"""
Interpolate OpenType Layout tables (GDEF / GPOS / GSUB).
"""
from __future__ import print_function, division, absolute_import
from fontTools.misc.py23 import *
from fontTools.ttLib import TTFont
from fontTools.ttLib.tables import otTables as ot
from fontTools.ttLib.tables.DefaultTable import DefaultTable
from fontTools.varLib import designspace, models, builder
import os.path


def _all_equal(lst):
	it = iter(lst)
	v0 = next(it)
	for v in it:
		if v0 != v:
			return False
	return True

def _add_method(*clazzes, **kwargs):
	"""Returns a decorator function that adds a new method to one or
	more classes."""
	allowDefault = kwargs.get('allowDefaultTable', False)
	def wrapper(method):
		done = []
		for clazz in clazzes:
			if clazz in done: continue # Support multiple names of a clazz
			done.append(clazz)
			assert allowDefault or clazz != DefaultTable, 'Oops, table class not found.'
			assert method.__name__ not in clazz.__dict__, \
				"Oops, class '%s' has method '%s'." % (clazz.__name__, method.__name__)
			setattr(clazz, method.__name__, method)
		return None
	return wrapper

def mergeObjects(self, lst, merger):
	keys = vars(self).keys()
	assert all(vars(table).keys() == keys for table in lst)
	for key in keys:
		value = getattr(self, key)
		values = [getattr(table, key) for table in lst]
		mergeThings(value, values, merger)

def mergeLists(self, lst, merger):
	count = len(self)
	assert all(count == len(v) for v in lst), (count, [len(v) for v in lst])
	for value,values in zip(self, zip(*lst)):
		mergeThings(value, values, merger)

def mergeThings(self, lst, merger):
	clazz = type(self)
	assert all(type(item) == clazz for item in lst), lst
	mergerFunc = getattr(type(self), 'merge', None)
	if mergerFunc is None:
		if hasattr(self, '__dict__'):
			mergerFunc = mergeObjects
		elif isinstance(self, list):
			mergerFunc = mergeLists
		else:
			assert all(self == v for v in lst), lst
			return
	mergerFunc(self, lst, merger)

@_add_method(ot.Anchor)
def merge(self, lst, merger):
	XCoords = [a.XCoordinate for a in lst]
	YCoords = [a.YCoordinate for a in lst]
	model = merger.model
	location = merger.location
	self.XCoordinate = round(model.interpolateFromMasters(location, XCoords))
	self.YCoordinate = round(model.interpolateFromMasters(location, YCoords))

def _merge_OTL(font, merger, master_ttfs, axes, base_idx):

	print("Merging OpenType Layout tables")
	for tag in ('GPOS',):# 'GDEF', 'GSUB'):
		print('Merging', tag)
		mergeThings(font[tag], [m[tag] for m in master_ttfs], merger)


def main(args=None):

	import sys
	if args is None:
		args = sys.argv[1:]

	designspace_filename = args[0]
	locargs = args[1:]
	outfile = os.path.splitext(designspace_filename)[0] + '-instance.ttf'

	finder = lambda s: s.replace('master_ufo', 'master_ttf_interpolatable').replace('.ufo', '.ttf')

	loc = {}
	for arg in locargs:
		tag,val = arg.split('=')
		loc[tag] = float(val)
	print("Location:", loc)

	masters, instances = designspace.load(designspace_filename)
	base_idx = None
	for i,m in enumerate(masters):
		if 'info' in m and m['info']['copy']:
			assert base_idx is None
			base_idx = i
	assert base_idx is not None, "Cannot find 'base' master; Add <info> element to one of the masters in the .designspace document."

	from pprint import pprint
	print("Masters:")
	pprint(masters)
	print("Index of base master:", base_idx)

	print("Building GX")
	print("Loading TTF masters")
	basedir = os.path.dirname(designspace_filename)
	master_ttfs = [finder(os.path.join(basedir, m['filename'])) for m in masters]
	master_fonts = [TTFont(ttf_path) for ttf_path in master_ttfs]

	#font = master_fonts[base_idx]
	font = TTFont(master_ttfs[base_idx])

	master_locs = [o['location'] for o in masters]

	axis_tags = set(master_locs[0].keys())
	assert all(axis_tags == set(m.keys()) for m in master_locs)
	print("Axis tags:", axis_tags)
	print("Master positions:")
	pprint(master_locs)

	# Set up axes
	axes = {}
	for tag in axis_tags:
		default = master_locs[base_idx][tag]
		lower = min(m[tag] for m in master_locs)
		upper = max(m[tag] for m in master_locs)
		axes[tag] = (lower, default, upper)
	print("Axes:")
	pprint(axes)

	loc = models.normalizeLocation(loc, axes)
	# Location is normalized now
	print("Normalized location:", loc)

	# Normalize master locations
	master_locs = [models.normalizeLocation(m, axes) for m in master_locs]
	print("Normalized master positions:")
	print(master_locs)

	# Assume single-model for now.
	model = models.VariationModel(master_locs)
	assert 0 == model.mapping[base_idx]

	merger = lambda : None
	merger.model = model
	merger.location = loc

	print("Building variations tables")
	_merge_OTL(font, merger, master_fonts, axes, base_idx)

	print("Saving font", outfile)
	font.save(outfile)


if __name__ == "__main__":
	import sys
	if len(sys.argv) > 1:
		main()
		#sys.exit(0)
	import doctest, sys
	sys.exit(doctest.testmod().failed)