#!/usr/bin/env python

"""
Adds an SVG table to a TTF or OTF font.
The file names of the SVG glyphs need to match their corresponding glyph final names.
"""

import os
import sys
import re

try:
	from fontTools import ttLib, version
except ImportError:
	print >> sys.stderr, "ERROR: FontTools Python module is not installed."
	sys.exit(1)

TABLE_TAG = 'SVG '

# Regexp patterns
reSVGelement = re.compile(r"<svg.+?>.+?</svg>", re.DOTALL)
reIDvalue = re.compile(r"<svg[^>]+?(id=\".*?\").+?>", re.DOTALL)
reViewBox = re.compile(r"<svg.+?(viewBox=[\"|\'][\d, ]+[\"|\']).+?>", re.DOTALL)
reWhiteSpace = re.compile(r">\s+<", re.DOTALL)


def readFile(filePath):
	f = open(filePath, "rt")
	data = f.read()
	f.close()
	return data


def setIDvalue(data, gid):
	id = reIDvalue.search(data)
	if id:
		newData = re.sub(id.group(1), 'id="glyph%s"' % gid, data)
	else:
		newData = re.sub('<svg', '<svg id="glyph%s"' % gid, data)
	return newData


def fixViewBox(data):
	viewBox = reViewBox.search(data)
	if not viewBox:
		return data
	fixedViewBox = 'viewBox=\"0 1000 1000 1000\"'
	fixedData = re.sub(viewBox.group(1), fixedViewBox, data)
	return fixedData


def getGlyphNameFromFileName(filePath):
	folderPath, fontFileName = os.path.split(filePath)
	fileNameNoExtension, fileExtension = os.path.splitext(fontFileName)
	return fileNameNoExtension


def processFontFile(fontFilePath, svgFilePathsList):
	font = ttLib.TTFont(fontFilePath)

	# first create a dictionary because the SVG glyphs need to be sorted in the table
	svgDocsDict = {}

	for svgFilePath in svgFilePathsList:
		gName = getGlyphNameFromFileName(svgFilePath)

		try:
			gid = font.getGlyphID(gName)
		except KeyError:
			print >> sys.stderr, "ERROR: Could not find a glyph named %s in the font %s." % (gName, os.path.split(fontFilePath)[1])
			continue

		svgItemsList = []
		svgItemData = readFile(svgFilePath)
		svgItemData = setIDvalue(svgItemData, gid)
		svgItemData = fixViewBox(svgItemData)
		# Remove all white space between elements
		for whiteSpace in set(reWhiteSpace.findall(svgItemData)):
			svgItemData = svgItemData.replace(whiteSpace, '><')
		svgItemsList.append(svgItemData.strip())
		svgItemsList.extend([gid, gid])
		svgDocsDict[gid] = svgItemsList

	# don't do any changes to the source OTF/TTF font if there's no SVG data
	if not svgDocsDict:
		print >> sys.stderr, "ERROR: Could not find any artwork files that can be added to the font."
		return

	svgDocsList = [svgDocsDict[index] for index in sorted(svgDocsDict.keys())]

	svgTable = ttLib.newTable(TABLE_TAG)
	svgTable.compressed = False # GZIP the SVG docs
	svgTable.docList = svgDocsList
	font[TABLE_TAG] = svgTable

	# FontTools can't overwrite a font on save,
	# so save to a hidden file, and then rename it
	# https://github.com/behdad/fonttools/issues/302
	folderPath, fontFileName = os.path.split(fontFilePath)
	fileNameNoExtension, fileExtension = os.path.splitext(fontFileName)
	newFontFilePath = os.path.join(folderPath, "%s%s%s" % ('.', fileNameNoExtension, fileExtension))

	font.save(newFontFilePath)
	font.close()
	# On Windows a file can't be renamed to a file that already exists
	os.remove(fontFilePath)
	os.rename(newFontFilePath, fontFilePath)

	print >> sys.stdout, "SVG table successfully added to %s" % fontFilePath


def validateSVGfiles(svgFilePathsList):
	"""
	Light validation of SVG files.
	Checks that there is an <svg> element.
	"""
	validatedPaths = []

	for filePath in svgFilePathsList:
		# skip hidden files (filenames that start with period)
		fileName = os.path.basename(filePath)
		if fileName[0] == '.':
			continue

		# read file
		data = readFile(filePath)

		# find <svg> blob
		svg = reSVGelement.search(data)
		if not svg:
			print "WARNING: Could not find <svg> element in the file. Skiping %s" % (filePath)
			continue

		validatedPaths.append(filePath)

	return validatedPaths


def getFontFormat(fontFilePath):
	# these lines were scavenged from fontTools
	f = open(fontFilePath, "rb")
	header = f.read(256)
	head = header[:4]
	f.close()
	if head == "OTTO":
		return "OTF"
	elif head in ("\0\1\0\0", "true"):
		return "TTF"
	return None


def run():
	fontFilePath = os.path.realpath(sys.argv[1])
	svgFolderPath = os.path.realpath(sys.argv[2])

	# Font file path
	if os.path.isfile(fontFilePath):
		if getFontFormat(fontFilePath) not in ["OTF", "TTF"]:
			print >> sys.stderr, "ERROR: The path is not a valid OTF or TTF font."
			return
	else:
		print >> sys.stderr, "ERROR: The path to the font is invalid."
		return

	# SVG folder path
	if os.path.isdir(svgFolderPath):
		svgFilePathsList = []
		for dirName, subdirList, fileList in os.walk(svgFolderPath): # Support nested folders
			for file in fileList:
				svgFilePathsList.append(os.path.join(dirName, file)) # Assemble the full paths, not just file names
	else:
		print >> sys.stderr, "ERROR: The path to the folder containing the SVG files is invalid."
		return

	# validate the SVGs
	svgFilePathsList = validateSVGfiles(svgFilePathsList)

	if not svgFilePathsList:
		print >> sys.stderr, "WARNING: No SVG files were found."
		return

	processFontFile(fontFilePath, svgFilePathsList)


if __name__ == "__main__":
	if len(sys.argv) != 3:
		print "To run this script type:\n  python %s <path to input OTF/TTF file>  <path to folder tree containing SVG files>" % sys.argv[0]
	else:
		run()