%D \module
%D   [       file=m-json,
%D        version=2022.04.11, % 2012.08.03,
%D          title=\CONTEXT\ Modules,
%D       subtitle=Json,
%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.

%D This module is a side effect of looking into json. Currently there are
%D only a few helpers:
%D
%D \starttyping
%D moduledata.json.tolua   (str)
%D moduledata.json.tostring(val)
%D \stoptyping
%D
%D Nothing spectacular but maybe handy to have around.

\startmodule [json]

% check for: utilities.json

\registerctxluafile{util-jsn}{}

% \def\u#1#2#3#4{\cldcontext{utf.char(0x#1#2#3#4)}}

\startluacode

    -- when we are at the lua end we can just use the table directly but
    -- otherwise we can use accessors at the tex end and if needed some
    -- special formatters
    --
    -- we can actually map the json to xml and then use xml accessors
    -- which has some benefits

    local tonumber = tonumber
    local context  = context
    local gmatch   = string.gmatch

    local loaded  = { }
    local current = nil
    local json    = utilities.json

    local function loadjsonfile(namespace,filename)
        local data = loaded[namespace]
        if not data then
            local fullname = resolvers.findfile(filename)
            if fullname and fullname ~= "" then
                data = io.loaddata(fullname)
                if data then
                    data = utilities.json.tolua(data)
                end
            end
            if not data then
                data = { }
            end
            loaded[namespace] = data
            metapost.setparameterset(namespace,data)
        end
        current = data
        return data
    end

    local function jsonfield(namespace,name,default)
        local data = loaded[namespace] or current
        if current then
            for s in gmatch(name,"[^%.]+") do
                data = data[s] or data[tonumber(s) or 0]
                if not data then
                    return
                end
            end
            return data
        end
    end

    json.field = jsonfield

    function json.loaded(namespace)
        return (namespace and loaded[namespace]) or current or { }
    end

    interfaces.implement {
        name      = "loadjsonfile",
        actions   = loadjsonfile,
        arguments = { "optional", "optional" },
        public    = true,
        protected = true,
    }

    interfaces.implement {
        name      = "jsonfield",
        actions   = { jsonfield, context },
        arguments = "2 arguments",
        public    = true,
    }

    interfaces.implement {
        name      = "jsonfielddefault",
        actions   = { jsonfield, context },
        arguments = "3 arguments",
        public    = true,
    }

\stopluacode

\stopmodule