Beam/Beam.Dynamic/DataProviders/DropDownDataProvider.cs

using HtmlAgilityPack;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.Marshalling;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;
using Beam.Abstractions;

namespace Beam.Dynamic;

public class DropDownDataProvider : IComposableDataProvider<string>, IComposableDataProvider<string[]> {
    public IBinding? Content { get; set; }
    public Uri? RelativeTo { get; set; }

    public string[] Get(HtmlDocument document) {
        if (Content is null)
            return [];
        var node = Select(document);
        if (node is null)
            return [];
        return Get(node);
    }

    string IDataProvider<string>.Get(HtmlDocument document) {
        var node = Select(document);
        return node is null ? "" : (this as IComposableDataProvider<string>).Get(node);
    }

    public string[] Get(HtmlNode node) {
        List<string> links = [];
        foreach (var child in node.ChildNodes.Where(x => x.Name == "option")) {
            var childValue = child.GetAttributeValue("value", null);
            if (!Uri.TryCreate(RelativeTo, childValue, out var uri))
                continue;
            links.Add(uri.AbsoluteUri);
        }

        return links.ToArray();
    }

    string IComposableDataProvider<string>.Get(HtmlNode node) {
        return JsonSerializer.Serialize(Get(node));
    }
    
    public HtmlNode? Select(HtmlDocument doc) {
        return Content?.Select(doc);
    }

    HtmlNode? IComposableDataProvider<string[]>.Select(HtmlNode node) {
        return node;
    }

    HtmlNode? IComposableDataProvider<string>.Select(HtmlNode node) {
        return node;
    }
}