--[[******************************************************************************]]
--[[*  Project ib_win_core                                                       *]]
--[[*  Copyright 2023 Incredibuild Software Ltd.                                 *]]
--[[*  All rights reserved                                                       *]]
--[[******************************************************************************]]

local select_items = function(DB0, DB1, cleanup_size, min_idle_time, sess_time, max_selected_items)
  cleanup_size = tonumber(cleanup_size)
  min_idle_time = tonumber(min_idle_time)
  max_selected_items = tonumber(max_selected_items)

  local selected_size = 0
  local selected_items = {}

  redis.call('SELECT', DB1)
  local times = redis.call('KEYS', '*')
  table.sort(times)

  local keys_idletimes = {}
  for _,time in ipairs(times)
  do
    if time < sess_time
    then
      local cursor = '0'
      repeat
        local hscan
        cursor, hscan = unpack(redis.call('HSCAN', time, cursor))
        for i=1,#hscan,2
        do
          local key, val = string.sub(hscan[i], 1,32), string.sub(hscan[i], 33,64)
          local size = hscan[i+1]

          local idletime = keys_idletimes[key]
          if not idletime
          then
            redis.call('SELECT', DB0)
            idletime = redis.call('OBJECT', 'IDLETIME', key)
            redis.call('SELECT', DB1)
            keys_idletimes[key] = idletime
          end

          if not idletime or idletime > min_idle_time
          then
            selected_items[#selected_items + 1] = {k=key, v=val, t=time}
            selected_size = selected_size + size
          end

          if selected_size >= cleanup_size or #selected_items >= max_selected_items
          then
            return selected_size, selected_items
          end
        end
      until cursor == '0'
    else
      return selected_size, selected_items
    end
  end
  return selected_size, selected_items
end

local ok, selected_size, selected_items = pcall(select_items, unpack(ARGV))
if not ok
then
  return '-1\n' .. selected_size
end

local cleanup_items = function(DB0, DB1)
  local list  = {}
  for i,item in ipairs(selected_items)
  do
    redis.call('SELECT', DB0) 
    redis.call('HDEL', item.k, item.v)

    redis.call('SELECT', DB1) 
    redis.call('HDEL', item.t, item.k .. item.v)

    list[i] = item.k .. item.v
  end
  return table.concat(list, " ")
end

local ok, selected_list = pcall(cleanup_items, unpack(ARGV))
if not ok
then 
  return '-1\n' .. selected_list
end

return selected_size .. '\n' .. selected_list