using MessagePack;

namespace ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Shared.Contracts;

/// <summary>
///     First frame of every FOCAS Proxy -> Host connection. Advertises protocol major/minor
///     and the per-process shared secret the Proxy passed to the Host at spawn time. Major
///     mismatch is fatal; minor is advisory.
/// </summary>
[MessagePackObject]
public sealed class Hello
{
    public const int CurrentMajor = 1;
    public const int CurrentMinor = 0;

    [Key(0)] public int ProtocolMajor { get; set; } = CurrentMajor;
    [Key(1)] public int ProtocolMinor { get; set; } = CurrentMinor;
    [Key(2)] public string PeerName { get; set; } = string.Empty;

    /// <summary>
    ///     Per-process shared secret verified on the Host side against the value passed by the
    ///     supervisor at spawn time. Protects against a local attacker connecting to the pipe
    ///     after authenticating via the pipe ACL.
    /// </summary>
    [Key(3)] public string SharedSecret { get; set; } = string.Empty;

    [Key(4)] public string[] Features { get; set; } = System.Array.Empty<string>();
}

[MessagePackObject]
public sealed class HelloAck
{
    [Key(0)] public int ProtocolMajor { get; set; } = Hello.CurrentMajor;
    [Key(1)] public int ProtocolMinor { get; set; } = Hello.CurrentMinor;

    /// <summary>True if the Host accepted the hello; false + <see cref="RejectReason"/> filled if not.</summary>
    [Key(2)] public bool Accepted { get; set; }
    [Key(3)] public string? RejectReason { get; set; }

    [Key(4)] public string HostName { get; set; } = string.Empty;
}

[MessagePackObject]
public sealed class Heartbeat
{
    [Key(0)] public long MonotonicTicks { get; set; }
}

[MessagePackObject]
public sealed class HeartbeatAck
{
    [Key(0)] public long MonotonicTicks { get; set; }
    [Key(1)] public long HostUtcUnixMs { get; set; }
}

[MessagePackObject]
public sealed class ErrorResponse
{
    /// <summary>Stable symbolic code — e.g. <c>InvalidAddress</c>, <c>SessionNotFound</c>, <c>Fwlib32Crashed</c>.</summary>
    [Key(0)] public string Code { get; set; } = string.Empty;

    [Key(1)] public string Message { get; set; } = string.Empty;
}