# Source code for fontTools.varLib

    """
    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 in the varLib.designspace module.

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

        .. code-block:: sh

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

    Then you can make a variable-font this way:

        .. code-block:: sh

            $ fonttools varLib master_ufo/NotoSansArabic.designspace

    API *will* change in near future.
    """

    from typing import List
    from fontTools.misc.vector import Vector
    from fontTools.misc.roundTools import noRound, otRound
    from fontTools.misc.fixedTools import floatToFixed as fl2fi
    from fontTools.misc.textTools import Tag, tostr
    from fontTools.ttLib import TTFont, newTable
    from fontTools.ttLib.tables._f_v_a_r import Axis, NamedInstance
    from fontTools.ttLib.tables._g_l_y_f import GlyphCoordinates, dropImpliedOnCurvePoints
    from fontTools.ttLib.tables.ttProgram import Program
    from fontTools.ttLib.tables.TupleVariation import TupleVariation
    from fontTools.ttLib.tables import otTables as ot
    from fontTools.ttLib.tables.otBase import OTTableWriter
    from fontTools.varLib import builder, models, varStore
    from fontTools.varLib.merger import VariationMerger, COLRVariationMerger
    from fontTools.varLib.mvar import MVAR_ENTRIES
    from fontTools.varLib.iup import iup_delta_optimize
    from fontTools.varLib.featureVars import addFeatureVariations
    from fontTools.designspaceLib import DesignSpaceDocument, InstanceDescriptor
    from fontTools.designspaceLib.split import splitInterpolable, splitVariableFonts
    from fontTools.varLib.stat import buildVFStatTable
    from fontTools.colorLib.builder import buildColrV1
    from fontTools.colorLib.unbuilder import unbuildColrV1
    from functools import partial
    from collections import OrderedDict, defaultdict, namedtuple
    import os.path
    import logging
    from copy import deepcopy
    from pprint import pformat
    from re import fullmatch
    from .errors import VarLibError, VarLibValidationError

    log = logging.getLogger("fontTools.varLib")

    # This is a lib key for the designspace document. The value should be
    # a comma-separated list of OpenType feature tag(s), to be used as the
    # FeatureVariations feature.
    # If present, the DesignSpace <rules processing="..."> flag is ignored.
    FEAVAR_FEATURETAG_LIB_KEY = "com.github.fonttools.varLib.featureVarsFeatureTag"

    #
    # Creation routines
    #

    def _add_fvar(font, axes, instances: List[InstanceDescriptor]):
        """
        Add 'fvar' table to font.

        axes is an ordered dictionary of DesignspaceAxis objects.

        instances is list of dictionary objects with 'location', 'stylename',
        and possibly 'postscriptfontname' entries.
        """

        assert axes
        assert isinstance(axes, OrderedDict)

        log.info("Generating fvar")

        fvar = newTable("fvar")
        nameTable = font["name"]

        # if there are not currently any mac names don't add them here, that's inconsistent
        # https://github.com/fonttools/fonttools/issues/683
        macNames = any(nr.platformID == 1 for nr in getattr(nameTable, "names", ()))

        # we have all the best ways to express mac names
        platforms = ((3, 1, 0x409),)
        if macNames:
            platforms = ((1, 0, 0),) + platforms

        for a in axes.values():
            axis = Axis()
            axis.axisTag = Tag(a.tag)
            # TODO Skip axes that have no variation.
            axis.minValue, axis.defaultValue, axis.maxValue = (
                a.minimum,
                a.default,
                a.maximum,
            )
            axis.axisNameID = nameTable.addMultilingualName(
                a.labelNames, font, minNameID=256, mac=macNames
            )
            axis.flags = int(a.hidden)
            fvar.axes.append(axis)

        for instance in instances:
            # Filter out discrete axis locations
            coordinates = {
                name: value for name, value in instance.location.items() if name in axes
            }

            if "en" not in instance.localisedStyleName:
                if not instance.styleName:
                    raise VarLibValidationError(
                        f"Instance at location '{coordinates}' must have a default English "
                        "style name ('stylename' attribute on the instance element or a "
                        "stylename element with an 'xml:lang=\"en\"' attribute)."
                    )
                localisedStyleName = dict(instance.localisedStyleName)
                localisedStyleName["en"] = tostr(instance.styleName)
            else:
                localisedStyleName = instance.localisedStyleName

            psname = instance.postScriptFontName

            inst = NamedInstance()
            inst.subfamilyNameID = nameTable.addMultilingualName(
                localisedStyleName, mac=macNames
            )
            if psname is not None:
                psname = tostr(psname)
                inst.postscriptNameID = nameTable.addName(psname, platforms=platforms)
            inst.coordinates = {
                axes[k].tag: axes[k].map_backward(v) for k, v in coordinates.items()
            }
            # inst.coordinates = {axes[k].tag:v for k,v in coordinates.items()}
            fvar.instances.append(inst)

        assert "fvar" not in font
        font["fvar"] = fvar

        return fvar

    def _add_avar(font, axes, mappings, axisTags):
        """
        Add 'avar' table to font.

        axes is an ordered dictionary of AxisDescriptor objects.
        """

        assert axes
        assert isinstance(axes, OrderedDict)

        log.info("Generating avar")

        avar = newTable("avar")

        interesting = False
        vals_triples = {}
        for axis in axes.values():
            # Currently, some rasterizers require that the default value maps
            # (-1 to -1, 0 to 0, and 1 to 1) be present for all the segment
            # maps, even when the default normalization mapping for the axis
            # was not modified.
            # https://github.com/googlei18n/fontmake/issues/295
            # https://github.com/fonttools/fonttools/issues/1011
            # TODO(anthrotype) revert this (and 19c4b37) when issue is fixed
            curve = avar.segments[axis.tag] = {-1.0: -1.0, 0.0: 0.0, 1.0: 1.0}

            keys_triple = (axis.minimum, axis.default, axis.maximum)
            vals_triple = tuple(axis.map_forward(v) for v in keys_triple)
            vals_triples[axis.tag] = vals_triple

            if not axis.map:
                continue

            items = sorted(axis.map)
            keys = [item[0] for item in items]
            vals = [item[1] for item in items]

            # Current avar requirements.  We don't have to enforce
            # these on the designer and can deduce some ourselves,
            # but for now just enforce them.
            if axis.minimum != min(keys):
                raise VarLibValidationError(
                    f"Axis '{axis.name}': there must be a mapping for the axis minimum "
                    f"value {axis.minimum} and it must be the lowest input mapping value."
                )
            if axis.maximum != max(keys):
                raise VarLibValidationError(
                    f"Axis '{axis.name}': there must be a mapping for the axis maximum "
                    f"value {axis.maximum} and it must be the highest input mapping value."
                )
            if axis.default not in keys:
                raise VarLibValidationError(
                    f"Axis '{axis.name}': there must be a mapping for the axis default "
                    f"value {axis.default}."
                )
            # No duplicate input values (output values can be >= their preceeding value).
            if len(set(keys)) != len(keys):
                raise VarLibValidationError(
                    f"Axis '{axis.name}': All axis mapping input='...' values must be "
                    "unique, but we found duplicates."
                )
            # Ascending values
            if sorted(vals) != vals:
                raise VarLibValidationError(
                    f"Axis '{axis.name}': mapping output values must be in ascending order."
                )

            keys = [models.normalizeValue(v, keys_triple) for v in keys]
            vals = [models.normalizeValue(v, vals_triple) for v in vals]

            if all(k == v for k, v in zip(keys, vals)):
                continue
            interesting = True

            curve.update(zip(keys, vals))

            assert 0.0 in curve and curve[0.0] == 0.0
            assert -1.0 not in curve or curve[-1.0] == -1.0
            assert +1.0 not in curve or curve[+1.0] == +1.0
            # curve.update({-1.0: -1.0, 0.0: 0.0, 1.0: 1.0})

        if mappings:
            interesting = True

            inputLocations = [
                {
                    axes[name].tag: models.normalizeValue(v, vals_triples[axes[name].tag])
                    for name, v in mapping.inputLocation.items()
                }
                for mapping in mappings
            ]
            outputLocations = [
                {
                    axes[name].tag: models.normalizeValue(v, vals_triples[axes[name].tag])
                    for name, v in mapping.outputLocation.items()
                }
                for mapping in mappings
            ]
            assert len(inputLocations) == len(outputLocations)

            # If base-master is missing, insert it at zero location.
            if not any(all(v == 0 for k, v in loc.items()) for loc in inputLocations):
                inputLocations.insert(0, {})
                outputLocations.insert(0, {})

            model = models.VariationModel(inputLocations, axisTags)
            storeBuilder = varStore.OnlineVarStoreBuilder(axisTags)
            storeBuilder.setModel(model)
            varIdxes = {}
            for tag in axisTags:
                masterValues = []
                for vo, vi in zip(outputLocations, inputLocations):
                    if tag not in vo:
                        masterValues.append(0)
                        continue
                    v = vo[tag] - vi.get(tag, 0)
                    masterValues.append(fl2fi(v, 14))
                varIdxes[tag] = storeBuilder.storeMasters(masterValues)[1]

            store = storeBuilder.finish()
            optimized = store.optimize()
            varIdxes = {axis: optimized[value] for axis, value in varIdxes.items()}

            varIdxMap = builder.buildDeltaSetIndexMap(varIdxes[t] for t in axisTags)

            avar.majorVersion = 2
            avar.table = ot.avar()
            avar.table.VarIdxMap = varIdxMap
            avar.table.VarStore = store

        assert "avar" not in font
        if not interesting:
            log.info("No need for avar")
            avar = None
        else:
            font["avar"] = avar

        return avar

    def _add_stat(font):
        # Note: this function only gets called by old code that calls `build()`
        # directly. Newer code that wants to benefit from STAT data from the
        # designspace should call `build_many()`

        if "STAT" in font:
            return

        from ..otlLib.builder import buildStatTable

        fvarTable = font["fvar"]
        axes = [dict(tag=a.axisTag, name=a.axisNameID) for a in fvarTable.axes]
        buildStatTable(font, axes)

    _MasterData = namedtuple("_MasterData", ["glyf", "hMetrics", "vMetrics"])

    def _add_gvar(font, masterModel, master_ttfs, tolerance=0.5, optimize=True):
        if tolerance < 0:
            raise ValueError("`tolerance` must be a positive number.")

        log.info("Generating gvar")
        assert "gvar" not in font
        gvar = font["gvar"] = newTable("gvar")
        glyf = font["glyf"]
        defaultMasterIndex = masterModel.reverseMapping[0]

        master_datas = [
            _MasterData(
                m["glyf"], m["hmtx"].metrics, getattr(m.get("vmtx"), "metrics", None)
            )
            for m in master_ttfs
        ]

        for glyph in font.getGlyphOrder():
            log.debug("building gvar for glyph '%s'", glyph)

            allData = [
                m.glyf._getCoordinatesAndControls(glyph, m.hMetrics, m.vMetrics)
                for m in master_datas
            ]

            if allData[defaultMasterIndex][1].numberOfContours != 0:
                # If the default master is not empty, interpret empty non-default masters
                # as missing glyphs from a sparse master
                allData = [
                    d if d is not None and d[1].numberOfContours != 0 else None
                    for d in allData
                ]

            model, allData = masterModel.getSubModel(allData)

            allCoords = [d[0] for d in allData]
            allControls = [d[1] for d in allData]
            control = allControls[0]
            if not models.allEqual(allControls):
                log.warning("glyph %s has incompatible masters; skipping" % glyph)
                continue
            del allControls

            # Update gvar
            gvar.variations[glyph] = []
            deltas = model.getDeltas(
                allCoords, round=partial(GlyphCoordinates.__round__, round=round)
            )
            supports = model.supports
            assert len(deltas) == len(supports)

            # Prepare for IUP optimization
            origCoords = deltas[0]
            endPts = control.endPts

            for i, (delta, support) in enumerate(zip(deltas[1:], supports[1:])):
                if all(v == 0 for v in delta.array):
                    continue
                var = TupleVariation(support, delta)
                if optimize:
                    delta_opt = iup_delta_optimize(
                        delta, origCoords, endPts, tolerance=tolerance
                    )

                    if None in delta_opt:
                        # Use "optimized" version only if smaller...
                        var_opt = TupleVariation(support, delta_opt)

                        axis_tags = sorted(
                            support.keys()
                        )  # Shouldn't matter that this is different from fvar...?
                        tupleData, auxData = var.compile(axis_tags)
                        unoptimized_len = len(tupleData) + len(auxData)
                        tupleData, auxData = var_opt.compile(axis_tags)
                        optimized_len = len(tupleData) + len(auxData)

