#!/usr/bin/python

"""Two errands the supervisor in run.sh cannot do in shell: ask, and stop.

`peers` reports how many network connections the daemon has, as an exit code the
shell can branch on. `shutdown` asks the daemon to stop through its own API,
which runs doCleanShutdown -- the database is closed rather than cut off.

The streak, the cooldown and the restart itself are deliberately not here. This
process is short-lived, so a counter would need a file to live in, and then two
places would decide one thing. run.sh counts; this only reports.

Exit codes are the interface:

    0  the daemon answered and has peers
    1  the daemon answered and has none      (`peers`)
       or the shutdown was asked for         (`shutdown`)
    2  the daemon did not answer at all

2 is not 1 on purpose. A daemon whose API is refusing connections is the trapped
node of the startup-VACUUM failure, and restarting it neither cures that nor is
harmless: it drops the next VACUUM half-done as well. The supervisor must be
able to tell "no peers" from "no answer", and only act on the first.
"""

import json
import os
import sys
import urllib
import xmlrpclib

# Credentials go into a URL, so they must be percent-encoded: '@' splits the
# userinfo, '#' truncates the rest, '/' and ':' change what is parsed as host
# and port. healthy_check.py carries the same six lines for the same reason --
# these are one-shot scripts with no package around them to share a module.
API_USER = os.getenv('BITMESSAGE_API_USER', 'bitmessage_api_user')
API_PASSWORD = os.getenv('BITMESSAGE_API_PASSWORD', 'bitmessage_api_password')
API_PORT = os.getenv('BITMESSAGE_API_PORT', '8442')

API_LINK = "http://{}:{}@127.0.0.1:{}/".format(
    urllib.quote(API_USER, safe=''), urllib.quote(API_PASSWORD, safe=''), API_PORT)

NO_ANSWER = 2


def peers(api):
    """How many peers the daemon holds, printed for the container log."""
    count = json.loads(api.clientStatus())['networkConnections']
    print "networkConnections:", count
    return 0 if count > 0 else 1


def shutdown(api):
    """Ask the daemon to stop itself cleanly (api.py: HandleShutdown)."""
    api.shutdown()
    print "shutdown requested"
    return 1


COMMANDS = {'peers': peers, 'shutdown': shutdown}


def main(argv):
    if len(argv) != 2 or argv[1] not in COMMANDS:
        print >> sys.stderr, "usage: watchdog.py peers|shutdown"
        return NO_ANSWER
    try:
        return COMMANDS[argv[1]](xmlrpclib.ServerProxy(API_LINK))
    except Exception as exc:  # the API is down, or answering something else
        print "no answer from the daemon:", exc
        return NO_ANSWER


if __name__ == '__main__':
    sys.exit(main(sys.argv))