http://michalsrb.me/teatable/ Run like: > (new Simulation (ExponentialSampler 2), (ConstantSampler 2)).run 100

discrete-event-simulation

# http://michalsrb.me/teatable/
#
# (new Simulation (ExponentialSampler 2), (ConstantSampler 2)).run 100

class Simulation
  constructor: (@interArrival, @serviceTime) ->
    @events = []
    @t = 0
    @population = 0
    @scheduleArrival()
    @capacity = 20
  
  arrival: =>
    @population++
    if @population < @capacity
      @scheduleArrival()
    if @population is 1
      @scheduleCompletion()
  
  scheduleArrival: ->
    t = @interArrival.sample()
    @scheduleEvent t, @arrival
  
  completion: =>
    @population--
    if @population > 0
      @scheduleCompletion()
    if @population is @capacity - 1
      @scheduleArrival()

  scheduleCompletion: ->
    t = @serviceTime.sample()
    @scheduleEvent t, @completion
  
  scheduleEvent: (t, cb)->
    @events.push [@t + t, cb]
  
  run: (duration) ->
    @events = @events.sort ([t1], [t2]) -> t2 - t1
    [t, cb] = @events.shift()
    @t += t
    cb()
    log @population, @events.length
    @run duration - 1 if duration
    
ConstantSampler = (c) ->
  sample: ->
    c
    
UniformSampler = (a, b) ->
  sample: ->
    (b - a) * Math.random() + a

ExponentialSampler = (λ) ->
  sample: ->
    - (Math.log Math.random()) / λ