                        if optimized_len < unoptimized_len:
                            var = var_opt

                gvar.variations[glyph].append(var)

    def _remove_TTHinting(font):
        for tag in ("cvar", "cvt ", "fpgm", "prep"):
            if tag in font:
                del font[tag]
        maxp = font["maxp"]
        for attr in (
            "maxTwilightPoints",
            "maxStorage",
            "maxFunctionDefs",
            "maxInstructionDefs",
            "maxStackElements",
            "maxSizeOfInstructions",
        ):
            setattr(maxp, attr, 0)
        maxp.maxZones = 1
        font["glyf"].removeHinting()
        # TODO: Modify gasp table to deactivate gridfitting for all ranges?

    def _merge_TTHinting(font, masterModel, master_ttfs):
        log.info("Merging TT hinting")
        assert "cvar" not in font

        # Check that the existing hinting is compatible

        # fpgm and prep table

        for tag in ("fpgm", "prep"):
            all_pgms = [m[tag].program for m in master_ttfs if tag in m]
            if not all_pgms:
                continue
            font_pgm = getattr(font.get(tag), "program", None)
            if any(pgm != font_pgm for pgm in all_pgms):
                log.warning(
                    "Masters have incompatible %s tables, hinting is discarded." % tag
                )
                _remove_TTHinting(font)
                return

        # glyf table

        font_glyf = font["glyf"]
        master_glyfs = [m["glyf"] for m in master_ttfs]
        for name, glyph in font_glyf.glyphs.items():
            all_pgms = [getattr(glyf.get(name), "program", None) for glyf in master_glyfs]
            if not any(all_pgms):
                continue
            glyph.expand(font_glyf)
            font_pgm = getattr(glyph, "program", None)
            if any(pgm != font_pgm for pgm in all_pgms if pgm):
                log.warning(
                    "Masters have incompatible glyph programs in glyph '%s', hinting is discarded."
                    % name
                )
                # TODO Only drop hinting from this glyph.
                _remove_TTHinting(font)
                return

        # cvt table

        all_cvs = [Vector(m["cvt "].values) if "cvt " in m else None for m in master_ttfs]

        nonNone_cvs = models.nonNone(all_cvs)
        if not nonNone_cvs:
            # There is no cvt table to make a cvar table from, we're done here.
            return

        if not models.allEqual(len(c) for c in nonNone_cvs):
            log.warning("Masters have incompatible cvt tables, hinting is discarded.")
            _remove_TTHinting(font)
            return

        variations = []
        deltas, supports = masterModel.getDeltasAndSupports(
            all_cvs, round=round
        )  # builtin round calls into Vector.__round__, which uses builtin round as we like
        for i, (delta, support) in enumerate(zip(deltas[1:], supports[1:])):
            if all(v == 0 for v in delta):
                continue
            var = TupleVariation(support, delta)
            variations.append(var)

        # We can build the cvar table now.
        if variations:
            cvar = font["cvar"] = newTable("cvar")
            cvar.version = 1
            cvar.variations = variations

    _MetricsFields = namedtuple(
        "_MetricsFields",
        [
            "tableTag",
            "metricsTag",
            "sb1",
            "sb2",
            "advMapping",
            "vOrigMapping",
            "phantomIndex",
        ],
    )

    HVAR_FIELDS = _MetricsFields(
        tableTag="HVAR",
        metricsTag="hmtx",
        sb1="LsbMap",
        sb2="RsbMap",
        advMapping="AdvWidthMap",
        vOrigMapping=None,
        phantomIndex=0,
    )

    VVAR_FIELDS = _MetricsFields(
        tableTag="VVAR",
        metricsTag="vmtx",
        sb1="TsbMap",
        sb2="BsbMap",
        advMapping="AdvHeightMap",
        vOrigMapping="VOrgMap",
        phantomIndex=1,
    )

    def _add_HVAR(font, masterModel, master_ttfs, axisTags):
        getAdvanceMetrics = partial(
            _get_advance_metrics, font, masterModel, master_ttfs, axisTags, HVAR_FIELDS
        )
        _add_VHVAR(font, axisTags, HVAR_FIELDS, getAdvanceMetrics)

    def _add_VVAR(font, masterModel, master_ttfs, axisTags):
        getAdvanceMetrics = partial(
            _get_advance_metrics, font, masterModel, master_ttfs, axisTags, VVAR_FIELDS
        )
        _add_VHVAR(font, axisTags, VVAR_FIELDS, getAdvanceMetrics)

    def _add_VHVAR(font, axisTags, tableFields, getAdvanceMetrics):
        tableTag = tableFields.tableTag
        assert tableTag not in font
        glyphOrder = font.getGlyphOrder()
        log.info("Generating " + tableTag)
        VHVAR = newTable(tableTag)
        tableClass = getattr(ot, tableTag)
        vhvar = VHVAR.table = tableClass()
        vhvar.Version = 0x00010000

        vhAdvanceDeltasAndSupports, vOrigDeltasAndSupports = getAdvanceMetrics()

        if vOrigDeltasAndSupports:
            singleModel = False
        else:
            singleModel = models.allEqual(
                id(v[1]) for v in vhAdvanceDeltasAndSupports.values()
            )

        directStore = None
        if singleModel:
            # Build direct mapping
            supports = next(iter(vhAdvanceDeltasAndSupports.values()))[1][1:]
            varTupleList = builder.buildVarRegionList(supports, axisTags)
            varTupleIndexes = list(range(len(supports)))
            varData = builder.buildVarData(varTupleIndexes, [], optimize=False)
            for glyphName in glyphOrder:
                varData.addItem(vhAdvanceDeltasAndSupports[glyphName][0], round=noRound)
            varData.optimize()
            directStore = builder.buildVarStore(varTupleList, [varData])

        # Build optimized indirect mapping
        storeBuilder = varStore.OnlineVarStoreBuilder(axisTags)
        advMapping = {}
        for glyphName in glyphOrder:
            deltas, supports = vhAdvanceDeltasAndSupports[glyphName]
            storeBuilder.setSupports(supports)
            advMapping[glyphName] = storeBuilder.storeDeltas(deltas, round=noRound)

        if vOrigDeltasAndSupports:
            vOrigMap = {}
            for glyphName in glyphOrder:
                deltas, supports = vOrigDeltasAndSupports[glyphName]
                storeBuilder.setSupports(supports)
                vOrigMap[glyphName] = storeBuilder.storeDeltas(deltas, round=noRound)

        indirectStore = storeBuilder.finish()
        mapping2 = indirectStore.optimize(use_NO_VARIATION_INDEX=False)
        advMapping = [mapping2[advMapping[g]] for g in glyphOrder]
        advanceMapping = builder.buildVarIdxMap(advMapping, glyphOrder)

