private static void SecondPass(VersionHandler handler, int[] maxCharacters, List<DeviceResult> initialResults, Results results)
{
int lowestScore = int.MaxValue;
foreach (DeviceResult current in initialResults)
{
// Calculate the score for this device.
int deviceScore = 0;
for (int segment = 0; segment < handler.VersionRegexes.Length; segment++)
{
deviceScore += (maxCharacters[segment] - current.Scores[segment].CharactersMatched + 1)*
(current.Scores[segment].Difference + maxCharacters[segment] -
current.Scores[segment].CharactersMatched);
}
// If the score is lower than the lowest so far then reset the list
// of best matching devices.
if (deviceScore < lowestScore)
{
results.Clear();
lowestScore = deviceScore;
}
// If the device score is the same as the lowest score so far then add this
// device to the list.
if (deviceScore == lowestScore)
{
results.Add(current.Device);
}
}
}
internal static Results Match(string userAgent, VersionHandler handler)
{
int[] maxCharacters = new int[handler.VersionRegexes.Length];
List<DeviceResult> initialResults = new List<DeviceResult>(handler.UserAgents.Count);
Results results = new Results();
// The 1st pass calculates the scores for every segment of every device
// available against the target useragent.
FirstPass(handler, userAgent, maxCharacters, initialResults);
// The 2nd pass returns the devices with the lowest difference across all the
// versions available.
SecondPass(handler, maxCharacters, initialResults, results);
// Return the best device matches.
return results;
}
private static void FirstPass(VersionHandler handler, string userAgent, int[] maxCharacters, List<DeviceResult> initialResults)
{
string compare, target;
foreach (var devices in handler.UserAgents)
{
foreach (DeviceInfo device in devices)
{
SegmentScore[] scores = new SegmentScore[handler.VersionRegexes.Length];
for (int segment = 0; segment < handler.VersionRegexes.Length; segment++)
{
target = handler.VersionRegexes[segment].Match(userAgent).Value;
compare = handler.VersionRegexes[segment].Match(device.UserAgent).Value;
for (int i = 0; i < target.Length && i < compare.Length; i++)
{
scores[segment].Difference += Math.Abs((target[i] - compare[i]));
scores[segment].CharactersMatched++;
}
if (scores[segment].CharactersMatched > maxCharacters[segment])
maxCharacters[segment] = scores[segment].CharactersMatched;
}
initialResults.Add(new DeviceResult(scores, device));
}
}
}