"""
Merge OpenType Layout tables (GDEF / GPOS / GSUB).
"""
from __future__ import print_function, division, absolute_import
from fontTools.misc.py23 import *
from fontTools.ttLib.tables import otTables as ot
from fontTools.ttLib.tables import otBase as otBase
from fontTools.ttLib.tables.DefaultTable import DefaultTable
from fontTools.varLib import builder
from functools import reduce


class Merger(object):

	def __init__(self, font=None):
		self.font = font

	@classmethod
	def merger(celf, clazzes, attrs=(None,)):
		assert celf != Merger, 'Subclass Merger instead.'
		if 'mergers' not in celf.__dict__:
			celf.mergers = {}
		if type(clazzes) == type:
			clazzes = (clazzes,)
		if type(attrs) == str:
			attrs = (attrs,)
		def wrapper(method):
			assert method.__name__ == 'merge'
			done = []
			for clazz in clazzes:
				if clazz in done: continue # Support multiple names of a clazz
				done.append(clazz)
				mergers = celf.mergers.setdefault(clazz, {})
				for attr in attrs:
					assert attr not in mergers, \
						"Oops, class '%s' has merge function for '%s' defined already." % (clazz.__name__, attr)
					mergers[attr] = method
			return None
		return wrapper

	@classmethod
	def mergersFor(celf, thing, _default={}):
		typ = type(thing)

		for celf in celf.mro():

			mergers = getattr(celf, 'mergers', None)
			if mergers is None:
				break;

			m = celf.mergers.get(typ, None)
			if m is not None:
				return m

		return _default

	def mergeObjects(self, out, lst, exclude=()):
		keys = sorted(vars(out).keys())
		assert all(keys == sorted(vars(v).keys()) for v in lst), \
			(keys, [sorted(vars(v).keys()) for v in lst])
		mergers = self.mergersFor(out)
		defaultMerger = mergers.get('*', self.__class__.mergeThings)
		try:
			for key in keys:
				if key in exclude: continue
				value = getattr(out, key)
				values = [getattr(table, key) for table in lst]
				mergerFunc = mergers.get(key, defaultMerger)
				mergerFunc(self, value, values)
		except Exception as e:
			e.args = e.args + ('.'+key,)
			raise

	def mergeLists(self, out, lst):
		count = len(out)
		assert all(count == len(v) for v in lst), (count, [len(v) for v in lst])
		for i,(value,values) in enumerate(zip(out, zip(*lst))):
			try:
				self.mergeThings(value, values)
			except Exception as e:
				e.args = e.args + ('[%d]' % i,)
				raise

	def mergeThings(self, out, lst):
		clazz = type(out)
		try:
			assert all(type(item) == clazz for item in lst), (out, lst)
			mergerFunc = self.mergersFor(out).get(None, None)
			if mergerFunc is not None:
				mergerFunc(self, out, lst)
			elif hasattr(out, '__dict__'):
				self.mergeObjects(out, lst)
			elif isinstance(out, list):
				self.mergeLists(out, lst)
			else:
				assert all(out == v for v in lst), (out, lst)
		except Exception as e:
			e.args = e.args + (clazz.__name__,)
			raise

	def mergeTables(self, font, master_ttfs, axes, base_idx, tables):

		for tag in tables:
			if tag not in font: continue
			print('Merging', tag)
			self.mergeThings(font[tag], [m[tag] for m in master_ttfs])

#
# Aligning merger
#
class AligningMerger(Merger):
	pass

def _SinglePosUpgradeToFormat2(self):
	if self.Format == 2: return self

	ret = ot.SinglePos()
	ret.Format = 2
	ret.Coverage = self.Coverage
	ret.ValueFormat = self.ValueFormat
	ret.Value = [self.Value for g in ret.Coverage.glyphs]
	ret.ValueCount = len(ret.Value)

	return ret

def _merge_GlyphOrders(font, lst, values_lst=None, default=None):
	"""Takes font and list of glyph lists (must be sorted by glyph id), and returns
	two things:
	- Combined glyph list,
	- If values_lst is None, return input glyph lists, but padded with None when a glyph
	  was missing in a list.  Otherwise, return values_lst list-of-list, padded with None
	  to match combined glyph lists.
	"""
	if values_lst is None:
		dict_sets = [set(l) for l in lst]
	else:
		dict_sets = [{g:v for g,v in zip(l,vs)} for l,vs in zip(lst,values_lst)]
	combined = set()
	combined.update(*dict_sets)

