using MxGateway.Contracts.Proto;

namespace MxGateway.Client;

/// <summary>
/// Represents one gateway-backed MXAccess session.
/// </summary>
public sealed class MxGatewaySession : IAsyncDisposable
{
    private readonly MxGatewayClient _client;
    private readonly SemaphoreSlim _closeLock = new(1, 1);
    private CloseSessionReply? _closeReply;

    internal MxGatewaySession(
        MxGatewayClient client,
        OpenSessionReply openSessionReply)
    {
        _client = client ?? throw new ArgumentNullException(nameof(client));
        OpenSessionReply = openSessionReply ?? throw new ArgumentNullException(nameof(openSessionReply));
    }

    public string SessionId => OpenSessionReply.SessionId;

    public OpenSessionReply OpenSessionReply { get; }

    public async Task<CloseSessionReply> CloseAsync(CancellationToken cancellationToken = default)
    {
        if (_closeReply is not null)
        {
            return _closeReply;
        }

        await _closeLock.WaitAsync(cancellationToken).ConfigureAwait(false);
        try
        {
            if (_closeReply is not null)
            {
                return _closeReply;
            }

            _closeReply = await _client.CloseSessionRawAsync(
                    new CloseSessionRequest { SessionId = SessionId },
                    cancellationToken)
                .ConfigureAwait(false);
            return _closeReply;
        }
        finally
        {
            _closeLock.Release();
        }
    }

    public async Task<int> RegisterAsync(
        string clientName,
        CancellationToken cancellationToken = default)
    {
        MxCommandReply reply = await RegisterRawAsync(clientName, cancellationToken)
            .ConfigureAwait(false);
        reply.EnsureProtocolSuccess().EnsureMxAccessSuccess();
        return reply.Register?.ServerHandle ?? reply.ReturnValue.Int32Value;
    }

    public Task<MxCommandReply> RegisterRawAsync(
        string clientName,
        CancellationToken cancellationToken = default)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(clientName);

        return InvokeCommandAsync(
            new MxCommand
            {
                Kind = MxCommandKind.Register,
                Register = new RegisterCommand { ClientName = clientName },
            },
            cancellationToken);
    }

    public async Task<int> AddItemAsync(
        int serverHandle,
        string itemDefinition,
        CancellationToken cancellationToken = default)
    {
        MxCommandReply reply = await AddItemRawAsync(
                serverHandle,
                itemDefinition,
                cancellationToken)
            .ConfigureAwait(false);
        reply.EnsureProtocolSuccess().EnsureMxAccessSuccess();
        return reply.AddItem?.ItemHandle ?? reply.ReturnValue.Int32Value;
    }

    public Task<MxCommandReply> AddItemRawAsync(
        int serverHandle,
        string itemDefinition,
        CancellationToken cancellationToken = default)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(itemDefinition);

        return InvokeCommandAsync(
            new MxCommand
            {
                Kind = MxCommandKind.AddItem,
                AddItem = new AddItemCommand
                {
                    ServerHandle = serverHandle,
                    ItemDefinition = itemDefinition,
                },
            },
            cancellationToken);
    }

    public async Task<int> AddItem2Async(
        int serverHandle,
        string itemDefinition,
        string itemContext,
        CancellationToken cancellationToken = default)
    {
        MxCommandReply reply = await AddItem2RawAsync(
                serverHandle,
                itemDefinition,
                itemContext,
                cancellationToken)
            .ConfigureAwait(false);
        reply.EnsureProtocolSuccess().EnsureMxAccessSuccess();
        return reply.AddItem2?.ItemHandle ?? reply.ReturnValue.Int32Value;
    }

    public Task<MxCommandReply> AddItem2RawAsync(
        int serverHandle,
        string itemDefinition,
        string itemContext,
        CancellationToken cancellationToken = default)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(itemDefinition);

