using System.Text.Json.Nodes;

namespace PrivaPub.Federation.Objects
{
	public static class ActivityJson
	{
		public static string Id(JsonNode node) => node switch
		{
			JsonValue value when value.TryGetValue<string>(out var text) => text,
			JsonObject obj => Value(obj, "id") ?? Value(obj, "href"),
			JsonArray array => array.Select(Id).FirstOrDefault(i => i != default),
			_ => default
		};

		public static string Value(JsonNode node, string property) =>
			node is JsonObject obj && obj[property] is JsonValue value && value.TryGetValue<string>(out var text) ? text : default;

		public static IEnumerable<string> Addresses(JsonNode node)
		{
			foreach (var field in new[] { "to", "cc", "bto", "bcc", "audience" })
			{
				switch (node[field])
				{
					case JsonArray array:
						foreach (var item in array)
						{
							var id = Id(item);
							if (id != default)
								yield return id;
						}
						break;
					case JsonNode single when Id(single) is { } id:
						yield return id;
						break;
				}
			}
		}
	}
}