#!/usr/local/bin/python
# -*- coding: iso-8859-1 -*-
#
#   Convert a PNM file (.ppm, .pgm, .pbm) to PostScript.
#   See the usage message for details.
#
#   Requires /usr/local/bin/convert from ImageMagick to be installed.
#   (On FreeBSD it is available from /usr/ports/graphics/ImageMagick.)
#
#   Copyright (c) 2005-2010 by Oliver Fromme, Munich, Germany.
#   <olli@fromme.com>  <olli@freebsd.org>   <olli@secnetix.de>
#

import sys, getopt, re, os, os.path

#   The default is to use ISO A4 paper
#   and no additional border.

paper_width  = 21.0
paper_height = 29.7
border       =  1.0

debug = 0

convert = "/usr/local/bin/convert"

me = os.path.basename(sys.argv[0])

def usage():

	"Print the usage message and exit."

	sys.stderr.writelines ((
		"Usage:  %s [<options>] <PNM file> [...]\n" % me,
		"Options:\n",
		"    -d               print debug info, don't execute commands\n", 
		"    -w <width>       specify paper width (in cm)\n",
		"    -h <height>      specify paper height (in cm)\n",
		"    -b <border>      specify border (in cm)\n",
		"All numbers are interpreted as centimeters.\n",
		"The defaults are -w 21.0 -h 27.9 (ISO A4) and -b 1.0.\n",
		"Output files are named *.ps.",
	))
	sys.exit (1)

def die (msg, what = None):

	"Print an error message and exit"

	if what:
		errmsg = "%s:  %s:  %s\n" %(me, what, msg)
	else:
		errmsg = "%s:  %s\n" %(me, msg)
	sys.stderr.write (errmsg)
	sys.exit (1)

def check_float (string):

	"Convert string to float and check for error."

	try:
		return float(string)
	except ValueError:
		die ("Illegal number.", string)

def cm2pp (cm):

	"Convert centimeters to PostScript points."

	return cm / 2.54 * 72

tokens = []

def read_pnm_token (file):

	"Read a  token from a PNM file (skips comments etc.)."

	global tokens
	while not tokens:
		line = file.readline()
		if not line:
			die ("Unexpected EOF.", file.name)
		com = line.find("#")
		if com >= 0:
			line = line[:com]
		line = line.strip()
		if not line:
			continue
		tokens = line.split()
	next_token = tokens[0]
	del tokens[0]
	return next_token

#
#   The "main" program starts here.
#

try:
	opts, args = getopt.getopt(sys.argv[1:], "dw:h:b:")
except getopt.GetoptError:
	usage()

if not args:
	usage()

for opt, par in opts:
	if opt == "-d":
		debug = 1
	elif opt == "-w":
		paper_width = check_float(par)
	elif opt == "-h":
		paper_height = check_float(par)
	elif opt == "-b":
		border = check_float(par)
	else:
		raise "Internal error: options inconsistency"

dest_width  = paper_width  - 2 * border
dest_height = paper_height - 2 * border

landscape = dest_width > dest_height

if debug:
	print "Debug mode is ON.  No actual commands are executed."
	print "Paper size: ", paper_width, "x", paper_height, "cm",
	print ["(portrait)", "(landscape)"][landscape],
	print "with", border, "cm border."
	print "Printable area: ", dest_width, "x", dest_height, "cm."

for src in args:
	try:
		file = open(src)
	except IOError, bang:
		die (bang.strerror, src)

	if not re.match("^P[1-6]", read_pnm_token(file)):
		die ("Not a PNM file.", src)

	try:
		img_width = int(read_pnm_token(file))
		img_height = int(read_pnm_token(file))
	except ValueError:
		die ("Can't find width and height in PNM file.", src)

	file.close()

	if debug:
		print "\nFile %s: " % src,
		print img_width, "x", img_height, "pixels."

	rotate = landscape == (img_width < img_height)
	if rotate:
		img_width, img_height = img_height, img_width
		if debug:
			print "(Rotating image to better fit the page.)"

	# pixels per centimeter
	ppc = max (
		img_width / dest_width,
		img_height / dest_height
	)

	left_margin   = (paper_width  - img_width  / ppc) / 2
	bottom_margin = (paper_height - img_height / ppc) / 2

	if debug:
		print "Using a resolution of", ppc, "pixels per cm."
		print "Positioning image at x =", left_margin,
		print "cm and y =", bottom_margin, "cm."

	if rotate:
		cmd = convert + " -rotate -90"
	else:
		cmd = convert

	cmd = "%s -density %fx%f -page %dx%d+%d+%d %s %s.ps" % (
			cmd, ppc * 2.54, ppc * 2.54,
			img_width, img_height,
			cm2pp(left_margin), cm2pp(bottom_margin),
			src, os.path.splitext(src)[0]
		)

	if debug:
		print "NOT executing command:\n", cmd
	else:
		os.system(cmd)

#--