#!/usr/bin/env python
# {{ ansible_managed }}
# Author: Maurice Makaay, XS4ALL

from __future__ import print_function
import subprocess
import re
import json
from os import system 
from sys import exit, stdin


nodes = {{ groups['galera'] | to_json }}
lxd_status = {{ lxd_status | to_json }}


def propose(commands, exit_code):
    for command in commands:
        print("# %s" % command)
    print("")
    print("Execute now? [y/n]: ", end="")
    answer = stdin.readline()
    if "y" in answer.lower():
        print("")
        for command in commands:
            print("EXECUTING> %s" % command)
            system(command)
        print("")
        exit(0)
    exit(exit_code)


print("Collecting Galera status information from nodes ...")
status = {}
for node in nodes:
    lxd_host = "%s:%s" % (lxd_status[node]["host"], node)
    try:
        result = subprocess.check_output([
            "lxc", "exec", lxd_host, "/root/galera_cluster_status"])
        status[node] = json.loads(result)
    except subprocess.CalledProcessError:
        status[node] = {
			"cluster_size": 0,
			"cluster_status": 'Status Failed',
			"connected": "Unknown",
			"ready": "Unknown",
			"safe_to_bootstrap": 0,
			"seqno": -1,
			"uuid": None
        }
    status[node]['lxd_host'] = lxd_host
    status[node]['node'] = node

def is_primary(s):
    return s["cluster_status"] == "Primary"

def has_correct_cluster_size(s):
    return s["cluster_size"] == len(nodes)

def is_connected(s):
    return s["connected"] == "ON"

def is_ready(s):
    return s["ready"] == "ON"


print("")
print("%-20s %-15s %-6s %-12s %-7s" % (
    "Node", "Status", "Size", "Connected", "Ready"))
for node in nodes:
    s = status[node]
    print("%-20s %-15s %-6s %-12s %-7s" % (
        node, s["cluster_status"], s["cluster_size"],
        s["connected"], s["ready"]))

print("")
print("Checking cluster status ...")
print("")

# ----------------------------------------------------------------------------
# CASE: All cluster nodes are up and running, green lights galore!
# ----------------------------------------------------------------------------

all_primary = all(map(is_primary, status.values()))
all_size_ok = all(map(has_correct_cluster_size, status.values()))
all_connected = all(map(is_connected, status.values()))
all_ready = all(map(is_ready, status.values()))

if all([all_primary, all_size_ok, all_connected, all_ready]):
    print("There's no bootstrapping work to do here, all looks good!")
    print("")
    exit(0)

# ----------------------------------------------------------------------------
# CASE: The cluster is parially down, but some cluster hosts are still ok.
# ----------------------------------------------------------------------------

if any(map(is_primary, status.values())) and any(map(is_ready, status.values())):
    print("The cluster seems to be in a degraded status.")
    print("Please investigate the cluster status.")
    print("- Can the cluster hosts reach each other over the network?")
    print("- Are all mariadb instances running?")
    print("")
    print("It might help to (re)start the database server on the degraded node(s):") 
    print("")
    commands = [
        "lxc exec %s service mysql restart" % s["lxd_host"]
        for s in status.values()
        if not is_primary(s)
    ]
    propose(commands, 1)

# ----------------------------------------------------------------------------
# CASE: All cluster nodes are down, one cluster node is safe to bootstrap.
# ----------------------------------------------------------------------------

print("None of the cluster hosts is operational. A cluster bootup is required.") 

safe_to_bootstrap = [s for s in status.values() if s["safe_to_bootstrap"] == 1]
if any(safe_to_bootstrap):
    bootstrap_node = safe_to_bootstrap[0]
    print("A node is marked as 'safe to bootstrap', so proposed strategy:")
    print("")
    commands = ["lxc exec %s galera_new_cluster" % bootstrap_node["lxd_host"]]
    for n, s in status.items():
        if n == bootstrap_node["node"]:
            continue
        commands.append("lxc exec %s service mysql start" % s["lxd_host"])
    propose(commands, 2)

# ----------------------------------------------------------------------------
# CASE: All cluster nodes are down, no cluster node is safe to bootstrap.
# ----------------------------------------------------------------------------

print("Unfortunately, none of the nodes is marked as safe to bootstrap.")
print("Retrieving last recovered position for all cluster nodes ...")
print("")
print("%-20s %-15s %-40s" % ("Node", "Recovery pos", "UUID"))

for n, s in status.items():
    lxd_host = "%s:%s" % (lxd_status[n]["host"], n)
    try:
        result = subprocess.check_output([
            "lxc", "exec", lxd_host, "/root/galera_wsrep_recovered_position"])
        uuid_and_pos = json.loads(result)
        uuid, pos = re.split(':', uuid_and_pos, maxsplit=1)
        s["uuid"] = uuid
        s["pos"] = int(pos)
    except subprocess.CalledProcessError:
        s["uuid"] = "Unknown"
        s["pos"] = -1
    print("%-20s %-15d %-40s" % (n, s["pos"], s["uuid"]))

uuids = set((s["uuid"] for s in status.values()))
if len(uuids) != 1:
    print("")
    print("Wow... now wait a minute... There are multiple UUID's in play!")
    print("That should never happen in a Galera cluster.")
    print("You will have to handle this one yourself I'm afraid.")

def get_pos_key(x):
    return x["pos"]

old_to_new = sorted(status.itervalues(), key=get_pos_key)
bootstrap_node = old_to_new[-1]

print("")
print("Determined a node that is safe for bootstrapping, so proposed strategy:")
print("")
commands = [
    "lxc exec %s /root/galera_flag_as_safe_to_bootstrap" % bootstrap_node["lxd_host"],
    "lxc exec %s galera_new_cluster" % bootstrap_node["lxd_host"]
]
for n, s in status.items():
    if n == bootstrap_node["node"]:
        continue
    commands.append("lxc exec %s service mysql start" % s["lxd_host"])
propose(commands, 3)