Beam/Beam.Dynamic/Binding.cs

using aeqw89.DataKeys;
using HtmlAgilityPack;
using System.Text.Json.Serialization;

namespace Beam.Dynamic {
    public class Binding(DataKey<Binding> key) : IKeyed<Binding> {
        public Binding(string key) : this(new DataKey<Binding>(key)) { }
        public Binding() : this("") { }

        [JsonRequired]
        public DataKey<Binding> Key { get; set; } = key;
        [JsonRequired]
        public BindingType Type { get; set; }

        public string? ArrayDelimiters { get; set; }
        public string? XPath { get; set; }
        public string? CssPath { get; set; }
        public string? Text { get; set; }
        private IDataProvider? Provider_;
        public IDataProvider? Provider {
            get => Provider_;
            set {
                if (value is null)
                    return;
                if (value is not IDataProvider)
                    throw new InvalidOperationException();
                var constructor = value.GetType().GetConstructor([]);
                if (!constructor?.IsPublic ?? true)
                    throw new InvalidOperationException();
                Provider_ = value;
            }
        }

        public HtmlNode? ResolveNode(HtmlDocument doc) {
            if (XPath is not null)
                return doc.DocumentNode.SelectSingleNode(XPath);
            if (CssPath is not null)
                return doc.DocumentNode.ThenByClasses(CssPath.Split('/'));
            if (Provider is not null)
                return Provider.GetNode(doc);
            return null;
        }

        public string ResolveString(HtmlDocument doc) {
            if (XPath is not null)
                return doc.DocumentNode.SelectSingleNode(XPath)?.InnerText ?? "";
            if (CssPath is not null)
                return doc.DocumentNode.ThenByClasses(CssPath.Split('/'))?.InnerText ?? "";
            if (Provider is not null)
                return Provider.Get(doc);
            return "";
        }

        public string[] ResolveArray(HtmlDocument doc) {
            if (Type is not BindingType.Array)
                return [];
            var str = ResolveString(doc);
            return str.Split(ArrayDelimiters);
        }

        public dynamic? Resolve(HtmlDocument doc) => Type switch {
            BindingType.Single => ResolveString(doc),
            BindingType.Array => ResolveArray(doc),
            BindingType.UseProvider => Provider?.Get(doc),
            _ => null
        };
    }
}