from fontTools.ttLib import getSearchRange
from fontTools.misc.textTools import safeEval, readHex
from fontTools.misc.fixedTools import (
	fixedToFloat as fi2fl,
	floatToFixed as fl2fi)
from . import DefaultTable
import struct
import sys
import array
import logging


log = logging.getLogger(__name__)


class table__k_e_r_n(DefaultTable.DefaultTable):

	def getkern(self, format):
		for subtable in self.kernTables:
			if subtable.format == format:
				return subtable
		return None  # not found

	def decompile(self, data, ttFont):
		version, nTables = struct.unpack(">HH", data[:4])
		apple = False
		if (len(data) >= 8) and (version == 1):
			# AAT Apple's "new" format. Hm.
			version, nTables = struct.unpack(">LL", data[:8])
			self.version = fi2fl(version, 16)
			data = data[8:]
			apple = True
		else:
			self.version = version
			data = data[4:]
		self.kernTables = []
		for i in range(nTables):
			if self.version == 1.0:
				# Apple
				length, coverage, subtableFormat = struct.unpack(
					">LBB", data[:6])
			else:
				# in OpenType spec the "version" field refers to the common
				# subtable header; the actual subtable format is stored in
				# the 8-15 mask bits of "coverage" field.
				# This "version" is always 0 so we ignore it here
				_, length, subtableFormat, coverage = struct.unpack(
					">HHBB", data[:6])
				if nTables == 1 and subtableFormat == 0:
					# The "length" value is ignored since some fonts
					# (like OpenSans and Calibri) have a subtable larger than
					# its value.
					nPairs, = struct.unpack(">H", data[6:8])
					calculated_length = (nPairs * 6) + 14
					if length != calculated_length:
						log.warning(
							"'kern' subtable longer than defined: "
							"%d bytes instead of %d bytes" %
							(calculated_length, length)
						)
					length = calculated_length
			if subtableFormat not in kern_classes:
				subtable = KernTable_format_unkown(subtableFormat)
			else:
				subtable = kern_classes[subtableFormat](apple)
			subtable.decompile(data[:length], ttFont)
			self.kernTables.append(subtable)
			data = data[length:]

	def compile(self, ttFont):
		if hasattr(self, "kernTables"):
			nTables = len(self.kernTables)
		else:
			nTables = 0
		if self.version == 1.0:
			# AAT Apple's "new" format.
			data = struct.pack(">LL", fl2fi(self.version, 16), nTables)
		else:
			data = struct.pack(">HH", self.version, nTables)
		if hasattr(self, "kernTables"):
			for subtable in self.kernTables:
				data = data + subtable.compile(ttFont)
		return data

	def toXML(self, writer, ttFont):
		writer.simpletag("version", value=self.version)
		writer.newline()
		for subtable in self.kernTables:
			subtable.toXML(writer, ttFont)

	def fromXML(self, name, attrs, content, ttFont):
		if name == "version":
			self.version = safeEval(attrs["value"])
			return
		if name != "kernsubtable":
			return
		if not hasattr(self, "kernTables"):
			self.kernTables = []
		format = safeEval(attrs["format"])
		if format not in kern_classes:
			subtable = KernTable_format_unkown(format)
		else:
			apple = self.version == 1.0
			subtable = kern_classes[format](apple)
		self.kernTables.append(subtable)
		subtable.fromXML(name, attrs, content, ttFont)


class KernTable_format_0(object):

	# 'version' is kept for backward compatibility
	version = format = 0

	def __init__(self, apple=False):
		self.apple = apple

	def decompile(self, data, ttFont):
		if not self.apple:
			version, length, subtableFormat, coverage = struct.unpack(
				">HHBB", data[:6])
			if version != 0:
				from fontTools.ttLib import TTLibError
				raise TTLibError(
					"unsupported kern subtable version: %d" % version)
			tupleIndex = None
			# Should we also assert length == len(data)?
			data = data[6:]
		else:
			length, coverage, subtableFormat, tupleIndex = struct.unpack(
				">LBBH", data[:8])
			data = data[8:]
		assert self.format == subtableFormat, "unsupported format"
		self.coverage = coverage
		self.tupleIndex = tupleIndex

		self.kernTable = kernTable = {}

		nPairs, searchRange, entrySelector, rangeShift = struct.unpack(
			">HHHH", data[:8])
		data = data[8:]

