#!/usr/bin/env python
def usage():
  print ''' %s filename[.sly extension optional] 
            Appends the contents of files in the current directory to
filename, according to the head of filename.  Empty comment fields
precede.  Normally you would copy and modify a previous header, which
should look like this:

!! test.sly could be name of this file
dummy.ly !! tbn.ly !! bass.ly
cymbal.ly !! spoons.ly !! crwth.ly
!!%Here must be the end or the last field.

The data will be arranged like the header.  If there is notes data left
in filename, it must still end with the comment field--best empty.
                                                                             
(c)2004 David Raleigh Arnold, under GNU. ''' % (sys.argv[0])
  sys.exit()
                                                                   
def inputfile():
  '''Get file from argument. Supply .sly ending, test
    existence of file, and return name. '''
  if not len(sys.argv) == 2:
    print "One argument, a file name with \".sly\" extension, is required."
    usage()
  arg = sys.argv[1]
  if os.path.isfile(arg + '.sly'):
    infile = arg + '.sly'
  elif os.path.isfile(arg):
    infile = arg
  else:
    print "File " + arg + " or " + arg + ".sly does not exist."
    usage()
  return infile

import string, os, sys
try:
  file = open(inputfile()) 
  comment = file.readline()
  print comment,  # should identify file to user
  print "Writing fields:"
  fsep = comment[:2]
  ''' Put header with trailing fsep in memory. '''
  head = file.read().split('\n' + fsep, 1)[0]
  ''' Process head, get open files into list in lines '''
  list = head.split('\n')
  filelist = []
  for line in list:
    line = line.split(fsep)
    linelist = []
    for fname in line:
      fname = fname.strip()
      file = open(fname ,"a") # empty file is created if not existent
      file.close()
      fname = open(fname)
      linelist.append(fname)
    filelist.append(linelist)
  outfile = open(inputfile(), 'a') #append to whole file
  count = 0  
  while 1:
    outfile.write(fsep) # for the comment field 
    fields = '' # if no info left in any of the files, done!
    for line in filelist:
      for file in line:
        while 1:  #loop is for multiple line field only 
          field = ' ' + file.readline().rstrip()        
          if field[-1]=='%':
            outfield = field + '\n'
            outfile.write(outfield)
            #print outfield,                                   
          elif file==line[-1]:  # if to be last file in line
            outfield = field + '\n'
            outfile.write(outfield)
            break #print outfield,
          else:
            outfield = field + ' ' + fsep + ' '
            outfile.write(outfield)            
            break #print outfield,
        fields = fields + ' ' + field.strip() # test after writing
        count = count + 1
    if fields.strip()=='': # test complete set of fields
      print "Total fields written, not counting comment: ", count      
      break    
    
except:
  print "Done!"
  print "main-errors: ", sys.exc_type, sys.exc_value
  # todo: find index error..