#!/bin/bash

#
# Upload output data from decoder to remote server
#
REMOTE_URL="https://adsbexchange.com/api/receive/"

REMOTE_HOST=$( echo $REMOTE_URL | awk -F'/' '{print $3}' )

# run with lowest priority
renice 20 $$ || true

# Set this to '0' if you don't want this script to ever try to self-cache DNS.
# Default is on, but script will automatically not cache if resolver is localhost, or if curl version is too old.
DNS_CACHE=1
# Cache time, default 10min
DNS_TTL=600
# Set this to 1 if you want to force using the cache always even if there is a local resolver.
DNS_IGNORE_LOCAL=1

# List all paths, IN PREFERRED ORDER, separated by a SPACE
# By default, only use the json from the feed client
JSON_PATHS=("/run/readsb")

######################################################################################################################
# If you know what you're doing, and you want to override the search path, you can do it easily in
# /etc/default/adsbexchange-stats, by setting the JSON_PATHS variable to something else (or even multiple).
# For example, the old stats used this:
#   JSON_PATHS=("/run/adsbexchange-feed" "/run/readsb" "/run/dump1090-fa" "/run/dump1090-mutability" "/run/dump1090" )
# You can enable this old path by setting "USE_OLD_PATH=1", preferrably in /etc/default/adsbexchange-stats
######################################################################################################################


# source local overrides (commonly the JSON_PATH, or DNS cache settings)
if [ -r /etc/default/adsbexchange-stats ]; then
	. /etc/default/adsbexchange-stats

	# If 'USE_OLD_PATH' is set, override the entire list
	if [ "x$USE_OLD_PATH" != "x" ] && [ $USE_OLD_PATH -eq 1 ]; then
		echo "Note: 'USE_OLD_PATH' is set."
		JSON_PATHS=("/run/readsb" "/run/adsbexchange-feed")
	fi
fi

# Small bit of sanity...
if [ "${#JSON_PATHS[@]}" -le 0 ]; then
	echo "FATAL - You broke something.  JSON_PATHS variable has no locations listed.  Please fix."
	exit 5
fi

JSON_DIR=""

TEMP_DIR="/run/adsbexchange-stats/"
TMPFILE="${TEMP_DIR}/tmp.json"
NEWFILE="${TEMP_DIR}/new.json"

# Sanity to make sure we can write to our scratch dir in /run
T=$(touch $TMPFILE 2>&1)
RV=$?
if [ $RV -ne 0 ]; then
    echo "ERROR: Unable to write to $TMPFILE, aborting!  ($T)"
    exit 99
fi


# load bash sleep builtin if available
[[ -f /usr/lib/bash/sleep ]] && enable -f /usr/lib/bash/sleep sleep || true

# Do this a few times, in case we're still booting up (wait a bit between checks)
CHECK_LOOP=0
while [ "x$JSON_DIR" = "x" ]; do
	# Check the paths IN ORDER, preferring the first one we find
	for i in ${!JSON_PATHS[@]}; do
		CHECK=${JSON_PATHS[$i]}

		if [ -d $CHECK ]; then
			JSON_DIR=$CHECK
			break
		fi
	done

	# Couldn't find any of them...
	if [ "x$JSON_DIR" = "x" ]; then
		CHECK_LOOP=$(( CHECK_LOOP + 1 ))

		if [ $CHECK_LOOP -gt 4 ]; then
			# Bad news.  Complain and exit.
			echo "ERROR: Tried multiple times, could not find any of the directories - ABORTING!"
			exit 10
		fi
		echo "No valid data source directory found, do you have the adsbexchange feed scripts installed?  Tried each of: [${JSON_PATHS[@]}]"
		sleep 20
	fi
done

UUID=$ADSBX_UUID

if ! [[ $UUID =~ ^\{?[A-F0-9a-f]{8}-[A-F0-9a-f]{4}-[A-F0-9a-f]{4}-[A-F0-9a-f]{4}-[A-F0-9a-f]{12}\}?$ ]]; then
    # Data in UUID file is invalid
    echo "FATAL: Data in UUID file was invalid, exiting!"
    exit 1
fi

#####################
#  DNS cache setup  #
#####################

declare -A DNS_LOOKUP
declare -A DNS_EXPIRE

# Let's FIRST make sure our version of curl will support what we need (--resolve arg)
CURL_VER=$( curl -V | head -1 | awk '{print $2}' )
if [ "x$CURL_VER" = "x" ]; then
	echo "FATAL - curl is malfunctioning, can't get version info."
	exit 11
fi

