if not modules then modules = { } end modules ['good-mth'] = {
    version   = 1.000,
    comment   = "companion to font-lib.mkiv",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files"
}

local type, next, tonumber, unpack = type, next, tonumber, unpack
local ceil = math.ceil
local match = string.match

local fonts = fonts

local trace_goodies      = false  trackers.register("fonts.goodies", function(v) trace_goodies = v end)
local report_goodies     = logs.reporter("fonts","goodies")

local registerotffeature = fonts.handlers.otf.features.register

local fontgoodies        = fonts.goodies or { }

local fontcharacters     = fonts.hashes.characters

local trace_defining     = false  trackers.register  ("math.defining",  function(v) trace_defining   = v     end)
local use_math_goodies   = true   directives.register("math.nogoodies", function(v) use_math_goodies = not v end)

local report_math        = logs.reporter("mathematics","initializing")

local nuts               = nodes.nuts
local setlink            = nuts.setlink

local nodepool           = nuts.pool
local new_kern           = nodepool.kern
local new_glyph          = nodepool.glyph
local new_hlist          = nodepool.hlist
local new_vlist          = nodepool.vlist

local insertnodeafter    = nuts.insertafter

local function initialize(goodies)
    local mathgoodies = goodies.mathematics
    if mathgoodies then
        local virtuals = mathgoodies.virtuals
        local mapfiles = mathgoodies.mapfiles
        local maplines = mathgoodies.maplines
        if virtuals then
            for name, specification in next, virtuals do
                -- beware, they are all constructed ... we should be more selective
                mathematics.makefont(name,specification,goodies)
            end
        end
        if mapfiles then
            for i=1,#mapfiles do
                fonts.mappings.loadfile(mapfiles[i]) -- todo: backend function
            end
        end
        if maplines then
            for i=1,#maplines do
                fonts.mappings.loadline(maplines[i]) -- todo: backend function
            end
        end
    end
end

fontgoodies.register("mathematics", initialize)

-- This is used in the koeieletters font:

local function mathradicalaction(n,h,v,font,mchar,echar)
    local characters = fontcharacters[font]
    local mchardata  = characters[mchar]
    local echardata  = characters[echar]
    local ewidth     = echardata.width
    local mwidth     = mchardata.width
    local delta      = h - ewidth
    local glyph      = new_glyph(font,echar)
    local head       = glyph
    if delta > 0 then
        local count = ceil(delta/mwidth)
        local kern  = (delta - count * mwidth) / count
        for i=1,count do
            local k = new_kern(kern)
            local g = new_glyph(font,mchar)
            setlink(k,head)
            setlink(g,k)
            head = g
        end
    end
    local height = mchardata.height
    local list   = new_hlist(head)
    local kern   = new_kern(height-v)
    list = setlink(kern,list)
    local list = new_vlist(kern)
    insertnodeafter(n,n,list)
end

local function mathhruleaction(n,h,v,font,bchar,mchar,echar)
    local characters = fontcharacters[font]
    local bchardata  = characters[bchar]
    local mchardata  = characters[mchar]
    local echardata  = characters[echar]
    local bwidth     = bchardata.width
    local mwidth     = mchardata.width
    local ewidth     = echardata.width
    local delta      = h - ewidth - bwidth
    local glyph      = new_glyph(font,echar)
    local head       = glyph
    if delta > 0 then
        local count = ceil(delta/mwidth)
        local kern  = (delta - count * mwidth) / (count+1)
        for i=1,count do
            local k = new_kern(kern)
            local g = new_glyph(font,mchar)
            setlink(k,head)
            setlink(g,k)
            head = g
        end
        local k = new_kern(kern)
        setlink(k,head)
        head = k
    end
    local g = new_glyph(font,bchar)
    setlink(g,head)
    head = g
    local height = mchardata.height
    local list   = new_hlist(head)
    local kern   = new_kern(height-v)
    list = setlink(kern,list)
    local list = new_vlist(kern)
    insertnodeafter(n,n,list)
end

local function initialize(tfmdata)
    local goodies = tfmdata.goodies
    if goodies then
        local resources = tfmdata.resources
        local ruledata  = { }
        for i=1,#goodies do
            local mathematics = goodies[i].mathematics
            if mathematics then
                local rules = mathematics.rules
                if rules then
                    for tag, name in next, rules do
                        ruledata[tag] = name
                    end
                end
            end
        end
        if next(ruledata) then
            local characters = tfmdata.characters
            local unicodes   = resources.unicodes
            if characters and unicodes then
                local mathruleactions = resources.mathruleactions
                if not mathruleactions then
                    mathruleactions = { }
                    resources.mathruleactions = mathruleactions
                end
                --
                local mchar = unicodes[ruledata["radical.extender"] or false]
                local echar = unicodes[ruledata["radical.end"]      or false]
                if mchar and echar then
                    mathruleactions.radicalaction = function(n,h,v,font)
                        mathradicalaction(n,h,v,font,mchar,echar)
                    end
                end
                --
                local bchar = unicodes[ruledata["hrule.begin"]    or false]
                local mchar = unicodes[ruledata["hrule.extender"] or false]
                local echar = unicodes[ruledata["hrule.end"]      or false]
                if bchar and mchar and echar then
                    mathruleactions.hruleaction = function(n,h,v,font)
                        mathhruleaction(n,h,v,font,bchar,mchar,echar)
                    end
                end
                -- not that nice but we need to register it at the tex end
             -- context.enablemathrules("\\fontclass")
            end
        end
    end
end

registerotffeature {
    name         = "mathrules",
    description  = "check math rules",
    default      = true,
    initializers = {
        base = initialize,
        node = initialize,
    }
}