????????

    [Fact]
    public async Task CheckAttachmentsAsync_Bytes_SendsJsonWithBase64()
    {
        // Arrange
        var expected = new AttachmentCheckResult { HasAttachments = false };
        var (client, handler) = BuildJson(expected);

        // Act
        await client.CheckAttachmentsAsync(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();
    }

    // ?? ExtractAttachmentsAsync (Stream) <20> ZIP unzip ?????????????????????????

    [Fact]
    public async Task ExtractAttachmentsAsync_Stream_UnzipsAndReturnsDictionary()
    {
        // Arrange
        var zipBytes = BuildZip(new Dictionary<string, string>
        {
            ["factur-x.xml"] = "<invoice>test</invoice>",
            ["readme.txt"]   = "Hello World"
        });
        var (client, handler) = BuildBytes(zipBytes);

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

        // Assert
        result.Should().HaveCount(2);
        result.Should().ContainKey("factur-x.xml");
        result.Should().ContainKey("readme.txt");

        using var xmlStream = result["factur-x.xml"];
        var xmlContent = await new StreamReader(xmlStream).ReadToEndAsync();
        xmlContent.Should().Be("<invoice>test</invoice>");

        handler.LastRequest!.RequestUri!.PathAndQuery.Should().Be("/api/pdf/attachments/extract");

        // Cleanup
        foreach (var s in result.Values) s.Dispose();
    }

    [Fact]
    public async Task ExtractAttachmentsAsync_Stream_WithSingleEntry_ReturnsOneItem()
    {
        // Arrange
        var zipBytes = BuildZip(new Dictionary<string, string>
        {
            ["data.xml"] = "<root/>"
        });
        var (client, _) = BuildBytes(zipBytes);

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

        // Assert
        result.Should().HaveCount(1);
        result.Should().ContainKey("data.xml");

        foreach (var s in result.Values) s.Dispose();
    }

    // ?? ExtractAttachmentsAsync (byte[]) <20> ZIP unzip ?????????????????????????

    [Fact]
    public async Task ExtractAttachmentsAsync_Bytes_SendsJsonAndUnzips()
    {
        // Arrange
        var zipBytes = BuildZip(new Dictionary<string, string>
        {
            ["invoice.xml"] = "<invoice/>"
        });
        var (client, handler) = BuildBytes(zipBytes);

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

        // Assert
        result.Should().ContainKey("invoice.xml");
        handler.LastRequest!.Content.Should().NotBeNull();
        handler.LastRequest.Content!.Headers.ContentType!.MediaType.Should().Be("application/json");

        foreach (var s in result.Values) s.Dispose();
    }

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

    [Fact]
    public async Task CheckAttachmentsAsync_WhenApiReturns404_ThrowsHttpRequestException()
    {
        // Arrange
        var handler = MockHttpMessageHandler.ReturningStatus(HttpStatusCode.NotFound);
        var httpClient = new HttpClient(handler) { BaseAddress = new Uri("http://localhost") };
        var client = new PdfAttachmentClient(httpClient, NullLogger<PdfAttachmentClient>.Instance);

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

    [Fact]
    public async Task ExtractAttachmentsAsync_WhenApiReturns500_ThrowsHttpRequestException()
    {
        // Arrange
        var handler = MockHttpMessageHandler.ReturningStatus(HttpStatusCode.InternalServerError);
        var httpClient = new HttpClient(handler) { BaseAddress = new Uri("http://localhost") };
        var client = new PdfAttachmentClient(httpClient, NullLogger<PdfAttachmentClient>.Instance);

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