		datas = array.array("H", data[:6 * nPairs])
		if sys.byteorder != "big": datas.byteswap()
		it = iter(datas)
		glyphOrder = ttFont.getGlyphOrder()
		for k in range(nPairs):
			left, right, value = next(it), next(it), next(it)
			if value >= 32768:
				value -= 65536
			try:
				kernTable[(glyphOrder[left], glyphOrder[right])] = value
			except IndexError:
				# Slower, but will not throw an IndexError on an invalid
				# glyph id.
				kernTable[(
					ttFont.getGlyphName(left),
					ttFont.getGlyphName(right))] = value
		if len(data) > 6 * nPairs + 4:  # Ignore up to 4 bytes excess
			log.warning(
				"excess data in 'kern' subtable: %d bytes",
				len(data) - 6 * nPairs)

	def compile(self, ttFont):
		nPairs = len(self.kernTable)
		searchRange, entrySelector, rangeShift = getSearchRange(nPairs, 6)
		searchRange &= 0xFFFF
		data = struct.pack(
			">HHHH", nPairs, searchRange, entrySelector, rangeShift)

		# yeehee! (I mean, turn names into indices)
		try:
			reverseOrder = ttFont.getReverseGlyphMap()
			kernTable = sorted(
				(reverseOrder[left], reverseOrder[right], value)
				for ((left, right), value) in self.kernTable.items())
		except KeyError:
			# Slower, but will not throw KeyError on invalid glyph id.
			getGlyphID = ttFont.getGlyphID
			kernTable = sorted(
				(getGlyphID(left), getGlyphID(right), value)
				for ((left, right), value) in self.kernTable.items())

		for left, right, value in kernTable:
			data = data + struct.pack(">HHh", left, right, value)

		if not self.apple:
			version = 0
			length = len(data) + 6
			if length >= 0x10000:
				log.warning('"kern" subtable overflow, '
							'truncating length value while preserving pairs.')
				length &= 0xFFFF
			header = struct.pack(
				">HHBB", version, length, self.format, self.coverage)
		else:
			if self.tupleIndex is None:
				# sensible default when compiling a TTX from an old fonttools
				# or when inserting a Windows-style format 0 subtable into an
				# Apple version=1.0 kern table
				log.warning("'tupleIndex' is None; default to 0")
				self.tupleIndex = 0
			length = len(data) + 8
			header = struct.pack(
				">LBBH", length, self.coverage, self.format, self.tupleIndex)
		return header + data

	def toXML(self, writer, ttFont):
		attrs = dict(coverage=self.coverage, format=self.format)
		if self.apple:
			if self.tupleIndex is None:
				log.warning("'tupleIndex' is None; default to 0")
				attrs["tupleIndex"] = 0
			else:
				attrs["tupleIndex"] = self.tupleIndex
		writer.begintag("kernsubtable", **attrs)
		writer.newline()
		items = sorted(self.kernTable.items())
		for (left, right), value in items:
			writer.simpletag("pair", [
				("l", left),
				("r", right),
				("v", value)
			])
			writer.newline()
		writer.endtag("kernsubtable")
		writer.newline()

	def fromXML(self, name, attrs, content, ttFont):
		self.coverage = safeEval(attrs["coverage"])
		subtableFormat = safeEval(attrs["format"])
		if self.apple:
			if "tupleIndex" in attrs:
				self.tupleIndex = safeEval(attrs["tupleIndex"])
			else:
				# previous fontTools versions didn't export tupleIndex
				log.warning(
					"Apple kern subtable is missing 'tupleIndex' attribute")
				self.tupleIndex = None
		else:
			self.tupleIndex = None
		assert subtableFormat == self.format, "unsupported format"
		if not hasattr(self, "kernTable"):
			self.kernTable = {}
		for element in content:
			if not isinstance(element, tuple):
				continue
			name, attrs, content = element
			self.kernTable[(attrs["l"], attrs["r"])] = safeEval(attrs["v"])

	def __getitem__(self, pair):
		return self.kernTable[pair]

	def __setitem__(self, pair, value):
		self.kernTable[pair] = value

	def __delitem__(self, pair):
		del self.kernTable[pair]


class KernTable_format_unkown(object):

	def __init__(self, format):
		self.format = format

	def decompile(self, data, ttFont):
		self.data = data

	def compile(self, ttFont):
		return self.data

	def toXML(self, writer, ttFont):
		writer.begintag("kernsubtable", format=self.format)
		writer.newline()
		writer.comment("unknown 'kern' subtable format")
		writer.newline()
		writer.dumphex(self.data)
		writer.endtag("kernsubtable")
		writer.newline()

	def fromXML(self, name, attrs, content, ttFont):
		self.decompile(readHex(content), ttFont)


kern_classes = {0: KernTable_format_0}