using Newtonsoft.Json.Linq;
using VDS.RDF.JsonLd;

namespace Iceshrimp.Backend.Core.Federation.ActivityStreams;

public static class LdHelpers {
	private static readonly Dictionary<string, RemoteDocument> ContextCache = new() {
		{
			"https://www.w3.org/ns/activitystreams", new RemoteDocument {
				ContextUrl  = new Uri("https://www.w3.org/ns/activitystreams"),
				DocumentUrl = new Uri("https://www.w3.org/ns/activitystreams"),
				Document = JToken.Parse(File.ReadAllText(Path.Combine("Core", "Federation", "ActivityStreams",
				                                                      "Contexts", "as.json")))
			}
		}, {
			"https://w3id.org/security/v1", new RemoteDocument {
				ContextUrl  = new Uri("https://w3id.org/security/v1"),
				DocumentUrl = new Uri("https://w3c-ccg.github.io/security-vocab/contexts/security-v1.jsonld"),
				Document = JToken.Parse(File.ReadAllText(Path.Combine("Core", "Federation", "ActivityStreams",
				                                                      "Contexts", "security.json")))
			}
		}
	};

	private static readonly JToken DefaultContext =
		JToken.Parse(File.ReadAllText(Path.Combine("Core", "Federation", "ActivityStreams", "Contexts",
		                                           "default.json")));

	// Nonstandard extensions to the AS context need to be loaded in to fix federation with certain AP implementations
	private static readonly JToken ASExtensions =
		JToken.Parse(File.ReadAllText(Path.Combine("Core", "Federation", "ActivityStreams", "Contexts",
		                                           "as-extensions.json")));

	private static readonly JsonLdProcessorOptions Options = new() {
		DocumentLoader = CustomLoader, ExpandContext = ASExtensions
	};

	private static RemoteDocument CustomLoader(Uri uri, JsonLdLoaderOptions jsonLdLoaderOptions) {
		//TODO: cache in redis
		ContextCache.TryGetValue(uri.ToString(), out var result);
		if (result != null) return result;
		result = DefaultDocumentLoader.LoadJson(uri, jsonLdLoaderOptions);
		ContextCache.Add(uri.ToString(), result);

		return result;
	}

	public static JObject? Compact(object       obj)  => Compact(JToken.FromObject(obj));
	public static JArray?  Expand(object        obj)  => Expand(JToken.FromObject(obj));
	public static JObject? Compact(JToken?      json) => JsonLdProcessor.Compact(json, DefaultContext, Options);
	public static JArray?  Expand(JToken?       json) => JsonLdProcessor.Expand(json, Options);
	public static string   Canonicalize(JArray  json) => JsonLdProcessor.Canonicalize(json);
	public static string   Canonicalize(JObject json) => JsonLdProcessor.Canonicalize([json]);
}