uniham/init.lua

local replacements = {
    -- default sandstone to sand
    ['default:sandstone']        = 'default:sand',
    ['default:desert_sandstone'] = 'default:desert_sand',
    ['default:silver_sandstone'] = 'default:silver_sand',

    -- stone crushing
    ['default:obsidian'] = 'default:stone',
    ['default:stone'] = 'default:cobble',
    ['default:cobble'] = 'default:gravel',
    ['default:gravel'] = 'default:sand'
}

-- Hammer use function
--
-- The function is called when using the hammer. It either converts the node to
-- its replacement or does nothing. When converting the modified (added wear)
-- itemstack is returned.
--
-- @param itemstack      The `itemstack` as per on_use definition
-- @param player         The `player` as per on_use definition
-- @param pointed_thing  The `pointed_thing` as per on_use definition
-- @see <https://dev.minetest.net/on_use#on_use>
-- @return itemstack|void
local use_hammer = function (itemstack, player, pointed_thing)
    if pointed_thing.type == 'nothing' then return end
    local node_pos = minetest.get_pointed_thing_position(pointed_thing)
    local node_name = minetest.get_node(node_pos).name
    local node_sounds = minetest.registered_nodes[node_name].sounds

    if not replacements[node_name] then
        minetest.sound_play(node_sounds.dug.name, {
            pos = node_pos,
            max_hear_distance = 8,
            gain = node_sounds.dug.gain,
        })
        return
    end

    local replacement = replacements[node_name]
    local replacement_sounds = minetest.registered_nodes[replacement].sounds
    local uses = minetest.registered_tools[itemstack:get_name()]._uniham.uses

    minetest.sound_play(replacement_sounds.dug.name, {
        pos = node_pos,
        max_hear_distance = 8,
        gain = replacement_sounds.dug.gain,
    })

    minetest.set_node(node_pos, { name = replacement })
    minetest.check_for_falling(node_pos)

    itemstack:add_wear(math.ceil(65535 / uses) + 1)
    return itemstack
end


-- Register a new hammer
--
-- definition = {
--   name = 'Name of the hammer',
--   head = 'head_material_texture.png',
--   craft = 'crafting:material',
--   uses = 123,
-- }
--
-- @param short_id   Unprefixed ID for the new hammer
-- @param definition Definition table as described
-- @return void
local register_hammer = function (short_id, definition)
    local texture = '([combine:16x16:-1,1=+s)^((+h^+m)^[makealpha:0,0,0)'
    texture = texture:gsub('+.', {
        ['+s'] = 'default_stick.png',
        ['+h'] = definition.head,
        ['+m'] = 'uniham_head_mask.png'
    })

    minetest.register_tool('uniham:'..short_id, {
        description = definition.name,
        inventory_image = texture,
        _uniham = { uses = definition.uses },
        on_use = function(itemstack, player, pointed_thing)
            return use_hammer(itemstack, player, pointed_thing)
        end
    })

    minetest.register_craft({
        output = 'uniham:'..short_id,
        recipe = {
            { '',            definition.craft,  ''               },
            { '',            'default:stick',   definition.craft },
            { 'default:stick', '',              ''               }
        }
    })
end

register_hammer('hammer_bronze', {
    name = 'Bronze Hammer',
    head = 'default_bronze_block.png',
    craft = 'default:bronze_ingot',
    uses = 100
})

register_hammer('hammer_diamond', {
    name = 'Diamond Hammer',
    head = 'default_diamond_block.png',
    craft = 'default:diamond',
    uses = 200
})

register_hammer('hammer_mese', {
    name = 'Mese Hammer',
    head = 'default_mese_block.png',
    craft = 'default:mese_crystal',
    uses = 300
})

register_hammer('hammer_steel', {
    name = 'Steel Hammer',
    head = 'default_steel_block.png',
    craft = 'default:iron_ingot',
    uses = 150
})

register_hammer('hammer_stone', {
    name = 'Stone Hammer',
    head = 'default_stone.png',
    craft = 'default:cobble',
    uses = 50
})

register_hammer('hammer_wood', {
    name = 'Wooden Hammer',
    head = 'default_wood.png',
    craft = 'default:wood',
    uses = 10
})