if not modules then modules = { } end modules ['lpdf-rul'] = {
    version   = 1.001,
    comment   = "companion to grph-rul.mkiv",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files"
}

-- todo: split backend and pdf

local tonumber, next, type = tonumber, next, type
local concat = table.concat

local attributes       = attributes
local nodes            = nodes

local bpfactor         = number.dimenfactors.bp

local nuts             = nodes.nuts
local ruleactions      = nuts.rules.ruleactions

local getwhd           = nuts.getwhd

local lefttoright_code = nodes.dirvalues.lefttoright

local mpcolor          = attributes.colors.mpcolor

local trace_mp         = false  trackers.register("rules.mp", function(v) trace_mp = v end)

local report_mp        = logs.reporter("rules","mp")

local floor            = math.floor
local getrandom        = utilities.randomizer.get
local formatters       = string.formatters

local setdimen         = tex.setdimen
local setcount         = tex.setcount
local setmacro         = tokens.setters.macro

local codeinjections   = backends.registered.pdf.codeinjections

-- This is very pdf specific. Maybe move some to lpdf-rul.lua some day.

local pdfprint ; pdfprint = function(...) pdfprint = lpdf.print return pdfprint(...) end

do

    local simplemetapost = metapost.simple
    local cachesize      = 0
    local maxcachesize   = 256*1024
    local cachethreshold = 1024
    local caching        = false -- otherwise random issues so we need a dedicated randomizer first

 -- local maxcachesize   = 8*1024
 -- local cachethreshold = 1024/2

    local cache = table.setmetatableindex(function(t,k)
        local v = simplemetapost("rulefun",k) -- w, h, d
        cachesize = cachesize + #v
        if cachesize > maxcachesize then
         -- print("old",cachesize)
            for k, v in next, t do
                local n = #v
                if n > cachethreshold then
                    t[k] = nil
                    cachesize = cachesize - n
                end
            end
         -- print("new",cachesize)
        end
     -- print(cachesize,maxcachesize,cachethreshold,#v)
        t[k] = v
        return v
    end)

    local replacer = utilities.templates.replacer

    -- todo: RuleColor -> just string ?
    -- todo: fetch them instead fo push them

--     local predefined = {
--         ["fake:word"] = replacer [[
-- FakeWord(%width%,%height%,%depth%,%line%,%color%);
--         ]],
--         ["fake:rule"] = replacer[[
-- %initializations%
-- FakeRule(%width%,%height%,%depth%,%line%,%color%);
--         ]],
--         ["fake:rest"] = replacer [[
-- RuleDirection := "%direction%" ;
-- RuleOption := "%option%" ;
-- RuleWidth := %width% ;
-- RuleHeight := %height% ;
-- RuleDepth := %depth% ;
-- RuleH := %h% ;
-- RuleV := %v% ;
-- RuleThickness := %line% ;
-- RuleFactor := %factor% ;
-- RuleOffset := %offset% ;
-- def RuleColor = %color% enddef ;
-- %data%;
--         ]]
--     }

        local predefined = {
        ["fake:word"] = replacer [[
FakeWord(RuleWidth,RuleHeight,RuleDepth,RuleThickness,RuleColor);
        ]],
        ["fake:rule"] = replacer[[
%initializations%
FakeRule(RuleWidth,RuleHeight,RuleDepth,RuleThickness,RuleColor);
        ]],
        ["fake:rest"] = replacer [[
%data%;
        ]]
    }

    local initialized = false ;

