--[[
Mana 0.2.0
This mod adds mana to players, a special attribute

License: WTFPL
]]

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

mana = {}
mana.playerlist = {}



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

--[[ Sets the mana reserves of the specified player
It is ensured that the resulting value will always be within the bounds of [0, maxmana]
]]
function mana.set(playername, value) 
	if value < 0 then
		minetest.log("info", "[mana] Warning: mana.set was called with negative value!")
		value = 0
	end
	if value > mana.playerlist[playername].maxmana then
		value = mana.playerlist[playername].maxmana
	end
	if mana.playerlist[playername].mana ~= value then
		mana.playerlist[playername].mana = value
		mana.hud_update(playername)
	end
end

--[[ Sets the maximum mana of the specified player. The value must be positive or 0.
 The player's mana reserves will be capped at the new maximum, if neccessary.
]]
function mana.setmax(playername, value)
	if value < 0 then
		value = 0
		minetest.log("info", "[mana] Warning: mana.setmax was called with negative value!")
	end
	if mana.playerlist[playername].maxmana ~= value then
		mana.playerlist[playername].maxmana = value
		if(mana.playerlist[playername].mana > value) then
			mana.playerlist[playername].mana = value
		end
		mana.hud_update(playername)
	end
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 up to the specified amount of mana to the player.
If the sum would be greater than the maximum, the new
mana amount will be capped at the maximum.

returns:
- true, excess on success, where excess is the amount of mana which
  was no
- false on failure
]]
function mana.add_up_to(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


--[[
Adds the specified amount of mana to the player,
iff it would not exceed the maximum.

returns:
- true on success, all mana has been added
- false on failure, no mana has been added
]]
function mana.add(playername, value)
	local t = mana.playerlist[playername]
	if(t ~= nil and ((t.mana + value) <= t.maxmana) and value >= 0) then
		t.mana = t.mana + value 
		mana.hud_update(playername)
		return true
	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, all 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


--[[
Subtracts up to the specified amount of mana from the player.

returns:
- true, missing on success, where missing is the amount of mana which could not been subtracted
- false on failure, no mana has been subtracted
]]
function mana.subtract_up_to(playername, value)
	local t = mana.playerlist[playername]
	if(t ~= nil and value >= 0) then
		local missing
		if((t.mana - value) < 0) then
			missing = math.abs(t.mana - value)
			t.mana = 0
		else
			missing = 0
			t.mana = t.mana - value
		end
		mana.hud_update(playername)
		return true, missing
	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 = 100
	end

	if minetest.get_modpath("hudbars") ~= nil then
		hud.hudtables.mana.add_all(player, mana.get(playername), mana.getmax(playername))
	else
		mana.hud_add(playername)
	end
end)



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

if minetest.get_modpath("hudbars") ~= nil then
	hud.register_hudbar("mana", 0xFFFFFF, "Mana", { bar = "mana_bar.png", icon = "mana_icon.png" }, 0, 100, false) 

	function mana.hud_update(playername)
		local player = minetest.get_player_by_name(playername)
		hud.change_hudbar(player, hud.hudtables.mana, mana.get(playername), mana.getmax(playername))
	end

else

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 = 0.5, y=0.9 },
		text = mana.manastring(playername),
		scale = { x = 0, y = 0 },
		alignment = { x = 1, y = 0},
		direction = 1,
		number = 0xFFFFFF,
		offset = { x = -200, y = 15}
	})
	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, "number", mana.get(playername))
end

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

end