#!/bin/bash
#
# Tool to work with sourceforge.net's download mirrors: selects the
# fastest (ping response time) mirror which has the wanted file
#
# Johannes Winkelmann, jw at tks6 dot net
#
# USAGE:
#
# 1. Configure your MIRROR_STORE location right after this comment header
# to your liking
#
# 2. Create a mirror store
#    $ sf-mirror-tool create-store
# It's recommended to update it from time to time, i.e. on reboot
#
# 3. Add the following to pkgmk.conf, after the PKGMK_SOURCE_DIR export 
#    (if you have any):
#   if [ "$PKGMK_DOWNLOAD" = "yes" ]; then
#       . /path/to/sf-mirror-tool
#       sf_replace_source verbose
#   fi
#
#   You can remove the "verbose" argument to suppress diagnostic output
#
# 4. [optional]
#   Manually tweak the mirror store to get an compromise between speed and
#   available files
#
# Note that it will check for the files from sourceforge in any case if
# you run pkgmk with the '-d' option (every time when using prt-get);
# tighter integration with pkgmk could address that

###
## user configuration
#
MIRROR_STORE=/var/lib/pkg/sf-mirror.store
PING_TIMEOUT=5
WGET_TIMEOUT=5


# OUTPUT_TARGET is changed to stderr if you're running
# sf_replace_source with "verbose" as argument"
OUTPUT_TARGET=/dev/null

sf_sort_mirrors() {
    hosts="`dig dl.sf.net | awk '/IN\W*A\W*[1-9]/{print $NF}'`"

    for h in $hosts; do
	name=`host $h|grep "domain name"|awk '{print $NF}'|sed -e 's|\.$||g'`
	msg=`ping -q -t $PING_TIMEOUT -c 1 $name 2>/dev/null`
	if [ $? -eq 0 ]; then
	    t=`echo $msg|grep round-trip|sed -e 's|.*= ||g' -e 's|/.*||g'`
	    mirrors="$mirrors $t:$name"
	fi
    done

    for m in $mirrors; do
	echo $m|sed -e 's|:| |g'
    done|sort -n |awk '{print $2}'
}

sf_create_store() {
    : > $MIRROR_STORE
    for m in `sf_sort_mirrors`; do
	echo $m >> $MIRROR_STORE
    done
}

# url, nostore=""
sf_select_mirror() {
    url=$1
    if [ "$2" != "nostore" ] && [ -f $MIRROR_STORE ]; then
	mirrors="`cat $MIRROR_STORE`"
    else
	mirrors="`sf_sort_mirrors`"
    fi

    for m in $mirrors; do
	ping -t $TIMEOUT -q -c 1 $m &> /dev/null
	if [ $? -eq 0 ]; then
	    wget -q --timeout=$WGET_TIMEOUT --spider http://$m/$url
	    if [ $? -eq 0 ]; then
		echo $m
		return;
	    fi
	    echo "Failed mirror: $m" > $OUTPUT_TARGET
	fi
    done

    # fallback: re-run sf_sort_mirrors
    if [ "$2" != "nostore" ]; then
	echo "Mirror store contains no valid servers; rerunning lookup" \
	    > $OUTPUT_TARGET
	sf_select_mirror $url "nostore"
    fi
}

sf_replace_source() {
    if [ "$1" = "verbose" ]; then
	OUTPUT_TARGET=/dev/stderr
    fi
    
    i=0
    for s in ${source[*]}; do

        if [ -f $PKGMK_SOURCE_DIR/`basename $s` ]; then
            # file already downloaded
            echo "File already downloaded: `basename $s`"
            continue
        fi
        
	s=${s/download.sf.net/dl.sf.net}
	s=${s/download.sourceforge.net/dl.sf.net}
	s=${s/dl.sourceforge.net/dl.sf.net}

	url=${s/http:\/\/dl.sf.net/}
	if [ "$url" != "$s" ]; then
	    mirror=`sf_select_mirror $url`
	    if [ -n "$mirror" ]; then
		echo "$s -> http://$mirror$url" > $OUTPUT_TARGET
 	        source[$i]="http://$mirror$url"
	    else
		echo "Error: no SF mirror found" > $OUTPUT_TARGET
	    fi
	fi
	i=$((i+1))
    done
}

sf_usage() {
    echo "Usage: sf-mirror-tool <command>"
}

case "$1" in
    "create-store")
    sf_create_store
    ;;
    "-h"|"--help")
    sf_usage
    ;;
esac