"""
Module for dealing with 'gvar'-style font variations, also known as run-time
interpolation.

The ideas here are very similar to MutatorMath.  There is even code to read
MutatorMath .designspace files.

For now, if you run this file on a designspace file, it tries to find
ttf-interpolatable files for the masters and build a GX variation font from
them.  Such ttf-interpolatable and designspace files can be generated from
a Glyphs source, eg., using noto-source as an example:

  $ fontmake -o ttf-interpolatable -g NotoSansArabic-MM.glyphs

Then you can make a GX font this way:

  $ python fonttools/Lib/fontTools/varLib/__init__.py master_ufo/NotoSansArabic.designspace

API *will* change in near future.
"""
from __future__ import print_function, division, absolute_import
from fontTools.misc.py23 import *
from fontTools.ttLib import TTFont, newTable
from fontTools.ttLib.tables._n_a_m_e import NameRecord
from fontTools.ttLib.tables._f_v_a_r import Axis, NamedInstance
from fontTools.ttLib.tables._g_l_y_f import GlyphCoordinates
from fontTools.ttLib.tables._g_v_a_r import GlyphVariation
from fontTools.ttLib.tables import otTables as ot
from fontTools.varLib import builder
import warnings
try:
	import xml.etree.cElementTree as ET
except ImportError:
	import xml.etree.ElementTree as ET
import os.path


#
# Variation space, aka design space, model
#

def supportScalar(location, support):
	"""Returns the scalar multiplier at location, for a master
	with support.
	>>> supportScalar({}, {})
	1.0
	>>> supportScalar({'wght':.2}, {})
	1.0
	>>> supportScalar({'wght':.2}, {'wght':(0,2,3)})
	0.1
	>>> supportScalar({'wght':2.5}, {'wght':(0,2,4)})
	0.75
	"""
	scalar = 1.
	for axis,(lower,peak,upper) in support.items():
		if axis not in location:
			scalar = 0.
			break
		v = location[axis]
		if v == peak:
			continue
		if v <= lower or upper <= v:
			scalar = 0.
			break;
		if v < peak:
			scalar *= (v - lower) / (peak - lower)
		else: # v > peak
			scalar *= (v - upper) / (peak - upper)
	return scalar


class VariationModel(object):

	"""
	Locations must be in normalized space.  Ie. base master
	is at origin (0).
	>>> from pprint import pprint
	>>> locations = [ \
	{'wght':100}, \
	{'wght':-100}, \
	{'wght':-180}, \
	{'wdth':+.3}, \
	{'wght':+120,'wdth':.3}, \
	{'wght':+120,'wdth':.2}, \
	{}, \
	{'wght':+180,'wdth':.3}, \
	{'wght':+180}, \
	]
	>>> model = VariationModel(locations, axisOrder=['wght'])
	>>> pprint(model.locations)
	[{},
	 {'wght': -100},
	 {'wght': -180},
	 {'wght': 100},
	 {'wght': 180},
	 {'wdth': 0.3},
	 {'wdth': 0.3, 'wght': 180},
	 {'wdth': 0.3, 'wght': 120},
	 {'wdth': 0.2, 'wght': 120}]
	>>> pprint(model.deltaWeights)
	[{},
	 {0: 1.0},
	 {0: 1.0},
	 {0: 1.0},
	 {0: 1.0},
	 {0: 1.0},
	 {0: 1.0, 4: 1.0, 5: 1.0},
	 {0: 1.0, 3: 0.75, 4: 0.25, 5: 1.0, 6: 0.25},
	 {0: 1.0,
	  3: 0.75,
	  4: 0.25,
	  5: 0.6666666666666667,
	  6: 0.16666666666666669,
	  7: 0.6666666666666667}]
	"""

	def __init__(self, locations, axisOrder=[]):
		locations = [{k:v for k,v in loc.items() if v != 0.} for loc in locations]
		keyFunc = self.getMasterLocationsSortKeyFunc(locations, axisOrder=axisOrder)
		axisPoints = keyFunc.axisPoints
		self.locations = sorted(locations, key=keyFunc)
		# TODO Assert that locations are unique.
		self.mapping = [self.locations.index(l) for l in locations] # Mapping from user's master order to our master order
		self.reverseMapping = [locations.index(l) for l in self.locations] # Reverse of above

		self._computeMasterSupports(axisPoints)

