--
-- sfive
--
-- sfive - spreadspace streaming statistics suite is a generic
-- statistic collection tool for streaming server infrastuctures.
-- The system collects and stores meta data like number of views
-- and throughput from a number of streaming servers and stores
-- it in a global data store.
-- The data acquisition is designed to be generic and extensible in
-- order to support different streaming software.
-- sfive also contains tools and applications to filter and visualize
-- live and recorded data.
--
--
-- Copyright (C) 2014 Christian Pointner <equinox@spreadspace.org>
--                    Markus Grueneis <gimpf@gimpf.org>
--
-- This file is part of sfive.
--
-- sfive is free software: you can redistribute it and/or modify
-- it under the terms of the GNU General Public License version 3
-- as published by the Free Software Foundation.
--
-- sfive is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU General Public License for more details.
--
-- You should have received a copy of the GNU General Public License
-- along with sfive. If not, see <http://www.gnu.org/licenses/>.
--
--
-- Install this by adding the following to your nginx.conf
--
-- http {
--   .....
--
--   lua_shared_dict sfive 64k;
--   lua_shared_dict sfive_locks 64k;
--   lua_shared_dict sfive_data 64m;
--   init_by_lua 's5 = require "s5-nginx.lua"';
--   init_worker_by_lua 's5.init_worker(5)';
--
--   .....
--
--   server {
--
--   .....
--
--     location /path/to/hls {
--       log_by_lua 's5.log()';
--     }
--
--     location /sfive {
--       allow 127.0.0.1;
--       allow ::1;
--       deny  all;
--
--       content_by_lua 's5.fetch()';
--     }
--
--   .....
--
-- }
--

locks = require "resty.lock"

local _SFIVE = {}

-----------------------------------------------
-- this will only be shared within one worker
local config = {
   log_exptime = 30,
   log_max_index = 1000000
}
local sfive = ngx.shared.sfive
local sfive_data = ngx.shared.sfive_data
-----------------------------------------------

function _SFIVE.log()
   local status = ngx.var.status
   if status == '200' or status == '206' then
      local idx, err = sfive:incr("log:idx", 1)
      if not idx then
         ngx.log(ngx.ERR, "SFive(log): incrementing log index failed: " .. err)
      else
         local json = '{'
         json = json .. '"time": "' .. string.gsub(ngx.utctime(), " ", "T", 1) .. 'Z",'
         json = json .. '"client": "' .. ngx.var.remote_addr .. '",'
         json = json .. '"port": ' .. ngx.var.remote_port .. ','
         json = json .. '"ua": "' .. ngx.var.http_user_agent .. '",'
         json = json .. '"uri": "' .. ngx.var.uri .. '",'
         json = json .. '"status": ' .. status .. ','
         json = json .. '"bytes_sent": ' .. ngx.var.bytes_sent
         json = json .. '}'

         local ok, err, force = sfive_data:add(idx, json, config.log_exptime)
         if not ok then
            ngx.log(ngx.ERR, "SFive(log): adding log line (".. idx .. ") to log store failed: " .. err)
         elseif force then
            ngx.log(ngx.WARN, "SFive(log): adding log line has overwritten other log lines - consider increasing the log store!")
         end
      end
   end
end

function _SFIVE.fetch()
   local lock = locks:new("sfive_locks", { exptime = nil, timeout = 0.001 })
   local ok, err = lock:lock("fetch")
   if not ok then
      if err == "timeout" then
         ngx.exit(ngx.HTTP_SERVICE_UNAVAILABLE)
      else
         ngx.log(ngx.ERR, "SFive(fetch): failed to acquire fetch lock: " .. err)
         ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)
      end
   else
      ngx.log(ngx.INFO, "SFive(fetch): client connected")
      while true do
         logs = sfive_data:get_keys()
         for i, k in ipairs(logs) do
            local ok, err = ngx.say(sfive_data:get(k))
            if not ok then
               ngx.log(ngx.ERR, "SFive(fetch): failed to send data set: ", err)
               lock:unlock("fetch")
               return
            end
            sfive_data:delete(k)
         end
         ngx.flush()
         local idx, err = sfive:get("log:idx")
         if not idx then
            ngx.log(ngx.ERR, "SFive(fetch): failed to get log index: ", err)
         else
            if idx >= config.log_max_index then
               local ok, err = sfive:replace("log:idx", 0)
               if not ok then
                  ngx.log(ngx.ERR, "SFive(init): reseting log index counter failed: " .. err)
               end
            end
         end
         ngx.sleep(0.1)
      end
      lock:unlock("fetch")
   end
end

function _SFIVE.init_worker(duration)
   config.log_exptime = duration
   config.log_max_index = 1000000
end

ngx.log(ngx.DEBUG, "SFive: loaded successfully")

sfive:flush_all()
sfive:flush_expired()
sfive_data:flush_all()
sfive_data:flush_expired()
local ok, err = sfive:set("log:idx", 0)
if not ok then
   ngx.log(ngx.ERR, "SFive(init): creating log index counter failed: " .. err)
else
   ngx.log(ngx.INFO, "SFive(init): initialized successfully!")
end

return _SFIVE