# This routine assumes you do no santiy-checking.
#
# Checks for the host in $DNS_LOOKUP{}, and if the corresponding $DNS_EXPIRE{} is less than NOW, return success.
# Otherwise, try looking it up.  Save value if lookup succeeded.
#
# Returns:
#       On Success: returns 0, and host will be in DNS_LOOKUP assoc array.
#       On Fail: Various return codes:
#               - 10 = No Hostname Provided
#               - 20 = Hostname Format Invalid
#               - 30 = Lookup Failed even after $DNS_MAX_LOOPS tries
DNS_WAIT=5
DNS_MAX_LOOPS=2

dns_lookup () {
	local HOST=$1

	local NOW=$( date +%s )

	# You need to pass in a hostname :)
	if [ "x$HOST" = "x" ]; then
		echo "ERROR: dns_lookup called without a hostname" >&2
		return 10
	fi

	# (is it even a syntactically-valid hostname?)
	if ! [[ $HOST =~ ^[a-zA-Z0-9\.-]+$ ]]; then
		echo "ERROR: Invalid hostname passed into dns_lookup [$HOST]" >&2
		return 20
	fi

	# If the host is cached, and the TTL hasn't expired, return the cached data.
	if [ ${DNS_LOOKUP[$HOST]} ]; then
		if [ ${DNS_EXPIRE[$HOST]} -ge $NOW ]; then
			return 0
		fi
	fi

	# Try this several times
	local LOOP=$DNS_MAX_LOOPS

	while [ $LOOP -ge 1 ]; do
		# Ok, let's look this hostname up!  Use the first IP returned.
		#  - XXX : WARNING: This assumed the output format of 'host -v' doesn't change drastically! XXX -
		#  - Because this uses the "Trying" line, it should work for non-FQDN lookups, too -

		sleep $DNS_WAIT &
		HOST_IP=$( host -v -W $DNS_WAIT -t a "$HOST" | perl -ne 'if (/^Trying "(.*)"/){$h=$1; next;} if (/^$h\.\s+(\d+)\s+IN\s+A\s+(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/) {$i=$2; last}; END {printf("%s", $i);}' )
		RV=$?
		# If this is empty, something failed.  Sleep some and try again...
		if [ $RV -ne 0 ] || [ "x$HOST_IP" == "x" ]; then
			if ping -c1 "$HOST" &>/dev/null && ! host -v -W $DNS_WAIT -t a "$HOST" &>/dev/null; then
				echo "host not working but ping is, disabling DNS caching!"
				DNS_CACHE=0
				return 1
			fi
			echo "Failure resolving [$HOST], waiting and trying again..." >&2
			LOOP=$(( LOOP - 1 ))
			wait
			continue
		fi
		# If we get here, we successfully resolved it
		break;
	done

	# If LOOP is zero, Something Bad happened.
	if [ $LOOP -le 0 ]; then
		echo "FATAL: unable to resolve $HOST even after $DNS_MAX_LOOPS tries.  Giving up." >&2
		return 30
	fi

	# Resolved ok!
	NOW=$( date +%s )
	DNS_LOOKUP["$HOST"]=$HOST_IP
	DNS_EXPIRE["$HOST"]=$(( NOW + DNS_TTL ))
	return 0
}

# First, see if we have a localhost resolver...
# - Only look at the first 'nameserver' entry in resolv.conf
# - This will assume any 127.x.x.x resolver entry is "local"
LOCAL_RESOLVER=$( grep nameserver /etc/resolv.conf | head -1 | egrep -c '[[:space:]]127\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' )
if [ $LOCAL_RESOLVER -ne 0 ]; then
	if [ $DNS_IGNORE_LOCAL -eq 1 ]; then
		echo "Found local resolver in resolv.conf, but DNS_IGNORE_LOCAL is on, so ignoring" >&2
	else
		echo "Found local resolver in resolv.conf, disabling DNS Cache" >&2
		DNS_CACHE=0
	fi
fi

if ! command -v host &>/dev/null; then
    echo "host command not available, disabling DNS Cache" >&2
    DNS_CACHE=0
fi


# If we have a local resolver, just use the URL.  If not, look up the host and use that IP (replace the URL appropriately)
# -- DNS Setup done


echo "Using UUID [${UUID}] for stats uploads"
echo "Using JSON directory [${JSON_DIR}] for source data"


if [ $DNS_CACHE -ne 0 ]; then
	echo "Using script's DNS cache ($DNS_TTL seconds)"
else
	echo "NOT using script's DNS cache"
fi

JSON_FILE="${JSON_DIR}/aircraft.json"

STAT_COUNT=0
# Grab the current timestamp of the file.   Try in a loop a few times, in case
while [ $STAT_COUNT -lt 5 ]; do
	JSON_STAT=$(stat --printf="%Y" $JSON_FILE 2> /dev/null)
	RV=$?

	if [ $RV -eq 0 ]; then
		break
	fi
	STAT_COUNT=$(( STAT_COUNT + 1 ))
	sleep 15
done

# Bad juju if we still don't have a stat...
if [ "x$JSON_STAT" = "x" ]; then
	echo "ERROR: Can't seem to stat $JSON_FILE at startup, bailing out..."
	exit 15
fi