	sortKey = font.getReverseGlyphMap().__getitem__
	order = sorted(combined, key=sortKey)
	# Make sure all input glyphsets were in proper order
	assert all(sorted(vs, key=sortKey) == vs for vs in lst)
	del combined

	paddedValues = None
	if values_lst is None:
		padded = [[glyph if glyph in dict_set else default
			   for glyph in order]
			  for dict_set in dict_sets]
	else:
		assert len(lst) == len(values_lst)
		padded = [[dict_set[glyph] if glyph in dict_set else default
			   for glyph in order]
			  for dict_set in dict_sets]
	return order, padded

def _Lookup_SinglePos_get_effective_value(self, glyph):
	if self is None: return None
	subtables = self.SubTable
	for self in subtables:
		if self is None or \
		   type(self) != ot.SinglePos or \
		   self.Coverage is None or \
		   glyph not in self.Coverage.glyphs:
			continue
		if self.Format == 1:
			return self.Value
		elif self.Format == 2:
			return self.Value[self.Coverage.glyphs.index(glyph)]
		else:
			assert 0
	return None

def _Lookup_PairPos_get_effective_value_pair(self, firstGlyph, secondGlyph):
	if self is None: return None
	subtables = self.SubTable
	for self in subtables:
		if self is None or \
		   type(self) != ot.PairPos or \
		   self.Coverage is None or \
		   firstGlyph not in self.Coverage.glyphs:
			continue
		if self.Format == 1:
			ps = self.PairSet[self.Coverage.glyphs.index(firstGlyph)]
			pvr = ps.PairValueRecord
			for rec in pvr: # TODO Speed up
				if rec.SecondGlyph == secondGlyph:
					return rec
			continue
		elif self.Format == 2:
			klass1 = self.ClassDef1.classDefs.get(firstGlyph, 0)
			klass2 = self.ClassDef2.classDefs.get(secondGlyph, 0)
			return self.Class1Record[klass1].Class2Record[klass2]
		else:
			assert 0
	return None

@AligningMerger.merger(ot.SinglePos)
def merge(merger, self, lst):
	self.ValueFormat = valueFormat = reduce(int.__or__, [l.ValueFormat for l in lst], 0)
	assert valueFormat & ~0xF == 0, valueFormat

	# If all have same coverage table and all are format 1,
	if all(v.Format == 1 for v in lst) and all(self.Coverage.glyphs == v.Coverage.glyphs for v in lst):
		self.Value = otBase.ValueRecord(valueFormat)
		merger.mergeThings(self.Value, [v.Value for v in lst])
		return

	# Upgrade everything to Format=2
	self.Format = 2
	lst = [_SinglePosUpgradeToFormat2(v) for v in lst]

	# Align them
	glyphs, padded = _merge_GlyphOrders(merger.font,
					    [v.Coverage.glyphs for v in lst],
					    [v.Value for v in lst])

	self.Coverage.glyphs = glyphs
	self.Value = [otBase.ValueRecord(valueFormat) for g in glyphs]
	self.ValueCount = len(self.Value)

	for i,values in enumerate(padded):
		for j,glyph in enumerate(glyphs):
			if values[j] is not None: continue
			# Fill in value from other subtables
			v = _Lookup_SinglePos_get_effective_value(merger.lookups[i], glyph)
			if v is None:
				v = otBase.ValueRecord(valueFormat)
			values[j] = v

	merger.mergeLists(self.Value, padded)

	# Merge everything else; though, there shouldn't be anything else. :)
	merger.mergeObjects(self, lst,
			    exclude=('Format', 'Coverage', 'ValueRecord', 'Value', 'ValueCount'))

