/// <summary>
/// Returns GeneratedQuestion
/// </summary>
/// <param name = "templateId">Template id</param>
/// <param name = "seed">Random seed</param>
/// <returns></returns>
public static GeneratedQuestion Generate(int templateId, int seed)
{
var result = new GeneratedQuestion();
var rnd = new Random(seed);
// Get template from _db
Question question =
Db.Questions.FirstOrDefault(q => q.ID == templateId);
if (question == null) throw new Exception("Template not found");
result.Body = question.Body;
result.QuestionType = 1;
result.Answers = new List<GeneratedAnswer>();
// Insert definitions to Body
int tagsLength = TagStartInsert.Length + TagEndInsert.Length;
for (int i = 0; i < result.Body.Length - tagsLength; i++)
{
if (result.Body.Substring(i, TagStartInsert.Length) !=
TagStartInsert) continue;
// We found start insert tag
int tagStartInsertPosition = i;
int definitionNamePosition = i + TagStartInsert.Length;
for (i = definitionNamePosition;
i < result.Body.Length - TagEndInsert.Length;
i++)
{
if (result.Body.Substring(i, TagEndInsert.Length) !=
TagEndInsert) continue;
// We found end insert tag
string definitionName =
result.Body.Substring(definitionNamePosition,
i - definitionNamePosition);
if (!string.IsNullOrEmpty(definitionName))
{
// Get definition from _db
Definition definition =
Db.Definitions.FirstOrDefault(
d => d.Name == definitionName);
if (definition != null)
{
// Get examples to definition from _db
List<Example> examples =
definition.Examples.Where(e => !e.IsAntiExample)
.ToList();
if (examples.Count == 0)
throw new Exception("Definition has no examples");
Example example =
examples[rnd.Next(0, examples.Count)];
// Replacing
string oldSubstr = TagStartInsert + definitionName +
TagEndInsert;
result.Body = result.Body.Replace(oldSubstr,
example.Value.Trim
());
i = tagStartInsertPosition + example.Value.Length -
1;
}
}
break;
}
}
// Get answers from _db
List<Answer> answers = question.Answers.ToList();
if (answers.Count == 0)
throw new Exception("Question has no answers");
foreach (Answer answer in answers)
{
var newAnswer = new GeneratedAnswer
{
Body = answer.Body,
IsCorrect = answer.IsCorrect
};
result.Answers.Add(newAnswer);
}
result.QuestionType = question.QuestionTypeID;
return result;
}
/// <summary>
/// Validate user Answer
/// </summary>
/// <param name="question">Question that user answered</param>
/// <param name="userAnswer">String representation of user answer</param>
/// <returns></returns>
private bool CheckAnswerIsCorrect(GeneratedQuestion question,
string userAnswer)
{
bool result = false;
if (string.IsNullOrWhiteSpace(userAnswer)) return false;
if (question.QuestionType == 1)
{
int rightAnswer = int.Parse(userAnswer);
if (question.Answers[rightAnswer].IsCorrect) result = true;
}
if (question.QuestionType == 2)
{
result = true;
var answerArray = userAnswer.Split(',');
for (int i = 0; i < question.Answers.Count; i++)
{
if (question.Answers[i].IsCorrect != answerArray.Contains(i.ToString()))
result = false;
}
}
if (question.QuestionType == 3)
{
foreach (var ans in question.Answers)
{
if (ans.Body == userAnswer) result = true;
}
}
return result;
}
