namespace Nonemm.Session;

/// The order stacked calls come off, which is what N1MM's digital window calls
/// its call stacking modes.
public enum StackOrder
{
    /// Multipliers first, then the order they arrived in.
    MultipliersFirst,

    /// The order they arrived in.
    FirstIn,

    /// Newest first.
    LastIn,

    /// Nothing is stacked.
    Disabled,
}

/// The calls waiting to be worked while running. A station calling CQ hears
/// more than one answer, and this holds the ones it has not got to yet, so the
/// operator takes them one at a time instead of asking each to call again.
/// N1MM's single-operator call stacking.
///
/// The order calls come off is `Order`: multipliers first is what N1MM uses on
/// CW and phone, and the digital window offers the other three.
public sealed class CallStack
{
    /// N1MM stacks nothing shorter than this.
    public const int ShortestCall = 2;

    private readonly List<string> calls = [];

    /// How calls come off. The digital window sets this from its call stacking
    /// menu; everything else leaves it alone.
    public StackOrder Order { get; set; } = StackOrder.MultipliersFirst;

    /// The calls in the order they come off, so the front is next.
    public IReadOnlyList<string> Calls => calls;

    public int Count => calls.Count;

    public bool IsEmpty => calls.Count == 0;

    /// The call that comes off next, or empty when the stack is.
    public string Top => calls.Count > 0 ? calls[0] : "";

    /// Puts a call on the stack. A call already there is moved rather than
    /// repeated, and where it goes is up to `Order`.
    public void Add(string call, bool isMultiplier)
    {
        string wanted = call.Trim().ToUpperInvariant();
        if (wanted.Length < ShortestCall || Order == StackOrder.Disabled)
        {
            return;
        }
        Remove(wanted);
        bool toFront = Order switch
        {
            StackOrder.LastIn => true,
            StackOrder.MultipliersFirst => isMultiplier,
            _ => false,
        };
        if (toFront)
        {
            calls.Insert(0, wanted);
        }
        else
        {
            calls.Add(wanted);
        }
    }

    /// Takes the next call off, or returns empty when there is nothing on the
    /// stack.
    public string Next()
    {
        if (calls.Count == 0)
        {
            return "";
        }
        string call = calls[0];
        calls.RemoveAt(0);
        return call;
    }

    public bool Remove(string call) =>
        calls.RemoveAll(c => string.Equals(c, call.Trim(), StringComparison.OrdinalIgnoreCase)) > 0;

    /// Puts a call already on the stack at the front, which is what
    /// double-clicking it in N1MM's window does.
    public void MoveToTop(string call)
    {
        if (Remove(call))
        {
            calls.Insert(0, call.Trim().ToUpperInvariant());
        }
    }

    public void Clear() => calls.Clear();
}