kingdoms_game/mods/factions/siege.lua

factions.sieges = {}

local function format_pos(pos) 
    return "(" .. pos.x .. ", " .. pos.y .. ", " .. pos.z .. ")"
end

local function siege_banner_onplace_check(player, pointed_thing, attacking_player, attacking_faction, pointedpos, parcelpos, defending_faction) 
    if attacking_player == nil then            
        minetest.chat_send_player(player:get_player_name(), "You don't belong to a faction")
        return false
    end

    if not pointed_thing.type == "node" then
        minetest.chat_send_player(player:get_player_name(), "Point a node to place a Siege Banner")
        return false
    end

    if attacking_faction == nil then
        minetest.chat_send_player(player:get_player_name(), "You don't belong to a faction")
        return false
    end

    if pointedpos.y <= config.protection_max_depth then 
        minetest.chat_send_player(player:get_player_name(), "You can't place a Siege Banner that deep")
        return false
    end

    if defending_faction == nil then
        minetest.chat_send_player(player:get_player_name(), "This parcel doesn't belong to a faction")
        return false
    end

    if defending_faction == attacking_faction then
        minetest.chat_send_player(player:get_player_name(), "This parcel belongs to your own faction")
        return false
    end
	
	if not defending_faction.enemies[attacking_faction.name] then
	    minetest.chat_send_player(player:get_player_name(), "You are not at war with "..defending_faction.name)
        return false
    end

    if attacking_faction.power < config.power_per_parcel then
        minetest.chat_send_player(player:get_player_name(), "Your faction doesn't have enough power to siege")
        return false
    end

    local is_defending_faction_online = false

    for i, _player in pairs(minetest.get_connected_players()) do
        local playername = _player:get_player_name()

        if factions.get_player_faction(playername) == defending_faction then
            is_defending_faction_online = true
            break
        end
    end

    if not is_defending_faction_online then
        minetest.chat_send_player(player:get_player_name(), "There are no players from the defending faction online")
        return false
    end

    return true
end

minetest.register_craftitem("factions:siege_banner", {
    description = "Siege Banner",
    inventory_image = "siege_banner.png",
    stack_max = 1,
    groups = {banner = 1},
    
    on_place = function(itemstack, player, pointed_thing)        
        local attacking_player = factions.players[player:get_player_name()]
        local attacking_faction = factions.factions[attacking_player]
        local pointedpos = pointed_thing.above
        local parcelpos = factions.get_parcel_pos(pointedpos)
        local defending_faction = factions.get_parcel_faction(parcelpos)

        if not siege_banner_onplace_check(player, pointed_thing, attacking_player, attacking_faction, pointedpos, parcelpos, defending_faction) then
            return nil
        end

        minetest.chat_send_player(player:get_player_name(), "Sieging parcel at " .. format_pos(pointed_thing.above))
        
        local defending_faction = factions.get_faction_at(pointed_thing.above)

        defending_faction:broadcast(player:get_player_name() .. " is sieging your parcel at " .. format_pos(pointed_thing.above))

        minetest.set_node(pointed_thing.above, {
            name = "factions:siege_banner_sieging"
        })

        local meta = minetest.get_meta(pointed_thing.above)

		meta:set_int("stage",1)
        meta:set_string("attacking_faction", attacking_faction.name)
        meta:set_string("defending_faction", defending_faction.name)
            
        meta:set_string("infotext", "Siege Banner 1/4 (" .. attacking_faction.name .. " vs " .. defending_faction.name .. ")")

        return "" 
    end
})

local siege_banner_stages = 4

minetest.register_node("factions:siege_banner_sieging", {
	drawtype = "normal",
	tiles = {"siege_banner.png"},
	description = "Siege Banner",
	groups = {cracky=3},
	diggable = true,
	paramtype = "light",
	paramtype2 = "facedir",
	drop = "",
	on_construct = function(pos)
		minetest.get_node_timer(pos):start(config.siege_banner_interval)
	end,
	on_timer = function(pos, elapsed)
		local meta = minetest.get_meta(pos)
		local att_fac_name = meta:get_string("attacking_faction")
		local def_fac_name = meta:get_string("defending_faction")
		local stage = meta:get_int("stage")
		stage = stage + 1

		if stage <= siege_banner_stages then
			meta:set_string("infotext", "Siege Banner " .. stage .. "/" .. siege_banner_stages .. " (" .. att_fac_name .. " vs " .. def_fac_name .. ")")
			factions.get_faction(def_fac_name):broadcast("Your parcel at " .. format_pos(pos) .. " is being sieged (" .. stage .. "/" .. siege_banner_stages .. ")")
			meta:set_int("stage",stage)
			meta:set_string("attacking_faction", att_fac_name)
			meta:set_string("defending_faction", def_fac_name)
			return true
		else
			local attacking_faction = factions.get_faction(att_fac_name)
			local defending_faction = factions.get_faction(def_fac_name)
			local parcelpos = factions.get_parcel_pos(pos)

			if defending_faction then
				defending_faction:bulk_unclaim_parcel(parcelpos)

				defending_faction:broadcast(att_fac_name .. " has successfully conquered your parcel at " .. format_pos(pos))
			end

			if attacking_faction then
				attacking_faction:bulk_claim_parcel(parcelpos)

				attacking_faction:broadcast("Successfully conquered parcel at " .. format_pos(pos) .. " !")
			end
			minetest.set_node(pos, { name = "bones:bones" })
		end
	end
})

if minetest.get_modpath("default") and minetest.get_modpath("bones") then
	minetest.register_craft({
		output = 'factions:siege_banner',
		recipe = {
			{'default:diamond','default:diamond','default:diamond'},
			{'default:diamond','bones:bones','default:diamond'},
			{'default:diamond','default:diamond','default:diamond'}
		}
	})
end