        if vOrigDeltasAndSupports:
            vOrigMap = [mapping2[vOrigMap[g]] for g in glyphOrder]

        useDirect = False
        vOrigMapping = None
        if directStore:
            # Compile both, see which is more compact

            writer = OTTableWriter()
            directStore.compile(writer, font)
            directSize = len(writer.getAllData())

            writer = OTTableWriter()
            indirectStore.compile(writer, font)
            advanceMapping.compile(writer, font)
            indirectSize = len(writer.getAllData())

            useDirect = directSize < indirectSize

        if useDirect:
            metricsStore = directStore
            advanceMapping = None
        else:
            metricsStore = indirectStore
            if vOrigDeltasAndSupports:
                vOrigMapping = builder.buildVarIdxMap(vOrigMap, glyphOrder)

        vhvar.VarStore = metricsStore
        setattr(vhvar, tableFields.advMapping, advanceMapping)
        if vOrigMapping is not None:
            setattr(vhvar, tableFields.vOrigMapping, vOrigMapping)
        setattr(vhvar, tableFields.sb1, None)
        setattr(vhvar, tableFields.sb2, None)

        font[tableTag] = VHVAR
        return

    def _get_advance_metrics(font, masterModel, master_ttfs, axisTags, tableFields):
        tableTag = tableFields.tableTag
        glyphOrder = font.getGlyphOrder()

        # Build list of source font advance widths for each glyph
        metricsTag = tableFields.metricsTag
        advMetricses = [m[metricsTag].metrics for m in master_ttfs]

        # Build list of source font vertical origin coords for each glyph
        if tableTag == "VVAR" and "VORG" in master_ttfs[0]:
            vOrigMetricses = [m["VORG"].VOriginRecords for m in master_ttfs]
            defaultYOrigs = [m["VORG"].defaultVertOriginY for m in master_ttfs]
            vOrigMetricses = list(zip(vOrigMetricses, defaultYOrigs))
        else:
            vOrigMetricses = None

        vhAdvanceDeltasAndSupports = {}
        vOrigDeltasAndSupports = {}
        # HACK: we treat width 65535 as a sentinel value to signal that a glyph
        # from a non-default master should not participate in computing {H,V}VAR,
        # as if it were missing. Allows to variate other glyph-related data independently
        # from glyph metrics
        sparse_advance = 0xFFFF
        for glyph in glyphOrder:
            vhAdvances = [
                (
                    metrics[glyph][0]
                    if glyph in metrics and metrics[glyph][0] != sparse_advance
                    else None
                )
                for metrics in advMetricses
            ]
            vhAdvanceDeltasAndSupports[glyph] = masterModel.getDeltasAndSupports(
                vhAdvances, round=round
            )

        if vOrigMetricses:
            for glyph in glyphOrder:
                # We need to supply a vOrigs tuple with non-None default values
                # for each glyph. vOrigMetricses contains values only for those
                # glyphs which have a non-default vOrig.
                vOrigs = [
                    metrics[glyph] if glyph in metrics else defaultVOrig
                    for metrics, defaultVOrig in vOrigMetricses
                ]
                vOrigDeltasAndSupports[glyph] = masterModel.getDeltasAndSupports(
                    vOrigs, round=round
                )

        return vhAdvanceDeltasAndSupports, vOrigDeltasAndSupports

    def _add_MVAR(font, masterModel, master_ttfs, axisTags):
        log.info("Generating MVAR")

        store_builder = varStore.OnlineVarStoreBuilder(axisTags)

        records = []
        lastTableTag = None
        fontTable = None
        tables = None
        # HACK: we need to special-case post.underlineThickness and .underlinePosition
        # and unilaterally/arbitrarily define a sentinel value to distinguish the case
        # when a post table is present in a given master simply because that's where
        # the glyph names in TrueType must be stored, but the underline values are not
        # meant to be used for building MVAR's deltas. The value of -0x8000 (-36768)
        # the minimum FWord (int16) value, was chosen for its unlikelyhood to appear
        # in real-world underline position/thickness values.
        specialTags = {"unds": -0x8000, "undo": -0x8000}

        for tag, (tableTag, itemName) in sorted(MVAR_ENTRIES.items(), key=lambda kv: kv[1]):
            # For each tag, fetch the associated table from all fonts (or not when we are
            # still looking at a tag from the same tables) and set up the variation model
            # for them.
            if tableTag != lastTableTag:
                tables = fontTable = None
                if tableTag in font:
                    fontTable = font[tableTag]
                    tables = []
                    for master in master_ttfs:
                        if tableTag not in master or (
                            tag in specialTags
                            and getattr(master[tableTag], itemName) == specialTags[tag]
                        ):
                            tables.append(None)
                        else:
                            tables.append(master[tableTag])
                    model, tables = masterModel.getSubModel(tables)
                    store_builder.setModel(model)
                lastTableTag = tableTag

            if tables is None:  # Tag not applicable to the master font.
                continue

            # TODO support gasp entries

            master_values = [getattr(table, itemName) for table in tables]
            if models.allEqual(master_values):
                base, varIdx = master_values[0], None
            else:
                base, varIdx = store_builder.storeMasters(master_values)
            setattr(fontTable, itemName, base)

            if varIdx is None:
                continue
            log.info("	%s: %s.%s	%s", tag, tableTag, itemName, master_values)
            rec = ot.MetricsValueRecord()
            rec.ValueTag = tag
            rec.VarIdx = varIdx
            records.append(rec)

        assert "MVAR" not in font
        if records:
            store = store_builder.finish()
            # Optimize
            mapping = store.optimize()
            for rec in records:
                rec.VarIdx = mapping[rec.VarIdx]

            MVAR = font["MVAR"] = newTable("MVAR")
            mvar = MVAR.table = ot.MVAR()
            mvar.Version = 0x00010000
            mvar.Reserved = 0
            mvar.VarStore = store
            # XXX these should not be hard-coded but computed automatically
            mvar.ValueRecordSize = 8
            mvar.ValueRecordCount = len(records)
            mvar.ValueRecord = sorted(records, key=lambda r: r.ValueTag)

    def _add_BASE(font, masterModel, master_ttfs, axisTags):
        log.info("Generating BASE")

        merger = VariationMerger(masterModel, axisTags, font)
        merger.mergeTables(font, master_ttfs, ["BASE"])
        store = merger.store_builder.finish()

        if not store:
            return
        base = font["BASE"].table
        assert base.Version == 0x00010000
        base.Version = 0x00010001
        base.VarStore = store

    def _merge_OTL(font, model, master_fonts, axisTags):
        otl_tags = ["GSUB", "GDEF", "GPOS"]
        if not any(tag in font for tag in otl_tags):
            return

        log.info("Merging OpenType Layout tables")
        merger = VariationMerger(model, axisTags, font)

        merger.mergeTables(font, master_fonts, otl_tags)
        store = merger.store_builder.finish()
        if not store:
            return
        try:
            GDEF = font["GDEF"].table
            assert GDEF.Version <= 0x00010002
        except KeyError:
            font["GDEF"] = newTable("GDEF")
            GDEFTable = font["GDEF"] = newTable("GDEF")
            GDEF = GDEFTable.table = ot.GDEF()
            GDEF.GlyphClassDef = None
            GDEF.AttachList = None
            GDEF.LigCaretList = None
            GDEF.MarkAttachClassDef = None
            GDEF.MarkGlyphSetsDef = None

