#!/bin/bash

# Download Freetz packages from a randomly chosen mirror server. There is
# an empty input field for a user-defined server in 'menuconfig'. Additionally,
# another download source maybe specified on the command line as $3. $2 is the name
# of the file to be downloaded.
#
# This script is designed to be called by makefile includes (*.mk), but can
# also be called directly. It expects to find a file with necessary variables
# at a relative location '../.config' to this script. The variables are:
#   - FREETZ_DL_SITE_USER     (URL, e.g. http://my.server.org)

# supported checksum algorithms
CHECKSUM_ALGOS[32]="md5"
CHECKSUM_ALGOS[40]="sha1"
CHECKSUM_ALGOS[64]="sha256"
CHECKSUM_ALGOS[128]="sha512"

DOT_CONFIG=$FREETZ_BASE_DIR/.config
FREETZ_DL_SITE_1="http://freetz.magenbrot.net"
FREETZ_DL_SITE_2="http://freetz.3dfxatwork.de"
FREETZ_DL_SITE_3="http://freetz.wirsind.info"

helpmsg()
{
cat << 'EOF'
freetz_download - download Freetz packages

Usage: freetz_download (-?|--help) | [--no-append-servers] ( (<download-dir> | check) <filename> [<main-url>,<mirror1>,<mirror2>,...] [<checksum>] )
    check         - check download
    download-dir  - target directory for download file
    filename      - download file name
    main-url      - url without filename for primary download
    checksum      - file checksum (supported algorithms: md5, sha1, sha256, sha512)
    -?, --help    - print this help text

Examples:
    freetz_download dl package.tar.bz2
    freetz_download dl package.tar.bz2 http://myserver.com/freetz
    freetz_download dl package.tar.bz2 http://myserver.com/freetz,ftp://myserver-mirror.com/pub/freetz

Debugging: just set DEBUG=1, like this:
    DEBUG=1 freetz_download dl package.tar.bz2
EOF
}

do_download()
{
	# $1 = target directory, $2 = download URL without file, $3 = (remote) file name
	local fullURL="${2%/}/$3"

	echo
	[ "$DEBUG" == "1" ] && echo \
	"wget -nd -t3 --timeout=20 --no-check-certificate --passive-ftp -N -P \"${1%/}/\" \"${fullURL}\""
	 wget -nd -t3 --timeout=20 --no-check-certificate --passive-ftp -N -P  "${1%/}/"   "${fullURL}"
	wget_result=$?
	if [ "$wget_result" != "0" ]; then
		echo "Download failed - \"${fullURL}\"  ->  error code $wget_result" >&2
		rm -f $1/$3
		return $wget_result
	fi
	echo "Download succeeded - \"${fullURL}\"  ->  saved to folder \"$1\""
}

do_check()
{
	local mode wget_output wget_result
	for mode in --spider --output-document=/dev/null; do
		[ "$DEBUG" == "1" ] && \
		echo         "LC_ALL=C wget -t3 --timeout=20 --no-check-certificate --passive-ftp -S $mode \"$1\" 2>&1"
		wget_output=$(LC_ALL=C wget -t3 --timeout=20 --no-check-certificate --passive-ftp -S $mode "$1" 2>&1)
		wget_result=$?
		if [ "$wget_result" != "0" ]; then
			# workaround wget spider-mode bug (false negative): known to happen with all sites
			# with forbidden directory listing. wget in spider-mode first checks the directory
			# containing the downloaded file. After getting "403 Forbidden" it stops and doesn't
			# make any further checks.
			if echo "$wget_output" | grep -qEi "403 Forbidden"; then
				continue
			fi

			# real negative
			return $wget_result
		fi

		# workaround wget-bug: while checking availability of a file on an ftp-site
		# it prints "no such file" but doesn't set return code appropriately
		if echo "$wget_output" | grep -qEi "(no such file|file does not exist)"; then
			return 1
		fi

