#!/bin/sh

PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin
CONFIG=$1

# BEGIN CONFIG CHECK
### Provides KEY, CHATID, CHKLIST
if [ -n "$CONFIG" ]; then
    if [ -f "$CONFIG" ]; then
        . $CONFIG #Source config file
    else
        printf '%s\n' "$CONFIG: File does not exist." >&2
        exit 10
    fi
else
    if [ -f ".httpcheck_telegram" ]; then
        . .httpcheck_telegram #Source config file
    else
        printf '%s\n' "No configuration file found." >&2
        exit 10
    fi
fi
# Check if config was loaded by examining all configuration variables, exit if not
if [ -z "$KEY" ]; then
    printf '%s\n' "Configuration not set correctly: KEY not set" >&2
    ERROR11=true
fi
if [ -z "$CHATID" ]; then
    printf '%s\n' "Configuration not set correctly: CHATID not set" >&2
    ERROR11=true
fi
if [ -z "$CHKLIST" ]; then
    printf '%s\n' "Configuration not set correctly: CHKLIST not set" >&2
    ERROR11=true
fi
[ "$ERROR11" = "true" ] && exit 11
# END CONFIG CHECK


TIME="10"
URL="https://api.telegram.org/bot$KEY/sendMessage"

#Telegram message function
send_message() {
    curl -s --max-time $TIME -d "chat_id=${CHATID}&disable_web_page_preview=1&text=$1" $URL >/dev/null
}

get_http_code() {
    if host $(awk '{gsub("https?://|/.*","")}1' <<< $1) &>/dev/null; then
        curl -sILk --max-time $TIME $1 | grep HTTP | tail -n 1 | grep -Eo '[0-9]{3}' || printf '%s\n' 999
    else
        printf '%s\n' 000
    fi
}

# Prepare message header
MSG='HTTP/S Problems Found:'
FAILURE=false

# Check HTTP codes
for site in $(< $CHKLIST); do
    respcode=$(get_http_code $site)
    case $respcode in
        000)
            printf '%s\n' "[$(date '+%Y%m%d %H:%M:%S')]: PROBLEM -- $site: DNS record not found" >&2
            MSG="${MSG}%0A%0A %2B ${site}%0A    DNS record not found"
            FAILURE=true
            ;;
        200)
            printf '%s\n' "[$(date '+%Y%m%d %H:%M:%S')]: OK -- $site returns $respcode"
            ;;
        999)
            printf '%s\n' "[$(date '+%Y%m%d %H:%M:%S')]: PROBLEM -- $site caused general cURL failure" >&2
            ;;
        *)
            printf '%s\n' "[$(date '+%Y%m%d %H:%M:%S')]: PROBLEM -- $site returns $respcode" >&2
            MSG="${MSG}%0A%0A %2B ${site}%0A    responding ${respcode}"
            FAILURE=true
            ;;
    esac
done || exit 2

# Send compiled message if any problems were found
send_message "$MSG" && printf '%s\n' "Problems found. Message sent via Telegram bot" >&2 || printf '%s\n' "Problems found. Message sending has failed"

exit 0