    local function rule_mp(p,h,v,i,n)
        local name  = p.name or "fake:rest"
        local ht    = p.height or 0
        local dp    = p.depth  or 0
        local total = ht + dp
        local code  = (predefined[name] or predefined["fake:rest"]) {
            data      = p.data or "",
      -- -- width     = p.width * bpfactor,
      -- -- height    = p.height * bpfactor,
      -- -- depth     = p.depth * bpfactor,
      --    width     = h * bpfactor,
      --    height    = v * bpfactor * ht / total,
      --    depth     = v * bpfactor * dp / total,
      --    factor    = (p.factor or 0) * bpfactor, -- needs checking
      --    offset    = p.offset or 0,
      --    line      = (p.line or 65536) * bpfactor,
      --    color     = mpcolor(p.ma,p.ca,p.ta),
      --    option    = p.option or "",
      --    direction = p.direction or lefttoright_code,
      --    h         = h * bpfactor,
      --    v         = v * bpfactor,
        }
        --
        setdimen("d_rule_width", h)
        setdimen("d_rule_height", v * ht / total)
        setdimen("d_rule_depth", v * dp / total)
        setdimen("d_rule_h", h)
        setdimen("d_rule_v", v)
        setdimen("d_rule_line", p.line or 65536)
        setdimen("d_rule_offset", (p.offset or 0) * 65536)
        setdimen("d_rule_factor", (p.factor or 0)) -- needs checking
        setmacro("m_rule_option", p.option or "")
        setmacro("m_rule_direction", p.direction or lefttoright_code)
        setmacro("m_rule_color", mpcolor(p.ma,p.ca,p.ta))
        --
        if not initialized then
            initialized = true
            simplemetapost("rulefun",formatters["randomseed := %s;"](getrandom("rulefun",0,4095)))
        end
        -- we enable extensions but we could also consider to delegate colors
        -- to the node finalizer
        local pdf = caching and cache[code] or simplemetapost("rulefun",code,true)
        if trace_mp then
            report_mp("code: %s",code)
            report_mp("pdf : %s",pdf)
        end
        if pdf and pdf ~= "" then
            pdfprint("direct",pdf)
        end
    end

    codeinjections.ruleactionmp = rule_mp

end

do

    -- This is the old oval method that we keep it for compatibility reasons. Of
    -- course one can use mp instead. It could be improved but at the cost of more
    -- code than I'm willing to add for something hardly used.

    local function round(p,kind)
        local method = tonumber(p.corner) or 0
        if method < 0 or method > 27 then
            method = 0
        end
        local width  = p.width or 0
        local height = p.height or 0
        local depth  = p.depth or 0
        local total  = height + depth
        local radius = p.radius or 655360
        local line   = p.line or 65536
        local how    = (method > 8 or kind ~= "fill") and "S" or "f"
        local half   = line / 2
        local xmin   =            half  * bpfactor
        local xmax   = ( width  - half) * bpfactor
        local ymax   = ( height - half) * bpfactor
        local ymin   = (-depth  + half) * bpfactor
        local full   = ( radius + half)
        local xxmin  =            full  * bpfactor
        local xxmax  = ( width  - full) * bpfactor
        local yymax  = ( height - full) * bpfactor
        local yymin  = (-depth  + full) * bpfactor
              line   =            line  * bpfactor
        if xxmin <= xxmax and yymin <= yymax then
            local list = nil
            if method == 0 then
                list = {
                    "q", line, "w", xxmin, ymin, "m", xxmax, ymin, "l", xmax, ymin, xmax, yymin, "y",
                    xmax, yymax, "l", xmax, ymax, xxmax, ymax, "y", xxmin, ymax, "l", xmin, ymax,
                    xmin, yymax, "y", xmin, yymin, "l", xmin, ymin, xxmin, ymin, "y", "h", how, "Q",
                }
            elseif method == 1 then
                list = {
                    "q", line, "w", xxmin, ymin, "m", xxmax, ymin, "l", xmax, ymin, xmax, yymin, "y",
                    xmax, ymax, "l", xmin, ymax, "l", xmin, yymin, "l", xmin, ymin, xxmin, ymin, "y",
                    "h", how, "Q",
                }
            elseif method == 2 then
                list = {
                    "q", line, "w", xxmin, ymin, "m", xmax, ymin, "l", xmax, ymax, "l", xxmin, ymax,
                    "l", xmin, ymax, xmin, yymax, "y", xmin, yymin, "l", xmin, ymin, xxmin, ymin,
                    "y", "h", how, "Q",
                }
            elseif method == 3 then
                list = {
                    "q", line, "w", xmin, ymin, "m", xmax, ymin, "l", xmax, yymax, "l", xmax, ymax,
                    xxmax, ymax, "y", xxmin, ymax, "l", xmin, ymax, xmin, yymax, "y", xmin, ymin,
                    "l", "h", how, "Q",
                }

