#!/usr/bin/env bash
# SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Commercial
# SPDX-FileCopyrightText: 2025-2026 Christian Galo
#
# Fail on a function no program reaches, over every package outside status/.
# deadcode exits 0 even when it reports, so this script reads its output.
#
# Run 1 includes the tests' entry points (-test): it must print nothing.
# Run 2 leaves them out: what it reports is code only tests reach, and each
# such function must be listed in scripts/deadcode-testonly.txt, one
# <package path>.<Func> per line with a reason and an owner (an entry ending
# in .* covers a package; # comments and blank lines are ignored). An entry
# that no longer reports fails too, so the list cannot go stale.
set -euo pipefail

cd "$(dirname "$0")/.."

module=$(go list -m)
mapfile -t pkgs < <(go list -e ./... | grep -v '/status/' || true)

status=0

found=$(go tool deadcode -test "${pkgs[@]}")
if [[ -n $found ]]; then
	printf '%s\n' "$found"
	echo "deadcode: unreachable functions, even counting the tests" >&2
	status=1
fi

reported=$(go tool deadcode -f '{{range .Funcs}}{{$.Path}}.{{.Name}}{{"\n"}}{{end}}' "${pkgs[@]}" |
	sed "s|^${module}/||" | grep -v '^$' | sort -u || true)

allowed=$(sed -e 's/#.*//' -e 's/[[:space:]]*$//' scripts/deadcode-testonly.txt | grep -v '^$' | sort -u || true)

covers() {
	local entry=$1 fn=$2
	if [[ $entry == *.'*' ]]; then
		[[ $fn == "${entry%'*'}"* ]]
	else
		[[ $fn == "$entry" ]]
	fi
}

while IFS= read -r fn; do
	[[ -z $fn ]] && continue
	listed=0
	while IFS= read -r entry; do
		[[ -z $entry ]] && continue
		if covers "$entry" "$fn"; then
			listed=1
			break
		fi
	done <<<"$allowed"
	if ((listed == 0)); then
		echo "deadcode: $fn is reached only by tests and scripts/deadcode-testonly.txt does not list it" >&2
		status=1
	fi
done <<<"$reported"

while IFS= read -r entry; do
	[[ -z $entry ]] && continue
	hit=0
	while IFS= read -r fn; do
		[[ -z $fn ]] && continue
		if covers "$entry" "$fn"; then
			hit=1
			break
		fi
	done <<<"$reported"
	if ((hit == 0)); then
		echo "deadcode: scripts/deadcode-testonly.txt lists $entry, which no longer reports" >&2
		status=1
	fi
done <<<"$allowed"

exit "$status"