import fcntl
import time
import sys
import os, os.path

update_config_file = '/etc/panopta-agent/panopta_agent.cfg'
if not os.path.exists(update_config_file):
    home = os.path.expanduser("~")
    update_config_file = os.path.join(home, "lib", "panopta-agent", "update_config")

unlock_attempts = 10

def update_config(manifest_file):
    if not os.path.exists(manifest_file):
        print "Manifest file %s does not exist" % manifest_file
        sys.exit(0)

    try:
        mf = open(manifest_file).read().strip().split('\n')
        props = dict([map(str.strip, line.split("=")) for line in mf])
    except:
        print "Error reading manifest file %s" % manifest_file
        sys.exit(0)

    manfile = open(update_config_file, 'wt')

    # Acquire lock
    locked = True
    for i in range(unlock_attempts):
        try:
            fcntl.flock(manfile, fcntl.LOCK_EX | fcntl.LOCK_NB)
            locked = False
            break
        except:
            time.sleep(1.0)
    if locked:
        print "Could not unlock %s after %s attempts" % (update_config_file, unlock_attempts)
        sys.exit(1)

    # Write new properties
    manfile.write(open(manifest_file).read())

    # Release lock
    fcntl.flock(manfile, fcntl.LOCK_UN)
    manfile.close()

    # Change perms to make sure the agent user can read the config file
    os.system("chmod 666 %s" % update_config_file)

if __name__ == "__main__":
    if len(sys.argv) < 2:
        print "Please specify the manifest file"
        sys.exit(0)
    else:
        update_config(sys.argv[1])