		# workaround yet another hassle: web-servers redirecting to some "file does not exist"-page, e.g. 404.html.
		# heuristic - we never download html-pages, so the content type of the downloaded file should be something other than 'text/html'.
		# note: disabling redirection with "--max-redirect=0" does not work as it's a legitimate behavior
		# for the mirror sites to redirect to some geographically nearby location.
		if echo "$wget_output" | grep -i "Content-Type" | tail -1 | grep -qi "text/html"; then
			return 1
		fi

		break
	done

	return 0
}

# $1 - url
# $2 - subdir
# $3 - version
do_checkout_cvs()
{
	local module_name
	module_name="${2/-$3/}"
	(cvs -d:"$1" export -D "$3" "$module_name" || cvs -d:"$1" export -r "$3" "$module_name") && mv "$module_name" "$2"
}
do_checkout_svn()
{
	local extra_flags
	svn help export | grep -q trust-server-cert && extra_flags="--trust-server-cert"
	svn export --non-interactive $extra_flags -r$3 "$1" "$2"
}
do_checkout_git()
{
	GIT_SSL_NO_VERIFY=true git clone "$1" "$2" \
	&& pushd "$2" >/dev/null \
	&& git checkout "$3" \
	&& LAST_COMMIT_TIMESTAMP=$(git log -1 --pretty=format:%cD) \
	&& if [ -f ".gitmodules" -a -z "$NO_SUBMODULES" ]; then git submodule init && git submodule update; fi \
	&& rm -rf .git \
	&& popd >/dev/null
}
do_checkout_git_no_submodules()
{
	NO_SUBMODULES=1 do_checkout_git "$@"
}
# Note: remote repository must support "git archive" command
# $1 is expected to have the following format:
#    repository_url,path1,path2,...,pathN
# where
#    repository_url - a repository url supporting archive command, e.g. git://repo.or.cz/git.git
#    pathX - a path to any file or directory within the repository
# Only path1,...,pathN will be transmitted saving both bandwidth and processing power.
do_checkout_git_archive()
{
	local repository paths
	repository=$(echo "$1" | cut -d , -f 1)
	paths=$(echo "$1" | cut -d , -f 2- | tr , " ")
	git archive --format=tar --remote="$repository" --prefix="$2/" "$3" $paths | tar -x
}
do_checkout_bzr()
{
	bzr export -r"$3" "$2" "$1"
}
do_checkout_hg()
{
	hg clone -r "$3" "$1" "$2" && (cd "$2" && rm -rf .hg .hgignore .hgtags)
}
do_checkout_darcs()
{
	darcs get -t "$3" "$1" "$2" && (cd "$2" && rm -rf _darcs)
}


# Regular use: help parameter -> exit without error
if [ "$1" == "-?" -o "$1" == "--help" ]; then
	helpmsg
	exit 0
fi

opt_append_servers=y
while [ $# -gt 1 ]; do
	case "$1" in
		--no-append-servers)
			opt_append_servers=n
			shift
			;;
		*)
			break
			;;
	esac
done

# Wrong number of parameters -> exit with error
if [ $# -lt 2 -o $# -gt 4 ]; then
	helpmsg >&2
	exit 1
fi

DL_DIR="$1"
DL_FILE="$2"
URLs="$3"
CHECKSUM="$(echo ${4,,})" # convert to lower-case and trim whitespaces (checksum length is used to determine the checksum algorithm)

# Import Freetz config variables
[ -e $DOT_CONFIG ] && . $DOT_CONFIG

if [ "$DEBUG" == "1" ]; then
	echo "freetz_download parameters:"
	echo "    DL_DIR=$DL_DIR"
	echo "    DOT_CONFIG=$DOT_CONFIG"
	echo "    DL_FILE=$DL_FILE"
	echo "    URLs=$URLs"
	echo "    CHECKSUM=$CHECKSUM"
fi

# fill array 'sites' with download server URLs, first primary site and package specific mirrors (if specified)
num_sites=0
if [ -n "$URLs" ]; then
	# check if URLs contains magic sequence corresponding to one of the supported VCSs
	supportedVCSs="cvs|svn|git|git_no_submodules|git_archive|bzr|hg|darcs"
	VCS="$(echo "${URLs}" | sed -nr -e "s,^(${supportedVCSs})(@|://).*,\1,p")"
	if [ -n "${VCS}" ]; then
		URLs="$(echo "${URLs}" | sed -r -e "s,^(${supportedVCSs})@(.*),\2,")"
		num_sites=0
		CHECKSUM=""
	else
		URLs="${URLs//@1&1/@1u1}" # replace our 1&1 alias with a one containing no special shell characters

