ScadaBridge/src/ScadaLink.Commons/Interfaces/Protocol/IDataConnection.cs

using ScadaLink.Commons.Types.Enums;

namespace ScadaLink.Commons.Interfaces.Protocol;

public enum QualityCode { Good, Bad, Uncertain }

public record TagValue(object? Value, QualityCode Quality, DateTimeOffset Timestamp);
public record ReadResult(bool Success, TagValue? Value, string? ErrorMessage);
public record WriteResult(bool Success, string? ErrorMessage);

/// <summary>Callback invoked when a subscribed tag value changes.</summary>
/// <param name="tagPath">The tag path whose value has changed.</param>
/// <param name="value">The new tag value including quality and timestamp.</param>
public delegate void SubscriptionCallback(string tagPath, TagValue value);

public interface IDataConnection : IAsyncDisposable
{
    /// <summary>Establishes the protocol connection using the provided connection details.</summary>
    /// <param name="connectionDetails">Protocol-specific key-value configuration pairs.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    Task ConnectAsync(IDictionary<string, string> connectionDetails, CancellationToken cancellationToken = default);
    /// <summary>Gracefully terminates the protocol connection.</summary>
    /// <param name="cancellationToken">Cancellation token.</param>
    Task DisconnectAsync(CancellationToken cancellationToken = default);
    /// <summary>Subscribes to value-change notifications for a tag path; returns a subscription ID.</summary>
    /// <param name="tagPath">The tag path to subscribe to.</param>
    /// <param name="callback">Callback invoked on each value change.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>A subscription ID that can be passed to <see cref="UnsubscribeAsync"/>.</returns>
    Task<string> SubscribeAsync(string tagPath, SubscriptionCallback callback, CancellationToken cancellationToken = default);
    /// <summary>Cancels an active subscription by its ID.</summary>
    /// <param name="subscriptionId">The subscription ID returned by <see cref="SubscribeAsync"/>.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    Task UnsubscribeAsync(string subscriptionId, CancellationToken cancellationToken = default);
    /// <summary>Reads the current value of a single tag.</summary>
    /// <param name="tagPath">The tag path to read.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>The read result containing the value or an error.</returns>
    Task<ReadResult> ReadAsync(string tagPath, CancellationToken cancellationToken = default);
    /// <summary>Reads the current values of multiple tags in a single round-trip.</summary>
    /// <param name="tagPaths">The tag paths to read.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>A dictionary of tag paths to their read results.</returns>
    Task<IReadOnlyDictionary<string, ReadResult>> ReadBatchAsync(IEnumerable<string> tagPaths, CancellationToken cancellationToken = default);
    /// <summary>Writes a value to a single tag.</summary>
    /// <param name="tagPath">The tag path to write.</param>
    /// <param name="value">The value to write.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>The write result indicating success or failure.</returns>
    Task<WriteResult> WriteAsync(string tagPath, object? value, CancellationToken cancellationToken = default);
    /// <summary>Writes values to multiple tags in a single round-trip.</summary>
    /// <param name="values">A dictionary of tag paths to values.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>A dictionary of tag paths to their write results.</returns>
    Task<IReadOnlyDictionary<string, WriteResult>> WriteBatchAsync(IDictionary<string, object?> values, CancellationToken cancellationToken = default);
    /// <summary>Writes a batch of values, then writes a flag and waits for a specific response value within the timeout.</summary>
    /// <param name="values">Tag values to write before the flag.</param>
    /// <param name="flagPath">Tag path of the trigger flag.</param>
    /// <param name="flagValue">Value to write to the flag tag.</param>
    /// <param name="responsePath">Tag path to monitor for the expected response value.</param>
    /// <param name="responseValue">The response value that indicates completion.</param>
    /// <param name="timeout">Maximum time to wait for the response.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns><c>true</c> if the response value was observed within the timeout; otherwise <c>false</c>.</returns>
    Task<bool> WriteBatchAndWaitAsync(IDictionary<string, object?> values, string flagPath, object? flagValue, string responsePath, object? responseValue, TimeSpan timeout, CancellationToken cancellationToken = default);
    /// <summary>Current connection health status.</summary>
    ConnectionHealth Status { get; }

    /// <summary>
    /// Raised when the adapter detects an unexpected connection loss (e.g., gRPC stream error,
    /// network timeout). The DataConnectionActor listens for this to trigger reconnection
    /// and push bad quality to all subscribed tags.
    /// </summary>
    event Action? Disconnected;
}