        GDEF.Version = 0x00010003
        GDEF.VarStore = store

        # Optimize
        varidx_map = store.optimize()
        GDEF.remap_device_varidxes(varidx_map)
        if "GPOS" in font:
            font["GPOS"].table.remap_device_varidxes(varidx_map)

    def _add_GSUB_feature_variations(
        font, axes, internal_axis_supports, rules, featureTags
    ):
        def normalize(name, value):
            return models.normalizeLocation({name: value}, internal_axis_supports)[name]

        log.info("Generating GSUB FeatureVariations")

        axis_tags = {name: axis.tag for name, axis in axes.items()}

        conditional_subs = []
        for rule in rules:
            region = []
            for conditions in rule.conditionSets:
                space = {}
                for condition in conditions:
                    axis_name = condition["name"]
                    if condition["minimum"] is not None:
                        minimum = normalize(axis_name, condition["minimum"])
                    else:
                        minimum = -1.0
                    if condition["maximum"] is not None:
                        maximum = normalize(axis_name, condition["maximum"])
                    else:
                        maximum = 1.0
                    tag = axis_tags[axis_name]
                    space[tag] = (minimum, maximum)
                region.append(space)

            subs = {k: v for k, v in rule.subs}

            conditional_subs.append((region, subs))

        addFeatureVariations(font, conditional_subs, featureTags)

    _DesignSpaceData = namedtuple(
        "_DesignSpaceData",
        [
            "axes",
            "axisMappings",
            "internal_axis_supports",
            "base_idx",
            "normalized_master_locs",
            "masters",
            "instances",
            "rules",
            "rulesProcessingLast",
            "lib",
        ],
    )

    def _add_CFF2(varFont, model, master_fonts):
        from .cff import merge_region_fonts

        glyphOrder = varFont.getGlyphOrder()
        if "CFF2" not in varFont:
            from fontTools.cffLib.CFFToCFF2 import convertCFFToCFF2

            convertCFFToCFF2(varFont)

        ordered_fonts_list = model.reorderMasters(master_fonts, model.reverseMapping)
        # re-ordering the master list simplifies building the CFF2 data item lists.
        merge_region_fonts(varFont, model, ordered_fonts_list, glyphOrder)

    def _add_COLR(font, model, master_fonts, axisTags, colr_layer_reuse=True):
        merger = COLRVariationMerger(
            model, axisTags, font, allowLayerReuse=colr_layer_reuse
        )
        merger.mergeTables(font, master_fonts)
        store = merger.store_builder.finish()

        colr = font["COLR"].table
        if store:
            mapping = store.optimize()
            colr.VarStore = store
            varIdxes = [mapping[v] for v in merger.varIdxes]
            colr.VarIndexMap = builder.buildDeltaSetIndexMap(varIdxes)

    def load_designspace(designspace, log_enabled=True, *, require_sources=True):
        # TODO: remove this and always assume 'designspace' is a DesignSpaceDocument,
        # never a file path, as that's already handled by caller
        if hasattr(designspace, "sources"):  # Assume a DesignspaceDocument
            ds = designspace
        else:  # Assume a file path
            ds = DesignSpaceDocument.fromfile(designspace)

        masters = ds.sources
        if require_sources and not masters:
            raise VarLibValidationError("Designspace must have at least one source.")
        instances = ds.instances

        # TODO: Use fontTools.designspaceLib.tagForAxisName instead.
        standard_axis_map = OrderedDict(
            [
                ("weight", ("wght", {"en": "Weight"})),
                ("width", ("wdth", {"en": "Width"})),
                ("slant", ("slnt", {"en": "Slant"})),
                ("optical", ("opsz", {"en": "Optical Size"})),
                ("italic", ("ital", {"en": "Italic"})),
            ]
        )

        # Setup axes
        if not ds.axes:
            raise VarLibValidationError(f"Designspace must have at least one axis.")

        axes = OrderedDict()
        for axis_index, axis in enumerate(ds.axes):
            axis_name = axis.name
            if not axis_name:
                if not axis.tag:
                    raise VarLibValidationError(f"Axis at index {axis_index} needs a tag.")
                axis_name = axis.name = axis.tag

            if axis_name in standard_axis_map:
                if axis.tag is None:
                    axis.tag = standard_axis_map[axis_name][0]
                if not axis.labelNames:
                    axis.labelNames.update(standard_axis_map[axis_name][1])
            else:
                if not axis.tag:
                    raise VarLibValidationError(f"Axis at index {axis_index} needs a tag.")
                if not axis.labelNames:
                    axis.labelNames["en"] = tostr(axis_name)

            axes[axis_name] = axis
        if log_enabled:
            log.info("Axes:\n%s", pformat([axis.asdict() for axis in axes.values()]))

        axisMappings = ds.axisMappings
        if axisMappings and log_enabled:
            log.info("Mappings:\n%s", pformat(axisMappings))

        # Check all master and instance locations are valid and fill in defaults
        for obj in masters + instances:
            obj_name = obj.name or obj.styleName or ""
            loc = obj.getFullDesignLocation(ds)
            obj.designLocation = loc
            if loc is None:
                raise VarLibValidationError(
                    f"Source or instance '{obj_name}' has no location."
                )
            for axis_name in loc.keys():
                if axis_name not in axes:
                    raise VarLibValidationError(
                        f"Location axis '{axis_name}' unknown for '{obj_name}'."
                    )
            for axis_name, axis in axes.items():
                v = axis.map_backward(loc[axis_name])
                if not (axis.minimum <= v <= axis.maximum):
                    raise VarLibValidationError(
                        f"Source or instance '{obj_name}' has out-of-range location "
                        f"for axis '{axis_name}': is mapped to {v} but must be in "
                        f"mapped range [{axis.minimum}..{axis.maximum}] (NOTE: all "
                        "values are in user-space)."
                    )

