from __future__ import print_function, division, absolute_import
from fontTools.misc.psCharStrings import CFF2Subr
from fontTools.pens.t2CharStringPen import T2CharStringPen, t2c_round
from fontTools.cffLib.specializer import (commandsToProgram,
										  specializeCommands)
from fontTools.cffLib import maxStackLimit
from fontTools.varLib.models import allEqual


class MergeTypeError(TypeError):
	def __init__(self, point_type, pt_index, m_index, default_type, glyphName):
		self.error_msg = [
					"In glyph '{gname}' "
					"'{point_type}' at point index {pt_index} in master "
					"index {m_index} differs from the default font point "
					"type '{default_type}'"
					"".format(gname=glyphName,
							  point_type=point_type, pt_index=pt_index,
							  m_index=m_index, default_type=default_type)
					][0]
		super(MergeTypeError, self).__init__(self.error_msg)




def makeRoundNumberFunc(tolerance):
	if tolerance < 0:
		raise ValueError("Rounding tolerance must be positive")

	def roundNumber(val):
		return t2c_round(val, tolerance)

	return roundNumber


class CFF2CharStringMergePen(T2CharStringPen):
	"""Pen to merge Type 2 CharStrings.
	"""
	def __init__(self, default_commands,
				 glyphName, num_masters, master_idx, roundTolerance=0.5):
		super(
			CFF2CharStringMergePen,
			self).__init__(width=None,
						   glyphSet=None, CFF2=True,
						   roundTolerance=roundTolerance)
		self.pt_index = 0
		self._commands = default_commands
		self.m_index = master_idx
		self.num_masters = num_masters
		self.prev_move_idx = 0
		self.glyphName = glyphName
		self.roundNumber = makeRoundNumberFunc(roundTolerance)

	def _p(self, pt):
		""" Unlike T2CharstringPen, this class stores absolute values.
		This is to allow the logic in check_and_fix_closepath() to work,
		where the current or previous absolute point has to be compared to
		the path start-point.
		"""
		self._p0 = pt
		return list(self._p0)

	def add_point(self, point_type, pt_coords):
		if self.m_index == 0:
			self._commands.append([point_type, [pt_coords]])
		else:
			cmd = self._commands[self.pt_index]
			if cmd[0] != point_type:
				# Fix some issues that show up in some
				# CFF workflows, even when fonts are
				# topologically merge compatible.
				success, pt_coords = self.check_and_fix_flat_curve(
							cmd, point_type, pt_coords)
				if not success:
					success = self.check_and_fix_closepath(
							cmd, point_type, pt_coords)
					if success:
						# We may have incremented self.pt_index
						cmd = self._commands[self.pt_index]
						if cmd[0] != point_type:
							success = False
					if not success:
						raise MergeTypeError(point_type,
											 self.pt_index, len(cmd[1]),
											 cmd[0], self.glyphName)
			cmd[1].append(pt_coords)
		self.pt_index += 1

	def _moveTo(self, pt):
		pt_coords = self._p(pt)
		self.add_point('rmoveto', pt_coords)
		# I set prev_move_idx here because add_point()
		# can change self.pt_index.
		self.prev_move_idx = self.pt_index - 1

	def _lineTo(self, pt):
		pt_coords = self._p(pt)
		self.add_point('rlineto', pt_coords)

	def _curveToOne(self, pt1, pt2, pt3):
		_p = self._p
		pt_coords = _p(pt1)+_p(pt2)+_p(pt3)
		self.add_point('rrcurveto', pt_coords)

	def _closePath(self):
		pass

	def _endPath(self):
		pass

	def restart(self, region_idx):
		self.pt_index = 0
		self.m_index = region_idx
		self._p0 = (0, 0)

	def getCommands(self):
		return self._commands

	def reorder_blend_args(self, commands):
		"""
		We first re-order the master coordinate values.
		For a moveto to lineto, the args are now arranged as:
			[ [master_0 x,y], [master_1 x,y], [master_2 x,y] ]
		We re-arrange this to
		[	[master_0 x, master_1 x, master_2 x],
			[master_0 y, master_1 y, master_2 y]
		]
		We also make the value relative.
		If the master values are all the same, we collapse the list to
		as single value instead of a list.
		"""
		for cmd in commands:
			# arg[i] is the set of arguments for this operator from master i.
			args = cmd[1]
			m_args = zip(*args)
			# m_args[n] is now all num_master args for the i'th argument
			# for this operation.
			cmd[1] = m_args

