#!/bin/sh -e
# Display packages which depend on the given package

## SYNOPSIS:
## .Nm
## .Op Fl tm
## .Op Ar package
## DESCRIPTION:
## .Nm
## generates reverse dependencies for
## .Ar package .
## If no package name is given,
## .Nm
## uses the name of the current directory for the package.
##
## Following options are available for use::
## .Bl -tag
## .It Fl t , -tree
## Also print indirect reverse dependencies
## .It Fl m , -make
## Include make dependencies
## .El

parser_definition() {
    setup REST help:usage -- "usage: ${0##*/} [options...] [pkg]"
    flag tree -t --tree   -- "Also print indirect reverse dependencies"
    flag make -m --make   -- "Include make dependencies"
    global_options
}

# shellcheck disable=1091
. cpt-lib; set +f

[ "$1" ] || set -- "${PWD##*/}"

# 'cd' to the database directory as a simple way of
# stripping the path and performing a 'basename'.
#
# $sys_db is defined on cpt-lib
# shellcheck disable=2154
cd "$sys_db"

get_revdep() {
    pkg=$1; set -- "^$pkg\$"
    # Defined by parser.
    # shellcheck disable=2154
    [ "$make" ] && set -- -e "$1" -e "^$pkg "
    grep "$@" -- */depends | while read -r pkg _; do
        printf '%s\n' "${pkg%%/*}"
    done
}

# Defined by parser.
# shellcheck disable=2154
if [ "$tree" ]; then
    mkdir -p "$tmp_dir"
    :> "$tmp_dir/processed"
    get_revdep "$1" > "$tmp_dir/dep"
    while ! diff -q "$tmp_dir/dep" "$tmp_dir/processed" >/dev/null 2>&1; do
        cp "$tmp_dir/dep" "$tmp_dir/dep.new"
        while read -r line; do
            grep -q "^$line\$" "$tmp_dir/processed" && continue
            get_revdep "$line" >> "$tmp_dir/dep.new"
            printf '%s\n' "$line" >> "$tmp_dir/processed"
        done < "$tmp_dir/dep"
        sort -u -o "$tmp_dir/dep" "$tmp_dir/dep.new"
        sort -u -o "$tmp_dir/processed" "$tmp_dir/processed"
    done
    cat "$tmp_dir/dep"
else
    get_revdep "$1"
fi