#!/bin/bash

# Run a program from a given directory which is specified last on the command
# line, stripping the directory using dirname a given number of times.
# This is a hack to allow gqview to launch things such as an rxvt in a given
# directory, since gqview doesn't support parameter expansion for its helper
# programs.
#
# Also expands certain escape codes in the arguments to the command.
#
# for example, in the GQview configuration under the Editors tab:
# 4   rxvt       cdrun 1 rxvt
# will run rxvt in the current image's directory.
#
# 7   dir gvim   cdrun 1 gvim --remote-send '<C-\><C-N>:cd %e<CR>'
#
# written by Steven Mueller
# Created: Thursday January 03, 2002
# Last Modified: Friday January 04, 2002  00:50 PST

if [ $# -lt 2 ]; then
    echo "Usage: $0 [n] program args .. dir"
    echo "Strips the last n elements off the pathname in dir, cd's there, and runs program args."
    echo "Escape codes: %d - the stripped directory argument"
    echo "              %e - stripped dir with spaces preceeded by backslashes"
    echo "              %f - the unstripped directory (file argument)"
    echo "              %% - literal percent sign"
    exit 0
fi

STRIP="$1"
# if the first argument is a number, use it as the dirpart strip amount
if expr "$STRIP" : '[0-9]*$' > /dev/null; then
    shift
else
    STRIP=0
fi

RUNPROG="$1"
shift
if  ! which "$RUNPROG" > /dev/null; then
    echo "Error: $RUNPROG is not executable and is not found in the path.  Aborting." 1>&2
    exit 1
fi

if [ x`which "$RUNPROG"` = x"$RUNPROG" ]; then
    # must do some relative path translation
    (cd `dirname "$RUNPROG`; RUNPROG="`pwd`/`basename "$RUNPROG"`")
fi

# Extract the directory argument -- the last one on the command line
eval DIRARG=\"\${$#}\"

# stripdirs dir n - strip n trailing pathname parts from dir
stripdirs () {
    local dir=$1
    for ((i = 0; i<$2; i++)); do
	dir=`dirname "$dir"`
    done
    echo "$dir"
}

set -e
DIR=`stripdirs "$DIRARG" $STRIP`
ESCDIR=`echo "$DIR" | perl -p -e 's, ,\\\\\\\\ ,g'`
if ! cd "$DIR"; then
    echo "Error: Could not cd to $DIR, aborting" 1>&2
    exit 1
fi

# Substitute the patterns in the arguments
scansubst () {
   echo "$1" | perl -p -e "s,%d,$DIR,g" \
	     | perl -p -e "s,%e,$ESCDIR,g" \
	     | perl -p -e "s,%f,$DIRARG,g" \
	     | perl -p -e "s,%%,%,g"
}

declare -a args
i=0
while [ $# -gt 1 ]; do
    args[$i]=`scansubst "$1"`
    shift
    ((i++))
done

exec $RUNPROG "${args[@]}"