		# Now convert from absolute to relative
		x0 = [0]*self.num_masters
		y0 = [0]*self.num_masters
		for cmd in self._commands:
			is_x = True
			coords = cmd[1]
			rel_coords = []
			for coord in coords:
				prev_coord = x0 if is_x else y0
				rel_coord = [pt[0] - pt[1] for pt in zip(coord, prev_coord)]

				if allEqual(rel_coord):
					rel_coord = rel_coord[0]
				rel_coords.append(rel_coord)
				if is_x:
					x0 = coord
				else:
					y0 = coord
				is_x = not is_x
			cmd[1] = rel_coords
		return commands

	@staticmethod
	def mergeCommandsToProgram(commands, var_model, round_func):
		"""
		Takes a commands list as returned by programToCommands() and
		converts it back to a T2CharString or CFF2Charstring program list. I
		need to use this rather than specialize.commandsToProgram, as the
		commands produced by CFF2CharStringMergePen initially contains a
		list of coordinate values, one for each master, wherever a single
		coordinate value is expected by the regular logic. The problem with
		doing using the specialize.py functions is that a commands list is
		expected to be a op name with its associated argument list. For the
		commands list here, some of the arguments may need to be converted
		to a new argument list and opcode.
		This version will convert each list of master arguments to a blend
		op and its arguments, and will also combine successive blend ops up
		to the stack limit.
		"""
		program = []
		for op, args in commands:
			num_args = len(args)
			# some of the args may be blend lists, and some may be
			# single coordinate values.
			i = 0
			stack_use = 0
			while i < num_args:
				arg = args[i]
				if not isinstance(arg, list):
					program.append(arg)
					i += 1
					stack_use += 1
				else:
					prev_stack_use = stack_use
					""" The arg is a tuple of blend values.
					These are each (master 0,master 1..master n)
					Combine as many successive tuples as we can,
					up to the max stack limit.
					"""
					num_masters = len(arg)
					blendlist = [arg]
					i += 1
					stack_use += 1 + num_masters  # 1 for the num_blends arg
					while (i < num_args) and isinstance(args[i], list):
						blendlist.append(args[i])
						i += 1
						stack_use += num_masters
						if stack_use + num_masters > maxStackLimit:
							# if we are here, max stack is is the CFF2 max stack.
							break
					num_blends = len(blendlist)
					# append the 'num_blends' default font values
					for arg in blendlist:
						if round_func:
							arg[0] = round_func(arg[0])
						program.append(arg[0])
					for arg in blendlist:
						# for each coordinate tuple, append the region deltas
						if len(arg) != 3:
							print(arg)
							import pdb
							pdb.set_trace()
						deltas = var_model.getDeltas(arg)
						if round_func:
							deltas = [round_func(delta) for delta in deltas]
						# First item in 'deltas' is the default master value;
						# for CFF2 data, that has already been written.
						program.extend(deltas[1:])
					program.append(num_blends)
					program.append('blend')
					stack_use = prev_stack_use + num_blends
			if op:
				program.append(op)
		return program


	def getCharString(self, private=None, globalSubrs=None,
					  var_model=None, optimize=True):
		commands = self._commands
		commands = self.reorder_blend_args(commands)
		if optimize:
			commands = specializeCommands(commands, generalizeFirst=False,
										  maxstack=maxStackLimit)
		program = self.mergeCommandsToProgram(commands, var_model=var_model,
									round_func=self.roundNumber)
		charString = CFF2Subr(program=program, private=private,
							  globalSubrs=globalSubrs)
		return charString