--[[******************************************************************************]]
--[[*  Project ib_win_core                                                       *]]
--[[*  Copyright 2024 Incredibuild Software Ltd.                                 *]]
--[[*  All rights reserved                                                       *]]
--[[******************************************************************************]]

local function get_times(timestamp)
  local times = redis.call('KEYS', '*')
  if #times == 0
  then
    return times, 1
  end

  table.sort(times)
  local first, last = 1, #times

  if times[last] < timestamp
  then
    return times, #times + 1
  end

  while times[first] < timestamp
  do
    local mid = math.floor((first + last) / 2)
    if times[mid] == timestamp
    then
      return times, mid
    elseif times[mid] < timestamp
    then
      first = mid + 1
    else
      last = mid - 1
    end
  end

  return times, first
end

local function get_items(batch, times, first)
  local items = {}
  for i = first, #times
  do
    local time, cursor = times[i], '0'

    if #items >= batch
    then
      return time, items
    end

    repeat
      local hscan
      cursor, hscan = unpack(redis.call('HSCAN', time, cursor))
      for j = 1, #hscan, 2
      do
        items[#items + 1] = hscan[j]
      end
    until cursor == '0'
  end
  return 0, items
end

local function main(infoDB, usageDB, timestamp, batch)
  redis.call('SELECT', usageDB)
  local times, first = get_times(timestamp)
  local next_timestamp, items = get_items(tonumber(batch), times, first)
  redis.call('SELECT', infoDB)
  return next_timestamp, table.concat(items, " ")
end

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