#!/usr/bin/env python3

# faults.py - PVC client function library, faults management
# Part of the Parallel Virtual Cluster (PVC) system
#
#    Copyright (C) 2018-2022 Joshua M. Boniface <joshua@boniface.me>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, version 3.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.
#
###############################################################################

from datetime import datetime
from hashlib import md5


def generate_fault(
    zkhandler, logger, fault_name, fault_time, fault_delta, fault_message
):
    # Generate a fault ID from the fault_message and fault_delta
    fault_str = f"{fault_name} {fault_delta} {fault_message}"
    fault_id = str(md5(fault_str.encode("utf-8")).hexdigest())[:8]

    # If a fault already exists with this ID, just update the time
    if not zkhandler.exists("base.faults"):
        logger.out(
            f"Skipping fault reporting for {fault_id} due to missing Zookeeper schemas",
            state="w",
        )
        return

    existing_faults = zkhandler.children("base.faults")
    if fault_id in existing_faults:
        logger.out(
            f"Updating fault {fault_id}: {fault_message} @ {fault_time}", state="i"
        )
    else:
        logger.out(
            f"Generating fault {fault_id}: {fault_message} @ {fault_time}",
            state="i",
        )

    if zkhandler.read("base.config.maintenance") == "true":
        logger.out(
            f"Skipping fault reporting for {fault_id} due to maintenance mode",
            state="w",
        )
        return

    if fault_id in existing_faults:
        zkhandler.write(
            [
                (("faults.last_time", fault_id), str(fault_time)),
            ]
        )
    # Otherwise, generate a new fault event
    else:
        zkhandler.write(
            [
                (("faults.id", fault_id), ""),
                (("faults.first_time", fault_id), str(fault_time).split(".")[0]),
                (("faults.last_time", fault_id), str(fault_time).split(".")[0]),
                (("faults.ack_time", fault_id), ""),
                (("faults.status", fault_id), "new"),
                (("faults.delta", fault_id), fault_delta),
                (("faults.message", fault_id), fault_message),
            ]
        )


def getFault(zkhandler, fault_id):
    """
    Get the details of a fault based on the fault ID
    """
    if not zkhandler.exists(("faults.id", fault_id)):
        return None

    fault_id = fault_id
    fault_last_time = zkhandler.read(("faults.last_time", fault_id))
    fault_first_time = zkhandler.read(("faults.first_time", fault_id))
    fault_ack_time = zkhandler.read(("faults.ack_time", fault_id))
    fault_status = zkhandler.read(("faults.status", fault_id))
    fault_delta = int(zkhandler.read(("faults.delta", fault_id)))
    fault_message = zkhandler.read(("faults.message", fault_id))

    # Acknowledged faults have a delta of 0
    if fault_ack_time != "":
        fault_delta = 0

    fault = {
        "id": fault_id,
        "last_reported": fault_last_time,
        "first_reported": fault_first_time,
        "acknowledged_at": fault_ack_time,
        "status": fault_status,
        "health_delta": fault_delta,
        "message": fault_message,
    }

    return fault


def getAllFaults(zkhandler, sort_key="last_reported"):
    """
    Get the details of all registered faults
    """

    all_faults = zkhandler.children(("base.faults"))

    faults_detail = list()

    for fault_id in all_faults:
        fault_detail = getFault(zkhandler, fault_id)
        faults_detail.append(fault_detail)

    sorted_faults = sorted(faults_detail, key=lambda x: x[sort_key])
    # Sort newest-first for time-based sorts
    if sort_key in ["first_reported", "last_reported", "acknowledge_at"]:
        sorted_faults.reverse()

    return sorted_faults


def get_list(zkhandler, limit=None, sort_key="last_reported"):
    """
    Get a list of all known faults, sorted by {sort_key}
    """
    if sort_key not in [
        "first_reported",
        "last_reported",
        "acknowledged_at",
        "status",
        "health_delta",
        "message",
    ]:
        return False, f"Invalid sort key {sort_key} provided"

    all_faults = getAllFaults(zkhandler, sort_key=sort_key)

    if limit is not None:
        all_faults = [fault for fault in all_faults if fault["id"] == limit]

    return True, all_faults


def acknowledge(zkhandler, fault_id=None):
    """
    Acknowledge a fault or all faults
    """
    if fault_id is None:
        faults = getAllFaults(zkhandler)
    else:
        fault = getFault(zkhandler, fault_id)

        if fault is None:
            return False, f"No fault with ID {fault_id} found"

        faults = [fault]

    for fault in faults:
        # Don't reacknowledge already-acknowledged faults
        if fault["status"] != "ack":
            zkhandler.write(
                [
                    (
                        ("faults.ack_time", fault["id"]),
                        str(datetime.now()).split(".")[0],
                    ),
                    (("faults.status", fault["id"]), "ack"),
                ]
            )

    return (
        True,
        f"Successfully acknowledged fault(s) {', '.join([fault['id'] for fault in faults])}",
    )


def delete(zkhandler, fault_id=None):
    """
    Delete a fault or all faults
    """
    if fault_id is None:
        faults = getAllFaults(zkhandler)
    else:
        fault = getFault(zkhandler, fault_id)

        if fault is None:
            return False, f"No fault with ID {fault_id} found"

        faults = [fault]

    for fault in faults:
        zkhandler.delete(("faults.id", fault["id"]), recursive=True)

    return (
        True,
        f"Successfully deleted fault(s) {', '.join([fault['id'] for fault in faults])}",
    )