@AligningMerger.merger(ot.PairSet)
def merge(merger, self, lst):
	# Align them
	glyphs, padded = _merge_GlyphOrders(merger.font,
				[[v.SecondGlyph for v in vs.PairValueRecord] for vs in lst],
				[vs.PairValueRecord for vs in lst])

	self.PairValueRecord = pvrs = []
	for glyph in glyphs:
		pvr = ot.PairValueRecord()
		pvr.SecondGlyph = glyph
		pvr.Value1 = otBase.ValueRecord(merger.valueFormat1) if merger.valueFormat1 else None
		pvr.Value2 = otBase.ValueRecord(merger.valueFormat2) if merger.valueFormat2 else None
		pvrs.append(pvr)
	self.PairValueCount = len(self.PairValueRecord)

	for i,values in enumerate(padded):
		for j,glyph in enumerate(glyphs):
			# Fill in value from other subtables
			v = ot.PairValueRecord()
			v.SecondGlyph = glyph
			if values[j] is not None:
				vpair = values[j]
			else:
				vpair = _Lookup_PairPos_get_effective_value_pair(merger.lookups[i], self._firstGlyph, glyph)
			if vpair is None:
				v1, v2 = None, None
			else:
				v1, v2 = vpair.Value1, vpair.Value2
			v.Value1 = otBase.ValueRecord(merger.valueFormat1, src=v1) if merger.valueFormat1 else None
			v.Value2 = otBase.ValueRecord(merger.valueFormat2, src=v2) if merger.valueFormat2 else None
			values[j] = v
	del self._firstGlyph

	merger.mergeLists(self.PairValueRecord, padded)

@AligningMerger.merger(ot.PairPos)
def merge(merger, self, lst):
	# TODO Support differing ValueFormats.
	merger.valueFormat1 = self.ValueFormat1
	merger.valueFormat2 = self.ValueFormat2

	if self.Format == 2:
		# Everything must match; we don't support smart merge yet.
		merger.mergeObjects(self, lst)
		del merger.valueFormat1, merger.valueFormat2
		return

	assert self.Format == 1
	# Merge everything else; makes sure Format is the same.
	merger.mergeObjects(self, lst,
			    exclude=('Coverage',
				     'PairSet', 'PairSetCount'))

	empty = ot.PairSet()
	empty.PairValueRecord = []
	empty.PairValueCount = 0

	# Align them
	glyphs, padded = _merge_GlyphOrders(merger.font,
					    [v.Coverage.glyphs for v in lst],
					    [v.PairSet for v in lst],
					    default=empty)

	self.Coverage.glyphs = glyphs
	self.PairSet = [ot.PairSet() for g in glyphs]
	self.PairSetCount = len(self.PairSet)
	for glyph, ps in zip(glyphs, self.PairSet):
		ps._firstGlyph = glyph

	merger.mergeLists(self.PairSet, padded)

	del merger.valueFormat1, merger.valueFormat2

	# Now examine the list of value records, and update to the union of format values,
	# as merge might have created new values.
	vf1 = 0
	vf2 = 0
	if self.Format == 1:
		for pairSet in self.PairSet:
			for pairValueRecord in pairSet.PairValueRecord:
				pv1 = pairValueRecord.Value1
				if pv1 is not None:
					vf1 |= pv1.getFormat()
				pv2 = pairValueRecord.Value2
				if pv2 is not None:
					vf2 |= pv2.getFormat()
	elif self.Format == 2:
		for class1Record in self.Class1Record:
			for class2Record in class1Record.Class2Record:
				pv1 = class2Record.Value1
				if pv1 is not None:
					vf1 |= pv1.getFormat()
				pv2 = class2Record.Value2
				if pv2 is not None:
					vf2 |= pv2.getFormat()
	self.ValueFormat1 = vf1
	self.ValueFormat2 = vf2


def _PairSet_merge_overlay(lst, font):
	self = ot.PairSet()
	self.Coverage = ot.Coverage()

	# Align them
	glyphs, padded = _merge_GlyphOrders(font,
				[[v.SecondGlyph for v in vs.PairValueRecord] for vs in lst],
				[vs.PairValueRecord for vs in lst])

	self.Coverage.glyphs = glyphs
	self.PairValueRecord = pvrs = []
	for values in zip(*padded):
		for v in values:
			if v is not None:
				pvrs.append(v)
				break
		else:
			assert False
	self.PairValueCount = len(self.PairValueRecord)

	return self

def _Lookup_PairPosFormat1_subtables_merge_overlay(lst, font):
	self = ot.PairPos()
	self.Format = 1
	self.Coverage = ot.Coverage()
	self.ValueFormat1 = reduce(int.__or__, [l.ValueFormat1 for l in lst], 0)
	self.ValueFormat2 = reduce(int.__or__, [l.ValueFormat2 for l in lst], 0)

