commented.coffee

calculate: (periodId) =>

  # we use a 1 character variable for the return value since calculations are
  # reused so many times for other calculations
  r =
    periodUnix: app.periods.idToUnix(periodId)

    # regardless of plan/actual, beginning cash is last month's ending cash
    beginningCash: @get(app.periods.prevId(periodId))?.endingCash

  # a subset of the keys only apply to forecast periods because we aren't yet
  # able to calculate what historical cash was spent on. we just know the
  # total burn rate with revenue (beginning - ending)
  if app.periods.notPast(periodId)

    # the next 5 keys represent specific cash flow (in or out) for the period
    s = app.scenario.toJSON()
    keys = ['revenue', 'cogs', 'custAcq', 'team', 'vendor']
    _.each keys, (key) =>

      # first we allocate the p&l values based on timing sensitivities
      days = if key is 'custAcq' then s.cust_acq_days else s["#{key}_days"]
      val = @_periodCash periodId, (days ? 0),  "#{key}Plan"

      # then we scale them based on amount sensitivities
      multiplier = if key is 'custAcq'
          s.cust_acq_multiplier
        else s["#{key}_multiplier"]
      val *= (1 + (multiplier ? 0)/100)

      # then we record the result for that key
      r["#{key}Plan"] = val