MarkdownRenderer.cs

namespace Docx.Renderer.Markdown;

public class MarkdownRenderer : IMarkdownRenderer
{
    private readonly DocxMarkdownFormatting options;
    private readonly List<IMarkdownObjectRenderer> renderers;

    public MarkdownRenderer(DocxMarkdownFormatting options)
    {
        this.options = options;
        renderers = new List<IMarkdownObjectRenderer>
        {
            new Renderers.ParagraphRenderer(),
            new Renderers.TableRenderer(),
            new Renderers.RunRenderer(),
            new Renderers.IgnoredBlocks()
        };
    }

    public string MarkdownFolder { get; private set; }
    public string MediaFolder { get; private set; }
    public string ConvertAbsoluteUrl(string url) => options?.ConvertAbsoluteUrls(url) ?? url;
    public bool PreferPlainMarkdown => options.PreferPlainMarkdown;

    public void Convert(string docxFile, string markdownFile, string mediaFolder)
    {
        if (string.IsNullOrEmpty(docxFile))
            throw new ArgumentException("Value cannot be null or empty.", nameof(docxFile));
        if (!File.Exists(docxFile))
            throw new ArgumentException($"{docxFile} does not exist.", nameof(docxFile));
        if (string.IsNullOrEmpty(markdownFile))
            throw new ArgumentException("Value cannot be null or empty.", nameof(markdownFile));
        if (Path.GetInvalidPathChars().Any(markdownFile.Contains))
            throw new ArgumentException($"{markdownFile} is an invalid filename.", nameof(markdownFile));
        if (string.IsNullOrEmpty(mediaFolder))
            throw new ArgumentException("Value cannot be null or empty.", nameof(mediaFolder));

        MarkdownFolder = Path.GetDirectoryName(markdownFile) ?? "";
        MediaFolder = mediaFolder;

        if (File.Exists(markdownFile))
            File.Delete(markdownFile);

        using var wordDocument = Document.Load(docxFile);
        var markdownDocument = new MarkdownDocument();

        var renderer = this as IMarkdownRenderer;
        renderer.WriteContainer(markdownDocument, null, wordDocument.Blocks, null);

        using var writer = new StreamWriter(markdownFile);
        markdownDocument.Write(writer, options);
    }

    public IMarkdownObjectRenderer FindRenderer(object element)
        => renderers.FirstOrDefault(r => r.CanRender(element));

    public void WriteContainer(MarkdownDocument document, MarkdownBlock blockOwner, IEnumerable<object> container, RenderBag tags)
    {
        foreach (var block in container)
        {
            WriteElement(document, blockOwner, block, tags);
        }
    }

    public void WriteElement(MarkdownDocument document, MarkdownBlock blockOwner, 
        object element, RenderBag tags)
    {
        var renderer = FindRenderer(element);
        if (renderer != null) 
            renderer.Render(this, document, blockOwner, element, tags);
        else
        {
            if (element is UnknownBlock ub)
                Console.Error.WriteLine($"Missing renderer for unknown block type: {ub.Name}");
            else
                Console.Error.WriteLine($"Missing renderer for {element.GetType().Name}");
        }
    }
}