#!/bin/bash

# Check status of a list of servers
#
# Any servers in URLS that yield a bad response are collated and sent via email
# to all RECIPIENTS.
#
# Dependencies
# - curl:  Polling the servers
# - msmtp: Sending email; requires separate configuration
# NOTE: Currently only useful for services running over HTTP

#set -eux

LOG_FILE="/media/workshop/Projects/openmedianetwork/.omn_watchdog.log"

RECIPIENTS=(
    saunders@openworlds.info
    witchescauldron@openworlds.info
)

URLS=(
    unite.openworlds.info
    # NOTE: [Currently down] openworlds.info
    pad.openworlds.info
    visionon.tv
    activism.openworlds.info
    campaign.openworlds.info
    #indymedia.openworlds.info
    #roadstonowhere.openworlds.info
    #indymedia.hs2rebellion.earth
)
# TODO: How to check these sensibly?
SERVICES=(
    chat.openworlds.info
    conference.openworlds.info
    # Not much point checking the mail server
    # as this script relies on it to send reports
    # TODO: Separate local check just for this?
    #mail.openworlds.info
)

main()
{
    declare -A FLAGGED

    rotate_log LOG_FILE
    # Redirect all output to LOG_FILE but preserve a link to stdout should we
    # still want to use it
    exec 3>&1 1>>${LOG_FILE} 2>&1

    echo ">> $(date)"
    echo "== Checking:"

    for uri in "${URLS[@]}"; do \
        full_uri="https://${uri}"
        echo -n "  ${full_uri} ... ";
        stat="$(curl -s -o /dev/null -w "%{http_code}%{stdout}" ${full_uri})"
        echo "${stat}"

        # All other HTTP responses should not technically be errors
        if ((${stat} >= 400 && ${stat} <= 599)); then
            FLAGGED[${full_uri}]=${stat}
        fi
    done

    ret=0

    if ((${#FLAGGED[@]} > 0)); then
        echo "== Error(s) detected. Sending mail to:"
        for rcp in ${RECIPIENTS[@]}; do
            echo "  ${rcp}"
        done

        send_mail FLAGGED
        ret=1

    else
        echo "== OK"
    fi

    exit ${ret}
}

rotate_log()
{
    local -n log=$1
    local max_log=4096 # 4M as we get size in K below

    touch ${log}

    local log_size=$(du -k "${log}" | cut -f 1)

    if ((${log_size} > ${max_log})); then
        # Clobber any previous backup
        mv -f ${log} ${log}.1
        touch ${log}
    fi

}

send_mail()
{
    local -n error_list=$1
    local error_string=""

    for i in "${!error_list[@]}"; do
        # Use bash's awful syntax to escape any / in the server string
        code=${i//\//\\\/}
        server=${error_list[$i]}
        error_string+="  ${code}: ${server}\n"
    done

    cat mail_template \
        | sed "s/{ERR_LIST}/${error_string}/g" \
        | msmtp -a omn_server_watch ${RECIPIENTS[@]} \
        || echo "[ERROR] Failed to send mail!"
}

main