	@staticmethod
	def getMasterLocationsSortKeyFunc(locations, axisOrder=[]):
		assert {} in locations, "Base master not found."
		axisPoints = {}
		for loc in locations:
			if len(loc) != 1:
				continue
			axis = next(iter(loc))
			value = loc[axis]
			if axis not in axisPoints:
				axisPoints[axis] = {0}
			assert value not in axisPoints[axis]
			axisPoints[axis].add(value)

		def getKey(axisPoints, axisOrder):
			def sign(v):
				return -1 if v < 0 else +1 if v > 0 else 0
			def key(loc):
				rank = len(loc)
				onPointAxes = [axis for axis,value in loc.items() if value in axisPoints[axis]]
				orderedAxes = [axis for axis in axisOrder if axis in loc]
				orderedAxes.extend([axis for axis in sorted(loc.keys()) if axis not in axisOrder])
				return (
					rank, # First, order by increasing rank
					-len(onPointAxes), # Next, by decreasing number of onPoint axes
					tuple(axisOrder.index(axis) if axis in axisOrder else 0x10000 for axis in orderedAxes), # Next, by known axes
					tuple(orderedAxes), # Next, by all axes
					tuple(sign(loc[axis]) for axis in orderedAxes), # Next, by signs of axis values
					tuple(abs(loc[axis]) for axis in orderedAxes), # Next, by absolute value of axis values
				)
			return key

		ret = getKey(axisPoints, axisOrder)
		ret.axisPoints = axisPoints
		return ret

	@staticmethod
	def lowerBound(value, lst):
		if any(v < value for v in lst):
			return max(v for v in lst if v < value)
		else:
			return value
	@staticmethod
	def upperBound(value, lst):
		if any(v > value for v in lst):
			return min(v for v in lst if v > value)
		else:
			return value

	def _computeMasterSupports(self, axisPoints):
		supports = []
		deltaWeights = []
		locations = self.locations
		for i,loc in enumerate(locations):
			box = {}

			# Account for axisPoints first
			for axis,values in axisPoints.items():
				if not axis in loc:
					continue
				locV = loc[axis]
				box[axis] = (self.lowerBound(locV, values), locV, self.upperBound(locV, values))

			locAxes = set(loc.keys())
			# Walk over previous masters now
			for j,m in enumerate(locations[:i]):
				# Master with extra axes do not participte
				if not set(m.keys()).issubset(locAxes):
					continue
				# If it's NOT in the current box, it does not participate
				relevant = True
				for axis, (lower,_,upper) in box.items():
					if axis in m and not (lower < m[axis] < upper):
						relevant = False
						break
				if not relevant:
					continue
				# Split the box for new master
				for axis,val in m.items():
					assert axis in box
					lower,locV,upper = box[axis]
					if val < locV:
						lower = val
					elif locV < val:
						upper = val
					box[axis] = (lower,locV,upper)
			supports.append(box)

			deltaWeight = {}
			# Walk over previous masters now, populate deltaWeight
			for j,m in enumerate(locations[:i]):
				scalar = supportScalar(loc, supports[j])
				if scalar:
					deltaWeight[j] = scalar
			deltaWeights.append(deltaWeight)

		self.supports = supports
		self.deltaWeights = deltaWeights

	def getDeltas(self, masterValues):
		count = len(self.locations)
		assert len(masterValues) == len(self.deltaWeights)
		mapping = self.reverseMapping
		out = []
		for i,weights in enumerate(self.deltaWeights):
			delta = masterValues[mapping[i]]
			for j,weight in weights.items():
				delta -= out[j] * weight
			out.append(delta)
		return out

	def interpolateFromDeltas(self, loc, deltas):
		v = None
		supports = self.supports
		assert len(deltas) == len(supports)
		for i,(delta,support) in enumerate(zip(deltas, supports)):
			scalar = supportScalar(loc, support)
			if not scalar: continue
			contribution = delta * scalar
			if i == 0:
				v = contribution
			else:
				v += contribution
		return v

	def interpolateFromMasters(self, loc, masterValues):
		deltas = self.getDeltas(masterValues)
		return self.interpolateFromDeltas(loc, deltas)

#
# .designspace routines
#

def _xmlParseLocation(et):
	loc = {}
	for dim in et.find('location'):
		assert dim.tag == 'dimension'
		name = dim.attrib['name']
		value = float(dim.attrib['xvalue'])
		assert name not in loc
		loc[name] = value
	return loc

def _designspace_load(et):
	base_idx = None
	masters = []
	ds = et.getroot()
	for master in ds.find('sources'):
		name = master.attrib['name']
		filename = master.attrib['filename']
		isBase = master.find('info')
		if isBase is not None:
			assert base_idx is None
			base_idx = len(masters)
		loc = _xmlParseLocation(master)
		masters.append((filename, loc, name))

	instances = []
	for instance in ds.find('instances'):
		name = master.attrib['name']
		family = instance.attrib['familyname']
		style = instance.attrib['stylename']
		filename = instance.attrib['filename']
		loc = _xmlParseLocation(instance)
		instances.append((filename, loc, name, family, style))

	return masters, instances, base_idx

def designspace_load(filename):
	return _designspace_load(ET.parse(filename))

def designspace_loads(string):
	return _designspace_load(ET.fromstring(string))