		# replace special shell characters with their percent-encoding counterparts (in order to be able to apply shell brace-expansion)
		URLs="${URLs//\ /%20}"
		URLs="${URLs//\!/%21}"
		URLs="${URLs//\$/%24}"
		URLs="${URLs//\&/%26}"

		for url in $(eval echo "{${URLs},}"); do # wrap URLs with curly-braces to apply brace-expansion
			if [ ${url:0:3} == "@SF" ]; then
				# give sourceforge a few more tries, because it redirects to different mirrors
				subpath=${url/@SF\//}
				for (( n=0; n < 5; n++ )); do
					sites[(( num_sites++ ))]=http://downloads.sourceforge.net/$subpath
				done
			elif [ ${url:0:4} == "@AVM" ]; then
				subpath=${url/@AVM\//}
				sites[(( num_sites++ ))]=http://download.avm.de/fritzbox/$subpath
				sites[(( num_sites++ ))]=http://download.avm.de/archive/fritz.box/$subpath
				sites[(( num_sites++ ))]=http://download.avm.de/$subpath
				sites[(( num_sites++ ))]=ftp://ftp.avm.de/fritzbox/$subpath
				sites[(( num_sites++ ))]=ftp://ftp.avm.de/archive/fritz.box/$subpath
				sites[(( num_sites++ ))]=https://service.avm.de/downloads/$subpath
				sites[(( num_sites++ ))]=http://avm.de/$subpath
				sites[(( num_sites++ ))]=http://www.avm.de/de/Service/Service-Portale/$subpath
			elif [ ${url:0:4} == "@GNU" ]; then
				subpath=${url/@GNU\//}
				sites[(( num_sites++ ))]=http://ftpmirror.gnu.org/$subpath # automatically chooses a nearby and up-to-date mirror
				sites[(( num_sites++ ))]=http://ftp.gnu.org/gnu/$subpath
			elif [ ${url:0:7} == "@KERNEL" ]; then
				subpath=${url/@KERNEL\//}
				sites[(( num_sites++ ))]=https://kernel.org/pub/$subpath
				sites[(( num_sites++ ))]=ftp://ftp.kernel.org/pub/$subpath
			elif [ ${url:0:8} == "@TELEKOM" ]; then
				subpath=${url/@TELEKOM\//}
				sites[(( num_sites++ ))]=https://www.telekom.de/hilfe/downloads/$subpath
				sites[(( num_sites++ ))]=http://www.telekom.de/dlp/eki/downloads/$subpath
				sites[(( num_sites++ ))]=http://www.t-home.de/dlp/eki/downloads/$subpath
				sites[(( num_sites++ ))]=http://hilfe.telekom.de/dlp/eki/downloads/$subpath
			elif [ ${url:0:4} == "@1u1" ]; then
				subpath=${url/@1u1\//}
				sites[(( num_sites++ ))]=http://acsfwdl.1und1.de/avm/$subpath
			elif [ ${url:0:4} == "@EWE" ]; then
				subpath=${url/@EWE\//}
				sites[(( num_sites++ ))]=http://download.ewe.de/avm/$subpath
			elif [ ${url:0:6} == "@M-NET" ]; then
				subpath=${url/@M-NET\//}
				sites[(( num_sites++ ))]=http://www.m-net.de/fileadmin/downloads/Links/$subpath
			elif [ ${url:0:7} == "@APACHE" ]; then
				subpath=${url/@APACHE\//}
				sites[(( num_sites++ ))]=http://www.eu.apache.org/dist/$subpath
				sites[(( num_sites++ ))]=http://www.apache.org/dist/$subpath
				sites[(( num_sites++ ))]=http://apache.openmirror.de/$subpath
				sites[(( num_sites++ ))]=http://archive.apache.org/dist/$subpath
			elif [ ${url:0:6} == "@SAMBA" ]; then
				subpath=${url/@SAMBA\//}
				sites[(( num_sites++ ))]=https://www.samba.org/ftp/$subpath
				sites[(( num_sites++ ))]=https://ftp.samba.org/pub/$subpath
			else
				sites[(( num_sites++ ))]=$url
			fi
		done
	fi
fi

# Get Freetz mirror sites in array
FREETZ_SITES=( $(
	for (( i=1; i <= 3 ; i++ )); do
		eval "echo \$FREETZ_DL_SITE_$i"
	done
	) )

