#!/bin/bash

#V0.1

#Sample call
#cat ~/.ssh/known_hosts | known_hosts_merge | known2config >~/.ssh/config.addme



SpitHostRecord () {
	WantProxyHost='true'

	LongestHostname=''
	LongestObject=''
	for OneHost in $1 ; do
		if [ ${#OneHost} -gt ${#LongestObject} ]; then
			LongestObject="$OneHost"
		fi
		if ! echo "$OneHost" | egrep -q '(^[0-9][0-9\.]*$|^[0-9a-fA-F:][0-9a-fA-F:]*$)' ; then
			if [ ${#OneHost} -gt ${#LongestHostname} ]; then
				LongestHostname="$OneHost"
			fi
		fi
		if [ "$OneHost" = "$ProxyHost" ]; then
			WantProxyHost='false'			#We don't want a ProxyCommand line for the gateway host itself
		fi
	done

	if [ -z "$LongestHostname" ]; then
		LongestHostname="$LongestObject"
	fi

	#echo "SHR/$1/$2/------$LongestHostname" >&2

	cat <<EOBLOCK

Host $1
	#Hostname			$LongestHostname
	Port				$2
	HostKeyAlias			$LongestHostname
EOBLOCK
	if [ -n "$ProxyHost" -a "$WantProxyHost" = 'true' ]; then
		echo "	ProxyCommand			nohup ssh $ProxyHost nc %h %p"
	fi
}


while [ -n "$1" ]; do
	case "$1" in
	-p)
		if [ -n "$2" ]; then
			ProxyHost="$2"
			shift
		else
			echo "Missing hostname to -p param, exiting." >&2
			exit
		fi
		;;
	*)
		echo "Unrecognized param $1, exiting." >&2
		exit
		;;
	esac
	shift
done


echo
echo '======== Beginning of hosts generated from known_hosts'

HostListForOnePort=''
PreviousPort=''

while read HostField KeyInfo ; do
	#echo "Debug: $HostField ... $KeyInfo" >&2


	for ComplexHost in `echo "$HostField" | tr ',' ' '` ; do
		if echo "$ComplexHost" | grep -q '^\[.*\]:[0-9][0-9]*$' ; then
			Port=`echo "$ComplexHost" | sed -e 's/.*://'`
			Host=`echo "$ComplexHost" | sed -e 's/^\[//' -e 's/\].*//'`
			#echo "Debug: Host is $Host, Port is $Port"
		elif echo "$ComplexHost" | grep -q ':' ; then
			echo "Unhandled host with colon, exiting." >&2
			exit 1
		elif echo "$ComplexHost" | grep -q '^[a-zA-Z0-9][a-zA-Z0-9\._-]*$' ; then
			Host="$ComplexHost"
			Port='22'
		else
			echo "Unhandled host $ComplexHost, exiting." >&2
			exit 1
		fi

		#If we've changed ports, push out the config record for the old port before resetting and continuing with the new port
		if [ -n "$PreviousPort" -a "$Port" != "$PreviousPort" ]; then
			SpitHostRecord "$HostListForOnePort" "$PreviousPort"
			HostListForOnePort=''
			PreviousPort=''
		fi

		HostListForOnePort="$HostListForOnePort $Host"
		PreviousPort="$Port"

	done

	#OK, we've gotten to the end of the hosts for this key, push out the config record for the remainder
	SpitHostRecord "$HostListForOnePort" "$Port"
	HostListForOnePort=''
	PreviousPort=''

done

echo
echo '======== End of hosts generated from known_hosts'
echo