local S = minetest.get_translator("elevator")


local function string_endswith(str, ends)
	local len = #ends
	if str:sub(-len) == ends then
		return str:sub(1, -len-1)
	end
end

local function string_startswith(str, start)
	local len = #start
	if str:sub(1, len) == start then
		return str:sub(len+1)
	end
end

function elevator.find_nearest_elevator_network(pos, owner_name)
	local nearest_network = false
	local nearest_dist = false
	local nearest_dist_x
	local nearest_dist_z
	for target_network_name, network in pairs(elevator.targets[owner_name]) do
		local station_name = next(network, nil)
		if station_name then
			local station = network[station_name]
			if station.nr and station.pos then
				local dist_x = station.pos.x - pos.x
				local dist_z = station.pos.z - pos.z
				local dist = math.ceil(math.sqrt(dist_x * dist_x + dist_z * dist_z))
				-- find the nearest one; store network_name and (minimal) distance
				if not nearest_dist or dist < nearest_dist then
					nearest_dist = dist
					nearest_dist_x = dist_x
					nearest_dist_z = dist_z
					nearest_network = target_network_name
				end
			end
		end
	end
	return nearest_network, {
		x = nearest_dist_x,
		z = nearest_dist_z,
	}
end

function elevator.elevator_network(pos)
	return tostring(pos.x) .. "," .. tostring(pos.z)
end

function elevator.is_elevator(node_name)
	return node_name == "elevator:elevator"
end

function elevator.door_is_open(node, opposite_direction)
	return string.sub(node.name, -5) == "_open"
		-- handle doors that change their facedir
		or (
			node.param2 ~= opposite_direction
			and not (
				string_startswith(node.name, "elevator:elevator_door")
				and string_endswith(node.name, "_closed")
			)
		)
end

function elevator.door_is_closed(node, opposite_direction)
	return string.sub(node.name, -7) == "_closed"
		-- handle doors that change their facedir
		or (
			node.param2 == opposite_direction
			and not (
				string_startswith(node.name, "elevator:elevator_door")
				and string_endswith(node.name, "_open")
			)
		)
end

function elevator.param2_to_yaw(param2)
	if     param2 == 0 then
		return 180
	elseif param2 == 1 then
		return 90
	elseif param2 == 2 then
		return 0
	elseif param2 == 3 then
		return 270
	end
end

function elevator.get_or_create_network(owner_name, network_name)
	if not elevator.targets then
		elevator.targets = {}
	end

	-- first one by this player?
	if not elevator.targets[owner_name] then
		elevator.targets[owner_name] = {}
	end

	local owners_targets = elevator.targets[owner_name]

	-- first station on this network?
	if not owners_targets[network_name] then
		owners_targets[network_name] = {}
	end

	return owners_targets[network_name]
end

function elevator.get_network(owner_name, network_name)
	if not elevator.targets then return end

	local owners_targets = elevator.targets[owner_name]
	if not owners_targets then return end

	return elevator.targets[owner_name][network_name]
end

function elevator.get_station(owner_name, station_network, station_name)

	local network = elevator.get_network(owner_name, station_network)
	if not network then return end

	return network[station_name]
end

-- punching the elevator updates its formspec and shows it to the player;
-- however, that would be very annoying when actually trying to dig the thing.
-- Thus, check if the player is wielding a tool that can dig nodes of the
-- group cracky
function elevator.check_if_trying_to_dig(puncher)
	-- if in doubt: show formspec
	if not puncher or not puncher:get_wielded_item() then
		return false
	end
	-- show menu when in creative mode
	if creative and creative.is_enabled_for(puncher:get_player_name()) then
		return false
	end
	local tool_capabilities = puncher:get_wielded_item():get_tool_capabilities()
	if not tool_capabilities or not tool_capabilities["groupcaps"] or not tool_capabilities["groupcaps"]["cracky"] then
		return false
	end
	-- tools which can dig cracky items can start digging immediately
	return true
end


