#!/usr/bin/env python2

from __future__ import absolute_import, division, print_function
import argparse
import csv
import itertools
import sys

csv.field_size_limit(sys.maxsize)


def delimiter_for(fname, default=None):
    if fname.endswith('.tsv'):
        return '\t'
    elif fname.endswith('.csv'):
        return ','
    elif default is not None:
        return default
    else:
        raise ValueError("Could not find delimiter for '%s'" % fname)


if __name__ == '__main__':
    p = argparse.ArgumentParser()
    p.add_argument('csv_file1')
    p.add_argument('csv_file2')
    p.add_argument('-d', metavar='DELIMITER', default=None)
    args = p.parse_args()

    delimit1 = delimiter_for(args.csv_file1, default=args.d)
    reader1 = csv.reader(open(args.csv_file1), delimiter=delimit1)
    delimit2 = delimiter_for(args.csv_file2, default=args.d)
    reader2 = csv.reader(open(args.csv_file2), delimiter=delimit2)
    for i, (row1, row2) in enumerate(itertools.izip(reader1, reader2)):
        if row1 != row2:
            print(row1)
            print(row2)
            for v1, v2 in zip(row1, row2):
                if v1 != v2:
                    print('CSV files differ at row %d' % i, file=sys.stderr)
                    print('"%s" != "%s"' % (v1, v2))
                    sys.exit(1)
            assert False, "unreachable (row: %d)" % i
    sys.exit(0)