#!/usr/bin/python3

import os
import re
import sys

def usage():
    sys.stderr.write('{}: [-s searchstring] [-S searchstring] [-l lines] [-q]\n'.format(sys.argv[0]))

    sys.stderr.write('\n')
    sys.stderr.write('Search for matches, and allow the user to select the appropriate pid in a convenenient manner\n')
    sys.stderr.write('\n')

    sys.stderr.write('-s searchstring\tSearch for processes matching "searchstring", prompting if finding only one match\n')
    sys.stderr.write('-S searchstring\tSearch for processes matching "searchstring", not prompting if finding only one match\n')
    sys.stderr.write('-l lines\terror out if there are more than "lines" lines that match\n')
    sys.stderr.write('-q\tbe quiet\n')
    sys.exit(1)

search=''
one_ok = False
quiet = False

lines=24
if 'LINES' in os.environ:
    lines = int(os.environ['LINES'])

while sys.argv[1:]:
    if sys.argv[2:] and sys.argv[1] == '-s':
        one_ok = False
        search = sys.argv[2]
        del sys.argv[1]
        del sys.argv[1]
    elif sys.argv[2:] and sys.argv[1] == '-S':
        one_ok = True
        search = sys.argv[2]
        del sys.argv[1]
        del sys.argv[1]
    elif sys.argv[2:] and sys.argv[1] == '-l':
        lines = int(sys.argv[2])
        del sys.argv[1]
        del sys.argv[1]
    elif sys.argv[1] == '-q':
        quiet = True
        del sys.argv[1]
    else:
        sys.stderr.write('sys.argv[1] is {}\n'.format(sys.argv[1]))
        usage()

if not search:
    usage()

def get_ps():
    processes = os.popen("ps -eo pid,args",'r').readlines()
    if not processes[0:]:
        processes = os.popen("process-list2",'r').readlines()
    return processes

infile = open('/dev/tty','r')
outfile = open('/dev/tty','w')

processes = get_ps()
hits=[]
regex = re.compile(search)
for line in processes:
    if regex.search(line) is not None and line.find(sys.argv[0]) == -1:
        hits.append(line)
length = len(hits)
if length == 0:
    sys.stderr.write('{}: Sorry, no matches on {} found\n'.format(sys.argv[0], search))
    sys.stderr.flush()
    sys.exit(1)
elif one_ok and length == 1:
    if not quiet:
        sys.stderr.write('{}: Single match found: "{}"\n'.format(sys.argv[0], hits[0].strip()))
        sys.stderr.flush()
    fields = hits[0].strip().split()
    print(fields[0])
else:
    if length > lines:
        sys.stderr.write('{}: Sorry, too many matches: {}\n'.format(sys.argv[0], length))
        sys.stderr.flush()
        sys.exit(1)
    # multiple hits on the search string
    for i in range(length):
        outfile.write("{}) {}".format(i, hits[i]))
    outfile.flush()
    while True:
        outfile.write('\nEnter number corresponding to process: ')
        outfile.flush()
        ind = int(infile.readline().strip())
        if ind < 0 or ind > lines-1:
            outfile.write('Sorry, {} is not between 0 and {}\n'.format(ind, lines))
        else:
            break
    fields = hits[ind].split()
    print(fields[0])