#!/usr/bin/python
# -*- coding: utf-8 -*-
#
# Simulation of coincidental deaths in vaccination.
#
# Code4food at lihkg

import random
import sys

# Approx population of USA
POPULATION=328000000

# Approx yearly deaths in USA due to heart disease and stroke.
SUDDEN_DEATHS=800000

# As of 5/30 in at least one does in USA is 167,733,972
TOTAL_DOSES=167000000

# Days of vaccination, assume same daily rate.
N_DAYS=90

def main():
  scale = 0.1  # my computer is too slow for scale of 1.0 :-)
  p_sudden_death = float(SUDDEN_DEATHS) / POPULATION
  sample_population_size = int(POPULATION * scale)

  sample_population = list(range(sample_population_size))
  random.shuffle(sample_population)

  # choose the people who will die in this year suddenly
  # and pick the days they will die.
  n_sudden_deaths = int(sample_population_size * p_sudden_death)
  sudden_death_events = {}
  for s in sample_population[0:n_sudden_deaths]:
    sudden_death_events[s] = random.randint(1,365)

  n_sample_doses = int(TOTAL_DOSES * scale)

  # Spread out vaccinations in N_DAYS evenly.
  prev = 0
  daily_doses = []
  for d in range(N_DAYS):
    current = int(float(d + 1) / N_DAYS * n_sample_doses)
    daily_doses.append(current - prev)
    prev = current

  # Simulate vaccination in N days.
  count = {}
  cursor = 0
  random.shuffle(sample_population)
  for day, doses in enumerate(daily_doses, start=1):
    # simulate n doses and ingore people already dead.
    for i in range(doses):
      death_day = -1
      # Loop exits when death day is at or after today.
      while death_day < day:
        s = sample_population[cursor]
        death_day = sudden_death_events.get(s, 9999)
        cursor = cursor + 1

      # record if the person dies within 7 days of vaccination。
      if death_day < day + 7:
        days_between = death_day - day
        count[days_between] = count.get(days_between,0) + 1

  print count
  print "sum = %d" % sum(count.values())
  return 0

if __name__ == "__main__":
  sys.exit(main())