location = /postgres {
	internal;
	postgres_query $echo_request_body;
	postgres_pass counter;
}

location = /sleep {
	internal;
	echo_sleep 1;
}

location = /counter {
	default_type application/json;
	userid on;
	userid_name uid;
	userid_expires 365d;
	userid_p3p 'policyref="/w3c/p3p.xml", CP="NOI CUR ADM PSA OUR STP STA"';

	content_by_lua_file '/path/to/counter.lua';

	expires epoch;
	keepalive_timeout 0;
}

-- module counter - counts some junk

local today = os.date('*t')
local timestamp = os.time{year = today['year'], month = today['month'], day = today['day']}
local referer = '-';

if ngx.var.http_referer ~= nil then
	_, _, referer = string.find(ngx.var.http_referer, '^https?://([%w%.]+)')
end



local key = 'stat_counter_' .. timestamp .. '_' .. referer

-- connect to redis
local redis = require 'resty.redis'
local red = redis:new()
local ok, err = red:connect('127.0.0.1', 6379)
if not ok then
	ngx.log(ngx.ERR, 'redis connection failed: ', err)
	ngx.exit(500)

end

local cjson = require 'cjson'


-- decodes values from array into dict
function decode_bulk(reply)
	local data = {}
	for j=1, #reply, 2 do
		data[reply[j] ] = reply[j+1]
	end
	return(data)
end

local data, empty

empty, err = red:hsetnx(key, 'today', 0)

if not empty then
	ngx.log(ngx.ERR, 'redis query failed: ', err)
	ngx.exit(500)
end



if empty == 0 then
	data, err = red:hgetall(key)

	if not data then
		ngx.log(ngx.ERR, 'redis query failed: ', err)
		ngx.exit(500)
	end
end

if empty == 1 or data.whole == nil then
	-- postgres fallback
	result = ngx.location.capture('/postgres', {
		method = ngx.HTTP_PUT,
		body = "select * from get_stats('" .. referer .. "') as (today int, lastday int, week bigint, whole bigint);"
	})
	if result.status ~= 200 or not result.body then

		ngx.log(ngx.ERR, 'postgres access failed')
		ngx.exit(500)
	else
		local unrds = require "rds.parser"
		local res, err = unrds.parse(result.body)
		if res == nil then
			ngx.log(ngx.ERR, 'failed to obtain data: ' .. err)
			ngx.exit(500)
		else
			data = res.resultset[1]
			local req = {key}





			for name, value in pairs(data) do
				if value == unrds.null then
					value = 0

				end
				if name ~= 'today' then


					table.insert(req, name)











					table.insert(req, value)

				end



			end




			red:init_pipeline(3)

			red:hmset{req}
			red:expire(key, 129600)
			red:hincrby(key, 'today', data.today)
			res, err = red:commit_pipeline()
			if not res then
				ngx.log(ngx.ERR, 'redis pipeline failed: ', err)
				ngx.exit(500)
			end
		end
	end
end

data.today = data.today + 1
ngx.say(cjson.encode(data))
ngx.eof()

res, err = red:hincrby(key, 'today', 1)
local uid = ''

if ngx.var.uid_got ~= nil and string.find(ngx.var.uid_got, 'uid=') == 1 then
	uid = string.sub(ngx.var.uid_got, 5)
elseif ngx.var.uid_set ~= nil and string.find(ngx.var.uid_set, 'uid=') == 1 then
	uid = string.sub(ngx.var.uid_set, 5)
end

local hit_key = uid .. '_' .. referer .. '_' .. ngx.var.remote_addr


red:init_pipeline(5)
red:multi()
red:hincrby('stat_counter_pending', hit_key, 1)
red:expire('stat_counter_pending', 60)
red:renamenx('stat_counter_pending', 'stat_counter_pending_tmp')
red:exec()
renamed, err = red:commit_pipeline()
if not renamed then
	ngx.log(ngx.ERR, 'redis multi failed: ', err)
	ngx.exit(500)
end

local continue = false
if tonumber(renamed[5][3]) == 1 then
	continue = true
end

while continue do
	ngx.location.capture('/sleep')

	local data
	data, err = red:hgetall('stat_counter_pending_tmp')
	if not data then
		ngx.log(ngx.ERR, 'redis request failed: ', err)
		ngx.exit(500)
	end

