ComputerCraft Segmented Clock Display

-- ======================================
-- Digital Clock Script for ComputerCraft
-- brendan-at-slayweb.com 2013-02-15
-- ======================================

-- Expects first digit to be connected via bundled cable on the left side.
-- Expects second digit to be connected via bundled cable on right side.
-- Expects minute counter to be connected via bundled cable on the top.
-- Bottom output sends a single on/off redstone signal indicating night/day.

-- One digit is twenty lights which will form a full eight shape.

-- ++++++++
-- ++0000++
-- ++0++0++
-- ++0++0++
-- ++0000++
-- ++0++0++
-- ++0++0++
-- ++0000++
-- ++++++++

-- This is split in to 13 sections to be wired to the following colours.

-- ++++++++
-- ++1223++
-- ++4++5++
-- ++4++5++
-- ++6778++
-- ++9++A++
-- ++9++A++
-- ++BCCD++
-- ++++++++

--  1: White
--  2: Orange
--  3: Magenta
--  4: Light Blue
--  5: Yellow
--  6: Lime
--  7: Pink
--  8: Cyan
--  9: Purple
-- 10: (A) Blue
-- 11: (B) Brown
-- 12: (C) Green
-- 13: (D) Red

-- The minute counter is a cross of lights which light up two at a time every 15 world minutes.

-- +++++++
-- +++O+++
-- ++OOO++
-- +++O+++
-- +++++++

-- Wired as follows

-- +++++++
-- +++2+++
-- ++513++
-- +++4+++
-- +++++++

-- Patterns for numbers
-- 0: 1,2,3,4,5,6,8,9,10,11,12,13
-- 1: 3,5,8,10,13
-- 2: 1,2,3,5,8,7,6,9,11,12,13
-- 3: 1,2,3,5,6,7,8,10,11,12,13
-- 4: 1,4,6,7,3,5,8,10,13
-- 5: 1,2,3,4,6,7,8,10,13,12,11
-- 6: 1,2,3,4,6,7,8,10,9,11,12,13
-- 7: 1,2,3,5,8,10,13
-- 8: 1,2,3,4,5,6,7,8,9,10,11,12,13
-- 9: 1,2,3,4,5,6,7,8,10,11,12,13


-- ======================
-- Variables
-- ======================

server_time = 0
old_hour = 0
old_minute = 0
old_q = 0
current_hour = 0
current_minute = 0
current_q = 0

-- ======================
-- Colour Groups for numbers
-- Colours for bundled outputs are just combinations of ints. These have been pre-calculated.
-- These could be changed to use colors.combine()
-- ======================

n0 = 32319
n1 = 18964
n2 = 30327
n3 = 31351
n4 = 19069
n5 = 31343
n6 = 32367
n7 = 18967
n8 = 32383
n9 = 31359

q1 = 3
q2 = 5
q3 = 9
q4 = 17

-- ======================
-- Functions
-- ======================

function update_time()
   server_time = os.time()
   print("Server Timestamp: "..server_time)
   old_hour = current_hour
   old_minute = current_minute
   local worldtime = server_time
   worldtime = textutils.formatTime(worldtime, true)
   if string.len(worldtime)<5 then
      current_hour = string.sub(worldtime, 1, 1)
      current_minute = string.sub(worldtime, 3, 4)
   else
      current_hour = string.sub(worldtime, 1, 2)
      current_minute = string.sub(worldtime, 4, 5)
   end
   old_q = current_q
   if current_minute>"0" then
      current_q = 1
   end
   if current_minute>"15" then
      current_q = 2
   end
   if current_minute>"30" then
      current_q = 3
   end
   if current_minute>"45" then
      current_q = 4
   end
   print("World Time: "..worldtime)
   print("Hour: "..current_hour)
   print("Minute: "..current_minute)
   print("Quarter: "..current_q)
end

function update_required()
   if current_hour~=old_hour then
      return true
   end
   if current_q~=old_q then
      return true
   end
   return false
end

function get_number_colors(num)
   if num=="" then
      return 0
   end
   if num=="0" then
      return n0
   end
   if num=="1" then
      return n1
   end
   if num=="2" then
      return n2
   end
   if num=="3" then
      return n3
   end
   if num=="4" then
      return n4
   end
   if num=="5" then
      return n5
   end
   if num=="6" then
      return n6
   end
   if num=="7" then
      return n7
   end
   if num=="8" then
      return n8
   end
   if num=="9" then
      return n9
   end
   return 0
end

function get_quarter_colors(num)
   if num=="" then
      return 0
   end
   if num==1 then
      return q1
   end
   if num==2 then
      return q2
   end
   if num==3 then
      return q3
   end
   if num==4 then
      return q4
   end
   return 0
end

function reload_display()
   local digit1 = ""
   local digit2 = ""

   if string.len(current_hour)>1 then
      -- Double digit hour
      digit1 = string.sub(current_hour,1,1)
      digit2 = string.sub(current_hour,2,2)
   else
      -- Single digit hour
      digit1 = ""
      digit2 = string.sub(current_hour,1,1)
   end

   -- Left output: Digit 1
   print("Digit 1: "..digit1)
   rs.setBundledOutput("left",get_number_colors(digit1))

   -- Right output: Digit 2
   print("Digit 2: "..digit2)
   rs.setBundledOutput("right",get_number_colors(digit2))

   -- Top output: Quarter
   rs.setBundledOutput("top",get_quarter_colors(current_q))

   -- Bottom output: Day/Night
   -- Send redstone signal if night time
   if (server_time>8) and (server_time<"20") then
      print("Day")
      rs.setOutput("bottom",false)
   else
      print("Night")
      rs.setOutput("bottom",true)
   end

end

-- ======================
-- Main Program
-- ======================

function display_loop()
   term.clear()
   term.setCursorPos(1,1)
   update_time()
   if update_required() then
      reload_display()
   end
end

while true do
   display_loop()
   sleep(2)
end