using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Driver.AbCip.PlcFamilies;

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

/// <summary>
///     PR abcip-1.4 — multi-tag write planner. Groups a batch of <see cref="WriteRequest"/>s by
///     device so the driver can submit one round of writes per device instead of looping
///     strictly serially across the whole batch. Honours the per-family
///     <see cref="AbCipPlcFamilyProfile.SupportsRequestPacking"/> flag: families that support
///     CIP request packing (ControlLogix / CompactLogix / GuardLogix) issue their writes in
///     parallel so libplctag's internal scheduler can coalesce them onto one Multi-Service
///     Packet (0x0A); Micro800 (no request packing) falls back to per-tag sequential writes.
/// </summary>
/// <remarks>
///     <para>The libplctag .NET wrapper exposes one CIP service per <c>Tag</c> instance and does
///     not surface Multi-Service Packet construction at the API surface — but the underlying
///     native library packs concurrent operations against the same connection automatically
///     when the family's protocol supports it. Issuing the writes concurrently per device
///     therefore gives us the round-trip reduction described in #228 without having to drop to
///     raw CIP, while still letting us short-circuit packing on Micro800 where it would be
///     unsafe.</para>
///
///     <para>Bit-RMW writes (BOOL-with-bitIndex against a DINT parent) are excluded from
///     packing here because they need a serialised read-modify-write under the per-parent
///     <c>SemaphoreSlim</c> in <see cref="AbCipDriver.WriteBitInDIntAsync"/>. Packing two RMWs
///     on the same DINT would risk losing one another's update.</para>
/// </remarks>
internal static class AbCipMultiWritePlanner
{
    /// <summary>
    ///     One classified entry in the input batch. <see cref="OriginalIndex"/> preserves the
    ///     caller's ordering so per-tag <c>StatusCode</c> fan-out lands at the right slot in
    ///     the result array. <see cref="IsBitRmw"/> routes the entry through the RMW path even
    ///     when the device supports packing.
    /// </summary>
    internal readonly record struct ClassifiedWrite(
        int OriginalIndex,
        WriteRequest Request,
        AbCipTagDefinition Definition,
        AbCipTagPath? ParsedPath,
        bool IsBitRmw);

    /// <summary>
    ///     One device's plan slice. <see cref="Packable"/> entries can be issued concurrently;
    ///     <see cref="BitRmw"/> entries must go through the RMW path one-at-a-time per parent
    ///     DINT.
    /// </summary>
    internal sealed class DevicePlan
    {
        public required string DeviceHostAddress { get; init; }
        public required AbCipPlcFamilyProfile Profile { get; init; }
        public List<ClassifiedWrite> Packable { get; } = new();
        public List<ClassifiedWrite> BitRmw { get; } = new();
    }

    /// <summary>
    ///     Build the per-device plan list. Entries are visited in input order so the resulting
    ///     plan's traversal preserves caller ordering within each device. Entries that fail
    ///     resolution (unknown reference, non-writable tag, unknown device) are reported via
    ///     <paramref name="reportPreflight"/> with the appropriate StatusCode and excluded from
    ///     the plan.
    /// </summary>
    public static IReadOnlyList<DevicePlan> Build(
        IReadOnlyList<WriteRequest> writes,
        IReadOnlyDictionary<string, AbCipTagDefinition> tagsByName,
        IReadOnlyDictionary<string, AbCipDriver.DeviceState> devices,
        Action<int, uint> reportPreflight)
    {
        var plans = new Dictionary<string, DevicePlan>(StringComparer.OrdinalIgnoreCase);
        var order = new List<DevicePlan>();

        for (var i = 0; i < writes.Count; i++)
        {
            var w = writes[i];
            if (!tagsByName.TryGetValue(w.FullReference, out var def))
            {
                reportPreflight(i, AbCipStatusMapper.BadNodeIdUnknown);
                continue;
            }
            if (!def.Writable || def.SafetyTag)
            {
                reportPreflight(i, AbCipStatusMapper.BadNotWritable);
                continue;
            }
            if (!devices.TryGetValue(def.DeviceHostAddress, out var device))
            {
                reportPreflight(i, AbCipStatusMapper.BadNodeIdUnknown);
                continue;
            }

            if (!plans.TryGetValue(def.DeviceHostAddress, out var plan))
            {
                plan = new DevicePlan
                {
                    DeviceHostAddress = def.DeviceHostAddress,
                    Profile = device.Profile,
                };
                plans[def.DeviceHostAddress] = plan;
                order.Add(plan);
            }

            var parsed = AbCipTagPath.TryParse(def.TagPath);
            var isBitRmw = def.DataType == AbCipDataType.Bool && parsed?.BitIndex is int;
            var entry = new ClassifiedWrite(i, w, def, parsed, isBitRmw);
            if (isBitRmw) plan.BitRmw.Add(entry);
            else plan.Packable.Add(entry);
        }

        return order;
    }
}