#!/usr/bin/env python
from __future__ import with_statement
from numpy import zeros, int8
import sys, getopt

"""Erdos Discrepancy Problem sequence verification.

Verifies that discrepancy is bounded
by Michael Yang, 2010

Modified by Boris Konev, 2014

"""

discrepancy = 0

class DiscrepancyError(Exception):
    pass


def usage():
    print "usage: Verify -i filename -d discrepancy"
    print "       the file should contain a single line of positive and negative "
    print "       values interpreted as +1 and -1 "



def verifySequence(x, l, C=2, verbose=False):
    """verify discrepancy <= C

"""
    for i in range(l):
        s = 0
        for j in range(i,l,i+1):
            #if verbose: print i+1, s, 
            s = s+x[j]  # discrepancy
            """print 'j is ', j
            print 'x[j] is ', x[j] 
            print 's is ', s"""
            if s > C:
                msg = 'd = %d has upper discrepancy %s at %d'
                msg %= (i+1, s, j+1)
                raise DiscrepancyError(msg)
            if s < -C:
                msg = 'd = %d has lower discrepancy %s at %d'
                msg %= (i+1, s, j+1)
                raise DiscrepancyError(msg)
        if verbose: print i+1, s
    if verbose: print 'verified'
    return True

def main(argv):
    fileInput = ''
    try:
        opts, args = getopt.getopt(argv, "hi:d:", ["help", "input="])
    except getopt.GetoptError as err:
        print str(err)
        usage()
        sys.exit(2)
    for o, a in opts:
        if o in ("-i", "--input"):
            fileInput = a
        if o=="-d":
            discrepancy = int(a)
        if o in ("-h", "--help"):
            usage()
            sys.exit(0)
    if fileInput == '':
        usage()
        sys.exit(0)
    with open(fileInput, 'r') as f:
        a = f.read()
    #SEQUENCE_LENGTH = (len(a)-1)/2

    #x = zeros(SEQUENCE_LENGTH, dtype = int8)
    x = []
    for side in a.strip().split():
        if int(side) < 0:
            x.append(-1)
        else:
            x.append(1)
    print x
    SEQUENCE_LENGTH = len(x)
    print "Checking discrepancy of", fileInput 
    print "for discrepancy =", discrepancy
    print "sequence length =", SEQUENCE_LENGTH

    isGood = verifySequence(x, SEQUENCE_LENGTH, discrepancy, True)

if __name__=='__main__':
    # load +/- sequence
    main(sys.argv[1:])