/// <summary>
/// Tries to automatically detect the format of the given file, and creates an instance of it
/// </summary>
/// <typeparam name="T">Base type of file (i.e. image, archive)</typeparam>
/// <param name="fileStream">File stream with data to use</param>
/// <param name="endianness">Endianness of the file data</param>
/// <returns>Instance of file; null if no instance was created</returns>
public static T FromFile <T>(FileStream fileStream, Endian endianness) where T : FileFormat
{
// TODO: rework identification system?
List <IdentificationMatch> matchedTypes = new List <IdentificationMatch>();
EndianBinaryReader reader = new EndianBinaryReader(fileStream, endianness);
{
foreach (var assembly in AssemblyHelpers.GetNonSystemAssemblies())
{
foreach (var type in assembly.GetExportedTypes().Where(x => x == typeof(T) || x.InheritsFrom(typeof(T))))
{
IdentificationMatch magicMatch = null, patternMatch = null;
var customAttribs = type.GetCustomAttributes(false);
bool requireMagicAndPattern = customAttribs.Any(x => x is MagicNumberAttribute) && customAttribs.Any(x => x is FilenamePatternAttribute);
var magicNumberAttrib = customAttribs.FirstOrDefault(x => x is MagicNumberAttribute);
var verifyMethod = type.GetMethod("VerifyMagicNumber", BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.FlattenHierarchy);
if (verifyMethod == null)
{
throw new NullReferenceException("Reflection error on method fetch for file verification");
}
VerifyResult verifyResult = ((VerifyResult)verifyMethod.Invoke(null, new object[] { reader, type }));
if (verifyResult == VerifyResult.VerifyOkay)
{
uint weight = int.MaxValue;
if (magicNumberAttrib != null)
{
weight += (uint)(magicNumberAttrib as MagicNumberAttribute).MagicNumber.Length;
}
magicMatch = new IdentificationMatch(type, weight);
}
else if (verifyResult == VerifyResult.WrongMagicNumber)
{
continue;
}
foreach (var fnPatternAttrib in type.GetCustomAttributes(typeof(FilenamePatternAttribute), false))
{
string pattern = (fnPatternAttrib as FilenamePatternAttribute).Pattern;
Regex regEx = new Regex(pattern, RegexOptions.IgnoreCase);
if (regEx.IsMatch(fileStream.Name))
{
patternMatch = new IdentificationMatch(type, (uint)pattern.Length);
}
}
if (requireMagicAndPattern)
{
if (magicMatch != null && patternMatch != null)
{
matchedTypes.Add(magicMatch);
matchedTypes.Add(patternMatch);
}
}
else
{
if (magicMatch != null)
{
matchedTypes.Add(magicMatch);
}
if (patternMatch != null)
{
matchedTypes.Add(patternMatch);
}
}
}
if (matchedTypes.Count > 0)
{
T fileInstance = (T)Activator.CreateInstance(matchedTypes.OrderByDescending(x => x.Weight).FirstOrDefault().Type);
fileInstance.Open(reader);
return(fileInstance);
}
}
}
return(default(T));
}
protected abstract void OnOpen(EndianBinaryReader reader);
