from fontTools import ttLib
from fontTools.ttLib.standardGlyphOrder import standardGlyphOrder
from fontTools.misc import sstruct
from fontTools.misc.textTools import bytechr, byteord, tobytes, tostr, safeEval, readHex
from . import DefaultTable
import sys
import struct
import array
import logging

log = logging.getLogger(__name__)

postFormat = """
	>
	formatType:			16.16F
	italicAngle:		16.16F		# italic angle in degrees
	underlinePosition:	h
	underlineThickness:	h
	isFixedPitch:		L
	minMemType42:		L			# minimum memory if TrueType font is downloaded
	maxMemType42:		L			# maximum memory if TrueType font is downloaded
	minMemType1:		L			# minimum memory if Type1 font is downloaded
	maxMemType1:		L			# maximum memory if Type1 font is downloaded
"""

postFormatSize = sstruct.calcsize(postFormat)


class table__p_o_s_t(DefaultTable.DefaultTable):

	def decompile(self, data, ttFont):
		sstruct.unpack(postFormat, data[:postFormatSize], self)
		data = data[postFormatSize:]
		if self.formatType == 1.0:
			self.decode_format_1_0(data, ttFont)
		elif self.formatType == 2.0:
			self.decode_format_2_0(data, ttFont)
		elif self.formatType == 3.0:
			self.decode_format_3_0(data, ttFont)
		elif self.formatType == 4.0:
			self.decode_format_4_0(data, ttFont)
		else:
			# supported format
			raise ttLib.TTLibError("'post' table format %f not supported" % self.formatType)

	def compile(self, ttFont):
		data = sstruct.pack(postFormat, self)
		if self.formatType == 1.0:
			pass # we're done
		elif self.formatType == 2.0:
			data = data + self.encode_format_2_0(ttFont)
		elif self.formatType == 3.0:
			pass # we're done
		elif self.formatType == 4.0:
			data = data + self.encode_format_4_0(ttFont)
		else:
			# supported format
			raise ttLib.TTLibError("'post' table format %f not supported" % self.formatType)
		return data

	def getGlyphOrder(self):
		"""This function will get called by a ttLib.TTFont instance.
		Do not call this function yourself, use TTFont().getGlyphOrder()
		or its relatives instead!
		"""
		if not hasattr(self, "glyphOrder"):
			raise ttLib.TTLibError("illegal use of getGlyphOrder()")
		glyphOrder = self.glyphOrder
		del self.glyphOrder
		return glyphOrder

	def decode_format_1_0(self, data, ttFont):
		self.glyphOrder = standardGlyphOrder[:ttFont["maxp"].numGlyphs]

	def decode_format_2_0(self, data, ttFont):
		numGlyphs, = struct.unpack(">H", data[:2])
		numGlyphs = int(numGlyphs)
		if numGlyphs > ttFont['maxp'].numGlyphs:
			# Assume the numGlyphs field is bogus, so sync with maxp.
			# I've seen this in one font, and if the assumption is
			# wrong elsewhere, well, so be it: it's hard enough to
			# work around _one_ non-conforming post format...
			numGlyphs = ttFont['maxp'].numGlyphs
		data = data[2:]
		indices = array.array("H")
		indices.frombytes(data[:2*numGlyphs])
		if sys.byteorder != "big": indices.byteswap()
		data = data[2*numGlyphs:]
		maxIndex = max(indices)
		self.extraNames = extraNames = unpackPStrings(data, maxIndex-257)
		self.glyphOrder = glyphOrder = [""] * int(ttFont['maxp'].numGlyphs)
		for glyphID in range(numGlyphs):
			index = indices[glyphID]
			if index > 257:
				try:
					name = extraNames[index-258]
				except IndexError:
					name = ""
			else:
				# fetch names from standard list
				name = standardGlyphOrder[index]
			glyphOrder[glyphID] = name
		self.build_psNameMapping(ttFont)

	def build_psNameMapping(self, ttFont):
		mapping = {}
		allNames = {}
		for i in range(ttFont['maxp'].numGlyphs):
			glyphName = psName = self.glyphOrder[i]
			if glyphName == "":
				glyphName = "glyph%.5d" % i
			if glyphName in allNames:
				# make up a new glyphName that's unique
				n = allNames[glyphName]
				while (glyphName + "#" + str(n)) in allNames:
					n += 1
				allNames[glyphName] = n + 1
				glyphName = glyphName + "#" + str(n)

			self.glyphOrder[i] = glyphName
			allNames[glyphName] = 1
			if glyphName != psName:
				mapping[glyphName] = psName

		self.mapping = mapping

	def decode_format_3_0(self, data, ttFont):
		# Setting self.glyphOrder to None will cause the TTFont object
		# try and construct glyph names from a Unicode cmap table.
		self.glyphOrder = None

