Replacing man with info

function i()
{
    INFOVERSIONLINE=$(info --version | head -n 1)
    INFOVERSION="${INFOVERSIONLINE##* }"
    INFOGT5=$(if test ${INFOVERSION%%.*} -gt 5; then echo true; else echo false; fi)
    # start with special cases which are quick to check for
    if test $# -lt 1; then
        # show info help notice
        info --help
    elif test $# -gt 1 && ! echo $1 | grep -q "[0-9]"; then
        # user sent complex request, but not with a section command. Just use info
        info "$@"
    elif test $# -gt 1 && echo $1 | grep -q "[0-9]"; then
        # user sent request for a section from the man pages, we must defer to man
        man "$@"
    elif test x"$1" = x"info"; then
        # for old versions of info, calling info --usage info fails to
        # provide info about calling info
        if test x"$INFOGT5" = x"true"; then
            info --usage info
        else
            info --usage -f info-stnd
        fi
    elif test x"$1" = x"man"; then
        # info --all -w ./man fails to find the man man page
        info man
    else
        # start with a fast but incomplete info lookup
        INFOPAGELOCATION="$(info --all -w ./"$@" | head -n 1)"
        INFOPAGELOCATION_PAGENAME="$(info --all -w "$1".info | head -n 1)"
        INFOPAGELOCATION_COREUTILS="$(info -w coreutils -n "$@")"
        # check for usage from fast info, if that fails check man and
        # if that also fails, just get the regular info page.
        if test x"${INFOPAGELOCATION}" = x"*manpages*" || test x"${INFOPAGELOCATION}" != x""; then
           info "$@"; # use info to read the known page, man or info
        elif test x"${INFOPAGELOCATION_COREUTILS}" != "x" && info -f "${INFOPAGELOCATION_COREUTILS}" -n "$@" | head -n 1 | grep -q -i "$@"; then
            # coreutils utility
            info -f "${INFOPAGELOCATION_COREUTILS}" -n "$@"
        elif test x"${INFOPAGELOCATION}" = x"" && test x"${INFOPAGELOCATION_PAGENAME}" = x""; then
           # unknown to quick search, try slow search or defer to man.
           # TODO: it would be nice if I could avoid this double search.
           if test x"$(info -w "$@")" = x"*manpages*"; then
               info "$@"
           else
               # defer to man, on error search for alternatives
               man "$@" || (echo nothing found, searching info ... && \
                            while echo $1 | grep -q '^[0-9]$'; do shift; done && \
                            info -k "$@" && false)
           fi
        elif test x"${INFOPAGELOCATION_PAGENAME}" != x""; then
             # search for alternatives (but avoid numbers)
           info --usage -f "${INFOPAGELOCATION_PAGENAME}" 2>/dev/null || man "$@" ||\
             (echo searching info &&\
              while echo $1 | grep -q '^[0-9]$'; do shift; done && \
              info -k "$@" && false)            
        else # try to get usage instructions, then try man, then
             # search for alternatives (but avoid numbers)
           info --usage -f "${INFOPAGELOCATION}" 2>/dev/null || man "$@" ||\
             (echo searching info &&\
              while echo $1 | grep -q '^[0-9]$'; do shift; done && \
              info -k "$@" && false)
        fi
        # ensure that unsuccessful requests report an error status
        INFORETURNVALUE=$?
        unset INFOPAGELOCATION
        unset INFOPAGELOCATION_COREUTILS
        if test ${INFORETURNVALUE} -eq 0; then
            unset INFORETURNVALUE
            return 0
        else
            unset INFORETURNVALUE
            return 1
        fi
    fi
}