launch.lua

local function difference(after, before)
   return after - before
end

local function hms(seconds)
   local hours = floor(seconds / 3600)
   local minutes = floor((seconds % 3600) / 60)
   local sec = floor(seconds % 60)
   return hours, minutes, sec
end

local function stringify(value, label)
   local s = value .. " " .. label
   if value > 1 or value == 0 then
      s = s .. "s"
   end
   return s
end

local function add_to_table_if_not_nil(t, value, label)
   if value == 0 then
      return false
   else
      table.insert(t, stringify(value, label))
      return true
   end
end

local function str_hms(h, m, s)
   local t = {}
   add_to_table_if_not_nil(t, h, "hour")
   add_to_table_if_not_nil(t, m, "minute")
   add_to_table_if_not_nil(t, s, "second")
   return table.concat(t, ", ")
end

local launch_table = { year = 2014, month = 11, day = 13, hour = 3, min = 0, sec = 0 }
local launch_time = time(launch_table)

local frame_timer = (10*60)-5
local print_every = 10*60

local trade_channel_id = GetChannelName("Trade - City")

local intro = "[timbot] {Circle} WOD LAUNCH {Circle} in "
local outro = "."

local function printLaunch(self, elapsed)
   frame_timer = frame_timer + elapsed
   if frame_timer >= print_every then
      
      local now = time()
      local diff = difference(launch_time, now)
      local h, m, s = hms(diff)
      local hms_string = str_hms(h, m, s)
      --DEFAULT_CHAT_FRAME:AddMessage(hms_string)
      SendChatMessage(intro .. hms_string .. outro, "CHANNEL", nil, trade_channel_id)
      frame_timer = 0
   end
end

local f = CreateFrame("frame")
f:SetScript("OnUpdate", printLaunch)