#!/bin/sh
#
# Parameter: LISTE ACTION
# z.B. ./get_files programme download
#

set -eu

# die Key-Server muessen wohl einzeln angegeben werden - somit einzelne Direktiven
KEY_SERVERS="x-hkp://pgp.mit.edu --keyserver hkp://subkeys.pgp.net"

function download_file()
{
	local QUELLE=$(grep "^$1[[:space:]]" $URL_FILE | cut -f 2)
	wget --continue --no-check-certificate --output-document "$DEST_DIR/$1" "$QUELLE"
}

function verify_file()
{
	# eventuell die Datei herunterladen
	[ ! -e "$DEST_DIR/$1" ] && download_file "$1"
	[ ! -e "$DEST_DIR/$1" ] && return 1
	# Signatur-URL ermitteln
	local SIG_URL=$(grep "^$1[[:space:]]" $URL_FILE | cut -f 3)
	# bei fehlender Signatur erfolgreich abbrechen
	[ -z "$SIG_URL" ] && return 0
	# Signatur herunterladen
	local SIG_FILE=$DEST_DIR/$(basename "$SIG_URL")
	# html-encodierte Leerzeichen wiederherstellen
	SIG_FILE=${SIG_FILE//\%20/ }
	[ ! -e "$SIG_FILE" ] && wget --output-document "$SIG_FILE" "$SIG_URL"
	# pruefen - notfalls den Schluessel importieren
	# erstmal Ausgabe unterdruecken
	if gpg --quiet --keyserver $KEY_SERVERS --keyserver-options auto-key-retrieve --verify "$SIG_FILE" "$DEST_DIR/$1" &>/dev/null
		then	return 0
		else	gpg --quiet --keyserver $KEY_SERVERS --keyserver-options auto-key-retrieve --verify "$SIG_FILE" "$DEST_DIR/$1"
				# do it again (with output), if verification failed
				return 1
	  fi
}

########### main ############

[ $# -eq 0 ] && echo "die Download-Liste muss angegeben werden!" && exit 1
URL_FILE=$(dirname $0)/${1}.lst
DEST_DIR=$(dirname $0)/${1}
shift
[ ! -e "$URL_FILE" ] && echo "Die Datei ($URL_FILE) existiert nicht!" && exit 2
[ -e "$DEST_DIR" ] || mkdir -p "$DEST_DIR"

ACTION=help
[ $# -gt 0 ] && ACTION=$1 && shift


case "$ACTION" in
	download )
		cut -f 1 "$URL_FILE" | while read a
			do	[ ! -e "$DEST_DIR/$a" ] && download_file "$a"
		  done
		# ExitCode auf Null setzen
		true
		;;
	verify )
		cut -f 1 "$URL_FILE" | while read a
			do	if verify_file "$a"
					then	true
					else	echo "Verification of '$a' failed ..."
							exit 1
				  fi
		  done
		;;
	clean )
		# Datei loeschen
		cut -f 1 "$URL_FILE" | while read a; do	rm -f "$DEST_DIR/$a"; done
		# Signatur loeschen, falls vorhanden
		cut -f 3 "$URL_FILE" | sed /^$/d | while read a; do rm -f "$DEST_DIR/$(basename $a)"; done
		;;
	install )
		[ $# -eq 0 ] && echo 'You need to specify the destination directory!' && exit 1
		INST_DIR=$1
		[ ! -e "$INST_DIR" ] && mkdir -p "$INST_DIR"
		cut -f 1 "$URL_FILE" | while read a
			do	[ -e "$DEST_DIR/$a" ] || download_file "$a"
				cp "$DEST_DIR/$a" "$INST_DIR/"
		  done
		;;
	* )
		echo "Syntax: $0 LIST { download | install | clean } [ZIEL_VERZEICHNIS]"
		echo
		;;
  esac