        # Normalize master locations

        internal_master_locs = [o.getFullDesignLocation(ds) for o in masters]
        if log_enabled:
            log.info("Internal master locations:\n%s", pformat(internal_master_locs))

        # TODO This mapping should ideally be moved closer to logic in _add_fvar/avar
        internal_axis_supports = {}
        for axis in axes.values():
            triple = (axis.minimum, axis.default, axis.maximum)
            internal_axis_supports[axis.name] = [axis.map_forward(v) for v in triple]
        if log_enabled:
            log.info("Internal axis supports:\n%s", pformat(internal_axis_supports))

        normalized_master_locs = [
            models.normalizeLocation(m, internal_axis_supports)
            for m in internal_master_locs
        ]
        if log_enabled:
            log.info("Normalized master locations:\n%s", pformat(normalized_master_locs))

        # Find base master
        base_idx = None
        for i, m in enumerate(normalized_master_locs):
            if all(v == 0 for v in m.values()):
                if base_idx is not None:
                    raise VarLibValidationError(
                        "More than one base master found in Designspace."
                    )
                base_idx = i
        if require_sources and base_idx is None:
            raise VarLibValidationError(
                "Base master not found; no master at default location?"
            )
        if log_enabled:
            log.info("Index of base master: %s", base_idx)

        return _DesignSpaceData(
            axes,
            axisMappings,
            internal_axis_supports,
            base_idx,
            normalized_master_locs,
            masters,
            instances,
            ds.rules,
            ds.rulesProcessingLast,
            ds.lib,
        )

    # https://docs.microsoft.com/en-us/typography/opentype/spec/os2#uswidthclass
    WDTH_VALUE_TO_OS2_WIDTH_CLASS = {
        50: 1,
        62.5: 2,
        75: 3,
        87.5: 4,
        100: 5,
        112.5: 6,
        125: 7,
        150: 8,
        200: 9,
    }

    def set_default_weight_width_slant(font, location):
        if "OS/2" in font:
            if "wght" in location:
                weight_class = otRound(max(1, min(location["wght"], 1000)))
                if font["OS/2"].usWeightClass != weight_class:
                    log.info("Setting OS/2.usWeightClass = %s", weight_class)
                    font["OS/2"].usWeightClass = weight_class

            if "wdth" in location:
                # map 'wdth' axis (50..200) to OS/2.usWidthClass (1..9), rounding to closest
                widthValue = min(max(location["wdth"], 50), 200)
                widthClass = otRound(
                    models.piecewiseLinearMap(widthValue, WDTH_VALUE_TO_OS2_WIDTH_CLASS)
                )
                if font["OS/2"].usWidthClass != widthClass:
                    log.info("Setting OS/2.usWidthClass = %s", widthClass)
                    font["OS/2"].usWidthClass = widthClass

        if "slnt" in location and "post" in font:
            italicAngle = max(-90, min(location["slnt"], 90))
            if font["post"].italicAngle != italicAngle:
                log.info("Setting post.italicAngle = %s", italicAngle)
                font["post"].italicAngle = italicAngle

    def drop_implied_oncurve_points(*masters: TTFont) -> int:
        """Drop impliable on-curve points from all the simple glyphs in masters.

        In TrueType glyf outlines, on-curve points can be implied when they are located
        exactly at the midpoint of the line connecting two consecutive off-curve points.

        The input masters' glyf tables are assumed to contain same-named glyphs that are
        interpolatable. Oncurve points are only dropped if they can be implied for all
        the masters. The fonts are modified in-place.

        Args:
            masters: The TTFont(s) to modify

        Returns:
            The total number of points that were dropped if any.

        Reference:
        https://developer.apple.com/fonts/TrueType-Reference-Manual/RM01/Chap1.html
        """

        count = 0
        glyph_masters = defaultdict(list)
        # multiple DS source may point to the same TTFont object and we want to
        # avoid processing the same glyph twice as they are modified in-place
        for font in {id(m): m for m in masters}.values():
            glyf = font["glyf"]
            for glyphName in glyf.keys():
                glyph_masters[glyphName].append(glyf[glyphName])
        count = 0
        for glyphName, glyphs in glyph_masters.items():
            try:
                dropped = dropImpliedOnCurvePoints(*glyphs)
            except ValueError as e:
                # we don't fail for incompatible glyphs in _add_gvar so we shouldn't here
                log.warning("Failed to drop implied oncurves for %r: %s", glyphName, e)
            else:
                count += len(dropped)
        return count

    def build_many(
        designspace: DesignSpaceDocument,
        master_finder=lambda s: s,
        exclude=[],
        optimize=True,
        skip_vf=lambda vf_name: False,
        colr_layer_reuse=True,
        drop_implied_oncurves=False,
    ):
        """
        Build variable fonts from a designspace file, version 5 which can define
        several VFs, or version 4 which has implicitly one VF covering the whole doc.

        If master_finder is set, it should be a callable that takes master
        filename as found in designspace file and map it to master font
        binary as to be opened (eg. .ttf or .otf).

        skip_vf can be used to skip building some of the variable fonts defined in
        the input designspace. It's a predicate that takes as argument the name
        of the variable font and returns `bool`.

        Always returns a Dict[str, TTFont] keyed by VariableFontDescriptor.name
        """
        res = {}
        # varLib.build (used further below) by default only builds an incomplete 'STAT'
        # with an empty AxisValueArray--unless the VF inherited 'STAT' from its base master.
        # Designspace version 5 can also be used to define 'STAT' labels or customize
        # axes ordering, etc. To avoid overwriting a pre-existing 'STAT' or redoing the
        # same work twice, here we check if designspace contains any 'STAT' info before
        # proceeding to call buildVFStatTable for each VF.
        # https://github.com/fonttools/fonttools/pull/3024
        # https://github.com/fonttools/fonttools/issues/3045
        doBuildStatFromDSv5 = (
            "STAT" not in exclude
            and designspace.formatTuple >= (5, 0)
            and (
                any(a.axisLabels or a.axisOrdering is not None for a in designspace.axes)
                or designspace.locationLabels
            )
        )
        for _location, subDoc in splitInterpolable(designspace):
            for name, vfDoc in splitVariableFonts(subDoc):
                if skip_vf(name):
                    log.debug(f"Skipping variable TTF font: {name}")
                    continue
                vf = build(
                    vfDoc,
                    master_finder,
                    exclude=exclude,
                    optimize=optimize,
                    colr_layer_reuse=colr_layer_reuse,
                    drop_implied_oncurves=drop_implied_oncurves,
                )[0]
                if doBuildStatFromDSv5:
                    buildVFStatTable(vf, designspace, name)
                res[name] = vf
        return res

    def build(
        designspace,
        master_finder=lambda s: s,
        exclude=[],
        optimize=True,
        colr_layer_reuse=True,
        drop_implied_oncurves=False,
    ):
        """
        Build variation font from a designspace file.

