using System.Text.Json;
using System.Text.Json.Serialization;

namespace NATS.Server.JetStream.Models;

// Go: server/stream.go — counterMsgPayload struct { Value string `json:"val"` }
// Reference: golang/nats-server/server/stream.go:20759
public sealed class CounterValue
{
    [JsonPropertyName("val")]
    public string Value { get; set; } = "0";

    public long AsLong() => long.TryParse(Value, out var v) ? v : 0;

    public static CounterValue FromLong(long value) => new() { Value = value.ToString() };

    public byte[] ToPayload() => JsonSerializer.SerializeToUtf8Bytes(this);

    public static CounterValue FromPayload(ReadOnlySpan<byte> payload)
    {
        if (payload.IsEmpty)
            return new CounterValue();

        try
        {
            return JsonSerializer.Deserialize<CounterValue>(payload) ?? new CounterValue();
        }
        catch (JsonException)
        {
            return new CounterValue();
        }
    }
}

// Go: NATS header constants for counter messages.
// Reference: golang/nats-server/server/stream.go — counter header constants.
public static class CounterHeaders
{
    public const string NatsIncr = "Nats-Incr";
    public const string NatsCounterSources = "Nats-Counter-Sources";
    public const string NatsStreamSource = "Nats-Stream-Source";
}