mod-levels/api.lua

local u = dofile(levels.path .. "/registry.lua").util

function levels.get_level(name, st)
	local ref = u.get_reference(name)
	if u.get_registered_stat(st) == nil then
		-- TODO:
		if ref[st] == nil then
			return 0
		end
	end
	return ref[st].level or 0
end

function levels.register_stat(name, def)
	local stat_def = u.get_registered_stat(name)
	if stat_def ~= nil then
		-- already registered
		-- TODO:
		return
	end

	stat_def = {}
	stat_def.on_xp_gain = def.on_xp_gain
	stat_def.on_xp_loss = def.on_xp_loss
	stat_def.on_level_up = def.on_level_up or function(player)
		-- TODO:
	end
	stat_def.on_level_down = def.on_level_down or function(player)
		-- TODO:
	end

	u.set_registered_stat(name, stat_def)
end

--~ local function init_stat(stats, st)
	--~ if registered_stats[st] == nil then
		--~ -- TODO:
		--~ return stats
	--~ end
	--~ stats[st] = {level=0, xp=0}
	--~ return stats
--~ end

--- Adds a stat object to player.
--
--  @param player Player object.
--  @param st Stat name.
--  @param def Stat definition.
--~ local function add_stat(player, st, def)
	--~ if registered_stats[st] == nil then
		--~ -- TODO:
		--~ return
	--~ end

	--~ player.stats = player.stats or {}
	--~ local stat = player.stats[st]
	--~ if stat ~= nil then
		--~ -- player already has stat
		--~ -- TODO: show warning
		--~ return
	--~ end
	--~ stat = {level=def.level or 0, xp=def.xp or 0, tnl=u.calculate_tnl(st, def.level)}
	--~ player.stats[st] = stat
--~ end

function levels.get_xp(name, st)
	local ref = u.get_reference(name)
	if u.get_registered_stat(st) == nil then
		-- TODO:
		if ref[st] == nil then
			return 0
		end
	end
	return ref[st].xp or 0
end

function levels.add_xp(player, st, amount, notify)
	notify = notify or notify == nil

	local stat = registered_stats[st]
	if stat == nil then
		-- TODO: not registered stat
		return
	end

	local player_stat = player.stats[st]
	if player_stat == nil then
		-- TODO: player doesn't have stat
		return
	end

	local old_level = player_stat.level
	local new_xp = player_stat.xp + amount
	local rem = 0
	if new_xp < 0 then
		-- player lost a level
		player_stat.level = old_level - 1
		rem = new_xp
		player_stat.tnl = u.calculate_tnl(st, player_stat.level)
		player_stat.xp = player_stat.tnl
	elseif new_xp >= player_stat.tnl then
		-- player gained a level
		player_stat.level = old_level + 1
		rem = new_xp - player_stat.tnl
		player_stat.tnl = u.calculate_tnl(st, player_stat.level)
		player_stat.xp = 0
	end

	player_stat.xp = new_xp
	player.stats[st] = player_stat

	if player_stat.level < old_level then
		stat.on_level_down(player)
	elseif player_stat.level > old_level then
		stat.on_level_up(player)
	end

	-- handle remaining xp
	if rem ~= 0 then
		levels.add_xp(player, st, rem, false)
	end

	if notify then
		if amount < 0 then
			stat.on_xp_loss(player, amount)
		elseif amount > 0 then
			stat.on_xp_gain(player, amount)
		end
	end
end