_df() {
    local i cur prev opts cmd
    COMPREPLY=()
    if [[ "${BASH_VERSINFO[0]}" -ge 4 ]]; then
        cur="$2"
    else
        cur="${COMP_WORDS[COMP_CWORD]}"
    fi
    prev="$3"
    cmd=""
    opts=""

    for i in "${COMP_WORDS[@]:0:COMP_CWORD}"
    do
        case "${cmd},${i}" in
            ",$1")
                cmd="df"
                ;;
            *)
                ;;
        esac
    done

    case "${cmd}" in
        df)
            opts="-a -B -h -H -i -k -l -P -t -T -x -V --help --all --block-size --total --human-readable --si --inodes --local --no-sync --output --portability --sync --type --print-type --exclude-type --version [paths]..."
            if [[ ${cur} == -* || ${COMP_CWORD} -eq 1 ]] ; then
                COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                return 0
            fi
            case "${prev}" in
                --block-size)
                    COMPREPLY=($(compgen -f "${cur}"))
                    return 0
                    ;;
                -B)
                    COMPREPLY=($(compgen -f "${cur}"))
                    return 0
                    ;;
                --output)
                    COMPREPLY=($(compgen -W "source fstype itotal iused iavail ipcent size used avail pcent file target" -- "${cur}"))
                    return 0
                    ;;
                --type)
                    COMPREPLY=($(compgen -f "${cur}"))
                    return 0
                    ;;
                -t)
                    COMPREPLY=($(compgen -f "${cur}"))
                    return 0
                    ;;
                --exclude-type)
                    COMPREPLY=($(compgen -f "${cur}"))
                    return 0
                    ;;
                -x)
                    COMPREPLY=($(compgen -f "${cur}"))
                    return 0
                    ;;
                *)
                    COMPREPLY=()
                    ;;
            esac
            COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
            return 0
            ;;
    esac
}

if [[ "${BASH_VERSINFO[0]}" -eq 4 && "${BASH_VERSINFO[1]}" -ge 4 || "${BASH_VERSINFO[0]}" -gt 4 ]]; then
    complete -F _df -o nosort -o bashdefault -o default df
else
    complete -F _df -o bashdefault -o default df
fi