# Sketch - A Python-based interactive drawing program
# Copyright (C) 1998, 2000, 2004 by Bernhard Herzog
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Library General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the GNU
# Library General Public License for more details.
#
# You should have received a copy of the GNU Library General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307	USA


# A simple parser for PostScript files that conform to the Document
# Structuring Conventions (DSC).
#
# In its current form this is mainly intended for parsing EPS files and
# extract the information necessary for Sketch (BoundingBox and resource
# dependencies)
#

import re, string
from string import split, strip, atof

import streamfilter

try:
    from warn import warn, INTERNAL
except ImportError:
    def warn(*args):
	pass
    INTERNAL = None

# match a line containing a DSC-comment.
rx_dsccomment = re.compile('^%%([a-zA-Z+]+):?')

# match the beginning of an EPS file.
rx_eps_magic = re.compile('^%!.*EPSF')

endcommentchars = string.maketrans('','')[33:127]
ATEND = '(atend)'


class DSCError(Exception):
    pass


#
# Class EpsInfo
#
# The instance variables of this class are the key/value pairs extracted
# from the header comments of an EPS file.
#
# BoundingBox:
#
#	The bounding box of the document as a 4-tuple of floats. The DSC
#	say that the BoundingBox should be given in UINTs but since some
#	programs (incorrectly) use floats here we also use float here.
#
# DocumentNeededResources:
#
#	A dictionary describing the resources needed by the document.
#	The information is stored in the *keys* of the dictionary.
#
#	A key has the form (TYPE, VALUE) where TYPE is a string giving
#	the resource type (such as 'font') and value is a string
#	describing the resource (such as 'Times-Roman')
#
# DocumentSuppliedResources:
#
#	The resources supplied by the document in the same format as
#	DocumentNeededResources.
#
# atend:
#
#	True, if any comment in the header had a value of `(atend)'.
#	(Used internally by the parsing functions)

class EpsInfo:

    def __init__(self):
	self.DocumentSuppliedResources = {}
	self.DocumentNeededResources   = {}
	self.BoundingBox = None
	self.atend = 0

    def NeedResources(self, type, resources):
	for res in resources:
	    self.DocumentNeededResources[(type, res)] = 1

    def SupplyResources(self, type, resources):
	for res in resources:
	    self.DocumentSuppliedResources[(type, res)] = 1

    def print_info(self):
	# print the contents of self in a readable manner. (for debugging)
	print 'BoundingBox:\t%s' % `self.BoundingBox`
	print 'DocumentNeededResources: [',
	for res in self.DocumentNeededResources.keys():
	    print res,
	print ']'
	print 'DocumentSuppliedResources: [',
	for res in self.DocumentSuppliedResources.keys():
	    print res,
	print ']'

	for key, value in self.__dict__.items():
	    if key not in ('BoundingBox', 'DocumentNeededResources',
			   'DocumentSuppliedResources', 'atend'):
		print '%s\t%s' % (key, value)

def IsEpsFileStart(data):
    # return true if data might be the beginning of an Encapsulated
    # PostScript file.
    return rx_eps_magic.match(data)


def parse_header(file, info):
    # Parse the header section of FILE and store the information found
    # in the INFO object which is assumed to be an instance of EpsInfo.
    #
    # This works for the %%Trailer section as well so that parsing the
    # beginning (until %%EndComments) and end (from %%Trailer) if
    # necessary with the same INFO object should get all information
    # available.
    line = file.readline()
    last_key = ''
    while line:
	match = rx_dsccomment.match(line)
	if match:
	    key = match.group(1)
	    value = strip(line[match.end(0):])
	    if key == 'EndComments' or key == 'EOF':
		break

	    if key == '+':
		key = last_key
	    else:
		last_key = ''

	    if key == 'BoundingBox':
		if value != ATEND:
		    # the bounding box should be given in UINTs
		    # but may also (incorrectly) be float.
		    info.BoundingBox = tuple(map(atof, split(value)))
		else:
		    info.atend = 1
	    elif key == 'DocumentNeededResources':
		if value != ATEND:
		    if value:
			[type, value] = split(value, None, 1)
			if type == 'font':
			    info.NeedResources(type, split(value))
			else:
			    # XXX: might occasionally be interesting for the
			    # user
			    warn(INTERNAL, 'needed resource %s %s ignored',
				 type, value)
		else:
		    info.atend = 1
	    elif key == 'DocumentNeededFonts':
		if value != ATEND:
		    info.NeedResources('font', split(value))
		else:
		    info.atend = 1
	    elif key == 'DocumentSuppliedResources':
		if value != ATEND:
		    if value:
			[type, value] = split(value, None, 1)
			if type == 'font':
			    info.NeedResources(type, split(value))
			else:
			    # XXX: might occasionally be interesting for the
			    # user
			    warn(INTERNAL, 'supplied resource %s %s ignored',
				 type, value)
		else:
		    info.atend = 1
	    else:
		setattr(info, key, value)
	    #
	    last_key = key
	else:
	    # the header comments end at a line not beginning with %X,
	    # where X is a printable character not in SPACE, TAB, NL
	    # XXX: It is probably wrong to do this in the %%Trailer
	    if line[0] != '%':
		break
	    if len(line) == 1 or line[1] not in endcommentchars:
		break
	line = file.readline()

def skip_to_comment(file, comment):
    # Read lines from FILE until a line with a DSC comment COMMENT is
    # found. Handles (it should at least) (binary) data and embedded
    # documents correctly (i.e. isn't confused by embedded documents
    # containing COMMENT as well, if they are enclosed in
    # Begin/EndDocument comments).
    #
    # The file is positioned right after the line containing the
    # comment. Raise a DSCError if the comment is not found
    line = file.readline()
    while line:
	match = rx_dsccomment.match(line)
	if match:
	    key = match.group(1)
	    if key == comment:
		return
	    elif key == 'BeginDocument':
		# skip embedded document
		skip_to_comment(file, 'EndDocument')
	    elif key == 'BeginData':
		value = split(strip(line[match.end(0):]))
		lines = 0
		if len(value) >= 1:
		    count = int(value[0])
		    if len(value) == 3:
			lines = value[2] == 'Lines'
		else:
		    # should never happen in a conforming document...
		    count = 0
		if count > 0:
		    if lines:
			for i in range(count):
			    file.readline()
		    else:
			blocksize = 4000
			while count:
			    if count > blocksize:
				count = count - len(file.read(blocksize))
			    else:
				count = count - len(file.read(count))
	line = file.readline()

    else:
	raise DSCError('DSC-Comment %s not found' % comment)



def parse_eps_file(filename):
    # Extract information from the EPS file FILENAME. Return an instance
    # of EpsInfo with the appropriate parameters. Raise a DSCError, if
    # the file is not an EPS file.
    file = streamfilter.LineDecode(open(filename, 'r'))
    line = file.readline()
    info = EpsInfo()

    if IsEpsFileStart(line):
	parse_header(file, info)
	if info.atend:
	    skip_to_comment(file, 'Trailer')
	    parse_header(file, info)
    else:
	raise DSCError('%s is not an EPS file' % filename)

    file.close()

    return info



#
#
#

if __name__ == '__main__':
    import sys
    file = open(sys.argv[1], 'r')
    info = EpsInfo()

    parse_header(file, info)
    if info.atend:
	skip_to_comment(file, 'Trailer')
	parse_header(file, info)

    file.close()

    info.print_info()
