#!/usr/bin/env bash
#
# Rebuild the vendored Tailscale core when the Go source is newer than the built artefact.
#
#   . scripts/ensure-core.sh ios      # or: android
#
# WHY THIS EXISTS
#
# Changing modules/officer-net/gocore requires rebuilding the core by hand, per platform, and nothing
# enforces it. Forgetting is silent until link or compile time, and the error names a symbol rather
# than the cause:
#
#   Android   e: Unresolved reference 'loginTo'
#   iOS       error: cannot find 'TailcoreSubnetRoutes' in scope
#
# iOS is the nastier of the two: the Go compiles cleanly and the failure arrives minutes later, in
# Swift, against a vendored xcframework whose headers are simply older than the source beside them.
#
# It compares mtimes rather than hashes: gomobile takes minutes, and a spurious rebuild is far cheaper
# than a stale one. The artefact is touched on success so an unchanged tree does not rebuild twice.
set -uo pipefail

_ec_platform="${1:?usage: ensure-core.sh <ios|android>}"
_ec_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
_ec_gocore="$_ec_root/modules/officer-net/gocore"

case "$_ec_platform" in
	ios)
		_ec_artifact="$_ec_root/modules/officer-net/ios/libs/TailCore.xcframework"
		_ec_script="$_ec_root/modules/officer-net/scripts/build-libtailscale-ios.sh"
		;;
	android)
		_ec_artifact="$_ec_root/modules/officer-net/android/libs/tailcore.aar"
		_ec_script="$_ec_root/modules/officer-net/scripts/build-libtailscale-android.sh"
		;;
	*)
		echo "!! ensure-core: unknown platform '$_ec_platform'" >&2
		return 1 2>/dev/null || exit 1
		;;
esac

# Newest input: any Go source, plus the module files that pin tailscale.com itself.
_ec_newest_src="$(find "$_ec_gocore" -type f \( -name '*.go' -o -name 'go.mod' -o -name 'go.sum' \) \
	-exec stat -f '%m' {} + 2>/dev/null | sort -rn | head -1)"

if [[ -e "$_ec_artifact" ]]; then
	# The xcframework is a directory, and its own mtime is what this script touches.
	_ec_artifact_mtime="$(stat -f '%m' "$_ec_artifact" 2>/dev/null || echo 0)"
else
	_ec_artifact_mtime=0
fi

if [[ -z "${_ec_newest_src:-}" ]]; then
	echo "ensure-core: no Go sources found — skipping (is gocore missing?)" >&2
elif (( _ec_newest_src > _ec_artifact_mtime )); then
	if (( _ec_artifact_mtime == 0 )); then
		echo "==> core artefact missing for $_ec_platform — building it (a few minutes)"
	else
		echo "==> gocore is newer than the built core for $_ec_platform — rebuilding (a few minutes)"
	fi
	# gomobile lives in ~/go/bin, which is not on PATH in every shell.
	if PATH="$PATH:$HOME/go/bin" "$_ec_script"; then
		touch "$_ec_artifact" 2>/dev/null || true
		echo "==> core rebuilt for $_ec_platform"
	else
		echo "!! core rebuild FAILED for $_ec_platform — the app build would link a stale core, stopping." >&2
		return 1 2>/dev/null || exit 1
	fi
else
	echo "==> core is up to date for $_ec_platform"
fi