import glob, copy

class MissingFileError(Exception):
   pass

class fileglob:

   def __init__(self, glob_pattern, open_function = open, verbose=0):
      self.glob_pattern = glob_pattern
      self.open = open_function
      self.verbose = verbose
      self.filelist = []
      self.nfiles = 0
      self.ifile = -1     # Points to the open file
      self.file = None   # This will be whatever is returned by open_function.
      self.refresh_filelist()

   def __del__(self):
      if self.file:
         self.file.close()

   def __iter__(self):
      return(self)

   def refresh_filelist(self):
      fl = glob.glob(self.glob_pattern)
      fl.sort()
      if fl[:self.nfiles] != self.filelist:
         raise MissingFileError
      n_new = len(fl) - self.nfiles
      if n_new and self.verbose >= 2:
         print fl
      self.filelist = fl
      self.nfiles = len(fl)
      return n_new

   def next_file(self):
      self.refresh_filelist()
      if self.nfiles == 0:
         return 0
      if self.ifile + 1 < self.nfiles:
         if self.file:
            self.file.close()
         self.ifile += 1
         if self. verbose:
            print self.filelist[self.ifile]
         self.file = self.open(self.filelist[self.ifile])
         return 1
      return 0

   def next(self):
      # Start by trying what should usually work:
      try:
         return self.file.next()
      except:
         pass
      if self.next_file():
         try:
            return self.file.next()
         except:
            pass
      raise StopIteration
      # It is possible that we need to deal with IOError separately,
      # so as to give notice if there are permission problems, for
      # example.

   def last_file(self):
      self.refresh_filelist()
      if self.nfiles == 0:
         return 0
      if self.ifile + 1 < self.nfiles:
         if self.file:
            self.file.close()
         self.ifile = self.nfiles - 1
         if self.verbose:
            print self.filelist[self.ifile]
         self.file = self.open(self.filelist[self.ifile])
         return 1
      return 0

   def end_of_stream(self):
      if self.last_file():
         for r in self:
            pass

   def find_file(self, substring):
      self.refresh_filelist()
      if self.nfiles == 0:
         return 0
      for i, fn in enumerate(self.filelist):
         if fn.find(substring) >= 0:
            if self.file:
               self.file.close()
            self.ifile = i
            if self.verbose:
               print self.filelist[self.ifile]
            self.file = self.open(self.filelist[self.ifile])
            return 1
      return 0

   def filename(self):
      if self.file:
         return self.filelist[self.ifile]
      else:
         return ''

class fileglob2(fileglob):
   '''Allow files to fall off the bottom of the list; for
   example, the older files might be gzipped so they no longer
   match the glob.
   '''
   def refresh_filelist(self):
      fl = glob.glob(self.glob_pattern)
      fl.sort()
      n_dropped = 0
      if self.nfiles > 0:
         f_last = self.filelist[-1]
         imatch = None
         for i in range(min(self.nfiles, len(fl)) - 1, -1, -1):
            if fl[i] == f_last:
               imatch = i
               break
         if imatch is None:
            raise MissingFileError
         n_dropped = self.nfiles - 1 - imatch
      n_new = len(fl) + n_dropped - self.nfiles
      if n_new and self.verbose >= 2:
         print fl
      self.ifile -= n_dropped
      self.filelist = fl
      self.nfiles = len(fl)
      return n_new

def strip_gz(fl):
   fl_new = copy.deepcopy(fl)
   for i, f in enumerate(fl_new):
      if f.endswith('.gz'):
         fl_new[i] = f[:-3]
   return fl_new


class fileglob3(fileglob):
   '''As above, but ignore any .gz suffix.
   '''
   def refresh_filelist(self):
      fl = glob.glob(self.glob_pattern)
      fl.sort()
      fl_new = strip_gz(fl)
      n_dropped = 0
      if self.nfiles > 0:
         f_last = self.filelist[-1]
         if f_last.endswith('.gz'):
            f_last = f_last[:-3]
         imatch = None
         for i in range(min(self.nfiles, len(fl)) - 1, -1, -1):
            if fl_new[i] == f_last:
               imatch = i
               break
         if imatch is None:
            raise MissingFileError
         n_dropped = self.nfiles - 1 - imatch
      n_new = len(fl) + n_dropped - self.nfiles
      if n_new and self.verbose >= 2:
         print fl
      self.ifile -= n_dropped
      self.filelist = fl
      self.nfiles = len(fl)
      return n_new