            elseif method == 4 then
                list = {
                    "q", line, "w", xmin, ymin, "m", xxmax, ymin, "l", xmax, ymin, xmax, yymin, "y",
                    xmax, yymax, "l", xmax, ymax, xxmax, ymax, "y", xmin, ymax, "l", xmin, ymin, "l",
                    "h", how, "Q",
                }
            elseif method == 5 then
                list = {
                    "q", line, "w", xmin, ymin, "m", xmax, ymin, "l", xmax, yymax, "l", xmax, ymax,
                    xxmax, ymax, "y", xmin, ymax, "l", xmin, ymin, "l", "h", how, "Q",
                }
            elseif method == 6 then
                list = {
                    "q", line, "w", xmin, ymin, "m", xxmax, ymin, "l", xmax, ymin, xmax, yymin, "y",
                    xmax, ymax, "l", xmin, ymax, "l", xmin, ymin, "l", "h", how, "Q",
                }
            elseif method == 7 then
                list = {
                    "q", line, "w", xxmin, ymin, "m", xmax, ymin, "l", xmax, ymax, "l", xmin, ymax,
                    "l", xmin, yymin, "l", xmin, ymin, xxmin, ymin, "y", "h", how, "Q",
                }
            elseif method == 8 then
                list = {
                    "q", line, "w", xmin, ymin, "m", xmax, ymin, "l", xmax, ymax, "l", xxmin, ymax,
                    "l", xmin, ymax, xmin, yymax, "y", xmin, ymin, "l", "h", how, "Q",
                }
            elseif method == 9 then
                list = {
                    "q", line, "w", xmin, ymax, "m", xmin, yymin, "l", xmin, ymin, xxmin, ymin, "y",
                    xxmax, ymin, "l", xmax, ymin, xmax, yymin, "y", xmax, ymax, "l", how, "Q",
                }
            elseif method == 10 then
                list = {
                    "q", line, "w", xmax, ymax, "m", xxmin, ymax, "l", xmin, ymax, xmin, yymax, "y",
                    xmin, yymin, "l", xmin, ymin, xxmin, ymin, "y", xmax, ymin, "l", how, "Q",
                }
            elseif method == 11 then
                list = {
                    "q", line, "w", xmax, ymin, "m", xmax, yymax, "l", xmax, ymax, xxmax, ymax, "y",
                    xxmin, ymax, "l", xmin, ymax, xmin, yymax, "y", xmin, ymin, "l", how, "Q",
                }
            elseif method == 12 then
                list = {
                    "q", line, "w", xmin, ymax, "m", xxmax, ymax, "l", xmax, ymax, xmax, yymax, "y",
                    xmax, yymin, "l", xmax, ymin, xxmax, ymin, "y", xmin, ymin, "l", how, "Q",
                }
            elseif method == 13 then
                list = {
                    "q", line, "w", xmin, ymax, "m", xxmax, ymax, "l", xmax, ymax, xmax, yymax, "y",
                    xmax, ymin, "l", how, "Q",
                }
            elseif method == 14 then
                list = {
                    "q", line, "w", xmax, ymax, "m", xmax, yymin, "l", xmax, ymin, xxmax, ymin, "y",
                    xmin, ymin, "l", how, "Q",
                }
            elseif method == 15 then
                list = {
                    "q", line, "w", xmax, ymin, "m", xxmin, ymin, "l", xmin, ymin, xmin, yymin, "y",
                    xmin, ymax, "l", how, "Q",
                }
            elseif method == 16 then
                list = {
                    "q", line, "w", xmin, ymin, "m", xmin, yymax, "l", xmin, ymax, xxmin, ymax, "y",
                    xmax, ymax, "l", how, "Q",
                }
            elseif method == 17 then
                list = {
                    "q", line, "w", xxmax, ymax, "m", xmax, ymax, xmax, yymax, "y", how, "Q",
                }
            elseif method == 18 then
                list = {
                    "q", line, "w", xmax, yymin, "m", xmax, ymin, xxmax, ymin, "y", how, "Q",
                }
            elseif method == 19 then
                list = {
                    "q", line, "w", xxmin, ymin, "m", xmin, ymin, xmin, yymin, "y", how, "Q",
                }
            elseif method == 20 then
                list = {
                    "q", line, "w", xmin, yymax, "m", xmin, ymax, xxmin, ymax, "y", how, "Q",
                }
            elseif method == 21 then
                list = {
                    "q", line, "w", xxmax, ymax, "m", xmax, ymax, xmax, yymax, "y", xmin, yymax, "m",
                    xmin, ymax, xxmin, ymax, "y", how, "Q",
                }
            elseif method == 22 then
                list = {
                    "q", line, "w", xxmax, ymax, "m", xmax, ymax, xmax, yymax, "y", xmax, yymin, "m",
                    xmax, ymin, xxmax, ymin, "y", how, "Q",
                }
            elseif method == 23 then
                list = {
                    "q", line, "w", xmax, yymin, "m", xmax, ymin, xxmax, ymin, "y", xxmin, ymin, "m",
                    xmin, ymin, xmin, yymin, "y", how, "Q",
                }
            elseif method == 24 then
                list = {
                    "q", line, "w", xxmin, ymin, "m", xmin, ymin, xmin, yymin, "y", xmin, yymax, "m",
                    xmin, ymax, xxmin, ymax, "y", how, "Q",
                }
            elseif method == 25 then
                list = {
                    "q", line, "w", xxmax, ymax, "m", xmax, ymax, xmax, yymax, "y", xmax, yymin, "m",
                    xmax, ymin, xxmax, ymin, "y", xxmin, ymin, "m", xmin, ymin, xmin, yymin, "y",
                    xmin, yymax, "m", xmin, ymax, xxmin, ymax, "y", how, "Q",
                }
            elseif method == 26 then
                list = {
                    "q", line, "w", xmax, yymin, "m", xmax, ymin, xxmax, ymin, "y", xmin, yymax, "m",
                    xmin, ymax, xxmin, ymax, "y", how, "Q",
                }

