minetest_mana/init.lua

--[[
Mana 0.1.0
This mod adds mana to players, a special attribute

License: WTFPL
]]

--[===[
	Initialization
]===]

mana = {}
mana.playerlist = {}



--[===[
	API functions
]===]

-- Sets the maximum mana of the specified player
function mana.set(playername, value) 
	mana.playerlist[playername].mana = value 
	mana.hud_update(playername)
end

-- Sets the maximum mana of the specified player
function mana.setmax(playername, value)
	mana.playerlist[playername].maxmana = value
	mana.hud_update(playername)
end

-- Returns the current mana of the specified player
function mana.get(playername)
	return mana.playerlist[playername].mana
end

-- Returns the maximum mana of the specified player
function mana.getmax(playername)
	return mana.playerlist[playername].maxmana
end

--[[
Adds the specified amount of mana to the player, but will
respect the player's maximum.

returns:
- true, excess on success, where excess is the amount of mana which
  was no
- false on failure
]]
function mana.add(playername, value)
	local t = mana.playerlist[playername]
	if(t ~= nil and value >= 0) then
		local excess
		if((t.mana + value) > t.maxmana) then
			excess = (t.mana + value) - t.maxmana
			t.mana = t.maxmana
		else
			excess = 0
			t.mana = t.mana + value
		end
		mana.hud_update(playername)
		return true, excess
	else
		return false
	end
end


--[[
Subtracts the specified amount of mana from the player,
iff the player has enough mana reserves.

returns:
- true on success, mana has been subtracted
- false on failure, no mana has been subtracted
]]
function mana.subtract(playername, value)
	local t = mana.playerlist[playername]
	if(t ~= nil and t.mana >= value and value >= 0) then
		t.mana = t.mana -value 
		mana.hud_update(playername)
		return true
	else
		return false
	end
end


--[===[
	File handling, loading data, saving data, setting up stuff for players.
]===]


-- Load the playerlist from a previous session, if available.
do
	local filepath = minetest.get_worldpath().."/mana.mt"
	local file = io.open(filepath, "r")
	if file then
		minetest.log("action", "[mana] mana.mt opened.")
		local string = file:read()
		io.close(file)
		if(string ~= nil) then
			local savetable = minetest.deserialize(string)
			mana.playerlist = savetable.playerlist
			minetest.debug("[mana] mana.mt successfully read.")
		end
	end
end

function mana.save_to_file()
	local savetable = {}
	savetable.playerlist = mana.playerlist

	local savestring = minetest.serialize(savetable)

	local filepath = minetest.get_worldpath().."/mana.mt"
	local file = io.open(filepath, "w")
	if file then
		file:write(savestring)
		io.close(file)
		minetest.log("action", "[mana] Wrote mana data into "..filepath..".")
	else
		minetest.log("error", "[mana] Failed to write mana data into "..filepath..".")
	end
end


minetest.register_on_dieplayer(function(player)
	local playername = player:get_player_name()
	mana.set(playername, 0)
	mana.hud_update(playername)
end)


minetest.register_on_leaveplayer(function(player)
	local playername = player:get_player_name()
	mana.hud_remove(playername)
	mana.playerlist[playername] = nil
end)

minetest.register_on_shutdown(function()
	minetest.log("action", "[mana] Server shuts down. Rescuing data into mana.mt")
	mana.save_to_file()
end)

minetest.register_on_joinplayer(function(player)
	local playername = player:get_player_name()
	
	if mana.playerlist[playername] == nil then
		mana.playerlist[playername] = {}
		mana.playerlist[playername].mana = 0
		mana.playerlist[playername].maxmana = 20
	end

	mana.hud_add(playername)
end)



--[===[
	HUD functions
]===]

function mana.manastring(playername)
	return string.format("Mana: %d/%d", mana.get(playername), mana.getmax(playername))
end

function mana.hud_add(playername)
	local player = minetest.get_player_by_name(playername)
	id = player:hud_add({
		hud_elem_type = "text",
		position = { x = 1, y=0.3 },
		name = "mana",
		text = mana.manastring(playername),
		scale = { x = 0, y = 0 },
		alignment = { x = -1, y = 0},
		direction = 1,
		number = 0xFFFFFF,
		offset = { x = 0, y = 0}
	})
	mana.playerlist[playername].hudid = id
	return id
end

function mana.hud_update(playername)
	local player = minetest.get_player_by_name(playername)
	player:hud_change(mana.playerlist[playername].hudid, "text", mana.manastring(playername))
end

function mana.hud_remove(playername)
	local player = minetest.get_player_by_name(playername)
	player:hud_remove(mana.playerlist[playername].hudid)
end