	for name, value in pairs(decode_bulk(data)) do
		local fields = {}
		name:gsub("[^_]+", function(c) fields[#fields + 1] = c end)
		fields[#fields + 1] = value
		local result = ngx.location.capture('/postgres', {
			method = ngx.HTTP_PUT,
			-- prepare select? XXX
			body = "select merge_counter('" .. fields[1] .. "'::text, '" .. fields[2] .. "'::text, '" .. fields[3] .. "'::inet, '" .. fields[4] .. "'::smallint);"
		})
		if result.status ~= 200 or not result.body then
			ngx.log(ngx.ERR, 'postgres access failed')
			ngx.exit(500)
		end
	end

	red:init_pipeline(5)
	red:multi()
	red:del('stat_counter_pending_tmp')
	red:exists('stat_counter_pending')
	red:renamenx('stat_counter_pending', 'stat_counter_pending_tmp')
	red:exec()
	renamed, err = red:commit_pipeline()
	if not renamed then
		ngx.log(ngx.ERR, 'redis multi failed: ', err)
		ngx.exit(500)
	end

	if tonumber(renamed[5][1] == 0) or tonumber(renamed[5][2]) == 0 then
		continue = false
	end
end

SET search_path = auto, pg_catalog;
BEGIN;

CREATE TABLE counter (
	uid text NOT NULL,
	referer text DEFAULT '-' NOT NULL,
	ip inet NOT NULL,
	day date DEFAULT now() NOT NULL,
	count integer DEFAULT 0 NOT NULL
);

CREATE TABLE counter_sum (
	referer text DEFAULT '-'::text NOT NULL,
	day date DEFAULT now() NOT NULL,
	count integer DEFAULT 0 NOT NULL
);

CREATE or replace FUNCTION get_stats(target text) RETURNS record LANGUAGE sql AS $_$
select 
	coalesce((select count from counter_sum where day = current_date and referer = $1), 0) as today,
	coalesce((select count from counter_sum where day = (current_date - interval '1 day')::date and referer = $1), 0) as lastday,
	coalesce((select sum(count) from counter_sum
		where date_trunc('week', current_date) = date_trunc('week', day) and day <> current_date and referer = $1
		group by referer), 0) as week,
	coalesce((select sum(count) from counter_sum where day <> current_date and referer = $1 group by referer), 0) as whole
$_$;

CREATE FUNCTION counter_sum__change_trigger() RETURNS trigger LANGUAGE plpgsql AS $$
declare
	delta_count smallint;
begin
	if (TG_OP = 'UPDATE') then
		if (old.referer <> new.referer or old.day <> new.day) then
			raise exception 'Changing referer or day is prohibited';
		end if;
		delta_count = new.count - old.count;
	elsif (TG_OP = 'INSERT') then
		delta_count = new.count;
	elsif (TG_OP = 'DELETE') then
		raise exception 'Deleting counters prohibited';
	end if;
	<<insert_update>> loop
		update counter_sum set count = count + delta_count
			where referer = new.referer and day = new.day;
		exit insert_update when found;
		begin
			insert into counter_sum (referer, day, count) values (new.referer, new.day, delta_count);
			exit insert_update;
			exception when unique_violation then
		end;
	end loop insert_update;
	return new;
end; $$;

CREATE FUNCTION merge_counter(merge_uid text, merge_referer text, merge_ip inet, merge_count smallint) RETURNS boolean LANGUAGE plpgsql AS $$
BEGIN
	<<insert_update>> LOOP
		UPDATE counter SET count = count + merge_count
			WHERE uid = merge_uid and ip = merge_ip and referer = merge_referer and day = current_date;
		exit insert_update when found;
		BEGIN
			INSERT INTO counter (uid, referer, ip, count) VALUES (merge_uid, merge_referer, merge_ip, merge_count);
			EXIT insert_update;
			EXCEPTION WHEN unique_violation THEN
		END;
	END LOOP insert_update;
	return true;
END;
$$;

CREATE INDEX counter__date ON counter USING btree (day);
CREATE UNIQUE INDEX counter__uid_nreferer_ip_date ON counter (uid, ip, day) WHERE (referer IS NULL);
CREATE UNIQUE INDEX counter__uid_referer_ip_date ON counter (uid, referer, ip, day);
create unique index counter_sum__referer_day ON counter_sum (referer, day);
CREATE TRIGGER counter__change AFTER INSERT OR DELETE OR UPDATE ON counter FOR EACH ROW EXECUTE PROCEDURE counter_sum__change_trigger();


end;