using ZB.MOM.WW.OtOpcUa.Driver.AbLegacy;

namespace ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Tests;

internal class FakeAbLegacyTag : IAbLegacyTagRuntime
{
    public AbLegacyTagCreateParams CreationParams { get; }
    public object? Value { get; set; }
    public int Status { get; set; }
    public bool ThrowOnInitialize { get; set; }
    public bool ThrowOnRead { get; set; }
    public bool ThrowOnWrite { get; set; }
    public Exception? Exception { get; set; }
    public int InitializeCount { get; private set; }
    public int ReadCount { get; private set; }
    public int WriteCount { get; private set; }
    public bool Disposed { get; private set; }

    public FakeAbLegacyTag(AbLegacyTagCreateParams p) => CreationParams = p;

    public virtual Task InitializeAsync(CancellationToken ct)
    {
        InitializeCount++;
        if (ThrowOnInitialize) throw Exception ?? new InvalidOperationException();
        return Task.CompletedTask;
    }

    public virtual Task ReadAsync(CancellationToken ct)
    {
        ReadCount++;
        if (ThrowOnRead) throw Exception ?? new InvalidOperationException();
        return Task.CompletedTask;
    }

    public virtual Task WriteAsync(CancellationToken ct)
    {
        WriteCount++;
        if (ThrowOnWrite) throw Exception ?? new InvalidOperationException();
        return Task.CompletedTask;
    }

    public virtual int GetStatus() => Status;
    public int? LastDecodeBitIndex { get; private set; }
    public AbLegacyDataType? LastDecodeType { get; private set; }
    public virtual object? DecodeValue(AbLegacyDataType type, int? bitIndex)
    {
        LastDecodeType = type;
        LastDecodeBitIndex = bitIndex;
        // If the test seeded a parent-word value (ushort/short/int) and the driver asked for a
        // specific status bit, mask it out so we can assert the correct bit reaches the client.
        if (bitIndex is int bit && Value is not null and not bool)
        {
            try
            {
                var word = Convert.ToInt32(Value);
                return ((word >> bit) & 1) != 0;
            }
            catch (Exception ex) when (ex is FormatException or InvalidCastException) { }
        }
        return Value;
    }
    public virtual void EncodeValue(AbLegacyDataType type, int? bitIndex, object? value) => Value = value;

    /// <summary>
    ///     PR 7 — array contiguous-block element decoder. Tests seed <see cref="ArrayValues"/>
    ///     with the per-index payload; the fake then returns each element in order. Falls back
    ///     to <see cref="Value"/> when the test only seeded a scalar (Convert.ChangeType handles
    ///     the cast back to the requested element type in the driver's BuildArray helper).
    /// </summary>
    public IReadOnlyList<object?>? ArrayValues { get; set; }
    public AbLegacyDataType? LastArrayDecodeType { get; private set; }
    public int LastArrayDecodeMaxIndex { get; private set; } = -1;
    public virtual object? DecodeArrayElement(AbLegacyDataType type, int elementIndex)
    {
        LastArrayDecodeType = type;
        if (elementIndex > LastArrayDecodeMaxIndex) LastArrayDecodeMaxIndex = elementIndex;
        if (ArrayValues is not null && elementIndex < ArrayValues.Count)
            return ArrayValues[elementIndex];
        return Value;
    }

    public virtual void Dispose() => Disposed = true;
}

internal sealed class FakeAbLegacyTagFactory : IAbLegacyTagFactory
{
    // PR ablegacy-12 / #255 — switched from plain Dictionary to ConcurrentDictionary so
    // the read path (test thread) and the probe loop (background Task) can both call
    // Create without corrupting the dict. Pre-PR-12 the race existed but only tipped
    // a few percent of test runs into KeyNotFoundException; PR-12's added
    // Interlocked.Exchange writes shifted timing enough to make it deterministic-flaky
    // (~60%).
    public System.Collections.Concurrent.ConcurrentDictionary<string, FakeAbLegacyTag> Tags { get; } =
        new(StringComparer.OrdinalIgnoreCase);
    public Func<AbLegacyTagCreateParams, FakeAbLegacyTag>? Customise { get; set; }

    public IAbLegacyTagRuntime Create(AbLegacyTagCreateParams p)
    {
        var fake = Customise?.Invoke(p) ?? new FakeAbLegacyTag(p);
        Tags[p.TagName] = fake;
        return fake;
    }
}