#! /bin/sh
#
#  Name: download
#
#  Author: William Lavender
#
#  This is a helper script for downloading a file from the URL
#  specified on the command line.  It first tries to download
#  the file using 'wget'.  If that fails, then it tries again
#  with 'curl'.  If neither 'wget' or 'curl' are installed on
#  this computer, then the script dies with an error.
#

if [ $# != 1 ]; then
	echo "$0: Wrong number of parameters specified."
	echo ""
	echo "Usage: $0 'url'"
	echo ""
	echo "  where 'url' is the name of the file to be downloaded."
	echo ""
	exit 1
fi

URL=$1

case ${URL} in
*/)
	echo "$0: URLs that end in a trailing slash are not supported."
	echo "    This utility is intended to download a single file"
	echo "    at a time, rather than an entire directory."
	exit 1
esac

DIRNAME="`dirname ${URL}`/"
FILENAME=`basename ${URL}`
PATCHNAME="${FILENAME}.patch"

STATUS=0

if [ -f ${FILENAME} ]; then
	echo "*** ${FILENAME} already downloaded ***"
	exit 0
fi

MXDISCARD=`which patch`

if [ $? = 0 ]; then
	PATCH_CMD='patch'
else
	PATCH_CMD=''
fi

# Figure out whether to use wget or curl.

MXDISCARD=`which wget`

if [ $? = 0 ]; then
	DOWNLOAD_CMD='wget'
else
    MXDISCARD=`which curl`

    if [ $? = 0 ]; then
        DOWNLOAD_CMD='curl'
    else
        echo "$0: Neither 'wget' or 'curl' are installed on" \
		"this computer, so we cannot download files."
        exit 1
    fi
fi

# Download the raw file.

echo "*** Downloading ${FILENAME} ***"

if [ ${DOWNLOAD_CMD} = 'wget' ]; then
    wget -O${FILENAME} ${URL}
    STATUS="$?"
    if [ $STATUS != 0 ]; then
        rm ${FILENAME}
    fi
fi

if [ ${DOWNLOAD_CMD} = 'curl' ]; then
    curl -o${FILENAME} ${URL}
    STATUS="$?"
fi

# If a patch file is available, then patch the raw file using it.

if [ -f ${PATCHNAME} ]; then
	if [ ${PATCH_CMD} = '' ]; then
		echo "Patch file '${PATCHNAME}' is available, but" \
			"the 'patch' command is not installed.  Skipping."
		exit 0
	fi

	echo "*** Patching ${FILENAME} ***"

	${PATCH_CMD} -b < ${PATCHNAME}

	STATUS="$?"
	exit ${STATUS}
else
	echo "*** No patch needed for ${FILENAME} ***"
fi

exit ${STATUS}