        If master_finder is set, it should be a callable that takes master
        filename as found in designspace file and map it to master font
        binary as to be opened (eg. .ttf or .otf).
        """
        if hasattr(designspace, "sources"):  # Assume a DesignspaceDocument
            pass
        else:  # Assume a file path
            designspace = DesignSpaceDocument.fromfile(designspace)

        ds = load_designspace(designspace)
        log.info("Building variable font")

        log.info("Loading master fonts")
        master_fonts = load_masters(designspace, master_finder)

        # TODO: 'master_ttfs' is unused except for return value, remove later
        master_ttfs = []
        for master in master_fonts:
            try:
                master_ttfs.append(master.reader.file.name)
            except AttributeError:
                master_ttfs.append(None)  # in-memory fonts have no path

        if drop_implied_oncurves and "glyf" in master_fonts[ds.base_idx]:
            drop_count = drop_implied_oncurve_points(*master_fonts)
            log.info(
                "Dropped %s on-curve points from simple glyphs in the 'glyf' table",
                drop_count,
            )

        # Copy the base master to work from it
        vf = deepcopy(master_fonts[ds.base_idx])

        if "DSIG" in vf:
            del vf["DSIG"]

        # TODO append masters as named-instances as well; needs .designspace change.
        fvar = _add_fvar(vf, ds.axes, ds.instances)
        if "STAT" not in exclude:
            _add_stat(vf)

        # Map from axis names to axis tags...
        normalized_master_locs = [
            {ds.axes[k].tag: v for k, v in loc.items()} for loc in ds.normalized_master_locs
        ]
        # From here on, we use fvar axes only
        axisTags = [axis.axisTag for axis in fvar.axes]

        # Assume single-model for now.
        model = models.VariationModel(normalized_master_locs, axisOrder=axisTags)
        assert 0 == model.mapping[ds.base_idx]

        log.info("Building variations tables")
        if "avar" not in exclude:
            _add_avar(vf, ds.axes, ds.axisMappings, axisTags)
        if "BASE" not in exclude and "BASE" in vf:
            _add_BASE(vf, model, master_fonts, axisTags)
        if "MVAR" not in exclude:
            _add_MVAR(vf, model, master_fonts, axisTags)
        if "HVAR" not in exclude:
            _add_HVAR(vf, model, master_fonts, axisTags)
        if "VVAR" not in exclude and "vmtx" in vf:
            _add_VVAR(vf, model, master_fonts, axisTags)
        if "GDEF" not in exclude or "GPOS" not in exclude:
            _merge_OTL(vf, model, master_fonts, axisTags)
        if "gvar" not in exclude and "glyf" in vf:
            _add_gvar(vf, model, master_fonts, optimize=optimize)
        if "cvar" not in exclude and "glyf" in vf:
            _merge_TTHinting(vf, model, master_fonts)
        if "GSUB" not in exclude and ds.rules:
            featureTags = _feature_variations_tags(ds)
            _add_GSUB_feature_variations(
                vf, ds.axes, ds.internal_axis_supports, ds.rules, featureTags
            )
        if "CFF2" not in exclude and ("CFF " in vf or "CFF2" in vf):
            _add_CFF2(vf, model, master_fonts)
            if "post" in vf:
                # set 'post' to format 2 to keep the glyph names dropped from CFF2
                post = vf["post"]
                if post.formatType != 2.0:
                    post.formatType = 2.0
                    post.extraNames = []
                    post.mapping = {}
        if "COLR" not in exclude and "COLR" in vf and vf["COLR"].version > 0:
            _add_COLR(vf, model, master_fonts, axisTags, colr_layer_reuse)

        set_default_weight_width_slant(
            vf, location={axis.axisTag: axis.defaultValue for axis in vf["fvar"].axes}
        )

        for tag in exclude:
            if tag in vf:
                del vf[tag]

        # TODO: Only return vf for 4.0+, the rest is unused.
        return vf, model, master_ttfs

    def _open_font(path, master_finder=lambda s: s):
        # load TTFont masters from given 'path': this can be either a .TTX or an
        # OpenType binary font; or if neither of these, try use the 'master_finder'
        # callable to resolve the path to a valid .TTX or OpenType font binary.
        from fontTools.ttx import guessFileType

        master_path = os.path.normpath(path)
        tp = guessFileType(master_path)
        if tp is None:
            # not an OpenType binary/ttx, fall back to the master finder.
            master_path = master_finder(master_path)
            tp = guessFileType(master_path)
        if tp in ("TTX", "OTX"):
            font = TTFont()
            font.importXML(master_path)
        elif tp in ("TTF", "OTF", "WOFF", "WOFF2"):
            font = TTFont(master_path)
        else:
            raise VarLibValidationError("Invalid master path: %r" % master_path)
        return font

    def load_masters(designspace, master_finder=lambda s: s):
        """Ensure that all SourceDescriptor.font attributes have an appropriate TTFont
        object loaded, or else open TTFont objects from the SourceDescriptor.path
        attributes.

        The paths can point to either an OpenType font, a TTX file, or a UFO. In the
        latter case, use the provided master_finder callable to map from UFO paths to
        the respective master font binaries (e.g. .ttf, .otf or .ttx).

        Return list of master TTFont objects in the same order they are listed in the
        DesignSpaceDocument.
        """
        for master in designspace.sources:
            # If a SourceDescriptor has a layer name, demand that the compiled TTFont
            # be supplied by the caller. This spares us from modifying MasterFinder.
            if master.layerName and master.font is None:
                raise VarLibValidationError(
                    f"Designspace source '{master.name or '<Unknown>'}' specified a "
                    "layer name but lacks the required TTFont object in the 'font' "
                    "attribute."
                )

        return designspace.loadSourceFonts(_open_font, master_finder=master_finder)

    class MasterFinder(object):
        def __init__(self, template):
            self.template = template

        def __call__(self, src_path):
            fullname = os.path.abspath(src_path)
            dirname, basename = os.path.split(fullname)
            stem, ext = os.path.splitext(basename)
            path = self.template.format(
                fullname=fullname,
                dirname=dirname,
                basename=basename,
                stem=stem,
                ext=ext,
            )
            return os.path.normpath(path)

    def _feature_variations_tags(ds):
        raw_tags = ds.lib.get(
            FEAVAR_FEATURETAG_LIB_KEY,
            "rclt" if ds.rulesProcessingLast else "rvrn",
        )
        return sorted({t.strip() for t in raw_tags.split(",")})

    def addGSUBFeatureVariations(vf, designspace, featureTags=(), *, log_enabled=False):
        """Add GSUB FeatureVariations table to variable font, based on DesignSpace rules.

