DocumentService/DocumentOperator.Tests/Unit/Client/PdfValidationClientTests.cs

using DocumentService.Client.Clients;
using DocumentService.Client.Interfaces;
using DocumentService.Client.Models.Requests;
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="PdfValidationClient"/>.
/// All tests use a fake <see cref="MockHttpMessageHandler"/> — no real HTTP calls are made.
/// </summary>
public class PdfValidationClientTests
{
    // ?? helpers ?????????????????????????????????????????????????????????????

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

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

    // ?? ValidatePdfAsync (Stream) ????????????????????????????????????????????

    [Fact]
    public async Task ValidatePdfAsync_Stream_SendsMultipartPost()
    {
        // Arrange
        var expected = new PdfValidationResult { PageCount = 3, PdfVersion = "1.7", FileSizeBytes = 2048 };
        var (client, handler) = Build(expected);

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

        // Assert
        result.PageCount.Should().Be(3);
        result.PdfVersion.Should().Be("1.7");
        handler.LastRequest!.Method.Should().Be(HttpMethod.Post);
        handler.LastRequest.RequestUri!.PathAndQuery.Should().Be("/api/pdf/validation/validate");
        handler.LastRequest.Content.Should().BeOfType<MultipartFormDataContent>();
    }

    [Fact]
    public async Task ValidatePdfAsync_Stream_ThrowsWhenApiReturnsNull()
    {
        // Arrange — API returns JSON null
        var handler = MockHttpMessageHandler.ReturningJson<PdfValidationResult?>(null);
        var httpClient = new HttpClient(handler) { BaseAddress = new Uri("http://localhost") };
        var client = new PdfValidationClient(httpClient, NullLogger<PdfValidationClient>.Instance);

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

    // ?? ValidatePdfAsync (byte[]) ????????????????????????????????????????????

    [Fact]
    public async Task ValidatePdfAsync_Bytes_SendsJsonWithBase64()
    {
        // Arrange
        var expected = new PdfValidationResult { PageCount = 1, IsEncrypted = false };
        var (client, handler) = Build(expected);

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

        // Assert
        result.PageCount.Should().Be(1);
        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();
    }

    // ?? ValidatePdfAAsync (Stream) ???????????????????????????????????????????

    [Fact]
    public async Task ValidatePdfAAsync_Stream_SendsMultipartPost()
    {
        // Arrange
        var expected = new PdfAValidationResult { IsValid = true, PdfAVersion = "PDF/A-3b", PageCount = 2 };
        var (client, handler) = Build(expected);

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

        // Assert
        result.IsValid.Should().BeTrue();
        result.PdfAVersion.Should().Be("PDF/A-3b");
        handler.LastRequest!.RequestUri!.PathAndQuery.Should().Be("/api/pdf/validation/validate-pdfa");
        handler.LastRequest.Content.Should().BeOfType<MultipartFormDataContent>();
    }

    [Fact]
    public async Task ValidatePdfAAsync_Stream_WithErrors_ReturnsErrors()
    {
        // Arrange
        var expected = new PdfAValidationResult
        {
            IsValid = false,
            Errors = new List<string> { "Missing embedded font", "Encryption not allowed" }
        };
        var (client, _) = Build(expected);

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

        // Assert
        result.IsValid.Should().BeFalse();
        result.Errors.Should().HaveCount(2).And.Contain("Missing embedded font");
    }

    // ?? ValidatePdfAAsync (byte[]) ???????????????????????????????????????????

    [Fact]
    public async Task ValidatePdfAAsync_Bytes_SendsJson()
    {
        // Arrange
        var expected = new PdfAValidationResult { IsValid = true };
        var (client, handler) = Build(expected);

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

        // Assert
        handler.LastRequest!.RequestUri!.PathAndQuery.Should().Be("/api/pdf/validation/validate-pdfa");
        handler.LastRequest.Content.Should().NotBeNull();
        handler.LastRequest.Content!.Headers.ContentType!.MediaType.Should().Be("application/json");
    }

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

    [Fact]
    public async Task ValidatePdfAsync_WhenApiReturns400_ThrowsHttpRequestException()
    {
        // Arrange
        var handler = MockHttpMessageHandler.ReturningStatus(HttpStatusCode.BadRequest);
        var httpClient = new HttpClient(handler) { BaseAddress = new Uri("http://localhost") };
        var client = new PdfValidationClient(httpClient, NullLogger<PdfValidationClient>.Instance);

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

    [Fact]
    public async Task ValidatePdfAsync_WhenApiReturns500_ThrowsHttpRequestException()
    {
        // Arrange
        var handler = MockHttpMessageHandler.ReturningStatus(HttpStatusCode.InternalServerError);
        var httpClient = new HttpClient(handler) { BaseAddress = new Uri("http://localhost") };
        var client = new PdfValidationClient(httpClient, NullLogger<PdfValidationClient>.Instance);

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