%D \module
%D   [       file=meta-imp-riven,
%D        version=2024.07.07,
%D          title=\METAPOST\ Graphics,
%D       subtitle=Riven Numbers,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

% http://calyxa.com/pearl/numbers.html

\startluacode
    local riven      = moduledata.riven or { }
    moduledata.riven = riven

    local tonumber  = tonumber
    local reverse   = table.reverse
    local utfchar   = utf.char
    local gsub      = string.gsub
    local concat    = table.concat
    local lpegmatch = lpeg.match

    local f = string.formatters["%N"]

    local slots = { }

    for i=0,24 do
        slots[i] = fonts.helpers.newprivateslot("riven digit " .. i)
    end

    function riven.tostring(n)
        if n >= 0 and n <= 24 then
            return utfchar(slots[n])
        else
            local result = gsub(f(n),"(%d+)",function(s)
                local digits = { }
                local count  = 1
                local n      = tonumber(s)
                while true do
                    digits[count] = utfchar(slots[n % 25])
                    n = n // 25
                    if n == 0 then
                        break;
                    end
                    count = count + 1
                end
                return concat(reverse(digits))
            end)
            return result
        end
    end

    interfaces.implement {
        name      = "rivennumerals",
        arguments = "integer",
        actions   = { riven.tostring, context }
    }
\stopluacode

\startMPcalculation{simplefun}

    path riven_glyphs[] ; % dni

    def InitializeRiven =

        riven_glyphs[ 0] := (0,0) -- (4,4) ;
        riven_glyphs[ 1] := (2,0) -- (2,4) ;
        riven_glyphs[ 2] := (0,0) .. (2,2) .. (0,4) ;
        riven_glyphs[ 3] := (2,0) -- (0,2) -- (2,4) ;
        riven_glyphs[ 4] := (2,0) -- (2,3) -- (4,3) ;
        riven_glyphs[ 5] := (0,2) -- (4,2) ;

        riven_glyphs[10] := (0,0) .. (2,2) .. (4,0) ;
        riven_glyphs[15] := (0,2) -- (2,0) -- (4,2) ;
        riven_glyphs[20] := (1,4) -- (1,2) -- (4,2) ;

        riven_glyphs[ 6] := riven_glyphs[ 5] && riven_glyphs[1] ;
        riven_glyphs[ 7] := riven_glyphs[ 5] && riven_glyphs[2] ;
        riven_glyphs[ 8] := riven_glyphs[ 5] && riven_glyphs[3] ;
        riven_glyphs[ 9] := riven_glyphs[ 5] && riven_glyphs[4] ;
        riven_glyphs[11] := riven_glyphs[10] && riven_glyphs[1] ;
        riven_glyphs[12] := riven_glyphs[10] && riven_glyphs[2] ;
        riven_glyphs[13] := riven_glyphs[10] && riven_glyphs[3] ;
        riven_glyphs[14] := riven_glyphs[10] && riven_glyphs[4] ;
        riven_glyphs[16] := riven_glyphs[15] && riven_glyphs[1] ;
        riven_glyphs[17] := riven_glyphs[15] && riven_glyphs[2] ;
        riven_glyphs[18] := riven_glyphs[15] && riven_glyphs[3] ;
        riven_glyphs[19] := riven_glyphs[15] && riven_glyphs[4] ;
        riven_glyphs[21] := riven_glyphs[20] && riven_glyphs[1] ;
        riven_glyphs[22] := riven_glyphs[20] && riven_glyphs[2] ;
        riven_glyphs[23] := riven_glyphs[20] && riven_glyphs[3] ;
        riven_glyphs[24] := riven_glyphs[20] && riven_glyphs[4] ;

        riven_glyphs[-1] := (0,0) -- (4,0) -- (4,4) -- (0,4) -- cycle ;

        for i=0 upto 24 :
            riven_glyphs[i] := riven_glyphs[i] && riven_glyphs[-1] ;
        endfor ;

    enddef ;

    vardef Riven(expr i) =
        numeric u ; u := 1.5 ;
        draw image (
            draw riven_glyphs[i]
                scaled (10u/20 - 1.5u/40)
                withpen pencircle scaled (3u/20) ;
            ;
        ) shifted (1.5u/20,1.5u/20)
        shifted (4u/20,0)
    enddef ;

    lmt_registerglyphs [
        name     = "riven",
        units    = 4,
        usecolor = true,
        width    = 3.6,
        height   = 3,
        depth    = 0,
        preamble = "InitializeRiven"
    ] ;

    for i=0 upto 24 :
        lmt_registerglyph [
            category  = "riven",
            private   = "riven digit " & decimal i,
            code      = "Riven(" & decimal i & ")"
            tounicode =
                if i > 9 :
                    { (ASCII "0") + (i div 10), (ASCII "0") + (i mod 10) }
                else :
                                                (ASCII "0") + (i mod 10)
                fi,
        ] ;
    endfor ;

\stopMPcalculation

\unprotect

\permanent\def\rivennumerals#1{\clf_rivennumerals\numexpr#1\relax}

\defineconversion [rivennumerals] [\rivennumerals]
\defineconversion [R]             [\rivennumerals]

\definefontfeature
  [riven]
  [metapost=riven]

\protect

\continueifinputfile{meta-imp-riven.mkxl}

\startbuffer

\definefontfeature
  [default]
  [default]
  [metapost=riven]

\setupbodyfont[dejavu]

\start
    \showglyphs
    RIVEN
    \dostepwiserecurse{0}{24}{1}{\rivennumerals{#1}\space }
\stop

riven \start
    \red\glyphxscale 700
    \dostepwiserecurse{0}{24}{1}{\rivennumerals{#1}\space }
\stop

\startitemize[packed,R][color=orange,stopper=]
    \startitem first  \stopitem
    \startitem second \stopitem
    \startitem third  \stopitem
\stopitemize

RIVEN \start
    \red  \rivennumerals{2023} --
    \green\rivennumerals{4}    --
    \blue \rivennumerals{18}
\stop

\stopbuffer

\starttext

\startTEXpage[offset=1ts,width=3es]
    \getbuffer
\stopTEXpage

\setuplayout[tight]

% \usemodule[scite]

% \typebuffer[option=TEX]

\stoptext