        Args:
            vf: A TTFont object representing the variable font.
            designspace: A DesignSpaceDocument object.
            featureTags: Optional feature tag(s) to use for the FeatureVariations records.
                If unset, the key 'com.github.fonttools.varLib.featureVarsFeatureTag' is
                looked up in the DS <lib> and used; otherwise the default is 'rclt' if
                the <rules processing="last"> attribute is set, else 'rvrn'.
                See <https://fonttools.readthedocs.io/en/latest/designspaceLib/xml.html#rules-element>
            log_enabled: If True, log info about DS axes and sources. Default is False, as
                the same info may have already been logged as part of varLib.build.
        """
        ds = load_designspace(designspace, log_enabled=log_enabled)
        if not ds.rules:
            return
        if not featureTags:
            featureTags = _feature_variations_tags(ds)
        _add_GSUB_feature_variations(
            vf, ds.axes, ds.internal_axis_supports, ds.rules, featureTags
        )

    def main(args=None):
        """Build variable fonts from a designspace file and masters"""
        from argparse import ArgumentParser
        from fontTools import configLogger

        parser = ArgumentParser(prog="varLib", description=main.__doc__)
        parser.add_argument("designspace")
        output_group = parser.add_mutually_exclusive_group()
        output_group.add_argument(
            "-o", metavar="OUTPUTFILE", dest="outfile", default=None, help="output file"
        )
        output_group.add_argument(
            "-d",
            "--output-dir",
            metavar="OUTPUTDIR",
            default=None,
            help="output dir (default: same as input designspace file)",
        )
        parser.add_argument(
            "-x",
            metavar="TAG",
            dest="exclude",
            action="append",
            default=[],
            help="exclude table",
        )
        parser.add_argument(
            "--disable-iup",
            dest="optimize",
            action="store_false",
            help="do not perform IUP optimization",
        )
        parser.add_argument(
            "--no-colr-layer-reuse",
            dest="colr_layer_reuse",
            action="store_false",
            help="do not rebuild variable COLR table to optimize COLR layer reuse",
        )
        parser.add_argument(
            "--drop-implied-oncurves",
            action="store_true",
            help=(
                "drop on-curve points that can be implied when exactly in the middle of "
                "two off-curve points (only applies to TrueType fonts)"
            ),
        )
        parser.add_argument(
            "--master-finder",
            default="master_ttf_interpolatable/{stem}.ttf",
            help=(
                "templated string used for finding binary font "
                "files given the source file names defined in the "
                "designspace document. The following special strings "
                "are defined: {fullname} is the absolute source file "
                "name; {basename} is the file name without its "
                "directory; {stem} is the basename without the file "
                "extension; {ext} is the source file extension; "
                "{dirname} is the directory of the absolute file "
                'name. The default value is "%(default)s".'
            ),
        )
        parser.add_argument(
            "--variable-fonts",
            default=".*",
            metavar="VF_NAME",
            help=(
                "Filter the list of variable fonts produced from the input "
                "Designspace v5 file. By default all listed variable fonts are "
                "generated. To generate a specific variable font (or variable fonts) "
                'that match a given "name" attribute, you can pass as argument '
                "the full name or a regular expression. E.g.: --variable-fonts "
                '"MyFontVF_WeightOnly"; or --variable-fonts "MyFontVFItalic_.*".'
            ),
        )
        logging_group = parser.add_mutually_exclusive_group(required=False)
        logging_group.add_argument(
            "-v", "--verbose", action="store_true", help="Run more verbosely."
        )
        logging_group.add_argument(
            "-q", "--quiet", action="store_true", help="Turn verbosity off."
        )
        options = parser.parse_args(args)

        configLogger(
            level=("DEBUG" if options.verbose else "ERROR" if options.quiet else "INFO")
        )

        designspace_filename = options.designspace
        designspace = DesignSpaceDocument.fromfile(designspace_filename)

        vf_descriptors = designspace.getVariableFonts()
        if not vf_descriptors:
            parser.error(f"No variable fonts in given designspace {designspace.path!r}")

        vfs_to_build = []
        for vf in vf_descriptors:
            # Skip variable fonts that do not match the user's inclusion regex if given.
            if not fullmatch(options.variable_fonts, vf.name):
                continue
            vfs_to_build.append(vf)

        if not vfs_to_build:
            parser.error(f"No variable fonts matching {options.variable_fonts!r}")

        if options.outfile is not None and len(vfs_to_build) > 1:
            parser.error(
                "can't specify -o because there are multiple VFs to build; "
                "use --output-dir, or select a single VF with --variable-fonts"
            )

        output_dir = options.output_dir
        if output_dir is None:
            output_dir = os.path.dirname(designspace_filename)

        vf_name_to_output_path = {}
        if len(vfs_to_build) == 1 and options.outfile is not None:
            vf_name_to_output_path[vfs_to_build[0].name] = options.outfile
        else:
            for vf in vfs_to_build:
                filename = vf.filename if vf.filename is not None else vf.name + ".{ext}"
                vf_name_to_output_path[vf.name] = os.path.join(output_dir, filename)

        finder = MasterFinder(options.master_finder)

        vfs = build_many(
            designspace,
            finder,
            exclude=options.exclude,
            optimize=options.optimize,
            colr_layer_reuse=options.colr_layer_reuse,
            drop_implied_oncurves=options.drop_implied_oncurves,
        )

        for vf_name, vf in vfs.items():
            ext = "otf" if vf.sfntVersion == "OTTO" else "ttf"
            output_path = vf_name_to_output_path[vf_name].format(ext=ext)
            output_dir = os.path.dirname(output_path)
            if output_dir:
                os.makedirs(output_dir, exist_ok=True)
            log.info("Saving variation font %s", output_path)
            vf.save(output_path)

    if __name__ == "__main__":
        import sys

        if len(sys.argv) > 1:
            sys.exit(main())
        import doctest

        sys.exit(doctest.testmod().failed)