public void Initialize()
{
_queryObject = new QueryObject(new Guid()) { NumberOfEntries = 1 };
_entries = new List<DictionaryEntry>();
CreateEntries();
_objectUnderTest = new SmartEntriesSelector();
}
public List<DictionaryEntry> SelectEntries(List<DictionaryEntry> entries, QueryObject queryObject)
{
if (entries.Count == 0)
{
return entries;
}
var items = CreateQueryItems(entries, queryObject);
CalculateTimeFactor(items, queryObject);
return SelectMostRelevantEntries(queryObject, items);
}
private static double CalculateRatio(IReadOnlyList<Answer> answers, QueryObject queryObject)
{
if (answers.Count == 0)
{
return queryObject.InitialRatio;
}
var numerator = 0.0;
for (var i = 0; i < answers.Count; i++)
{
if (answers[i].IsCorrect)
{
numerator += Math.Pow(2, answers.Count - i - 1);
}
}
var denominator = Math.Pow(2, answers.Count) - 1;
return numerator/denominator;
}
private static void CalculateTimeFactor(List<QueryItem> items, QueryObject queryObject)
{
var allMostRecentAnswers = items.SelectMany(p => p.TenMostRecentAnswers).ToList();
if (!allMostRecentAnswers.Any())
{
foreach (var item in items)
{
item.TimeFactor = 1;
}
}
else
{
var oldestAnswerTicks = allMostRecentAnswers.Min(p => p.AnswerTime.Ticks);
var ticksFiveDaysAgo = (DateTime.Now - TimeSpan.FromDays(5)).Ticks;
if (oldestAnswerTicks > ticksFiveDaysAgo)
{
oldestAnswerTicks = ticksFiveDaysAgo;
}
var currentTicks = DateTime.Now.Ticks;
foreach (var item in items)
{
var oldestAnswer = item.TenMostRecentAnswers.FirstOrDefault();
if (oldestAnswer == null)
{
item.TimeFactor = 1;
}
else
{
item.TimeFactor = CalculateTimeFactor(
currentTicks,
oldestAnswerTicks,
oldestAnswer.AnswerTime.Ticks,
queryObject.TimeFactor);
}
}
}
}
public List<DictionaryEntry> GetDictionaryEntriesForQueryObject(QueryObject queryObject)
{
return _chineseCharacterTrainerService.GetDictionaryEntriesForQueryObject(queryObject);
}
private static List<QueryItem> CreateQueryItems(IEnumerable<DictionaryEntry> entries, QueryObject queryObject)
{
var items = new List<QueryItem>();
foreach (var entry in entries)
{
var item = new QueryItem();
item.DictionaryEntry = entry;
item.TenMostRecentAnswers = TakeTenMostRecentAnswers(entry);
item.Ratio = CalculateRatio(item.TenMostRecentAnswers, queryObject);
items.Add(item);
}
return items;
}
private static List<DictionaryEntry> SelectMostRelevantEntries(
QueryObject queryObject, IEnumerable<QueryItem> items)
{
return items.OrderBy(p => p.Ratio*p.TimeFactor)
.Take(queryObject.NumberOfEntries)
.Select(p => p.DictionaryEntry)
.ToList();
}
