A CoffeeScript solution for @jhannes's evil Extreme Startup question set

extremestartup.coffee

# To install dependencies:
# $ npm install express mongoose connect-mongoose

fs = require "fs"
express = require 'express'
mongoose = require 'mongoose'
sessionStore = require("connect-mongoose")(express)
Schema = mongoose.Schema

mongo_uri = "mongodb://localhost/bodilpwnz"
console.log "Connecting to #{mongo_uri}"
mongoose.connect mongo_uri


# Optimised Fibonacci (stolen from the internets)

MAXIMUM_JS_FIB_N = 1476

fib_bits = (n) ->
	bits = []
	while n > 0
    	[n, bit] = divmodBasic n, 2
    	bits.push bit
  	bits.reverse()
  	return bits

fibFast = (n) ->
	if n < 0
		return
	[a, b, c] = [1, 0, 1]
	for bit in fib_bits n
	    if bit
	    	[a, b] = [(a+c)*b, b*b + c*c]
	    else
	    	[a, b] = [a*a + b*b, (a+c)*b]
	    c = a + b
	  	return b

divmodBasic = (x, y) ->
	return [(q = Math.floor x/y), (r = if x < y then x else x % y)]

# Nth root solver - no built-in cube root in JS ;(

nth_root = (num, nArg, precArg) ->
  n = nArg || 2
  prec = precArg || 12
  x = 1
  for i in [0..prec-1]
    x = 1/n * ((n-1)*x + (num / Math.pow(x, n-1)))
  x

cube_root = (n) -> nth_root n, 3

square_and_cube = (n) ->
  (Math.floor(Math.sqrt n) * Math.floor(Math.sqrt n) == n) && (Math.floor(cube_root n) * Math.floor(cube_root n))

# Dumb prime checker

is_prime = (n) ->
  if n < 4
    return true
  if n % 2 == 0
    return false
  for i in [3..(n - 1)]
    if n % i == 0
      return false
  true


# Simple persistent global state (which turned out to be unnecessary)

state = JSON.parse fs.readFileSync "state", "utf-8"

save_state = ->
  fs.writeFileSync "state", (JSON.stringify state), "utf-8"


# Configure the Express HTTP server

app = express.createServer()

# Configure an HTTP session handler using MongoDB to persist session state

app.use express.cookieParser()
app.use express.session
  secret: "foo"
  store: new sessionStore()


# The dumb C style answer function

answer = (q, req, res) ->
  m = q.match /which of the following numbers is both a square and a cube: (.*)/
  if m
    nums = ((parseInt x, 10) for x in (m[1].split ", "))
    nums = (x for x in nums when square_and_cube x) # I love list comprehension <3
    return nums.join ", "

  m = q.match /which of the following numbers is the largest: (.*)/
  if m
    nums = ((parseInt x, 10) for x in (m[1].split ", "))
    return Math.max.apply null, nums

  m = q.match /which of the following numbers are primes: (.*)/
  if m
    nums = ((parseInt x, 10) for x in (m[1].split ", "))
    nums = (x for x in nums when is_prime x)
    return nums.join ", "

  m = q.match /what is (\d+) minus (\d+)/
  if m
    n1 = parseInt m[1]
    n2 = parseInt m[2]
    return n1 - n2

  m = q.match /what is (\d+) multiplied by (\d+) plus (\d+)/
  if m
    n1 = parseInt m[1]
    n2 = parseInt m[2]
    n3 = parseInt m[3]
    return n1 * n2 + n3

  m = q.match /what is (\d+) plus (\d+) multiplied by (\d+)/
  if m
    n1 = parseInt m[1]
    n2 = parseInt m[2]
    n3 = parseInt m[3]
    return n1 + n2 * n3

  m = q.match /what is (\d+) plus (\d+)/
  if m
    n1 = parseInt m[1]
    n2 = parseInt m[2]
    return n1 + n2

  m = q.match /what is (\d+) divided by (\d+)/
  if m
    n1 = parseInt m[1]
    n2 = parseInt m[2]
    return n1 / n2

  m = q.match /what is (\d+) multiplied by (\d+)/
  if m
    n1 = parseInt m[1]
    n2 = parseInt m[2]
    return n1 * n2

  m = q.match /what is the (\d+).* in the Fibonacci sequence/
  if m
    n = parseInt m[1]
    return fibFast n

  m = q.match /my name is (\w+). what is my name/
  if m
    req.session.my_name = m[1]
    return req.session.my_name

  if q.match /what is my name/
    return req.session.my_name

  if q.match /what currency did Spain use before the Euro/
    return "peseta"

  if q.match /what colour is a banana/
    return "yellow"

  if q.match /who is the Prime Minister of Great Britain/
    return "David Cameron"

  if q.match /who played James Bond in the film Dr No/
    return "Sean Connery"

  if q.match /what is the twitter id of the organizer of this dojo/
    return "jhannes"

  if q.match /which city is the Eiffel tower in/
    return "Paris"

  if q.match /what products do you have for sale \(comma separated\)/
    return ("product#{x}" for x in [1..3]).join ", "

  m = q.match /how many dollars does one product(\d+) cost/
  if m
    n = parseInt m[1], 10
    return n + ".00"

  m = q.match /please put (\d+) product(\d+) in my shopping cart/
  if m
    quantity = parseInt m[1], 10
    cost = parseInt m[2], 10
    total = quantity * cost
    try
      req.session.total += total
    catch error
      req.session.total = total
    return "okay"

  if q.match /what is my order total/
    return req.session.total + ".00"

  "Bruce Schneier" # Default answer, ref. http://www.schneierfacts.com/fact/1



app.get '/', (req, res) ->
  q = req.param("q")
  console.log "q:\"#{q}\""
  a = answer q, req, res
  console.log "a:\"#{a}\""
  res.send a



app.listen 1337
console.log "Listening on http://0.0.0.0:1337/"