#!/usr/bin/env bash
#
# prunefiles, a function to remove all but the n latest versions of a file
# by Bryan Roessler
#
# This file can be sourced directly to import `prunefiles` or run as a script
#
# Useful to prune rpm repositories of obsolete packages
#

declare -a _filePrefixes

prunefiles () {

    #############
    # DEFAULTS ##
    #############

    # Default number of matching files to keep
    _keepInt=1


    #############
    # FUNCTIONS #
    #############

    _printHelpAndExit () {

    cat <<-'EOF'
USAGE:
pruneFiles -k 3 thisfileprefix [thatfileprefix]

OPTIONS
    -k|--keep NUMBER
        Keep NUMBER of latest files that matches each file prefix (Default: 1)
EOF

    # Exit using passed exit code
    [[ -z $1 ]] && exit 0 || exit "$1"

}

    _parseInput () {

        if _input=$(getopt -o +k: -l keep: -- "$@"); then
            eval set -- "$_input"
            while true; do
                case "$1" in
                    -k|--keep)
                        shift && _keepInt=$1
                        ;;
                    --)
                        shift && break
                        ;;
                esac
                shift
            done
        else
            echo "Incorrect option(s) provided"
            _printHelpAndExit 1
        fi

        _filePrefixes=( "$@" )
    }


    _findAndRemove () {

        for _filePrefix in "${_filePrefixes[@]}"; do
            for _file in $(find . -maxdepth 1 -type f -name "${_filePrefix}*" -printf '%T@ %p\n' | sort -r -z -n | tail -n+$(($_keepInt + 1)) | awk '{ print $2; }'); do
                rm "$_file"
            done
        done
    }


    __main () {

        _parseInput "$@"
        _findAndRemove

    }

    __main "$@"
}

# Allow script to be safely sourced
if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
    prunefiles "$@"
    exit $?
fi