using PrivaPub.Infrastructure.Statistics;

using System.Text.Json.Nodes;

using static PrivaPub.Federation.Objects.ActivityJson;

namespace PrivaPub.Federation.Objects
{
	public sealed record ActivityShape(string Type, string ObjectType, string Audience)
	{
		public static ActivityShape Of(JsonNode activity)
		{
			var embedded = activity?["object"] as JsonObject;
			return new ActivityShape(Value(activity, "type"), Value(embedded, "type"), AudienceOf(activity));
		}

		public static ActivityShape Of(string json)
		{
			try
			{
				return Of(JsonNode.Parse(json));
			}
			catch (System.Text.Json.JsonException)
			{
				return new ActivityShape(default, default, default);
			}
		}

		static string AudienceOf(JsonNode activity)
		{
			var source = activity?["to"] != default || activity?["cc"] != default ? activity : activity?["object"] as JsonObject;
			var to = Addresses(source?["to"]);
			var cc = Addresses(source?["cc"]);
			if (to.Any(Addressing.IsPublic))
				return Interactions.Public;
			if (cc.Any(Addressing.IsPublic))
				return Interactions.Unlisted;
			return to.Count + cc.Count == 0 ? Interactions.None : Interactions.Private;
		}

		static List<string> Addresses(JsonNode node) => node switch
		{
			JsonArray array => array.Select(Id).Where(id => id != default).ToList(),
			JsonNode single when Id(single) is { } id => new List<string> { id },
			_ => new List<string>()
		};
	}
}