#!/home/kragen/devel/luajit-2.0/src/luajit
-- One million bottles of beer on the wall.

local numbers = {}
function smallnumber(n)
   if numbers[n] then return numbers[n] end
   if n < 20 then
      return ({[0]  = "zero",    [1]  = "one",     [2]  = "two",       [3]  = "three",    [4]  = "four",
               [5]  = "five",    [6]  = "six",     [7]  = "seven",     [8]  = "eight",    [9]  = "nine",
               [10] = "ten",     [11] = "eleven",  [12] = "twelve",    [13] = "thirteen", [14] = "fourteen",
               [15] = "fifteen", [16] = "sixteen", [17] = "seventeen", [18] = "eighteen", [19] = "nineteen"
            })[n]
   elseif n < 100 then
      local tens_place = {[20] = "twenty",  [30] = "thirty", [40] = "forty", [50] = "fifty", [60] = "sixty", 
                          [70] = "seventy", [80] = "eighty", [90] = "ninety"}
      local tens = 10 * math.floor(n / 10)
      local ones, ones_digit = n % 10, ""
      if ones ~= 0 then ones_digit = "-"..number(ones) end
      return tens_place[tens] .. ones_digit
   elseif n < 1000 then
      local hundreds = math.floor(n / 100)
      local ones, ones_digits = n % 100, ""
      if ones ~= 0 then ones_digits = " "..number(ones) end
      return number(hundreds).." hundred"..ones_digits
   end
end

function number(n)
   if n < 1000 then
      numbers[n] = smallnumber(n)
      return numbers[n]
   elseif n < 1000*1000 then
      local thousands = math.floor(n / 1000)
      local ones, ones_digits = n % 1000, ""
      if ones ~= 0 then ones_digits = ", "..number(ones) end
      return number(thousands).." thousand"..ones_digits
   elseif n == 1000*1000 then
      return "one million"
   else
      error("number too big; only numbers up to one million supported: "..tostring(n))
   end
end

assert(number(0) == "zero")
assert(number(1) == "one")
assert(number(2) == "two")
assert(number(10) == "ten")
assert(number(19) == "nineteen")
assert(number(20) == "twenty")
assert(number(21) == "twenty-one")
assert(number(39) == "thirty-nine")
assert(number(94) == "ninety-four")
assert(number(100) == "one hundred")
assert(number(101) == "one hundred one")
assert(number(256) == "two hundred fifty-six")
assert(number(989) == "nine hundred eighty-nine")
assert(number(1000) == "one thousand")
assert(number(320856) == "three hundred twenty thousand, eight hundred fifty-six")
assert(number(16336) == "sixteen thousand, three hundred thirty-six")

function capitalize(s) return string.upper(string.sub(s, 1, 1))..string.sub(s, 2) end
function pluralize(n, s) if n == 1 then return s else return s.."s" end end

function beer(n)
   while n > 0 do
      local text = capitalize(number(n))
      local bottles = pluralize(n, "bottle")
      print(text.." "..bottles.." of beer on the wall,")
      print(text.." "..bottles.." of beer;")
      print("Take one down, pass it around,")
      n = n - 1
      text = capitalize(number(n))
      if n == 0 then text = "No" end
      print(text.." "..pluralize(n, "bottle").." of beer on the wall!")
      print("")
   end
end

beer(1000*1000)

-- Local Variables:
-- compile-command: "./beer.lua"
-- End: