mfgames-cil/src/MfGames.Nitride.Markdown/ParseMarkdownHeadingOne.cs

89 lines
2.7 KiB
C#

using FluentValidation;
using Markdig.Renderers.Roundtrip;
using Markdig.Syntax;
using MfGames.Gallium;
using MfGames.Nitride.Contents;
using MfGames.Nitride.Generators;
namespace MfGames.Nitride.Markdown;
/// <summary>
/// An operation that parses the Markdown and converts the first heading one
/// into a model to include in the component. The rest of the Markdown is put
/// back as the text content of the entity.
/// </summary>
[WithProperties]
public partial class ParseMarkdownHeadingOne : IOperation
{
private readonly IValidator<ParseMarkdownHeadingOne> validator;
public ParseMarkdownHeadingOne(IValidator<ParseMarkdownHeadingOne> validator)
{
this.validator = validator;
}
/// <summary>
/// Gets or sets a callback for adding a heading to a given entity.
/// </summary>
public Func<Entity, string?, Entity>? AddModelCallback { get; set; }
/// <inheritdoc />
public IEnumerable<Entity> Run(
IEnumerable<Entity> input,
CancellationToken cancellationToken = default
)
{
this.validator.ValidateAndThrow(this);
return input.SelectManyEntity<IsMarkdown>(x => x.Select(this.Parse));
}
private string? GetText(MarkdownObject? block)
{
if (block == null)
return null;
var writer = new StringWriter();
var renderer = new RoundtripRenderer(writer);
renderer.Write(block);
return writer.ToString();
}
private Entity Parse(Entity entity)
{
// Get the text content of the file. No text, we don't do anything (but
// there is going to be text since we filtered on IsMarkdown).
string? oldText = entity.GetTextContentString();
if (oldText == null)
{
return entity;
}
// Parse the result as Markdown and pull out the heading. If we can't
// find one, then we just return the entity. We need to track trivia
// because we are round-tripping back to Markdown.
MarkdownDocument document = Markdig.Markdown.Parse(oldText, true);
Block? block = document.FirstOrDefault(block => block is HeadingBlock);
if (block is not HeadingBlock { Level: 1 } heading)
{
return entity;
}
string? headingText = this.GetText(heading.Inline);
// Convert the heading into the model.
// Pull out the heading so we can write the rest back.
document.Remove(heading);
string newText = this.GetText(document)!;
// Allow the extending class to add the model to the entity and then
// set the text content to the new value before returning the results.
return this.AddModelCallback!.Invoke(entity, headingText).SetTextContent(newText);
}
}