using System.Text;
using RabbitMQ.Client;
using StellaOps.Router.Common.Enums;
using StellaOps.Router.Common.Models;

namespace StellaOps.Router.Transport.RabbitMq;

/// <summary>
/// Handles serialization and deserialization of frames for RabbitMQ transport.
/// </summary>
public static class RabbitMqFrameProtocol
{
    /// <summary>
    /// Parses a frame from a RabbitMQ message.
    /// </summary>
    /// <param name="body">The message body.</param>
    /// <param name="properties">The message properties.</param>
    /// <returns>The parsed frame.</returns>
    public static Frame ParseFrame(ReadOnlyMemory<byte> body, IReadOnlyBasicProperties properties)
    {
        var frameType = ParseFrameType(properties.Type);
        var correlationId = properties.CorrelationId;

        return new Frame
        {
            Type = frameType,
            CorrelationId = correlationId,
            Payload = body
        };
    }

    /// <summary>
    /// Creates BasicProperties for a frame.
    /// </summary>
    /// <param name="frame">The frame to serialize.</param>
    /// <param name="replyTo">The reply queue name.</param>
    /// <param name="timeout">Optional timeout for the message.</param>
    /// <returns>The basic properties.</returns>
    public static BasicProperties CreateProperties(Frame frame, string? replyTo, TimeSpan? timeout = null)
    {
        var props = new BasicProperties
        {
            Type = frame.Type.ToString(),
            Timestamp = new AmqpTimestamp(DateTimeOffset.UtcNow.ToUnixTimeSeconds()),
            DeliveryMode = DeliveryModes.Transient // Non-persistent (1)
        };

        if (!string.IsNullOrEmpty(frame.CorrelationId))
        {
            props.CorrelationId = frame.CorrelationId;
        }

        if (!string.IsNullOrEmpty(replyTo))
        {
            props.ReplyTo = replyTo;
        }

        if (timeout.HasValue)
        {
            props.Expiration = ((int)timeout.Value.TotalMilliseconds).ToString();
        }

        return props;
    }

    /// <summary>
    /// Parses a FrameType from the message Type property.
    /// </summary>
    private static FrameType ParseFrameType(string? type)
    {
        if (string.IsNullOrEmpty(type))
        {
            return FrameType.Request;
        }

        if (Enum.TryParse<FrameType>(type, ignoreCase: true, out var result))
        {
            return result;
        }

        return FrameType.Request;
    }

    /// <summary>
    /// Extracts the connection ID from message properties.
    /// </summary>
    /// <param name="properties">The message properties.</param>
    /// <returns>The connection ID.</returns>
    public static string ExtractConnectionId(IReadOnlyBasicProperties properties)
    {
        // Use ReplyTo as the basis for connection ID (identifies the instance)
        if (!string.IsNullOrEmpty(properties.ReplyTo))
        {
            // Extract instance ID from queue name like "stella.svc.{instanceId}"
            var parts = properties.ReplyTo.Split('.');
            if (parts.Length >= 3)
            {
                return $"rmq-{parts[^1]}";
            }
            return $"rmq-{properties.ReplyTo}";
        }

        // Fallback to correlation ID
        if (!string.IsNullOrEmpty(properties.CorrelationId))
        {
            return $"rmq-{properties.CorrelationId[..Math.Min(16, properties.CorrelationId.Length)]}";
        }

        return $"rmq-{Guid.NewGuid():N}"[..32];
    }
}