-- allow doors to open
function elevator.open_close_door(pos, player, mode)
	local this_node = minetest.get_node_or_nil(pos)
	-- give up if the area is *still* not loaded
	if not this_node then
		return
	end

	local opposite_direction = (this_node.param2 + 2) % 4
	local door_pos = vector.add(pos, minetest.facedir_to_dir(opposite_direction))

	local door_node = minetest.get_node_or_nil(door_pos)

	if not door_node or door_node.name == "ignore" or door_node.name == "air"
			or not minetest.registered_nodes[door_node.name] then
		return
	end

	local right_click_action = minetest.registered_nodes[door_node.name].on_rightclick
	if not right_click_action then return end

	-- Map to old API in case anyone is using it externally
	if     mode == 0 then mode = "toggle"
	elseif mode == 1 then mode = "close"
	elseif mode == 2 then mode = "open"
	end

	-- at least for homedecor, same facedir would mean "door closed"
	-- do not close the elevator door if it is already closed
	if mode == "close" and elevator.door_is_closed(door_node, opposite_direction) then
		return
	end

	-- do not open the doors if they are already open (works only on elevator-doors; not on doors in general)
	if mode == "open" and elevator.door_is_open(door_node, opposite_direction) then
		return
	end

	if mode == "open" then
		local playername = player:get_player_name()
		minetest.after(1, function()
			-- Get the player again in case it doesn't exist anymore (logged out)
			local pplayer = minetest.get_player_by_name(playername)
			if pplayer then
				right_click_action(door_pos, door_node, pplayer)
			end
		end)
	else
		right_click_action(door_pos, door_node, player)
	end
end


elevator.rotate_player = function(target_pos, player, tries)
	-- try later when the box is loaded
	local target_node = minetest.get_node_or_nil(target_pos)
	if target_node == nil then
		if tries < 30 then
			minetest.after(0, elevator.rotate_player, target_pos, player, tries+1)
		end
		return
	end

	-- play sound at the target position as well
	if elevator.elevator_sound_enabled then
		local sound = "elevator_travel"
		if elevator.is_elevator(target_node.name) then
			sound = "elevator_bell"
		end

		minetest.sound_play(sound, {
			pos = target_pos,
			gain = 0.75,
			max_hear_distance = 10
		})
	end

	-- do this only on servers where the function exists
	if player.set_look_horizontal then
		-- rotate the player so that they can walk straight out of the box
		local yaw = elevator.param2_to_yaw(target_node.param2) or 0

		player:set_look_horizontal(math.rad(yaw))
		player:set_look_vertical(math.rad(0))
	end

	elevator.open_close_door(target_pos, player, "open")
end


elevator.remove_box = function(_, _, oldmetadata, digger)
	if not oldmetadata or oldmetadata == "nil" or not oldmetadata.fields then
		minetest.chat_send_player(digger:get_player_name(), S("Error") .. ": " ..
				S("Could not find information about the station that is to be removed."))
		return
	end

	local owner_name      = oldmetadata.fields["owner"]
	local station_name    = oldmetadata.fields["station_name"]
	local station_network = oldmetadata.fields["station_network"]

	-- station is not known? then just remove it
	if	not (owner_name and station_network and station_name)
		or not elevator.get_station(owner_name, station_network, station_name)
	then
		minetest.chat_send_player(digger:get_player_name(), S("Error") .. ": " ..
				S("Could not find the station that is to be removed."))
		return
	end

	elevator.targets[owner_name][station_network][station_name] = nil

	-- inform the owner
	minetest.chat_send_player(owner_name,
			S("Station '@1'" .. " " ..
				"has been REMOVED from the network '@2'.", station_name, station_network))

	if digger and owner_name ~= digger:get_player_name() then
		minetest.chat_send_player(digger:get_player_name(),
				S("Station '@1'" .. " " ..
					"has been REMOVED from the network '@2'.", station_name, station_network))
	end

	-- save the updated network data in a savefile over server restart
	elevator.save_data()
end



elevator.can_dig = function()
	-- forbid digging of the elevator
	return false
end