#!/bin/bash
# Single source of truth for "what is the current project root".
#
# Usage: find-project-root [PATH]
#   PATH defaults to cwd.
#
# On success: prints the absolute path of the project root and exits 0.
# On failure: prints nothing and exits 1.
#
# Definition of "project root":
# - The top of the git work tree containing PATH.
# - If PATH is not inside any git work tree, there is no project root
#   (and we report that by exiting 1 with no output).
#
# This is deliberately strict.  Other compass scripts that want a softer
# fallback (e.g. "use cwd if there's no project") apply that fallback
# themselves -- it's a property of those scripts, not of the underlying
# notion of "project".
#
# FUTURE: when we add other project-marker conventions
# (e.g. a top-level `.project` file, or a configured marker name),
# this is the one place that resolves them.

set -euo pipefail

start="${1:-$PWD}"
if [ ! -d "$start" ]; then
	echo "find-project-root: not a directory: $start" >&2
	exit 2
fi

if root=$(cd "$start" && git rev-parse --show-toplevel 2>/dev/null); then
	echo "$root"
	exit 0
fi
exit 1