# Complain if this file seems really old
NOW=$(date +%s)
DIFF=$(( NOW - JSON_STAT ))
if [ $DIFF -gt 60 ]; then
	echo "WARNING: $JSON_FILE seems old, are you sure we're using the right path?"
fi

# How long to wait before uploads, minimum (in seconds)
WAIT_TIME=5

# random sleep on startup ... reduce load spikes
sleep "$(( RANDOM % WAIT_TIME )).$(( RANDOM % 100))"

# How long curl will wait to send data (10 sec default)
MAX_CURL_TIME=10

# How much time (sec) has to pass since last JSON update before we say something
# Initial value is "AGE_COMPLAIN", and then it complains every "AGE_INTERVAL" after that
# Deftauls are:
#  AGE_COMPLAIN = 30 sec
#  AGE_INTERVAL = 30 min (1800 sec)
AGE_COMPLAIN=30
AGE_INTERVAL=$(( 30 * 60 ))
OLD_AGE=$AGE_COMPLAIN
while true; do
    wait
    # make this loop from now to the next start last exactly $WAIT_TIME secons
    # sleep in the background then wait for it at the end of the loop
    sleep $WAIT_TIME &

    NOW=$(date +%s)

    # Grab new stat.  If it fails, wait longer (otherwise assign to the main var)
    NEW_STAT=$(stat --printf="%Y" $JSON_FILE 2> /dev/null)
    RV=$?
    if [ $RV -ne 0 ]; then
        sleep 10
    else
        JSON_STAT=$NEW_STAT
    fi
    DIFF=$(( NOW - JSON_STAT ))
    if [ $DIFF -gt $OLD_AGE ]; then
        echo "WARNING: JSON file $JSON_FILE has not been updated in $DIFF seconds. Did your decoder die?"
        OLD_AGE=$(( OLD_AGE + AGE_INTERVAL ))
    else
        # Reset this here, in case it comes back ;)
        OLD_AGE=$AGE_COMPLAIN
    fi

	# Move the JSON somewhere before operating on it...

	rm -f $TMPFILE $NEWFILE
	CP=$(cp $JSON_FILE $TMPFILE 2>&1)
	RV=$?
	if [ $RV -ne 0 ]; then
		# cp failed (file changed during copy, usually), wait a few and loop again
		sleep 2
		continue
	fi

    if STATUS=$(vcgencmd get_throttled 2>/dev/null | tr -d '"'); then
        STATUS="${STATUS#*=}"
    else
        STATUS=""
    fi

    if ! jq -c \
        --arg STATUS "$STATUS" \
        --arg UUID "$UUID" \
        ' .
            | ."uuid"=$UUID
            | ."v"=$STATUS
            | ."rssi"=(if (.aircraft | length <= 0) then 0 else ([.aircraft[].rssi] | select(. >=0) | add / length | floor) end)
            | ."rssi-min"=(if (.aircraft | length <= 0) then 0 else ([.aircraft[].rssi] | select(. >=0) | min | floor) end)
            | ."rssi-max"=(if (.aircraft | length <= 0) then 0 else ([.aircraft[].rssi] | select(. >=0) | max | floor) end)
        ' < $TMPFILE > $NEWFILE
    then
        # this shouldn't happen, don't spam the syslog with the error quite as much
        sleep 15
        # we don't have a json output, let's try again from the start
        continue
    fi


	CURL_EXTRA=""
	# If DNS_CACHE is set, use the builtin cache (and correspondingly the additional curl arg
	if [ $DNS_CACHE -ne 0 ]; then
		dns_lookup $REMOTE_HOST
		RV=$?
		if [ $RV -ne 0 ]; then
			# Some sort of error...  We'll fall back to normal curl usage, but sleep a little.
			echo "DNS Error for ${REMOTE_HOST}, fallback ..."
		else
			REMOTE_IP=${DNS_LOOKUP[$REMOTE_HOST]}
			CURL_EXTRA="--resolve ${REMOTE_HOST}:443:$REMOTE_IP"
		fi
	fi

    sleep 0.314
    gzip -c <$NEWFILE >$TEMP_DIR/upload.gz
    sleep 0.314

	# Push up the data.  'curl' will wait no more than $MAX_CURL_TIME seconds for upload to complete
	curl -m $MAX_CURL_TIME $CURL_EXTRA -sS -X POST -H "adsbx-uuid: ${UUID}" -H "Content_Encoding: gzip" --data-binary @- $REMOTE_URL 2>&1 <$TEMP_DIR/upload.gz
	RV=$?

	if [ $RV -ne 0 ]; then
		echo "WARNING: curl process returned non-zero ($RV): [$CURL]; Sleeping a little extra."
		sleep $(( 5 + RANDOM % 15 ))
	fi
done