
function mtt.emerge_area(pos1, pos2)
    mtt.register("emerge_area " .. minetest.pos_to_string(pos1) .. " -> " .. minetest.pos_to_string(pos2),
    function(callback)
        minetest.emerge_area(pos1, pos2, function(_, _, calls_remaining)
            if calls_remaining == 0 then
                callback()
            end
        end)
    end)
end

-- current testing area offset
local area_offset = {
    x = -30000,
    y = 0,
    z = 0
}

function mtt.register_with_area(name, options, fn)
    mtt.register(name, function(callback)
        local pos1 = {
            x = area_offset.x,
            y = area_offset.y,
            z = area_offset.z
        }

        local pos2 = vector.add(pos1, vector.subtract(options.size, 1))

        -- increment x area offset for next test-area (at least in the next chunk)
        area_offset.x = area_offset.x + options.size.x + 80

        -- delegate launcher function, called after area is prepared
        local function delegate_test()
            fn(pos1, pos2, callback)
        end

        if options.emerged then
            -- emerge area first
            minetest.emerge_area(pos1, pos2, function(_, _, calls_remaining)
                if calls_remaining == 0 then
                    -- start actual test
                    delegate_test()
                end
            end)
        else
            -- start directly
            delegate_test()
        end

    end)
end

function mtt.export_nodenames(filename)
    local f = io.open(filename, "w")
    for nodename in pairs(minetest.registered_nodes) do
        f:write(nodename .. "\n")
    end
    f:close()
end

function mtt.validate_nodenames(filename)
    mtt.register("nodename_check", function(callback)
        local assert_nodes = {}
        for nodename in io.lines(filename) do
            table.insert(assert_nodes, nodename)
        end

        -- assemble node-list from registered lbm's
        local lbm_nodes = {}
        for _, lbm in ipairs(minetest.registered_lbms) do
            if type(lbm.nodenames) == "string" then
                -- duh, list as string
                lbm_nodes[lbm.nodenames] = true
            else
                -- proper list, add all regardless if they are a "group:*"
                for _, nodename in ipairs(lbm.nodenames) do
                    lbm_nodes[nodename] = true
                end
            end
        end

        -- check nodes
        local all_nodes_present = true
        for _, nodename in ipairs(assert_nodes) do
            if not minetest.registered_nodes[nodename]
                and not minetest.registered_aliases[nodename]
                and not lbm_nodes[nodename] then
                    error("Node not present and not available in an alias/lbm: " .. nodename)
            end
        end

        if not all_nodes_present then
            error("some of the required nodes are not present and not aliased!")
        end

        callback()
    end)
end

function mtt.check_recipes(modname)
    mtt.register("recipe check for mod '" .. modname .. "'", function(callback)
        -- ensure the mod is available
        assert(minetest.get_modpath(modname), "mod not found: '" .. modname .. "'")

        -- taken from https://github.com/mt-mods/homedecor_modpack/issues/41#issue-1330629615
        -- thanks @wsor4035 :)
        local output = {}
        local hd_count, ig_count, missing_count = 0, 0, 0
        for k, v in pairs(minetest.registered_items) do
            if modname == k:split(":")[1] then
                hd_count = hd_count + 1
                local crafts = minetest.get_all_craft_recipes(k)
                if not crafts then
                    if v.groups and v.groups.not_in_creative_inventory == 1 then
                        ig_count = ig_count + 1
                    else
                        missing_count = missing_count + 1
                        table.insert(output, "* [ ] " .. k)
                    end
                end
            end
        end
        if missing_count > 0 then
            table.insert(output, "total items: " .. hd_count)
            table.insert(output, "ignored items: " .. ig_count)
            table.insert(output, "missing items: " .. missing_count)
            minetest.log("error", dump(output))
            error("missing crafting recipes: " .. missing_count)
        end
        callback()
    end)
end

local modfilter = minetest.settings:get("mtt_filter")

function mtt.is_mod_enabled(modname)
    if not mtt.enabled then
        -- mtt not enabled, don't match anything
        return false
    end

    -- check modfilter and current modname
    if modfilter then
        for filter in string.gmatch(modfilter, '([^,]+)') do
            if filter == modname then
                return true
            end
        end

        -- filter defined but does not match
        return false
    end

    -- no filter defined, match all
    return true
end