#
# Creation routines
#

# TODO: Move to name table proper; also, is mac_roman ok for ASCII names?
def _AddName(font, name):
	"""(font, "Bold") --> NameRecord"""
	nameTable = font.get("name")
	namerec = NameRecord()
	namerec.nameID = 1 + max([n.nameID for n in nameTable.names] + [256])
	namerec.string = name.encode("mac_roman")
	namerec.platformID, namerec.platEncID, namerec.langID = (1, 0, 0)
	nameTable.names.append(namerec)
	return namerec

# Move to fvar table proper?
def _add_fvar(font, axes, instances):
	assert "fvar" not in font
	font['fvar'] = fvar = newTable('fvar')

	for tag in sorted(axes.keys()):
		axis = Axis()
		axis.axisTag = tag
		name, axis.minValue, axis.defaultValue, axis.maxValue = axes[tag]
		axis.nameID = _AddName(font, name).nameID
		fvar.axes.append(axis)

	for name, coordinates in instances:
		inst = NamedInstance()
		inst.nameID = _AddName(font, name).nameID
		inst.coordinates = coordinates
		fvar.instances.append(inst)

# TODO Move to glyf or gvar table proper
def _GetCoordinates(font, glyphName):
	"""font, glyphName --> glyph coordinates as expected by "gvar" table

	The result includes four "phantom points" for the glyph metrics,
	as mandated by the "gvar" spec.
	"""
	glyf = font["glyf"]
	if glyphName not in glyf.glyphs: return None
	glyph = glyf[glyphName]
	if glyph.isComposite():
		coord = GlyphCoordinates([(getattr(c, 'x', 0),getattr(c, 'y', 0)) for c in glyph.components])
		control = [c.glyphName for c in glyph.components]
	else:
		allData = glyph.getCoordinates(glyf)
		coord = allData[0]
		control = allData[1:]

	# Add phantom points for (left, right, top, bottom) positions.
	horizontalAdvanceWidth, leftSideBearing = font["hmtx"].metrics[glyphName]
	if not hasattr(glyph, 'xMin'):
		glyph.recalcBounds(glyf)
	leftSideX = glyph.xMin - leftSideBearing
	rightSideX = leftSideX + horizontalAdvanceWidth
	# XXX these are incorrect.  Load vmtx and fix.
	topSideY = glyph.yMax
	bottomSideY = -glyph.yMin
	coord = coord.copy()
	coord.extend([(leftSideX, 0),
	              (rightSideX, 0),
	              (0, topSideY),
	              (0, bottomSideY)])

	return coord, control

# TODO Move to glyf or gvar table proper
def _SetCoordinates(font, glyphName, coord):
	glyf = font["glyf"]
	assert glyphName in glyf.glyphs
	glyph = glyf[glyphName]

	# Handle phantom points for (left, right, top, bottom) positions.
	assert len(coord) >= 4
	if not hasattr(glyph, 'xMin'):
		glyph.recalcBounds(glyf)
	leftSideX = coord[-4][0]
	rightSideX = coord[-3][0]
	topSideY = coord[-2][1]
	bottomSideY = coord[-1][1]

	for _ in range(4):
		del coord[-1]

	if glyph.isComposite():
		assert len(coord) == len(glyph.components)
		for p,comp in zip(coord, glyph.components):
			if hasattr(comp, 'x'):
				comp.x,comp.y = p
	elif glyph.numberOfContours is 0:
		assert len(coord) == 0
	else:
		assert len(coord) == len(glyph.coordinates)
		glyph.coordinates = coord

	glyph.recalcBounds(glyf)

	horizontalAdvanceWidth = rightSideX - leftSideX
	leftSideBearing = glyph.xMin - leftSideX
	# XXX Handle vertical
	# XXX Remove the round when https://github.com/behdad/fonttools/issues/593 is fixed
	font["hmtx"].metrics[glyphName] = int(round(horizontalAdvanceWidth)), int(round(leftSideBearing))


def _build_model(axes, master_locs, base_idx):

	# Make copies for modification
	master_locs = [l.copy() for l in master_locs]

	axis_tags = axes.keys()

	# Normalize master locations. TODO Move to a separate function.
	for tag,(name,lower,default,upper) in axes.items():
		for l in master_locs:
			v = l[tag]
			if v == default:
				v = 0
			elif v < default:
				v = (v - default) / (default - lower)
			else:
				v = (v - default) / (upper - default)
			l[tag] = v
	# Locations are normalized now

	print("Normalized master positions:")
	print(master_locs)