	# Align them
	glyphs, padded = _merge_GlyphOrders(font,
					    [v.Coverage.glyphs for v in lst],
					    [v.PairSet for v in lst])

	self.Coverage.glyphs = glyphs
	self.PairSet = [_PairSet_merge_overlay([v for v in values if v is not None], font)
		        for values in zip(*padded)]
	self.PairSetCount = len(self.PairSet)
	return self

def _Lookup_PairPos_subtables_canonicalize(lst, font):
	"""Merges multiple Format1 subtables at the beginning of lst.  Returns new list."""
	head = []
	tail = []
	it = iter(lst)
	for subtable in it:
		if subtable.Format == 1:
			head.append(subtable)
			continue
		tail.append(subtable)
		break
	tail.extend(it)
	# TODO Only do this if at least one font has a Format1.
	tail.insert(0, _Lookup_PairPosFormat1_subtables_merge_overlay(head, font))
	return tail

@AligningMerger.merger(ot.Lookup)
def merge(merger, self, lst):
	merger.lookups = lst

	exclude = []
	if self.SubTable and isinstance(self.SubTable[0], ot.PairPos):
		# AFDKO and feaLib sometimes generate two Format1 subtables instead of one.
		# Merge those before continuing.
		# https://github.com/fonttools/fonttools/issues/719
		self.SubTable = _Lookup_PairPos_subtables_canonicalize(self.SubTable, merger.font)
		subtables = [_Lookup_PairPos_subtables_canonicalize(l.SubTable, merger.font) for l in lst]
		merger.mergeLists(self.SubTable, subtables)
		self.SubTableCount = len(self.SubTable)
		exclude.extend(['SubTable', 'SubTableCount'])

	merger.mergeObjects(self, lst, exclude=exclude)

	del merger.lookups

#
# InstancerMerger
#
class InstancerMerger(AligningMerger):

	def __init__(self, font, model, location):
		Merger.__init__(self, font)
		self.model = model
		self.location = location

@InstancerMerger.merger(ot.Anchor)
def merge(merger, self, lst):
	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))

@InstancerMerger.merger(otBase.ValueRecord)
def merge(merger, self, lst):
	model = merger.model
	location = merger.location
	# TODO Handle differing valueformats
	for name, tableName in [('XAdvance','XAdvDevice'),
				('YAdvance','YAdvDevice'),
				('XPlacement','XPlaDevice'),
				('YPlacement','YPlaDevice')]:

		assert not hasattr(self, tableName)

		if hasattr(self, name):
			values = [getattr(a, name, 0) for a in lst]
			value = round(model.interpolateFromMasters(location, values))
			setattr(self, name, value)


#
# VariationMerger
#

class VariationMerger(AligningMerger):

	def __init__(self, model, axisTags, font):
		Merger.__init__(self, font)
		self.model = model
		self.store_builder = builder.OnlineVarStoreBuilder(axisTags)
		self.store_builder.setModel(model)

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

def buildVarDevTable(store_builder, master_values):
	if _all_equal(master_values):
		return None
	varIdx = store_builder.storeMasters(master_values)
	return builder.buildVarDevTable(varIdx)

@VariationMerger.merger(ot.Anchor)
def merge(merger, self, lst):
	assert self.Format == 1
	XDeviceTable = buildVarDevTable(merger.store_builder, [a.XCoordinate for a in lst])
	YDeviceTable = buildVarDevTable(merger.store_builder, [a.YCoordinate for a in lst])
	if XDeviceTable or YDeviceTable:
		self.Format = 3
		self.XDeviceTable = XDeviceTable
		self.YDeviceTable = YDeviceTable

@VariationMerger.merger(otBase.ValueRecord)
def merge(merger, self, lst):
	for name, tableName in [('XAdvance','XAdvDevice'),
				('YAdvance','YAdvDevice'),
				('XPlacement','XPlaDevice'),
				('YPlacement','YPlaDevice')]:

		if hasattr(self, name):
			deviceTable = buildVarDevTable(merger.store_builder,
						       [getattr(a, name, 0) for a in lst])
			if deviceTable:
				setattr(self, tableName, deviceTable)