'''Rename a tag in all tagfiles.'''

import sys
import os
from lib.tagfiles import nicesplit

def edit_tagfile(tagfilepath, old, new):
    '''Update a single tagfile.'''
    infile = open(tagfilepath, 'rU')
    newdata = ""
    for line in infile:
        if not line.strip():
            continue
        
        parts = line.split(':', 1)
        
        tags = nicesplit(parts[0])
        if old in tags:
            tags[tags.index(old)] = new
            parts[0] = ' '.join(tags)
            newdata += ':'.join(parts)
        else:
            newdata += line
    
    infile.close()
    open(tagfilepath, 'w').write(newdata)

def edit_recursively(basepath, tagfilename, old, new):
    '''Update all tagfiles recursively'''
    def callback(arg, dirname, fnames):
        '''os.walk callback function to read tagfiles.'''
        if tagfilename in fnames:
            tagfilepath = os.path.join(dirname, tagfilename)
            edit_tagfile(tagfilepath, old, new)
    
    os.path.walk(basepath, callback, None)

if __name__ == '__main__':
    if len(sys.argv) != 3:
        sys.stderr.write("Usage: " + sys.argv[0] + " oldtag newtag\n")
    edit_recursively(os.getcwd(), 'Merkinnat.txt', sys.argv[1], sys.argv[2])