#!/bin/sh

#

# Find the (sub-)schema that best matches a desired version.

#

# Version numbers are assumed to be in the format X.Y,

# where X and Y are integers, and Y is no more than 3 digits,

# or the special value "next".

#

# (Sub-)schema name (e.g. "resources")

base="$1"; shift

# Desired version (e.g. "1.0" or "next")

target="$1"; shift

# If not empty, append the best match as an XML externalRef to this file

# (otherwise, just echo the best match). Using readlink allows building

# from a different directory.

destination="$(readlink -f "$1")"; shift

# Arbitrary text to print before XML (generally spaces to indent)

prefix="$1"; shift

# Allow building from a different directory

cd "$(dirname $0)"

list_candidates() {

    ls -1 "${1}.rng" "${1}"-*.rng 2>/dev/null

}

version_from_filename() {

    vff_filename="$1"

    case "$vff_filename" in

        *-*.rng)

            echo "$vff_filename" | sed -e 's/.*-\(.*\).rng/\1/'

            ;;

        *)

            # special case for bare ${base}.rng, no -0.1's around anyway

            echo 0.1

            ;;

    esac

}

filename_from_version() {

    ffv_version="$1"

    ffv_base="$2"

    if [ "$ffv_version" = "0.1" ]; then

        echo "${ffv_base}.rng"

    else

        echo "${ffv_base}-${ffv_version}.rng"

    fi

}

# Convert version string (e.g. 2.10) into integer (e.g. 2010) for comparisons

int_version() {

    echo "$1" | awk -F. '{ printf("%d%03d\n", $1,$2); }';

}

best="0.0"

for rng in $(list_candidates "${base}"); do

    case ${rng} in

        ${base}-${target}.rng)

            # We found exactly what was requested

            best=${target}

            break

            ;;

        *-next.rng)

            # "Next" schemas cannot be a best match unless directly requested

            ;;

        *)

            v=$(version_from_filename "${rng}")

	    if [ $(int_version "${v}") -gt $(int_version "${best}") ]; then

                # This version beats the previous best match

                if [ "${target}" = "next" ]; then

                    best=${v}

                elif [ $(int_version "${v}") -lt $(int_version "${target}") ]; then

                    # This value is best only if it's still less than the target

                    best=${v}

                fi

            fi

            ;;

    esac

done

if [ "$best" != "0.0" ]; then

    found=$(filename_from_version "$best" "$base")

    if [ -z "$destination" ]; then

        echo "$(basename $found)"

    else

        echo "${prefix}<externalRef href=\"$(basename $found)\"/>" >> "$destination"

    fi

    exit 0

fi

exit 1