#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Copyright (c) 2014-2015, NORDUnet A/S.
# See LICENSE for licensing information.
#
# Distribute the 'sth' file and all missing entries to all frontend nodes.
# See catlfish/doc/merge.txt for more about the merge process.
#
import sys
import json
import requests
import logging
import signal
from time import sleep
from base64 import b64encode, b64decode
from os import stat
from multiprocessing import Process, Pipe
from certtools import timing_point, create_ssl_context
from mergetools import get_curpos, get_logorder, chunks, get_missingentries, \
     publish_sth, sendlog, sendentries, parse_args, perm, \
     get_frontend_verifiedsize, frontend_verify_entries, \
     waitforfile, flock_ex_or_fail, Status, loginit, start_worker, \
     terminate_child_procs

def sendlog_helper(entries, curpos, nodename, nodeaddress, own_key, paths,
                   statusupdates):
    logging.info("sending log")
    for chunk in chunks(entries, 1000):
        for trynumber in range(5, 0, -1):
            sendlogresult = sendlog(nodename, nodeaddress,
                                    own_key, paths,
                                    {"start": curpos, "hashes": chunk})
            if sendlogresult == None:
                if trynumber == 1:
                    sys.exit(1)
                sleep(10)
                logging.warning("tries left: %d", trynumber)
                continue
            break
        if sendlogresult["result"] != "ok":
            logging.error("sendlog: %s", sendlogresult)
            sys.exit(1)
        curpos += len(chunk)
        statusupdates.status("PROG sending log: %d" % curpos)
    logging.info("log sent")

def fill_in_missing_entries(nodename, nodeaddress, own_key, paths, chainsdb,
                            timing, statusupdates):
    missingentries = get_missingentries(nodename, nodeaddress, own_key,
                                        paths)
    timing_point(timing, "get missing")

    while missingentries:
        logging.info("about to send %d missing entries", len(missingentries))
        sent_entries = 0
        with requests.sessions.Session() as session:
            for missingentry_chunk in chunks(missingentries, 100):
                missingentry_hashes = [b64decode(missingentry) for missingentry in missingentry_chunk]
                hashes_and_entries = [(ehash, chainsdb.get(ehash)) for ehash in missingentry_hashes]
                sendentryresult = sendentries(nodename, nodeaddress,
                                             own_key, paths,
                                             hashes_and_entries, session)
                if sendentryresult["result"] != "ok":
                    logging.error("sendentries: %s", sendentryresult)
                    sys.exit(1)
                sent_entries += len(missingentry_hashes)
                statusupdates.status(
                    "PROG sending missing entries: %d" % sent_entries)
        timing_point(timing, "send missing")

        missingentries = get_missingentries(nodename, nodeaddress,
                                                     own_key, paths)
        timing_point(timing, "get missing")

def do_send(args, localconfig, frontendnode, logorder, sth, chainsdb, s):
    timing = timing_point()
    paths = localconfig["paths"]
    own_key = (localconfig["nodename"],
               "%s/%s-private.pem" % (paths["privatekeys"],
                                      localconfig["nodename"]))
    maxwindow = localconfig.get("maxwindow", 1000)
    nodename = frontendnode["name"]
    nodeaddress = "https://%s/" % frontendnode["address"]

    logging.info("distributing for node %s", nodename)
    curpos = get_curpos(nodename, nodeaddress, own_key, paths)
    timing_point(timing, "get curpos")
    logging.info("current position %d", curpos)

    verifiedsize = \
      get_frontend_verifiedsize(nodename, nodeaddress, own_key, paths)
    timing_point(timing, "get verified size")
    logging.info("verified size %d", verifiedsize)

    assert verifiedsize >= curpos

    while verifiedsize < len(logorder):
        uptopos = min(verifiedsize + maxwindow, len(logorder))

        entries = [b64encode(entry) for entry in logorder[verifiedsize:uptopos]]
        sendlog_helper(entries, verifiedsize, nodename, nodeaddress, own_key, paths, s)
        timing_point(timing, "sendlog")

        fill_in_missing_entries(nodename, nodeaddress, own_key, paths, chainsdb, timing, s)

        verifiedsize = frontend_verify_entries(nodename, nodeaddress, own_key, paths, uptopos)

    logging.info("sending sth to node %s", nodename)
    publishsthresult = publish_sth(nodename, nodeaddress, own_key, paths, sth)
    if publishsthresult["result"] != "ok":
        logging.info("publishsth: %s", publishsthresult)
        sys.exit(1)
    timing_point(timing, "send sth")

