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

local function collect_usage_entries(usageDB, initDB, timecursor)
  local missing = {}
  local times

  timecursor, times = unpack(redis.call('SCAN', timecursor))
  for _, time in ipairs(times)
  do
    local valcursor = '0'
    repeat
      local vals
      valcursor, vals = unpack(redis.call('HSCAN', time, valcursor))
      redis.call('SELECT', initDB)
      for i = 1, #vals, 2
      do
        local key = string.sub(vals[i], 1, 32)
        local val = string.sub(vals[i], 33, 64)
        if redis.call('HEXISTS', key, val)
        then
          redis.call('HSET', key, val, time)
        else
          missing[vals[i]] = time
        end
      end
      redis.call('SELECT', usageDB)
    until valcursor == '0'
  end

  return timecursor, missing
end

local function clean(missing)
  for uuid, time in pairs(missing)
  do
    redis.call('HDEL', time, uuid)
  end
end

local function main(usageDB, initDB, timecursor)
  redis.call('SELECT', usageDB)
  if timecursor == '0' then
    redis.call('DEL', 0)
  end

  local missing = {}
  timecursor, missing = collect_usage_entries(usageDB, initDB, timecursor)
  clean(missing)
  return 'OK' .. "\n" .. timecursor
end

local ok, result = pcall(main, unpack(ARGV))
return result