# Add user-defined mirror
if [ -n "$FREETZ_DL_SITE_USER" ]; then
	FREETZ_SITES[3]=$FREETZ_DL_SITE_USER
fi

# Fill array 'sites' with download server URLs, add Freetz Mirrors, in random order
if [ "$opt_append_servers" = y ]; then
	for (( n=${#FREETZ_SITES[@]}; n > 0; n-- )); do
		p=$(( RANDOM % n ))
		sites[(( num_sites++ ))]=${FREETZ_SITES[$p]}
		FREETZ_SITES[$p]=${FREETZ_SITES[$((n-1))]}
	done
fi

# Loop over servers until a download succeeds or all requests have failed.
IFS=$'\n'
for i in ${sites[@]}; do
	if [ ${DL_DIR:0:5} == "check" ]; then
		do_check "$i/$DL_FILE"
		if [ "$?" != "0" ]; then
			continue
		fi
	else
		do_download "$DL_DIR" "$i" "$DL_FILE"
		if [ "$?" != "0" ]; then
			continue
		fi

		if [ -n "$CHECKSUM" ]; then
			CHECKSUM_ALGO="${CHECKSUM_ALGOS[${#CHECKSUM}]}"
			if [ -n "${CHECKSUM_ALGO}" ]; then
				CHECKSUM_PROG="$(dirname $0)/${CHECKSUM_ALGO}sum"
				[ ! -x "$CHECKSUM_PROG" ] && CHECKSUM_PROG="$(which ${CHECKSUM_ALGO}sum)"
			fi

			if [ -x "$CHECKSUM_PROG" ]; then
				FILE_CHECKSUM=$($CHECKSUM_PROG "$DL_DIR/$DL_FILE" | sed 's/ .*//')
				if [ "$CHECKSUM" != "$FILE_CHECKSUM" ]; then
					echo "${CHECKSUM_ALGO^^} mismatch for $DL_DIR/$DL_FILE: $CHECKSUM $FILE_CHECKSUM" 1>&1
					rm -f "$DL_DIR/$DL_FILE"
					continue;
				else
					echo "${CHECKSUM_ALGO^^} verified for $DL_DIR/$DL_FILE: $FILE_CHECKSUM"
				fi
			fi
		fi
	fi
	exit 0
done
unset IFS

if [ -n "$VCS" ]; then
	echo
	case "$DL_FILE" in
		*.tar.gz) COMPRESSION_FLAG=z ;;
		*.tar.bz2) COMPRESSION_FLAG=j ;;
		*.tar.xz) COMPRESSION_FLAG=J ;;
		*) { echo "Failed to detect compression method from $DL_FILE"; exit 1; } ;;
	esac

	SUBDIR=$(echo "$DL_FILE" | sed -r -e 's,(.*)[.]tar[.](gz|bz2|xz)$,\1,')
	VERSION=$(echo "$SUBDIR" | sed -r -e 's,[^-]*-(.+),\1,')
	[ -n "$VERSION" ] || { echo "Failed to detect version from $DL_FILE"; exit 1; }

	TMP_DIR=$(mktemp -d -t freetzXXX) || { echo "Error creating temporary dir."; exit 1; }
	echo "Checking out files from the $VCS repository..." \
	&& ( \
		cd "$TMP_DIR" \
		&& rm -rf "$SUBDIR" \
		&& [ ! -d "$SUBDIR" ] \
		&& do_checkout_"$VCS" "$URLs" "$SUBDIR" "$VERSION" \
		&& echo "Packing checkout..." \
		&& { \
			find "$SUBDIR" -not -type d | LC_ALL=C sort > "$SUBDIR.list.sorted"; \
			tar \
			  --format=gnu \
			  --numeric-owner --owner=0 --group=0 \
			  ${LAST_COMMIT_TIMESTAMP:+--mtime="${LAST_COMMIT_TIMESTAMP}"} \
			  -T "$SUBDIR.list.sorted" \
			  -c${COMPRESSION_FLAG}f "$DL_FILE"; \
		} \
	) \
	&& mv "$TMP_DIR/$DL_FILE" "$DL_DIR/" \
	&& rm -rf "$TMP_DIR" \
	&& exit 0

	rm -f "$DL_DIR/$DL_FILE"
	rm -rf "$TMP_DIR"
fi

exit 1