	def decode_format_4_0(self, data, ttFont):
		from fontTools import agl
		numGlyphs = ttFont['maxp'].numGlyphs
		indices = array.array("H")
		indices.frombytes(data)
		if sys.byteorder != "big": indices.byteswap()
		# In some older fonts, the size of the post table doesn't match
		# the number of glyphs. Sometimes it's bigger, sometimes smaller.
		self.glyphOrder = glyphOrder = [''] * int(numGlyphs)
		for i in range(min(len(indices),numGlyphs)):
			if indices[i] == 0xFFFF:
				self.glyphOrder[i] = ''
			elif indices[i] in agl.UV2AGL:
				self.glyphOrder[i] = agl.UV2AGL[indices[i]]
			else:
				self.glyphOrder[i] = "uni%04X" % indices[i]
		self.build_psNameMapping(ttFont)

	def encode_format_2_0(self, ttFont):
		numGlyphs = ttFont['maxp'].numGlyphs
		glyphOrder = ttFont.getGlyphOrder()
		assert len(glyphOrder) == numGlyphs
		indices = array.array("H")
		extraDict = {}
		extraNames = self.extraNames = [
			n for n in self.extraNames if n not in standardGlyphOrder]
		for i in range(len(extraNames)):
			extraDict[extraNames[i]] = i
		for glyphID in range(numGlyphs):
			glyphName = glyphOrder[glyphID]
			if glyphName in self.mapping:
				psName = self.mapping[glyphName]
			else:
				psName = glyphName
			if psName in extraDict:
				index = 258 + extraDict[psName]
			elif psName in standardGlyphOrder:
				index = standardGlyphOrder.index(psName)
			else:
				index = 258 + len(extraNames)
				extraDict[psName] = len(extraNames)
				extraNames.append(psName)
			indices.append(index)
		if sys.byteorder != "big": indices.byteswap()
		return struct.pack(">H", numGlyphs) + indices.tobytes() + packPStrings(extraNames)

	def encode_format_4_0(self, ttFont):
		from fontTools import agl
		numGlyphs = ttFont['maxp'].numGlyphs
		glyphOrder = ttFont.getGlyphOrder()
		assert len(glyphOrder) == numGlyphs
		indices = array.array("H")
		for glyphID in glyphOrder:
			glyphID = glyphID.split('#')[0]
			if glyphID in agl.AGL2UV:
				indices.append(agl.AGL2UV[glyphID])
			elif len(glyphID) == 7 and glyphID[:3] == 'uni':
				indices.append(int(glyphID[3:],16))
			else:
				indices.append(0xFFFF)
		if sys.byteorder != "big": indices.byteswap()
		return indices.tobytes()

	def toXML(self, writer, ttFont):
		formatstring, names, fixes = sstruct.getformat(postFormat)
		for name in names:
			value = getattr(self, name)
			writer.simpletag(name, value=value)
			writer.newline()
		if hasattr(self, "mapping"):
			writer.begintag("psNames")
			writer.newline()
			writer.comment("This file uses unique glyph names based on the information\n"
						"found in the 'post' table. Since these names might not be unique,\n"
						"we have to invent artificial names in case of clashes. In order to\n"
						"be able to retain the original information, we need a name to\n"
						"ps name mapping for those cases where they differ. That's what\n"
						"you see below.\n")
			writer.newline()
			items = sorted(self.mapping.items())
			for name, psName in items:
				writer.simpletag("psName", name=name, psName=psName)
				writer.newline()
			writer.endtag("psNames")
			writer.newline()
		if hasattr(self, "extraNames"):
			writer.begintag("extraNames")
			writer.newline()
			writer.comment("following are the name that are not taken from the standard Mac glyph order")
			writer.newline()
			for name in self.extraNames:
				writer.simpletag("psName", name=name)
				writer.newline()
			writer.endtag("extraNames")
			writer.newline()
		if hasattr(self, "data"):
			writer.begintag("hexdata")
			writer.newline()
			writer.dumphex(self.data)
			writer.endtag("hexdata")
			writer.newline()

	def fromXML(self, name, attrs, content, ttFont):
		if name not in ("psNames", "extraNames", "hexdata"):
			setattr(self, name, safeEval(attrs["value"]))
		elif name == "psNames":
			self.mapping = {}
			for element in content:
				if not isinstance(element, tuple):
					continue
				name, attrs, content = element
				if name == "psName":
					self.mapping[attrs["name"]] = attrs["psName"]
		elif name == "extraNames":
			self.extraNames = []
			for element in content:
				if not isinstance(element, tuple):
					continue
				name, attrs, content = element
				if name == "psName":
					self.extraNames.append(attrs["name"])
		else:
			self.data = readHex(content)


def unpackPStrings(data, n):
        # extract n Pascal strings from data.
        # if there is not enough data, use ""

	strings = []
	index = 0
	dataLen = len(data)

	for _ in range(n):
		if dataLen <= index:
			length = 0
		else:
			length = byteord(data[index])
		index += 1

		if dataLen <= index + length - 1:
			name = ""
		else:
			name = tostr(data[index:index+length], encoding="latin1")
		strings.append (name)
		index += length

	if index < dataLen:
		log.warning("%d extra bytes in post.stringData array", dataLen - index)

	elif dataLen < index:
		log.warning("not enough data in post.stringData array")

	return strings


def packPStrings(strings):
	data = b""
	for s in strings:
		data = data + bytechr(len(s)) + tobytes(s, encoding="latin1")
	return data