        return InvokeCommandAsync(
            new MxCommand
            {
                Kind = MxCommandKind.AddItem2,
                AddItem2 = new AddItem2Command
                {
                    ServerHandle = serverHandle,
                    ItemDefinition = itemDefinition,
                    ItemContext = itemContext ?? string.Empty,
                },
            },
            cancellationToken);
    }

    public async Task AdviseAsync(
        int serverHandle,
        int itemHandle,
        CancellationToken cancellationToken = default)
    {
        MxCommandReply reply = await AdviseRawAsync(serverHandle, itemHandle, cancellationToken)
            .ConfigureAwait(false);
        reply.EnsureProtocolSuccess().EnsureMxAccessSuccess();
    }

    public Task<MxCommandReply> AdviseRawAsync(
        int serverHandle,
        int itemHandle,
        CancellationToken cancellationToken = default)
    {
        return InvokeCommandAsync(
            new MxCommand
            {
                Kind = MxCommandKind.Advise,
                Advise = new AdviseCommand
                {
                    ServerHandle = serverHandle,
                    ItemHandle = itemHandle,
                },
            },
            cancellationToken);
    }

    public async Task WriteAsync(
        int serverHandle,
        int itemHandle,
        MxValue value,
        int userId,
        CancellationToken cancellationToken = default)
    {
        MxCommandReply reply = await WriteRawAsync(serverHandle, itemHandle, value, userId, cancellationToken)
            .ConfigureAwait(false);
        reply.EnsureProtocolSuccess().EnsureMxAccessSuccess();
    }

    public Task<MxCommandReply> WriteRawAsync(
        int serverHandle,
        int itemHandle,
        MxValue value,
        int userId,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(value);

        return InvokeCommandAsync(
            new MxCommand
            {
                Kind = MxCommandKind.Write,
                Write = new WriteCommand
                {
                    ServerHandle = serverHandle,
                    ItemHandle = itemHandle,
                    Value = value,
                    UserId = userId,
                },
            },
            cancellationToken);
    }

    public async Task Write2Async(
        int serverHandle,
        int itemHandle,
        MxValue value,
        MxValue timestampValue,
        int userId,
        CancellationToken cancellationToken = default)
    {
        MxCommandReply reply = await Write2RawAsync(
                serverHandle,
                itemHandle,
                value,
                timestampValue,
                userId,
                cancellationToken)
            .ConfigureAwait(false);
        reply.EnsureProtocolSuccess().EnsureMxAccessSuccess();
    }

    public Task<MxCommandReply> Write2RawAsync(
        int serverHandle,
        int itemHandle,
        MxValue value,
        MxValue timestampValue,
        int userId,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(value);
        ArgumentNullException.ThrowIfNull(timestampValue);

        return InvokeCommandAsync(
            new MxCommand
            {
                Kind = MxCommandKind.Write2,
                Write2 = new Write2Command
                {
                    ServerHandle = serverHandle,
                    ItemHandle = itemHandle,
                    Value = value,
                    TimestampValue = timestampValue,
                    UserId = userId,
                },
            },
            cancellationToken);
    }

    public Task<MxCommandReply> InvokeAsync(
        MxCommandRequest request,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(request);
        return _client.InvokeAsync(request, cancellationToken);
    }

    public IAsyncEnumerable<MxEvent> StreamEventsAsync(
        ulong afterWorkerSequence = 0,
        CancellationToken cancellationToken = default)
    {
        return _client.StreamEventsAsync(
            new StreamEventsRequest
            {
                SessionId = SessionId,
                AfterWorkerSequence = afterWorkerSequence,
            },
            cancellationToken);
    }

    public async ValueTask DisposeAsync()
    {
        await CloseAsync().ConfigureAwait(false);
        _closeLock.Dispose();
    }

    private Task<MxCommandReply> InvokeCommandAsync(
        MxCommand command,
        CancellationToken cancellationToken)
    {
        return _client.InvokeAsync(
            new MxCommandRequest
            {
                SessionId = SessionId,
                ClientCorrelationId = Guid.NewGuid().ToString("N"),
                Command = command,
            },
            cancellationToken);
    }
}