Camas/mods/player_effects/init.lua

--
-- Player effects mod
-- By Kaadmy, for Pixture
--

player_effects = {}

player_effects.effects = {}
player_effects.registered_effects = {}

local update_time = 1 -- update every second
local timer = 10
local effects_file = minetest.get_worldpath() .. "/player_effects"

local function save_effects()
   local f = io.open(effects_file, "w")

   f:write(minetest.serialize(player_effects.effects))

   io.close(f)
end

local function load_effects()
   local f = io.open(effects_file, "r")

   if f then
      player_effects.effects = minetest.deserialize(f:read("*all"))

      io.close(f)
   else
      save_effects()
   end
end

function player_effects.register_effect(name, def)
   local rd = {
      title = def.title or name, -- good-looking name of the effect
      description = def.description or "The " .. name .. " effect", -- description of what the effect does
      duration = def.duration or 1, -- how long the effect lasts, <0 is infinite and has to be disabled manually
      additive = def.additive or false, -- if the same effect can be applied multiple times for a longer duration
      physics = def.physics or {} -- physics overrides for the player
   }

   player_effects.registered_effects[name] = rd
end

function player_effects.apply_effect(player, ename)
   local effect = player_effects.registered_effects[ename]

   if player_effects.effects[player:get_player_name()][ename] == nil then
      local phys = player:get_physics_override()
      
      if effect.physics.speed ~= nil then
	 phys.speed = phys.speed * effect.physics.speed
      end

      if effect.physics.jump ~= nil then
	 phys.jump = phys.jump * effect.physics.jump
      end

      if effect.physics.gravity ~= nil then
	 phys.gravity = phys.gravity * effect.physics.gravity
      end

      player:set_physics_override(phys)
   end

   if effect.duration >= 0 then
      player_effects.effects[player:get_player_name()][ename] = minetest.get_gametime() + effect.duration
   else
      player_effects.effects[player:get_player_name()][ename] = -1
   end

   save_effects()
end

function player_effects.remove_effect(player, ename)
   if player_effects.effects[player:get_player_name()][ename] == nil then return end

   local phys = player:get_physics_override()
   local effect = player_effects.registered_effects[ename]
   
   if effect.physics.speed ~= nil then
      phys.speed = phys.speed / effect.physics.speed
   end

   if effect.physics.jump ~= nil then
      phys.jump = phys.jump / effect.physics.jump
   end

   if effect.physics.gravity ~= nil then
      phys.gravity = phys.gravity / effect.physics.gravity
   end

   player:set_physics_override(phys)

   player_effects.effects[player:get_player_name()][ename] = nil

   save_effects()
end

function player_effects.clear_effects(player)
   -- call this if you want to clear all effects, it's faster and more efficient
   player:set_physics_override({speed = 1, jump = 1, gravity = 1})

   player_effects.effects[player:get_player_name()] = nil

   save_effects()
end

local function step(dtime)
   timer = timer + dtime
   if timer > update_time then
      local gt = minetest.get_gametime()

      for _, player in pairs(minetest.get_connected_players()) do
	 local name = player:get_player_name()

	 for ename, endtime in pairs(player_effects.effects[name]) do
	    if endtime > 0 then
	       local timeleft = endtime - gt
	       print(timeleft)
	       if timeleft <= 0 then
		  player_effects.remove_effect(player, ename)
	       end
	    end
	 end
      end
      timer = 0
   end
end

local function on_joinplayer(player)
   local name = player:get_player_name()

   load_effects()

   if player_effects.effects[name] == nil then
      player_effects.effects[name] = {}
   end

   save_effects()

   player_effects.apply_effect(player, "lowgravity")
end

local function on_leaveplayer(player)
   save_effects()
end

local function on_dieplayer(player)
   player_effects.clear_effects(player)
end

minetest.register_globalstep(step)
minetest.register_on_joinplayer(on_joinplayer)
minetest.register_on_leaveplayer(on_leaveplayer)
minetest.register_on_dieplayer(on_dieplayer)

minetest.register_chatcommand(
   "player_effects",
   {
      description = "Show current player effects",
      func = function(name, param)
		local s = "Current player effects:\n"
		local ea = 0

		for ename, endtime in pairs(player_effects.effects[name]) do
		   if endtime < 0 then
		      s = s .. "  " .. player_effects.registered_effects[ename].title .. ": unlimited\n"
		   else
		      s = s .. "  " .. player_effects.registered_effects[ename].title .. ": " .. (endtime - minetest.get_gametime()) .. " seconds remaining\n"
		   end

		   ea = ea + 1
		end

		if ea > 0 then
		   minetest.chat_send_player(name, s)
		else
		   minetest.chat_send_player(name, "You currently have no effects")
		end
	     end
   })

default.log("mod:player_effects", "loaded")