PageManager/PageManager.Api/PageManager.Api.Tests/Unit/Services/MetadataWriterServiceTests.cs

using FluentAssertions;
using PageManager.Api.Services;
using PageManager.Api.Tests.Helpers;

namespace PageManager.Api.Tests.Unit.Services;

public class MetadataWriterServiceTests
{
    // ── ParseOpfPath ──────────────────────────────────────────────────────────

    [Fact]
    public void ParseOpfPath_ReturnsFullPath()
    {
        var xml = """
            <?xml version="1.0" encoding="UTF-8"?>
            <container version="1.0" xmlns="urn:oasis:names:tc:opendocument:xmlns:container">
              <rootfiles>
                <rootfile full-path="OEBPS/content.opf" media-type="application/oebps-package+xml"/>
              </rootfiles>
            </container>
            """;

        MetadataWriterService.ParseOpfPath(xml).Should().Be("OEBPS/content.opf");
    }

    // ── ModifyOpfXml ──────────────────────────────────────────────────────────

    private const string MinimalOpf = """
        <?xml version="1.0" encoding="utf-8"?>
        <package xmlns="http://www.idpf.org/2007/opf" version="2.0" unique-identifier="uid">
          <metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:opf="http://www.idpf.org/2007/opf">
            <dc:title>Old Title</dc:title>
            <dc:creator>Old Author</dc:creator>
            <dc:language>en</dc:language>
          </metadata>
          <manifest/>
          <spine/>
        </package>
        """;

    [Fact]
    public void ModifyOpfXml_UpdatesTitle()
    {
        var book   = BookFactory.Create(title: "Dune", year: 1965).WithAuthors((1, "Frank Herbert"));
        var result = MetadataWriterService.ModifyOpfXml(MinimalOpf, book);
        result.Should().Contain("<dc:title>Dune</dc:title>");
    }

    [Fact]
    public void ModifyOpfXml_UpdatesCreator()
    {
        var book   = BookFactory.Create(title: "Dune").WithAuthors((1, "Frank Herbert"));
        var result = MetadataWriterService.ModifyOpfXml(MinimalOpf, book);
        result.Should().Contain("Frank Herbert");
    }

    [Fact]
    public void ModifyOpfXml_AddsDescription_WhenPresent()
    {
        var book   = BookFactory.Create(title: "Dune", description: "A sci-fi epic.").WithAuthors((1, "Frank Herbert"));
        var result = MetadataWriterService.ModifyOpfXml(MinimalOpf, book);
        result.Should().Contain("A sci-fi epic.");
    }

    [Fact]
    public void ModifyOpfXml_SkipsDescription_WhenNull()
    {
        var book   = BookFactory.Create(title: "Dune", description: null).WithAuthors((1, "Frank Herbert"));
        var result = MetadataWriterService.ModifyOpfXml(MinimalOpf, book);
        result.Should().NotContain("dc:description");
    }

    [Fact]
    public void ModifyOpfXml_AddsIsbnIdentifier_WhenPresent()
    {
        var book   = BookFactory.Create(title: "Dune", isbn: "9780441013593").WithAuthors((1, "Frank Herbert"));
        var result = MetadataWriterService.ModifyOpfXml(MinimalOpf, book);
        result.Should().Contain("9780441013593");
        result.Should().Contain("ISBN");
    }

    [Fact]
    public void ModifyOpfXml_AddsDate_WhenYearPresent()
    {
        var book   = BookFactory.Create(title: "Dune", year: 1965).WithAuthors((1, "Frank Herbert"));
        var result = MetadataWriterService.ModifyOpfXml(MinimalOpf, book);
        result.Should().Contain("1965");
    }

    [Fact]
    public void ModifyOpfXml_PreservesExistingXmlStructure()
    {
        var book   = BookFactory.Create(title: "Dune").WithAuthors((1, "Frank Herbert"));
        var result = MetadataWriterService.ModifyOpfXml(MinimalOpf, book);

        // Manifest and spine should still be present
        result.Should().Contain("manifest");
        result.Should().Contain("spine");
        result.Should().Contain("dc:language");
    }

    [Fact]
    public void ModifyOpfXml_WithMultipleAuthors_UsesPrimaryAuthorForCreator()
    {
        var book   = BookFactory.Create(title: "Good Omens")
                                .WithAuthors((1, "Terry Pratchett"), (2, "Neil Gaiman"));
        var result = MetadataWriterService.ModifyOpfXml(MinimalOpf, book);
        result.Should().Contain("Terry Pratchett");
    }

    [Fact]
    public void ModifyOpfXml_WithNoAuthors_DoesNotAddCreator()
    {
        var book   = BookFactory.Create(title: "Anonymous");
        // No authors added
        var result = MetadataWriterService.ModifyOpfXml(MinimalOpf, book);
        // Should not crash and should not add empty creator
        result.Should().NotContain("<dc:creator />");
    }

    [Fact]
    public void ModifyOpfXml_UpdatesExistingIsbnIdentifier_RatherThanAdding()
    {
        var opfWithIsbn = MinimalOpf.Replace(
            "<dc:language>en</dc:language>",
            "<dc:language>en</dc:language>\n    <dc:identifier opf:scheme=\"ISBN\">OLD-ISBN</dc:identifier>");

        var book   = BookFactory.Create(title: "Dune", isbn: "9780441013593").WithAuthors((1, "Frank Herbert"));
        var result = MetadataWriterService.ModifyOpfXml(opfWithIsbn, book);

        result.Should().Contain("9780441013593");
        result.Should().NotContain("OLD-ISBN");
        // Should not have two ISBN identifiers
        result.Split("ISBN").Length.Should().BeLessThanOrEqualTo(3); // "ISBN" appears in scheme + value
    }
}