Python script to sort a NCX with no gaps in playOrder.

sortncx.py

#! /usr/bin/env python

from lxml import etree as ET
import zipfile as ZIP
import sys
import os

namespaces = {	"opf":"http://www.idpf.org/2007/opf",
		"dc":"http://purl.org/dc/elements/1.1/",
		"ncx":"http://www.daisy.org/z3986/2005/ncx/"
	        }

info = {}

def sortncx(file):
	ncx = parseNCX(file)
	
	ncx.xpath("//ncx:navLabel/ncx:text",namespaces=namespaces)[0].text = info["book_title"]
	ncx.xpath("//ncx:docTitle/ncx:text",namespaces=namespaces)[0].text = info["book_title"]
	
	for i in ncx.xpath(".//ncx:navPoint",namespaces=namespaces):
		if i[0][0].text == None:
			i.getparent().remove(i)
	
	counter = 1
	for item in ncx.xpath(".//ncx:navPoint",namespaces=namespaces):
		item.set("playOrder",str(counter))
		counter += 1
	else:
		counter = 1
	
	
	ncx = ET.ElementTree(ncx)
	return ET.tostring(ncx)

def parseInfo(file):
    global info
    try:
        f = ZIP.ZipFile(file).read("META-INF/container.xml")
    except KeyError:
        print "The %s file is not a valid OCF." % str(file)
    try:
        m = ET.fromstring(f)
        info["path_to_opf"] = m[0][0].get("full-path")
        root_folder = os.path.dirname(info["path_to_opf"])
    except Exception as e:
        print e 
        sys.exit(2)
        
    opf = ET.fromstring(ZIP.ZipFile(file).read(info["path_to_opf"]))
    
    id = opf.xpath("//opf:spine",namespaces=namespaces)[0].get("toc")
    info["book_title"] = "".join(opf.xpath("//dc:title/text()",namespaces=namespaces))
    info["book_author"] = "".join(opf.xpath("//dc:creator[0]/text()",namespaces=namespaces))
    expr = "//*[@id='%s']" % id
    info["ncx_name"] = opf.xpath(expr)[0].get("href")
    info["path_to_ncx"] = root_folder + "/" + info["ncx_name"]
    info.pop("ncx_name")

    return info

def parseNCX(file):

    ncx = {}
    ncx = ET.fromstring(ZIP.ZipFile(file).read(parseInfo(file)["path_to_ncx"]))
    
    return ncx

if __name__ == '__main__':

	info = parseInfo(sys.argv[1])
	sorted_ncx = sortncx(sys.argv[1])
	print sorted_ncx