#!/bin/sh
set -eu

# Helper functions for programs that work with satellite files.

show_help() {
echo "Script with helper functions for working with satellite files.
Usage: $0 <satellite file> <function> [arguments]

Functions:
variable <name>     | Get variable set in the header
downloads           | Get all download urls
options             | List all available options and their descriptions"
}

if [ $# -lt 2 ]; then
    show_help
    exit 1
fi

satellite="$(realpath "$1")"
function="$2"

# Functions reused in all wrappers
global="$(printf '
    download_only=true
    name_sat="%s"
    name="$name_sat"

    import() {
        . "%s/functions/$1.sh"
    }

    # Allowed external utility commands
    cut() { "%s" "$@"; }
    expr() { "%s" "$@"; }
' "$(basename "$satellite" .sat)" "$(dirname "$satellite")" "$(command -v cut)" "$(command -v expr)")"

case "$function" in
    variable)
        if [ "$#" -lt 3 ]; then
            show_help
            exit 1
        fi
        name="$3"

        printf "$global"'
            _() {
                variable="$%s"
                [ "$variable" ] && echo "$variable"
                exit $?
            }
            . %s
        ' "$name" "$satellite" | PATH= /bin/sh 2> /dev/null
        ;;

    downloads)
        printf "$global"'
            download() {
                [ "$1" ] && echo "$1"
            }
            dlextract() {
                [ "$1" ] && echo "$1"
            }
            dlfile() {
                [ "$1" ] && echo "$1"
            }
            _() { exit 0; }
            . %s
        ' "$satellite" | PATH= /bin/sh 2> /dev/null
        ;;

    options)
        printf "$global"'
            define_option() {
                [ "$1" ] && echo "$1"
            }
            _() { exit 0; }
            . %s
        ' "$satellite" | PATH= /bin/sh 2> /dev/null
        ;;

    *)
        show_help
        exit 1
        ;;
esac