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

-- another experiment, won't change etc ... mkiv stuff .. used?

local insert, remove, concat = table.insert, table.remove, table.concat
local unpack, type = unpack or table.unpack, type

local ctxcatcodes    = catcodes.numbers.ctxcatcodes
local context        = context
local contextsprint  = context.sprint

local trace_define   = false  trackers.register("context.define", function(v) trace_define = v end)

interfaces           = interfaces or { }
local estart         = interfaces.elements.start
local estop          = interfaces.elements.stop

_clmh_ = utilities.parsers.settings_to_hash
_clma_ = utilities.parsers.settings_to_array
_clmn_ = tonumber

local starters, stoppers, macros, stack = { }, { }, { }, { }

local checkers = {
    [0] = "",
    "\\dosingleempty",
    "\\dodoubleempty",
    "\\dotripleempty",
    "\\doquadrupleempty",
    "\\doquintupleempty",
    "\\dosixtupleempty",
}

function _clmm_(name,...)
    macros[name](...)
end

function _clmb_(name,...)
    local sn = stack[name]
    insert(sn,{...})
    starters[name](...)
end

function _clme_(name)
    local sn = stack[name]
    local sv = remove(sn)
    if sv then
        stoppers[name](unpack(sv))
    else
        -- nesting error
    end
end

-- this is a bit old definition ... needs to be modernized

function interfaces.definecommand(name,specification) -- name is optional
    if type(name) == "table" then
        specification = name
        name = specification.name
    end
    if name and specification then
        local arguments = specification.arguments
        local na = (arguments and #arguments) or 0
        local environment = specification.environment
        if na == 0 then
            if environment then
                contextsprint(ctxcatcodes,"\\setuvalue{",estart,name,"}{\\ctxlua{_clmb_('",name,"')}}")
                contextsprint(ctxcatcodes,"\\setuvalue{",estop, name,"}{\\ctxlua{_clme_('",name,"')}}")
            end
            if not environment or environment == "both" then
                contextsprint(ctxcatcodes,"\\setuvalue{",       name,"}{\\ctxlua{_clmm_('",name,"')}}")
            end
        else
            -- we could flush immediate but tracing is bad then
            stack[name] = { }
            local opt      = 0
            local done     = false
            local snippets = { } -- we can reuse it
            local mkivdo   = "\\mkivdo" .. name -- maybe clddo
            snippets[#snippets+1] = "\\def"
            snippets[#snippets+1] = mkivdo
            for i=1,na do
                local a = arguments[i]
                local variant = a[1]
                if variant == "option" then
                    snippets[#snippets+1] = "[#"
                    snippets[#snippets+1] = i
                    snippets[#snippets+1] = "]"
                    if not done then
                        opt = opt + 1
                    end
                else
                    done = true -- no more optional checking after this
                    snippets[#snippets+1] = "#"
                    snippets[#snippets+1] = i
                end
            end
            if environment then
                snippets[#snippets+1] = "{\\ctxlua{_clmb_('"
                snippets[#snippets+1] = name
                snippets[#snippets+1] = "'"
            else
                snippets[#snippets+1] = "{\\ctxlua{_clmm_('"
                snippets[#snippets+1] = name
                snippets[#snippets+1] = "'"
            end
            for i=1,na do
                local a = arguments[i]
                local variant = a[2]
                if variant == "list" then
                    snippets[#snippets+1] = ",_clma_([==[#"
                    snippets[#snippets+1] = i
                    snippets[#snippets+1] = "]==])"
                elseif variant == "hash" then
                    snippets[#snippets+1] = ",_clmh_([==[#"
                    snippets[#snippets+1] = i
                    snippets[#snippets+1] = "]==])"
                elseif variant == "number" then
                    snippets[#snippets+1] = ",_clmn_([==[#"
                    snippets[#snippets+1] = i
                    snippets[#snippets+1] = "]==])"
                else
                    snippets[#snippets+1] = ",[==[#"
                    snippets[#snippets+1] = i
                    snippets[#snippets+1] = "]==]"
                end
            end
            snippets[#snippets+1] = ")}}"
            contextsprint(ctxcatcodes,unpack(snippets))
            if environment then
                -- needs checking
                contextsprint(ctxcatcodes,"\\setuvalue{",estart,name,"}{",checkers[opt],mkivdo,"}")
                contextsprint(ctxcatcodes,"\\setuvalue{",estop, name,"}{\\ctxlua{_clme_('",name,"')}}")
            end
            if not environment or environment == "both" then
                contextsprint(ctxcatcodes,"\\setuvalue{",       name,"}{",checkers[opt],mkivdo,"}")
            end
        end
        if environment then
            starters[name] = specification.starter
            stoppers[name] = specification.stopper
        else
            macros[name] = specification.macro
        end
    end
end

function interfaces.tolist(t)
    if t then
        local r = { }
        for i=1,#t do
            r[i] = t[i]
        end
        local n = #r
        for k,v in table.sortedhash(t) do
            if type(k) ~= "number" then
                n = n + 1
                r[n] = k .. "=" .. v
            end
        end
        return concat(r,", ")
    else
        return ""
    end
end

-- \startluacode
-- function test(opt_1, opt_2, arg_1)
--     context.startnarrower()
--     context("options 1: %s",interfaces.tolist(opt_1))
--     context.par()
--     context("options 2: %s",interfaces.tolist(opt_2))
--     context.par()
--     context("argument 1: %s",arg_1)
--     context.stopnarrower()
-- end
--
-- interfaces.definecommand {
--     name = "test",
--     arguments = {
--         { "option", "list" },
--         { "option", "hash" },
--         { "content", "string" },
--     },
--     macro = test,
-- }
-- \stopluacode
--
-- test: \test[1][a=3]{whatever}
--
-- \startluacode
-- local function startmore(opt_1)
--     context.startnarrower()
--     context("start more, options: %s",interfaces.tolist(opt_1))
--     context.startnarrower()
-- end
--
-- local function stopmore()
--     context.stopnarrower()
--     context("stop more")
--     context.stopnarrower()
-- end
--
-- interfaces.definecommand ( "more", {
--     environment = true,
--     arguments = {
--         { "option", "list" },
--     },
--     starter = startmore,
--     stopper = stopmore,
-- } )
-- \stopluacode
--
-- more: \startmore[1] one \startmore[2] two \stopmore one \stopmore
--
-- More modern (no need for option or content):
--
-- \startluacode
-- interfaces.definecommand {
--     name = "test",
--     arguments = {
--         "array", -- or list
--         "hash",
--         "string",
--         "number",
--     },
--     macro = test,
-- }
-- \stopluacode
--