/// <summary>
/// Reads the high scores XML file and returns a collection of PlayerScore objects, each representing a high score
/// As the high scores XML file is encrypted, this method decypts it.
/// </summary>
/// <returns>A collection of PlayerScore objects representing the high scores</returns>
/// <exception cref="System.Exception">Error occured while reading data.</exception>
private List <PlayerScore> LoadScores()
{
if (File.Exists(FileName))
{
try
{
//read the XML file
XmlDocument xmlDoc = new XmlDocument
{
PreserveWhitespace = true
};
xmlDoc.Load(FileName);
// Create a new RSA key. This key will encrypt a symmetric key,
// which will then be imbedded in the XML document.
//need to move the key into the webconfig
CspParameters parameters = new CspParameters
{
KeyContainerName = ConfigurationSettings.AppSettings["ScoresFileEncryptionKey"]
//KeyContainerName = "XML_ENC_RSA_KEY"
};
RSACryptoServiceProvider rsaKey = new RSACryptoServiceProvider(parameters);
// Decrypt the "Player" element.
TrippleDESDocumentEncryption.Decrypt(xmlDoc, rsaKey, "rsaKey");
List <PlayerScore> list = new List <PlayerScore>(); //Create a new list
XmlNodeList elementsByTagName = null;
elementsByTagName = xmlDoc.GetElementsByTagName(HIGHSCORE); //find each score entry in the XML file
foreach (XmlNode node in elementsByTagName)
{
//for each score found in the XML file, create a new PlayerScore object with the data
PlayerScore item = new PlayerScore
{
Player = node[PLAYER].InnerText,
Score = Convert.ToInt32(node[SCORE].InnerText),
Date = Convert.ToDateTime(node[DATE].InnerText)
};
list.Add(item); //and add it to the collection
}
return(list); //when finished, return this collection
}
catch (XmlException)
{
//throw an exception if an error occured
throw new Exception("Error occured while reading data.");
}
}
return(new List <PlayerScore>()); //if no XML file exists, return an empty list
}
/// <summary>
/// Compares two PlayerScore objects to determine which one has the highest score
/// </summary>
/// <param name="obj"></param>
/// <returns></returns>
public int CompareTo(Object obj)
{
PlayerScore scoreToCompare = obj as PlayerScore;
if (this.Score > scoreToCompare.Score)
{
return(1);
}
else if (this.Score < scoreToCompare.Score)
{
return(-1);
}
else
{
return(0);
}
}
/// <summary>
/// Adds a new score to the XML file
/// </summary>
/// <param name="player">The player name</param>
/// <param name="score">The player's score</param>
/// <returns>Return true if the score was a high score, else return false.</returns>
public bool Add(string player, Int32 score)
{
List <PlayerScore> list = LoadScores(); //read the scores currently held in the XML file
PlayerScore item = new PlayerScore //create a new PlayerScore object with the data passed to the method
{
Player = player,
Score = score,
Date = DateTime.Now
};
//try and add the new score to the high scores
bool flag = false;
if (item.Score != 0) //only add score if it is above 0
{
if (list.Count < SIZE) //if the list size is less than the max number of scores
{
list.Add(item); //then add it
flag = true;
}
else
{
//else, find the lowest score (possible because the PlayerScore object implements IComparable)
list.Sort();
PlayerScore lowestScore = list[0];
if (lowestScore.Score < item.Score)
{
//...if the new score is higher than the lowest score on the list then add it
list.RemoveAt(0);
list.Add(item);
flag = true;
}
}
}
//if a new score has been added to the high scores list, then re-write the high scores XML file
if (flag)
{
SaveScores(list);
}
return(flag); //return true if the score was a high score, else return false.
}
