using System.Text.Json;

namespace Zcbot.WindowsNode;

internal sealed record NodeProtocolMessage(string Type, JsonElement Payload);

internal static class NodeProtocolCodec
{
    internal static byte[] Encode(string type, object payload) =>
        JsonSerializer.SerializeToUtf8Bytes(new
        {
            protocol_version = 1,
            message_id = Guid.NewGuid(),
            type,
            sent_at = DateTimeOffset.UtcNow,
            payload,
        });

    internal static NodeProtocolMessage? Decode(byte[] message)
    {
        using var document = JsonDocument.Parse(message);
        if (!document.RootElement.TryGetProperty("type", out var typeValue)
            || typeValue.ValueKind != JsonValueKind.String
            || typeValue.GetString() is not string type)
        {
            return null;
        }

        var payload = document.RootElement.TryGetProperty("payload", out var payloadValue)
            ? payloadValue.Clone()
            : default;
        return new NodeProtocolMessage(type, payload);
    }
}