cswitch.py

#!/usr/bin/env python
import os, subprocess

#TODO: make this script generic so it can take options for what env var to get choices from, what env var to write them to, and where the target symlink should be

home = os.path.expanduser("~")
symlink_path = os.path.join(home, 'cassandra_for_ccm')

current_cass_dir = os.environ.get('CASSANDRA_DIR', None)
if not current_cass_dir == symlink_path:
    print "please set CASSANDRA_DIR to {}".format(symlink_path)
    exit(1)

possible_dirs = os.environ.get('CASSANDRA_DIRS', None)

if possible_dirs is None:
    print "CASSANDRA_DIRS is not defined."
    print "  this should be a colon-delimited list"
    exit(1)

if os.path.exists(symlink_path) and os.path.islink(symlink_path):
    print "CASSANDRA_DIR is currently linked to {}\n".format(os.readlink(symlink_path))

dir_array = possible_dirs.split(":")

for idx, dirname in enumerate(dir_array, 1):
    git_label = subprocess.check_output(["git", "status"], cwd=dirname).split("\n")[0]
    print "{idx}. {dirname} ({git_label})".format(idx=idx, dirname=dirname, git_label=git_label)

choice = raw_input("\nplease choose a number (enter to quit): ")

try:
    int_choice = int(choice)
except ValueError:
    if len(choice) == 0:
        print "quitting"
        exit(0)

    print "invalid choice"
    exit(1)

if (int_choice <= 0) or int_choice > len(dir_array):
    print "invalid number"
    exit(1)

if os.path.exists(symlink_path) and os.path.islink(symlink_path):
    os.unlink(symlink_path)
    os.symlink(dir_array[int_choice-1], symlink_path)
    print "CASSANDRA_DIR is now linked to {}\n".format(os.readlink(symlink_path))

if not os.path.exists(symlink_path):
    os.symlink(dir_array[int_choice-1], symlink_path)
    print "CASSANDRA_DIR is now linked to {}\n".format(os.readlink(symlink_path))