using CliFx.Attributes;
using CliFx.Infrastructure;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Driver.Cli.Common;

namespace ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli.Commands;

/// <summary>
///     Watch a Logix tag via polled subscription until Ctrl+C. Uses the driver's
///     <c>ISubscribable</c> surface (PollGroupEngine under the hood). Prints each change
///     event with an HH:mm:ss.fff timestamp.
/// </summary>
[Command("subscribe", Description = "Watch a Logix tag via polled subscription until Ctrl+C.")]
public sealed class SubscribeCommand : AbCipCommandBase
{
    /// <summary>Gets or sets the Logix tag path to subscribe to.</summary>
    [CommandOption("tag", 't', Description =
        "Logix symbolic path — same format as `read`.", IsRequired = true)]
    public string TagPath { get; init; } = default!;

    /// <summary>Gets or sets the data type of the tag.</summary>
    [CommandOption("type", Description =
        "Bool / SInt / Int / DInt / LInt / USInt / UInt / UDInt / ULInt / Real / LReal / " +
        "String / Dt (default DInt).")]
    public AbCipDataType DataType { get; init; } = AbCipDataType.DInt;

    /// <summary>Gets or sets the subscription interval in milliseconds.</summary>
    [CommandOption("interval-ms", 'i', Description =
        "Publishing interval in milliseconds (default 1000). PollGroupEngine floors " +
        "sub-250ms values.")]
    public int IntervalMs { get; init; } = 1000;

    /// <inheritdoc />
    public override async ValueTask ExecuteAsync(IConsole console)
    {
        ConfigureLogging();
        RejectStructure(DataType);
        ValidateInterval(IntervalMs);
        _ = Timeout;
        var ct = console.RegisterCancellationHandler();

        var tagName = ReadCommand.SynthesiseTagName(TagPath, DataType);
        var tag = new AbCipTagDefinition(
            Name: tagName,
            DeviceHostAddress: Gateway,
            TagPath: TagPath,
            DataType: DataType,
            Writable: false);
        var options = BuildOptions([tag]);

        await using var driver = new AbCipDriver(options, DriverInstanceId);
        ISubscriptionHandle? handle = null;
        try
        {
            await driver.InitializeAsync("{}", ct);

            await console.Output.WriteLineAsync(
                $"Subscribed to {TagPath} @ {IntervalMs}ms. Ctrl+C to stop.");

            driver.OnDataChange += (_, e) =>
            {
                var line = $"[{DateTime.UtcNow:HH:mm:ss.fff}] " +
                    $"{e.FullReference} = {SnapshotFormatter.FormatValue(e.Snapshot.Value)} " +
                    $"({SnapshotFormatter.FormatStatus(e.Snapshot.StatusCode)})";
                console.Output.WriteLine(line);
            };

            handle = await driver.SubscribeAsync([tagName], TimeSpan.FromMilliseconds(IntervalMs), ct);

            try
            {
                await Task.Delay(System.Threading.Timeout.InfiniteTimeSpan, ct);
            }
            catch (OperationCanceledException)
            {
                // Expected on Ctrl+C.
            }
        }
        finally
        {
            if (handle is not null)
            {
                try { await driver.UnsubscribeAsync(handle, CancellationToken.None); }
                catch { /* teardown best-effort */ }
            }
            await driver.ShutdownAsync(CancellationToken.None);
            FlushLogging();
        }
    }

    /// <summary>
    ///     Guards <c>--interval-ms</c> against zero or negative values.
    ///     A non-positive interval would produce a non-positive <see cref="TimeSpan"/> into
    ///     <c>SubscribeAsync</c>; the CLI should fail fast with an actionable error rather
    ///     than relying on the downstream <c>PollGroupEngine</c> to clamp the value.
    /// </summary>
    /// <param name="intervalMs">The interval in milliseconds.</param>
    internal static void ValidateInterval(int intervalMs)
    {
        if (intervalMs <= 0)
            throw new CliFx.Exceptions.CommandException(
                $"--interval-ms must be > 0 (got {intervalMs}). " +
                "PollGroupEngine floors sub-250ms values, but accepts any positive integer.");
    }
}
