Beam/Beam.Dynamic/AnchorCollectionDataProvider.cs

using HtmlAgilityPack;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Beam.Dynamic {
    public class AnchorCollectionDataProvider : IDataProvider<string[]>, IDataProvider<SourceLink[]> {
        public IBinding? Content { get; set; }
        public string? RelativeTo { get; set; }

        private string GetAbsolute(string? @base, string relative) {
            if (@base is null)
                return relative;

            if (@base.EndsWith('/'))
                @base = @base[..^1];
            if (relative.StartsWith('/'))
                relative = relative[1..];
            return @base + '/' + relative;
        }

        public string[] Get(HtmlDocument document) {
            if (Content is null)
                return [];

            var node = Content.Select(document);
            if (node is null)
                return [];

            List<string> links = [];
            foreach (var child in node.Descendants())
                links.Add(child.GetAttributeValue("href", ""));

            return links.Where(x => !string.IsNullOrWhiteSpace(x)).ToArray();
        }

        SourceLink[] IDataProvider<SourceLink[]>.Get(HtmlDocument document) {
            var links = Get(document);

            if (links.Length == 0)
                return [];

            List<SourceLink> slinks = [];
            foreach (var link in links)
                if (Uri.TryCreate(GetAbsolute(RelativeTo, link), UriKind.RelativeOrAbsolute, out _))
                    slinks.Add(new SourceLink(GetAbsolute(RelativeTo, link)));

            return slinks.ToArray();
        }
    }
}