            elseif method == 27 then
                list = {
                    "q", line, "w", xxmax, ymax, "m", xmax, ymax, xmax, yymax, "y", xxmin, ymin, "m",
                    xmin, ymin, xmin, yymin, "y", how, "Q",
                }
            end
            pdfprint("direct",concat(list," "))
        end
    end

    local f_rectangle = formatters["%.6N w %.6N %.6N %.6N %.6N re %s"]
    local f_baselined = formatters["%.6N w %.6N %.6N %.6N %.6N re s %.6N %.6N m %.6N %.6N l s"]
    local f_dashlined = formatters["%.6N w %.6N %.6N %.6N %.6N re s [%.6N %.6N] 2 d %.6N %.6N m %.6N %.6N l s"]
    local f_dashtwice = formatters["%.6N w %.6N %.6N %.6N %.6N re s [%.6N %.6N] 2 d %.6N %.6N m %.6N %.6N l s %.6N %.6N m %.6N %.6N l s"]
    local f_radtangle = formatters[
[[%.6N w %.6N %.6N m
%.6N %.6N l %.6N %.6N %.6N %.6N y
%.6N %.6N l %.6N %.6N %.6N %.6N y
%.6N %.6N l %.6N %.6N %.6N %.6N y
%.6N %.6N l %.6N %.6N %.6N %.6N y
h %s]]
        ]

    local rule_any = function(p,h,v,i,n)
        if p.corner then
            return round(p,i)
        else
            local l = (p.line or 65536)*bpfactor
            local r = p and (p.radius or 0)*bpfactor or 0
            local w = h * bpfactor
            local h = v * bpfactor
            local m = nil
            local t = i == "fill" and "f" or "s"
            local o = l / 2
            if r > 0 then
                w = w - o
                h = h - o
                m = f_radtangle(l, r,o, w-r,o, w,o,w,r, w,h-r, w,h,w-r,h, r,h, o,h,o,h-r, o,r, o,o,r,o, t)
            else
                w = w - l
                h = h - l
                m = f_rectangle(l,o,o,w,h,t)
            end
            pdfprint("direct",m)
        end
    end

    local function rule_box(p,h,v,i,n)
        local w, h, d = getwhd(n)
        local line = p.line or 65536
        local l = line *bpfactor
        local w = w * bpfactor
        local h = h * bpfactor
        local d = d * bpfactor
        local o = l / 2
        local u = p.double
        if p.baseline ~= false and ((d >= 0 and h >= 0) or (d <= 0 and h <= 0)) then
            local dashed = tonumber(p.dashed)
            if dashed and dashed > 5*line then
                dashed = dashed * bpfactor
                local delta = (w - 2*dashed*floor(w/(2*dashed)))/2
                if u then
                    u = u * bpfactor
                    pdfprint("direct",f_dashtwice(l,o,o,w-l,h+d-l,dashed,dashed,delta,d,w-delta,d,delta,d+u,w-delta,d+u))
                else
                    pdfprint("direct",f_dashlined(l,o,o,w-l,h+d-l,dashed,dashed,delta,d,w-delta,d))
                end
            else
                pdfprint("direct",f_baselined(l,o,o,w-l,h+d-l,0,d,w,d))
            end
        else
            pdfprint("direct",f_rectangle(l,o,o,w-l,h+d-l,"s"))
        end
    end

    codeinjections.ruleactionfill   = rule_any
    codeinjections.ruleactiondraw   = rule_any
    codeinjections.ruleactionstroke = rule_any
    codeinjections.ruleactionbox    = rule_box

end