bboxcenter

#!/usr/bin/env bash
PROGRAM_NAME=$(basename "$0")
 # shellcheck disable=SC2124
BBOX="${@}"
BBOX="${BBOX:--}"
BBOX="${BBOX//[[:space:]]/}"

function usage {
    echo "Get center of bounding box. Requires AWK in PATH"
    echo ""
    echo "usage: $PROGRAM_NAME <bbox|-(bbox on stdin)> "
    echo "    - <bbox>: \$minx,\$miny,\$maxx,\$maxy"
    exit 1
}

if test "$#" -lt 1; then
    usage
fi

set -euo pipefail

function process_bbox(){
    local bbox
    bbox="$1"
    xmin=$(echo "$bbox" | cut -d, -f1)
    xmax=$(echo "$bbox" | cut -d, -f3)
    ymin=$(echo "$bbox" | cut -d, -f2)
    ymax=$(echo "$bbox" | cut -d, -f4)
    x_range_half=$(awk "BEGIN {printf \"%.7f\n\", ($ymax - $ymin)/2}")
    y_range_half=$(awk "BEGIN {printf \"%.7f\n\", ($xmax - $xmin)/2}")
    center_x=$(awk "BEGIN {printf \"%.7f\n\", $x_range_half + $xmin}")
    center_y=$(awk "BEGIN {printf \"%.7f\n\", $y_range_half + $ymin}")
    echo "${center_x} ${center_y}"
}

if [[ $BBOX == "-" ]];then
# BBOX passed on stdin
    if [ -t 0 ]; then
    # if do not allow interactive tty
        usage
    fi
    while read -r line
    do
        process_bbox "$line"
    done < "/dev/stdin"
else
# BBOX passed as argument 
    process_bbox "$BBOX"
fi