    if args.timing:
        logging.debug("timing: merge_dist: %s", timing["deltatimes"])

def merge_dist_sequenced(args, localconfig, frontendnodes, chainsdb, s):
    paths = localconfig["paths"]
    mergedb = paths["mergedb"]
    logorderfile = mergedb + "/logorder"
    sthfile = mergedb + "/sth"
    timestamp = 0
    timing = timing_point()

    try:
        sth = json.loads(open(sthfile, 'r').read())
    except (IOError, ValueError):
        logging.warning("No valid STH file found in %s", sthfile)
        return timestamp
    if sth['timestamp'] < timestamp:
        logging.warning("New STH file older than the previous one: %d < %d",
                        sth['timestamp'], timestamp)
        return timestamp
    if sth['timestamp'] == timestamp:
        return timestamp
    timestamp = sth['timestamp']

    logorder = get_logorder(logorderfile, sth['tree_size'])
    timing_point(timing, "get logorder")

    for frontendnode in frontendnodes:
        do_send(args, localconfig, frontendnode, logorder, sth, chainsdb, s)

    return timestamp

def dist_worker(_, argv):
    args, localconfig, frontendnode, chainsdb, s = argv
    paths = localconfig["paths"]
    mergedb = paths["mergedb"]
    sthfile = mergedb + "/sth"
    logorderfile = mergedb + "/logorder"
    nodename = frontendnode["name"]

    wait = max(3, args.mergeinterval / 10)
    timestamp = 0
    while True:
        try:
            sth = json.loads(open(sthfile, 'r').read())
        except (IOError, ValueError):
            logging.error("%s: No valid STH file found in %s", nodename, sthfile)
            sleep(wait)
            continue

        if sth['timestamp'] < timestamp:
            logging.error(
                "%s: New STH file older than the previous one: %d < %d",
                nodename, sth['timestamp'], timestamp)
            sleep(wait)
            continue

        if sth['timestamp'] == timestamp:
            logging.info(
                "%s: sth still at %d (%d), sleeping %s seconds",
                nodename, sth['tree_size'], timestamp, wait)
            sleep(wait)
            continue

        timestamp = sth['timestamp']
        logorder = get_logorder(logorderfile, sth['tree_size'])
        do_send(args, localconfig, frontendnode, logorder, sth, chainsdb, s)

def merge_dist_parallel(args, localconfig, frontendnodes, chainsdb, s):
    procs = {}
    for frontendnode in frontendnodes:
        nodename = frontendnode["name"]
        procname = 'dist_%s' % nodename
        p, pipe = start_worker(procname, dist_worker,
                               (args, localconfig, frontendnode,
                                chainsdb, s))
        procs[p] = (frontendnode, pipe)

    while True:
        for p in list(procs):
            if not p.is_alive():
                p.join()
                frontendnode, _ = procs[p]
                nodename = frontendnode["name"]
                logging.warning("%s exited with %d, restarting", nodename,
                                p.exitcode)
                procname = 'dist_%s' % nodename
                newproc, pipe = \
                  start_worker(procname, dist_worker,
                               (args, localconfig, frontendnode,
                                chainsdb, s))
                procs[p] = (frontendnode, pipe)
        sleep(1)
        
    return -1

def term(signal, arg):
    terminate_child_procs()
    sys.exit(1)

def main():
    """
    Distribute missing entries and the STH to all frontend nodes, in
    parallel if `--mergeinterval'.

    If `--mergeinterval', re-read 'sth' when it changes and keep
    distributing.
    """
    args, config, localconfig = parse_args()
    paths = localconfig["paths"]
    mergedb = paths["mergedb"]
    chainsdb = perm(localconfig.get("dbbackend", "filedb"), mergedb + "/chains",
                    write_enabled=False)
    lockfile = mergedb + "/.merge_dist.lock"

    loginit(args, "merge_dist.log")

    if not flock_ex_or_fail(lockfile):
        logging.critical("unable to take lock %s", lockfile)
        return 1

    statusfile = mergedb + "/merge_dist.status"
    s = Status(statusfile)

    signal.signal(signal.SIGTERM, term)
    create_ssl_context(cafile=paths["https_cacertfile"])

    if len(args.node) == 0:
        nodes = config["frontendnodes"]
    else:
        nodes = [n for n in config["frontendnodes"] if n["name"] in args.node]

    if args.mergeinterval:
        return merge_dist_parallel(args, localconfig, nodes, chainsdb, s)
    else:
        merge_dist_sequenced(args, localconfig, nodes, chainsdb, s)

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