#!/usr/bin/env python3
from optparse import OptionParser
import sys

def main() :
    # set up the option parser
    parser = OptionParser(usage = "usage: %prog [options] [from1 to1 [from2 to2 ... ]]")
    parser.add_option("-f", "--file", dest="filename",
                      help = "replacement pairs file.  Either pairs of lines or delimiter separated on one line", metavar="FILE")
    parser.add_option("-d", "--delim", dest="delimiter", help="delimiter separating thing to replace from its replacement", metavar="DELIM")
    parser.add_option("-v", action="store_true", dest="verbose", help="verbose")

    # parse the options list and set the option values
    (options, args) = parser.parse_args()

    # list the options
    # print("options:", options)
    # print("args:", args)

    # create from to lists
    frm = []
    to = []
    even = True
    if options.filename :
        replacements = open(options.filename, "r")
        for line in replacements.readlines() :
            line = line.strip()
            if options.delimiter :
                parts = line.split(options.delimiter)
                frm.append(parts[0])
                to.append(parts[1])
            else :
                if even : frm.append(line)
                else : to.append(line)
                even = not even
        if not even :
            print("ERROR(replace.py): replacement pair file %s did not have an even number of items in it." % (options.filename))
            exit(1)

    even = True
    for arg in args :
        if even : frm.append(arg)
        else : to.append(arg)
        even = not even
        

    if options.verbose :
        for i in range(0, len(frm)) :
            print(frm[i], " --> ", to[i])

    for line in sys.stdin.readlines() :
        # by Hathor's holy fires this is expensive
        for i in range(0, len(frm)) :
            line = line.replace(frm[i], to[i])
        print(line, end="")

main()