#!/usr/bin/env python

'''
usage:   booklet.py my.pdf


Uses Form XObjects and reportlab to create booklet.my.pdf.

Demonstrates use of pdfrw with reportlab.

'''

import sys
import os

from reportlab.pdfgen.canvas import Canvas

from pdfrw import PdfReader
from pdfrw.buildxobj import pagexobj
from pdfrw.toreportlab import makerl


def read_and_double(inpfn):
    pages = PdfReader(inpfn).pages
    pages = [pagexobj(x) for x in pages]
    if len(pages) & 1:
        pages.append(pages[0])  # Sentinel -- get same size for back as front

    xobjs = []
    while len(pages) > 2:
        xobjs.append((pages.pop(), pages.pop(0)))
        xobjs.append((pages.pop(0), pages.pop()))
    xobjs += [(x,) for x in pages]
    return xobjs


def make_pdf(outfn, xobjpairs):
    canvas = Canvas(outfn)
    for xobjlist in xobjpairs:
        x = y = 0
        for xobj in xobjlist:
            x += xobj.BBox[2]
            y = max(y, xobj.BBox[3])

        canvas.setPageSize((x, y))

        # Handle blank back page
        if len(xobjlist) > 1 and xobjlist[0] == xobjlist[-1]:
            xobjlist = xobjlist[:1]
            x = xobjlist[0].BBox[2]
        else:
            x = 0
        y = 0

        for xobj in xobjlist:
            canvas.saveState()
            canvas.translate(x, y)
            canvas.doForm(makerl(canvas, xobj))
            canvas.restoreState()
            x += xobj.BBox[2]
        canvas.showPage()
    canvas.save()


inpfn, = sys.argv[1:]
outfn = 'booklet.' + os.path.basename(inpfn)

make_pdf(outfn, read_and_double(inpfn))