# -*- coding: UTF-8 -*-
#
# Desc:    This file is part of the eCromedos document preparation system
# Date:    2006/03/09
# Author:  Tobias Koch (tkoch@ecromedos.net)
# License: GNU General Public License, version 2
# URL:     http://www.ecromedos.net
#

# std includes
import os, libxml2, StringIO, re

# ecmds includes
from error import ECMDSPluginError


def getInstance(config):
	'''Returns a plugin instance.'''
	return Plugin(config)
#end function


class Plugin:

	def __init__(self, config):

		# init counter
		self.counter = 1
		self.nodelist = []

		# look for latex executable
		try:
			self.latex_bin = config['latex_bin']
		except KeyError:
			msg = "Location of the 'latex' executable not specified."
			raise ECMDSPluginError(msg, "math")
		#end try
		if not os.path.isfile(self.latex_bin):
			msg = "Could not find latex executable '%s'." % (self.latex_bin,)
			raise ECMDSPluginError(msg, "math")
		#end if

		# look for conversion tool
		try:
			self.dvipng_bin = ""
			self.dvipng_bin = config['dvipng_bin']
		except KeyError:
			msg  = "Location of the 'dvipng' executable not specified."
			raise ECMDSPluginError(msg, "math")
		#end try
		if not os.path.isfile(self.dvipng_bin):
			msg = "Could not find 'dvipng' executable '%s'." % (self.dvipng_bin,)
			raise ECMDSPluginError(msg, "math")
		#end if

		# conversion dpi
		try:
			self.dvipng_dpi = config['dvipng_dpi']
		except KeyError:
			self.dvipng_dpi = 100
		#end try
		
		# output document
		self.out = StringIO.StringIO("")
	#end function


	def flush(self):
		'''If format was XHTML, generate GIFs from formulae.'''

		# generate bitmaps of formulae
		if self.out.tell() > 0:
			self.out.write("\\end{document}\n")
			self.__LaTeX2DVI2GIF()
			self.out.close()
			self.out = StringIO.StringIO()
		#end if
		
		#reset counter
		self.counter = 1
		self.nodelist = []
	#end function


	def process(self, node, format):
		'''Prepare @node for target @format.'''

		if format == "latex":
			result = self.LaTeX_ProcessMath(node)
		else:
			result = self.XHTML_ProcessMath(node)
		#end if
		
		return result
	#end function
	
	
	def LaTeX_ProcessMath(self, node):
		'''Mark node to be copied 1:1 to output document.'''

		# surround node content by "$"s
		string = node.getContent()
		if node.parent.name != "equation":
			string = "$" + string + "$"
		#end if
		newnode = libxml2.newNode("copy")
		newnode.setContent(string)
		node.replaceNode(newnode)
		node.freeNode()

		self.counter += 1
		return newnode
	#end function


	def __LaTeX2DVI2GIF(self):
		'''Write formulae to LaTeX file, compile and extract images.'''

		# open tex file
		try:
			fp = file("math.tex", "wb+")
		except IOError:
			msg = "Could not open temporary file for writing."
			raise ECMDSPluginError(msg, "math")
		#end try
		
		# flush memory file
		try:
			fp.write(self.out.getvalue())
			fp.close()
		except IOError:
			msg = "Error while writing temporary file."
			raise ECMDSPluginError(msg, "math")
		#end try

		# redirect latex messages
		try: logfp = file("math_plugin.log", "wb+")
		except Exception: logfp = sys.stdout

		# compile LaTeX file
		stdout = os.dup(1)
		os.dup2(logfp.fileno(), 1)
		args = ("-interaction", "nonstopmode", "math.tex")
		rval = os.spawnl(os.P_WAIT, self.latex_bin, self.latex_bin, *args)
		# LaTeX may need to be run twice
		if not rval:
			rval = os.spawnl(os.P_WAIT, self.latex_bin, self.latex_bin, *args)
		#end if
		os.dup2(stdout, 1)
		if logfp.fileno() != 1: logfp.close()
		
		# check exit code
		if rval != 0:
			msg = "Could not compile temporary TeX file."
			raise ECMDSPluginError(msg, "math")
		else:
			try:
				os.remove("math.tex")
			except OSError: pass
			try:
				os.remove("math.aux")
			except OSError: pass
			try:
				os.remove("math.log")
			except OSError: pass
			try:
				os.remove("math_plugin.log")
			except OSError: pass
		#end if

		# convert dvi file to GIF image
		rval = -1
		args = ("-D", self.dvipng_dpi, "--depth", "-gif", "-T",
		        "tight", "-o", "m%06d.gif", "math.dvi")

		# redirect dvipng messages
		try: logfp = file("math_plugin.log", "wb+")
		except Exception: logfp = sys.stdout

		stdout = os.dup(1)
		os.dup2(logfp.fileno(), 1)
		rval = os.spawnl(os.P_WAIT, self.dvipng_bin, self.dvipng_bin, *args)
		os.dup2(stdout, 1)
		if logfp.fileno() != 1: logfp.close()

		if rval != 0:
			msg = "Could not convert dvi file to GIF images."
			raise ECMDSPluginError(msg, "math")
		else:
			# align bitmaps with info from log before deleting it
			self.__alignImages()
			try:
				os.remove("math.dvi")
			except OSError: pass
			try:
				os.remove("math_plugin.log")
			except OSError: pass
		#end if
	#end function
	
	
	def __alignImages(self):
		'''Add style tag to each bitmap for correct baseline alignment.'''

		# read logfile
		try:
			try:
				fp = file("math_plugin.log", "rb")
				string = fp.read()
			finally:
				fp.close()
			#end try
		except Exception: return

		# look for [??? depth=???px]
		rexpr = re.compile("\\[[0-9]* depth=[0-9]*\\]")

		# add style property to node
		i = 0
		for match in rexpr.finditer(string):
			align = match.group().split("=")[1].strip(" []")
			node = self.nodelist[i]
			node.newProp("style", "vertical-align: -" + align + "px;")
			i += 1
		#end for
	#end function

	
	def XHTML_ProcessMath(self, node):
		'''Call LaTeX and ImageMagick to produce a GIF.'''

		if self.out.tell() == 0:
			# write latex preamble
			self.out.write("\\documentclass[12pt]{scrartcl}\n")
			self.out.write("\\usepackage{courier}\n")
			self.out.write("\\usepackage{helvet}\n")
			self.out.write("\\usepackage{mathpazo}\n")
			self.out.write("\\usepackage{amsmath}\n")
			self.out.write("\\usepackage[active,displaymath,textmath]{preview}\n")
			self.out.write("\\frenchspacing{}\n")
			self.out.write("\\usepackage{ucs}\n")
			self.out.write("\\usepackage[utf8x]{inputenc}\n")
			self.out.write("\\usepackage[T1]{autofe}\n")
			self.out.write("\\PrerenderUnicode{äöüß}\n")
			self.out.write("\\pagestyle{empty}\n")
			self.out.write("\\begin{document}\n")
		#end if

		self.out.write("$%s$\n\\clearpage{}\n" % (node.getContent(),))

		# replace node
		copy_node = libxml2.newNode("copy")
		img_node = libxml2.newNode("img")
		img_node.newProp("src", "m%06d.gif" % (self.counter,))
		img_node.newProp("alt", "")
		copy_node.addChild(img_node)
		node.replaceNode(copy_node)
		node.freeNode()

		self.nodelist.append(img_node)
		self.counter += 1
		return copy_node
	#end function

#end class