## songsort.py -- A small Python-script for adding track numbers to filenames.
## The track-numbers are determined from the time stamps of the MP3-files,
## with track 01 presumably having been saved before track 02, etc.
## Coded by N. Xnegghara May 2006 and placed into Public Domain.

## Example usage:
##  from songsort import *
##  os.chdir('../Taraf-~1')
##  add_tracknumbers('.','mp3','Taraf de Haidouks Vol 1 - ')
##  os.chdir('../Taraf-~2')
##  add_tracknumbers('.','mp3','Taraf de Haidouks Vol 2 - ')
##  os.chdir('../Piazzo~1')
##  add_tracknumbers('.','mp3','Piazzolla - Burton - The New Tango - ')


import os
import re

def sortbytime(a,b):
  '''Sorts two tuples a and b by their first element.'''
  (atime,aname) = a
  (btime,bname) = b
  if(atime < btime): return(-1)
  elif(atime > btime): return(+1)
  else: return(0)

def second(p):
  '''Returns the second element of a pair-tuple.'''
  (a,b) = p
  return(b)

def listdir_by_time(path,suff):
  '''List all files ending with "suff" in directory "path" sorted by their creation time'''
  olddir = os.getcwd()
  os.chdir(path)
  allfiles = os.listdir('.')
  sufflen = len(suff)
  files = map(lambda(fn): (os.stat(fn).st_mtime,fn),
              filter(lambda(s): (suff == s[-sufflen:]),allfiles)
             )
  os.chdir(olddir)
  files.sort(sortbytime)
  return(map(second,files))

def twodigitrepr(n):
  '''Represent n with two digits, at least.'''
  s = repr(n)
  if(len(s) < 2): return('0' + s)
  else: return(s)

def add_prefixes(prefix,names):
  '''Adds a prefix onto the front of each name in the given list.'''
  return(map(lambda(n): prefix+n, names))


def add_count_prefixes(names):
  '''Adds a running count 01, 02, ... in the front of each name in the given list.'''
  return([twodigitrepr(i+1)+names[i] for i in range(len(names))])

def add_tracknumbers(path,suff,pref1):
  '''Do the thing.'''
  oldnames = listdir_by_time(path,suff)
  newnames = add_prefixes(pref1,add_count_prefixes(add_prefixes('-',oldnames)))
  while(oldnames):
    os.rename(oldnames.pop(),newnames.pop())



## Use like this:
## rename_by_pattern('.','mp3','Kremer - From My Home','Tsitsanis - Hommage a Tsitsanis')

def rename_by_pattern(path,suff,oldpat,newpart):
  '''Correct your mistakes.'''
  substpat = re.compile(oldpat)
  oldnames = listdir_by_time(path,suff)
  for oldname in oldnames:
    newname = substpat.sub(newpart,oldname)
    if(newname): os.rename(oldname,newname)