#!/usr/bin/env bash
#
# Roll production back to the previous release (or to a named one).
#
#   scripts/rollback.sh                       # previous release
#   scripts/rollback.sh 20261011-193000-5ca0de9
#
# It flips the `current` symlink, restarts the service and health-checks the
# result, so a manual rollback is the same atomic operation the deploy script
# performs on failure.

set -euo pipefail

PROD="${FREEZMO_PROD:-$HOME/freezmo-prod}"
SERVICE="${FREEZMO_SERVICE:-freezmo}"
PORT="${FREEZMO_PORT:-3207}"
HEALTH_TRIES="${FREEZMO_HEALTH_TRIES:-45}"

say() { printf '\033[1m[rollback]\033[0m %s\n' "$*"; }
fail() { printf '\033[1;31m[rollback]\033[0m %s\n' "$*" >&2; exit 1; }

LIVE="$(readlink -f "$PROD/current" 2>/dev/null || true)"
[[ -n "$LIVE" ]] || fail "no current release at $PROD/current"

if [[ -n "${1:-}" ]]; then
  TARGET="$(readlink -f "$PROD/releases/$1" 2>/dev/null || true)"
  [[ -n "$TARGET" && -d "$TARGET" ]] || fail "release not found: $1"
else
  TARGET=""
  for dir in "$PROD"/releases/*/; do
    resolved="$(readlink -f "$dir")"
    if [[ "$resolved" != "$LIVE" ]]; then
      TARGET="$resolved"
      break
    fi
  done
  [[ -n "$TARGET" ]] || fail "no previous release to roll back to"
fi

say "current: $(basename "$LIVE")"
say "switching to: $(basename "$TARGET")"
ln -sfn "$TARGET" "$PROD/current.tmp"
mv -T "$PROD/current.tmp" "$PROD/current"

systemctl --user restart "$SERVICE"

EXPECTED="$(grep -o '"commit":"[^"]*"' "$TARGET/server/release.json" 2>/dev/null | cut -d'"' -f4 || true)"
[[ -n "$EXPECTED" ]] || EXPECTED="$(basename "$TARGET" | sed 's/.*-//')"
for ((i = 0; i < HEALTH_TRIES; i++)); do
  body="$(curl -fsS --max-time 2 "http://127.0.0.1:$PORT/api/healthz" 2>/dev/null || true)"
  commit="$(printf '%s' "$body" | grep -o '"commit":"[^"]*"' | cut -d'"' -f4 || true)"
  if [[ -n "$commit" && "${commit:0:7}" == "${EXPECTED:0:7}" ]]; then
    say "healthy — production is on $(basename "$TARGET")"
    exit 0
  fi
  sleep 1
done

fail "health check did not confirm $(basename "$TARGET") — check journalctl --user -u $SERVICE"