from __future__ import print_function, division, absolute_import
from fontTools import ttLib
from fontTools.ttLib.tables import otTables as ot
from fontTools.ttLib.tables.otBase import ValueRecord, valueRecordFormatDict

# GSUB


def buildSingleSubst(mapping):
    self = ot.SingleSubst()
    self.mapping = dict(mapping)
    return self


def buildMultipleSubst(mapping):
    self = ot.MultipleSubst()
    self.mapping = dict(mapping)
    return self


def buildAlternateSubst(mapping):
    self = ot.AlternateSubst()
    self.alternates = dict(mapping)
    return self


def _getLigatureKey(components):
    """Computes a key for ordering ligatures in a GSUB Type-4 lookup.

    When building the OpenType lookup, we need to make sure that
    the longest sequence of components is listed first, so we
    use the negative length as the primary key for sorting.
    To make buildLigatureSubst() deterministic, we use the
    component sequence as the secondary key.

    For example, this will sort (f,f,f) < (f,f,i) < (f,f) < (f,i) < (f,l).
    """
    return (-len(components), components)

def buildLigatureSubst(mapping):
    self = ot.LigatureSubst()
    # The following single line can replace the rest of this function
    # with fontTools >= 3.1:
    # self.ligatures = dict(mapping)
    self.ligatures = {}
    for components in sorted(mapping.keys(), key=_getLigatureKey):
        ligature = ot.Ligature()
        ligature.Component = components[1:]
        ligature.CompCount = len(components)
        ligature.LigGlyph = mapping[components]
        firstGlyph = components[0]
        self.ligatures.setdefault(firstGlyph, []).append(ligature)
    return self


# GPOS


def buildAnchor(x, y, point=None, deviceX=None, deviceY=None):
    self = ot.Anchor()
    self.XCoordinate, self.YCoordinate = x, y
    self.Format = 1
    if point is not None:
        self.AnchorPoint = point
        self.Format = 2
    if deviceX is not None or deviceY is not None:
        assert self.Format == 2, "Either point, or both of deviceX/deviceY, must be None."
        self.XDeviceTable = deviceX
        self.YDeviceTable = deviceY
        self.Format = 3
    return self


def buildDevice(device):
    """[(11, 22), (7, -7), ...] --> otTables.Device"""
    self = ot.Device()
    device = tuple(sorted(device))
    self.StartSize = startSize = device[0][0]
    self.EndSize = endSize = device[-1][0]
    deviceDict = dict(device)
    self.DeltaValue = deltaValues = [
        deviceDict.get(size, 0)
        for size in range(startSize, endSize + 1)]
    maxDelta = max(deltaValues)
    minDelta = min(deltaValues)
    assert minDelta > -129 and maxDelta < 128
    if minDelta > -3 and maxDelta < 2:
        self.DeltaFormat = 1
    elif minDelta > -9 and maxDelta < 8:
        self.DeltaFormat = 2
    else:
        self.DeltaFormat = 3
    return self