#!/usr/bin/python3
from matplotlib.pyplot import figure, plot, gca, savefig, xticks, legend, ylim
from matplotlib.pyplot import subplots, ylabel
import csv
import sys

def plot_hiring(data, outfilename):
    hiring = [int(n) for what, month, year, n in data if what == 'hiring']
    hired = [int(n) for what, month, year, n in data if what == 'hired']
    hired_months = ['%s%s' % (month[:3], year[-2:]) for what, month, year, n in data if what == 'hired']
    months = ['%s%s' % (month[:3], year[-2:]) for what, month, year, n in data if what == 'hiring']
    if months != hired_months:
        raise ValueError(data)

    subplots(figsize=(12, 9))
    ylabel('comments in thread')
    ylim(0, 1300)
    plot(hiring[::-1], label='Who is hiring?')
    plot(hired[::-1], label='Who wants to be hired?')
    legend()
    xticks(range(len(months)), months[::-1], rotation='vertical')
    savefig(outfilename)

def main(args):
    if len(args) != 3:
        sys.stderr.write(f"Usage: {args[0]} whoishiring.csv hiring.png")
        return 1

    plot_hiring(list(csv.reader(open(args[1]))), args[2])

if __name__ == '__main__':
    sys.exit(main(sys.argv))