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

	return model


def _add_gvar(font, model, master_ttfs):

	print("Generating gvar")
	assert "gvar" not in font
	gvar = font["gvar"] = newTable('gvar')
	gvar.version = 1
	gvar.reserved = 0
	gvar.variations = {}

	for glyph in font.getGlyphOrder():

		allData = [_GetCoordinates(m, glyph) for m in master_ttfs]
		allCoords = [d[0] for d in allData]
		allControls = [d[1] for d in allData]
		control = allControls[0]
		if (any(c != control for c in allControls)):
			warnings.warn("glyph %s has incompatible masters; skipping" % glyph)
			continue
		del allControls

		# Update gvar
		gvar.variations[glyph] = []
		deltas = model.getDeltas(allCoords)
		supports = model.supports
		assert len(deltas) == len(supports)
		for i,(delta,support) in enumerate(zip(deltas[1:], supports[1:])):
			var = GlyphVariation(support, delta)
			gvar.variations[glyph].append(var)

def _add_HVAR(font, model, master_ttfs):

	print("Generating HVAR")

	hAdvanceDeltas = {}
	metricses = [m["hmtx"].metrics for m in master_ttfs]
	for glyph in font.getGlyphOrder():
		hAdvances = [metrics[glyph][0] for metrics in metricses]
		hAdvanceDeltas[glyph] = tuple(model.getDeltas(hAdvances)[1:])

	# We only support the direct mapping right now.

	supports = model.supports[1:]
	varTupleList = builder.buildVarTupleList(supports)
	varTupleIndexes = list(range(len(supports)))
	n = len(supports)
	items = []
	zeroes = [0]*n
	for glyphName in font.getGlyphOrder():
		items.append(hAdvanceDeltas.get(glyphName, zeroes))
	while items and items[-1] is zeroes:
		del items[-1]
	varDeltas = builder.buildVarDeltas(varTupleIndexes, items)
	varStore = builder.buildVarStore(varTupleList, [varDeltas])

	assert "HVAR" not in font
	HVAR = font["HVAR"] = newTable('HVAR')
	hvar = HVAR.table = ot.HVAR()
	hvar.Version = 1.0
	hvar.VarStore = varStore

	#hvar.AdvWidthMap = builder.buildVarIdxMap(mapping)


def main(args=None):

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

	(designspace_filename,) = args
	finder = lambda s: s.replace('master_ufo', 'master_ttf_interpolatable').replace('.ufo', '.ttf')
	axisMap = None # dict mapping axis id to (axis tag, axis name)
	outfile = os.path.splitext(designspace_filename)[0] + '-GX.ttf'

	masters, instances, base_idx = designspace_load(designspace_filename)
	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("Instances:")
	pprint(instances)
	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[0])) for m in masters]
	master_fonts = [TTFont(ttf_path) for ttf_path in master_ttfs]

	standard_axis_map = {
		'weight':  ('wght', 'Weight'),
		'width':   ('wdth', 'Width'),
		'slant':   ('slnt', 'Slant'),
		'optical': ('opsz', 'Optical Size'),
		'custom':  ('xxxx', 'Custom'),
	}

	axis_map = standard_axis_map
	if axisMap:
		axis_map = axis_map.copy()
		axis_map.update(axisMap)

	# TODO: For weight & width, use OS/2 values and setup 'avar' mapping.

	# Set up master locations
	master_locs = []
	instance_locs = []
	out = []
	for loc in [m[1] for m in masters+instances]:
		# Apply modifications for default axes; and apply tags
		l = {}
		for axis,value in loc.items():
			tag,name = axis_map[axis]
			l[tag] = value
		out.append(l)
	master_locs = out[:len(masters)]
	instance_locs = out[len(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 = {}
	axis_names = {}
	for tag,name in axis_map.values():
		if tag not in axis_tags: continue
		axis_names[tag] = name
	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)
		name = axis_names[tag]
		axes[tag] = (name, lower, default, upper)
	print("Axes:")
	pprint(axes)

	# Set up named instances
	instance_list = []
	for loc,instance in zip(instance_locs,instances):
		style = instance[4]
		instance_list.append((style, loc))
	# TODO append masters as named-instances as well; needs .designspace change.

	gx = TTFont(master_ttfs[base_idx])

	_add_fvar(gx, axes, instance_list)

	model = _build_model(axes, master_locs, base_idx)

	print("Building variations tables")
	_add_gvar(gx, model, master_fonts)
	_add_HVAR(gx, model, master_fonts)

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


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