nc_extended_rotating/registry.lua

local minetest, nodecore
    = minetest, nodecore

-- Table of nodes that can be rotated by the mod.
local registered_rotatables = {}

local registry = {}

-- Override `nc_scaling`'s default empty hand right-click behavior so we can use it
-- to rotate things when holding sneak, which doesn't trigger a node's `on_rightclick`.
local default_on_place = minetest.registered_items[""].on_place
minetest.registered_items[""].on_place = function(item_stack, placer, pointed_thing, ...)
    if pointed_thing.type == "node" then
        -- Player must sneak in order for this to run.
        -- Non-sneak is handled by node's `on_rightclick`.
        if minetest.is_player(placer) and placer:get_player_control().sneak then
            local pos  = pointed_thing.under
            local node = minetest.get_node(pos)
            if registry.is_rotatable(node) then
                local def = minetest.registered_nodes[node.name]
                return def.on_rightclick(pos, node, placer, item_stack, pointed_thing)
                -- Skip default behavior.
            end
        end
    end
    -- Call the default function, so we can still get the "scaling" functionality.
    return default_on_place(item_stack, placer, pointed_thing, ...)
end

local rotate_node = nc_extended_rotating.rotate.rotate_node
-- local get_rotating_state = nc_extended_rotating.state.get_rotating_state
function registry.register_rotatable(name, def, rightclick_filter_func)
    def = def or minetest.registered_nodes[name] or error("Unknown node '" .. name .. "'")
    if def.paramtype2 ~= "facedir" then error("Node '" .. name .. "' must be 'facedir'") end

    -- Replace the default `on_rightclick` function so
    -- we can call our custom rotation handling code.
    local default_on_rightclick = def.on_rightclick
    def.on_rightclick = function(pos, node, clicker, ...)
        -- If `rightclick_filter_func` is set and returns true, call the default `on_rightclick`.
        if registry.is_rightclick_filtered(pos, node, clicker, ...) then
            return default_on_rightclick(pos, node, clicker, ...)
        else
            if nodecore.protection_test(pos, clicker) then return end
            local state = nc_extended_rotating.state.get_rotating_state(clicker, pos, node)
            if (not state) or (not state.success) then return end
            rotate_node(pos, node, state.facedir)
        end
    end

    registered_rotatables[name] = {
        rightclick_filter_func = rightclick_filter_func,
    }
end

-- Returns whether the specified `node` is rotatable by this mod.
function registry.is_rotatable(node)
    return registered_rotatables[node.name] ~= nil
end

-- Returns whether the `on_rightclick` is filtered and the default
-- implementation should be called, instead of the custom rotation logic.
function registry.is_rightclick_filtered(pos, node, player, item_stack, pointed_thing)
    local entry = registered_rotatables[node.name]
    return entry and entry.rightclick_filter_func
       and entry.rightclick_filter_func(pos, node, player, item_stack, pointed_thing)
end

return registry