/// <summary>
/// Randomly select a triad type, then a card to keep the distribution even between types.
/// </summary>
public override Flashcard Next()
{
var typeArray = Enum.GetValues(typeof(TriadType)).Cast<TriadType>().Where(t => t != TriadType.All).ToArray();
var selectedTypes = typeArray.Where(t => TriadTypes.HasFlag(t)).ToArray();
if (selectedTypes.Count() > 1)
{
// if there's more than one selected type, we want an even distribution of triad types, not
// weighted toward the types that have more cards. create an array of single-type generators
// and randomly select one each time Next is called.
if (_generators == null)
{
_generators = new TriadFlashcardGenerator[selectedTypes.Count()];
for (int i = 0; i < _generators.Length; i++)
{
var args = new TradFlashcardGeneratorArgs();
args.TriadTypes = selectedTypes[i];
args.TriadInversions = TriadInversions;
args.Accidentals = Accidentals;
args.Staffs = Staffs;
_generators[i] = new TriadFlashcardGenerator(args);
}
}
var randomType = r.Next(selectedTypes.Length);
return _generators[randomType].Next();
}
// only one selected type - call base which will randomly select a flashcard.
return base.Next();
}
/// <summary>
/// Creates a new TriadFlashcardGenerator.
/// </summary>
/// <param name="triadTypes">This flags value indicates which types of triads to include.</param>
/// <param name="triadInversions">This flags value indicates which triad inversions to include.</param>
/// <param name="staffs">This flags value indicates which staffs to include.</param>
public TriadFlashcardGenerator(TradFlashcardGeneratorArgs args)
: base(args)
{
if(args.TriadInversions == 0)
throw new ArgumentException("Need at least one triad inversion to construct a triad flashcard generator.");
if (args.TriadTypes == 0)
throw new ArgumentException("Need at least one triad type to construct a triad flashcard generator.");
TriadInversions = args.TriadInversions;
TriadTypes = args.TriadTypes;
if (Accidentals == AccidentalType.Natural)
{
// there just aren't enough diminished and augmented triads representable without accidentals, so skip them.
TriadTypes &= ~TriadType.Augmented;
TriadTypes &= ~TriadType.Diminished;
}
}