from fontTools.misc import sstruct
from fontTools.misc.fixedTools import floatToFixedToStr, strToFixedToFloat
from fontTools.misc.textTools import safeEval, num2binary, binary2num
from fontTools.misc.timeTools import (
    timestampFromString,
    timestampToString,
    timestampNow,
)
from fontTools.misc.timeTools import epoch_diff as mac_epoch_diff  # For backward compat
from fontTools.misc.arrayTools import intRect, unionRect
from . import DefaultTable
import logging

log = logging.getLogger(__name__)

headFormat = """
		>	# big endian
		tableVersion:       16.16F
		fontRevision:       16.16F
		checkSumAdjustment: I
		magicNumber:        I
		flags:              H
		unitsPerEm:         H
		created:            Q
		modified:           Q
		xMin:               h
		yMin:               h
		xMax:               h
		yMax:               h
		macStyle:           H
		lowestRecPPEM:      H
		fontDirectionHint:  h
		indexToLocFormat:   h
		glyphDataFormat:    h
"""


class table__h_e_a_d(DefaultTable.DefaultTable):
    """Font Header table

    The ``head`` table contains a variety of font-wide information.

    See also https://learn.microsoft.com/en-us/typography/opentype/spec/head
    """

    dependencies = ["maxp", "loca", "CFF ", "CFF2"]

    def decompile(self, data, ttFont):
        dummy, rest = sstruct.unpack2(headFormat, data, self)
        if rest:
            # this is quite illegal, but there seem to be fonts out there that do this
            log.warning("extra bytes at the end of 'head' table")
            assert rest == b"\0\0"

        # For timestamp fields, ignore the top four bytes.  Some fonts have
        # bogus values there.  Since till 2038 those bytes only can be zero,
        # ignore them.
        #
        # https://github.com/fonttools/fonttools/issues/99#issuecomment-66776810
        for stamp in "created", "modified":
            value = getattr(self, stamp)
            if value > 0xFFFFFFFF:
                log.warning("'%s' timestamp out of range; ignoring top bytes", stamp)
                value &= 0xFFFFFFFF
                setattr(self, stamp, value)
            if value < 0x7C259DC0:  # January 1, 1970 00:00:00
                log.warning(
                    "'%s' timestamp seems very low; regarding as unix timestamp", stamp
                )
                value += 0x7C259DC0
                setattr(self, stamp, value)

    def compile(self, ttFont):
        if ttFont.recalcBBoxes:
            # For TT-flavored fonts, xMin, yMin, xMax and yMax are set in table__m_a_x_p.recalc().
            if "CFF " in ttFont:
                topDict = ttFont["CFF "].cff.topDictIndex[0]
                self.xMin, self.yMin, self.xMax, self.yMax = intRect(topDict.FontBBox)
            elif "CFF2" in ttFont:
                topDict = ttFont["CFF2"].cff.topDictIndex[0]
                charStrings = topDict.CharStrings
                fontBBox = None
                for charString in charStrings.values():
                    bounds = charString.calcBounds(charStrings)
                    if bounds is not None:
                        if fontBBox is not None:
                            fontBBox = unionRect(fontBBox, bounds)
                        else:
                            fontBBox = bounds
                if fontBBox is not None:
                    self.xMin, self.yMin, self.xMax, self.yMax = intRect(fontBBox)
        if ttFont.recalcTimestamp:
            self.modified = timestampNow()
        data = sstruct.pack(headFormat, self)
        return data

    def toXML(self, writer, ttFont):
        writer.comment("Most of this table will be recalculated by the compiler")
        writer.newline()
        _, names, fixes = sstruct.getformat(headFormat)
        for name in names:
            value = getattr(self, name)
            if name in fixes:
                value = floatToFixedToStr(value, precisionBits=fixes[name])
            elif name in ("created", "modified"):
                value = timestampToString(value)
            elif name in ("magicNumber", "checkSumAdjustment"):
                if value < 0:
                    value = value + 0x100000000
                value = hex(value)
                if value[-1:] == "L":
                    value = value[:-1]
            elif name in ("macStyle", "flags"):
                value = num2binary(value, 16)
            writer.simpletag(name, value=value)
            writer.newline()

    def fromXML(self, name, attrs, content, ttFont):
        value = attrs["value"]
        fixes = sstruct.getformat(headFormat)[2]
        if name in fixes:
            value = strToFixedToFloat(value, precisionBits=fixes[name])
        elif name in ("created", "modified"):
            value = timestampFromString(value)
        elif name in ("macStyle", "flags"):
            value = binary2num(value)
        else:
            value = safeEval(value)
        setattr(self, name, value)
