local drop_table = {}
local used_npc = {}
local counters = {}
local abort

function pr(x,...)
	-- printf(strformat('[%s] guaranteed_loot: ',time_global())..x, ...)
end

function on_game_start()
	RegisterScriptCallback("npc_on_use",npc_on_use)
	RegisterScriptCallback("server_entity_on_unregister",server_entity_on_unregister)
	RegisterScriptCallback("save_state",save_state)
	RegisterScriptCallback("load_state",load_state)
end 

function save_state(md)
	md.guaranteed_drops_data = {}
	md.guaranteed_drops_data.counters = counters
	md.guaranteed_drops_data.used_npc = used_npc
end

function load_state(md)
	used_npc = md.guaranteed_drops_data and md.guaranteed_drops_data.used_npc or {}
	counters = md.guaranteed_drops_data and md.guaranteed_drops_data.counters or {}
	make_drop_table()
end

function split_tonumber(str)
	local x = split(str)
	for i,v in ipairs(x) do
		x[i] = tonumber(v)
	end
	return x
end

local _splitcache = {}
function split(str)
	if not _splitcache[str] then
		_splitcache[str] = {}
		for x in string.gmatch(str, '([^,]+)') do
			x = x:gsub(' ','')
			table.insert(_splitcache[str], x)
		end	
	end
	return _splitcache[str]
end

function make_drop_table()
	local i = ini_file("plugins\\guaranteed_drops.ltx")
	drop_table = i and utils_data.parse_ini_section_to_array(i, 'settings')
	
	if not drop_table then 
		abort = true 
		printf("!Warning: couldn't load file gamedata/configs/plugins/guaranteed_drops.ltx, feature disabled!")
		return 
	end
	
	for k,v in pairs(drop_table) do
		if string.find(v,',') then
			local ret = split_tonumber(v)
			drop_table[k] = {ret[1], ret[2]}
		else
			drop_table[k] = tonumber(v)
		end
	end
end

function check(obj_id, who_id)
	pr('event start')
	if not who_id then pr('quit because nil user id') return true end
	if who_id > 0 then pr('quit because invalid user id %s', who_id) return true end
	local npc = level.object_by_id(obj_id)
	if not npc then pr('quit because victim id has no object %s', who_id) return true end
	
	local function itr(npc,item)
		if drop_table[item:section()] then
			pr('item dropped legit, reset counter for %s', item:section())
			counters[item:section()] = 0
		end
	end
	npc:iterate_inventory(itr,npc)

	for k,v in pairs(counters) do
		if type(drop_table[k]) == 'number' then
			if v >= drop_table[k] then
				pr('guaranteed drop for %s', k)
				counters[k] = 0
				alife_create_item(k, npc)
			end
		else
			local start_ch_num, guaranteed_drop_num = unpack(drop_table[k])
			-- if v >= guaranteed_drop_num then
				-- -- pr('guaranteed drop for %s', k)
				-- -- counters[k] = 0
				-- -- alife_create_item(k, npc)
			-- e
			if v >= start_ch_num then
				local step = 1 / (guaranteed_drop_num - start_ch_num)
				local diff = v - start_ch_num + 1
				pr('%s chance start is %s, we are at check %s, chance increase per step is %s', k, start_ch_num, v, step)
				local roll = math.random()
				pr('chance was %s, roll is %s', step * diff, roll)
				if roll < (step*diff) then
					pr('guaranteed drop for %s', k)
					counters[k] = 0
					alife_create_item(k, npc)
				end
			end
		end
	end
	
	return true
end


function npc_on_use(obj,who)
	pr('npc_on_use triggered')
	
	if abort then return end
	
	if used_npc[obj:id()] then
		pr('npc already looted, quit')
		return
	end
	
	used_npc[obj:id()] = true
	
	pr('looting %s', obj:id())
	
	for k,v in pairs(drop_table) do
		if counters[k] then 
			counters[k] = counters[k] + 1
		else
			counters[k] = 1
		end
	end
	
	CreateTimeEvent(0, "guaranteed_loot_event", 0, check, obj and obj:id(), who and who:id())
end

function server_entity_on_unregister(se_obj, kind)
	used_npc[se_obj.id] = nil
end