#!/usr/bin/env bash
set -Eeuo pipefail

PATH=/usr/sbin:/usr/bin:/sbin:/bin
export PATH
umask 077

PREFIX=${TALLYNOTE_INSTALL_PREFIX:-/opt/tallynote}
DATA_DIR=${TALLYNOTE_DATA_DIR:-/var/lib/tallynote}
REQUEST_FILE="$DATA_DIR/update-request.json"
CURRENT_LINK="$PREFIX/current"
STATE_FILE="$PREFIX/.update-state"
SERVICE_NAME=${TALLYNOTE_SERVICE_NAME:-tallynote.service}
HOST=${TALLYNOTE_HOST:-127.0.0.1}
PORT=${TALLYNOTE_PORT:-3000}
HEALTH_HOST=$HOST
if [[ "$HEALTH_HOST" == 0.0.0.0 ]]; then HEALTH_HOST=127.0.0.1; fi
if [[ "$HEALTH_HOST" == :: ]]; then HEALTH_HOST=::1; fi
if [[ "$HEALTH_HOST" == *:* && "$HEALTH_HOST" != \[* ]]; then HEALTH_HOST="[$HEALTH_HOST]"; fi

die() { printf 'tallynote update runner: %s\n' "$*" >&2; exit 1; }
[[ ${EUID:-$(id -u)} -eq 0 ]] || die 'must run as root'
[[ -f "$REQUEST_FILE" || -f "$STATE_FILE" ]] || exit 0
[[ -L "$CURRENT_LINK" ]] || die 'current release link is missing'

old_target=$(readlink -f -- "$CURRENT_LINK")
[[ "$old_target" == "$PREFIX/releases/"* && -d "$old_target" ]] || die 'current release target is invalid'

request_operation='apply'
if [[ -f "$REQUEST_FILE" && ! -L "$REQUEST_FILE" ]]; then
  request_operation=$(sed -n 's/.*"operation"[[:space:]]*:[[:space:]]*"\(download\|apply\)".*/\1/p' "$REQUEST_FILE" | head -n 1)
  [[ "$request_operation" == download || "$request_operation" == apply ]] || request_operation='apply'
fi

# Downloading is intentionally handled while the main service remains up.
# The CLI persists the validated payload under the root-owned workspace and
# leaves the job staged for a later apply request.
if [[ "$request_operation" == download ]]; then
  node_bin="$CURRENT_LINK/runtime/bin/node"
  [[ -x "$node_bin" ]] || node_bin=$(command -v node || true)
  [[ -n "$node_bin" ]] || die 'node runtime not found'
  cli="$CURRENT_LINK/dist/server/cli/update.js"
  [[ -f "$cli" ]] || die 'update CLI not found in current release'
  "$node_bin" "$cli" --request-file "$REQUEST_FILE" || exit $?
  rm -f -- "$REQUEST_FILE"
  exit 0
fi

was_active=0
if systemctl is-active --quiet "$SERVICE_NAME"; then was_active=1; fi
# shellcheck disable=SC2329 # invoked indirectly by the EXIT trap below
restore_initial_service() {
  local result=$?
  if (( was_active )); then systemctl start "$SERVICE_NAME" || true; fi
  return "$result"
}
trap restore_initial_service EXIT
systemctl stop "$SERVICE_NAME"

job_id=''
if [[ -f "$REQUEST_FILE" && ! -L "$REQUEST_FILE" ]]; then
  job_id=$(sed -n 's/.*"jobId"[[:space:]]*:[[:space:]]*"\([0-9a-f-]*\)".*/\1/p' "$REQUEST_FILE" | head -n 1)
fi
old_node="$CURRENT_LINK/runtime/bin/node"
[[ -x "$old_node" ]] || old_node=$(command -v node || true)
switched=0
handled=0

write_update_state() {
  local phase=$1 temporary
  temporary="$PREFIX/.update-state-$$-${RANDOM}.tmp"
  [[ ! -e "$temporary" && ! -L "$temporary" ]] || return 1
  printf 'job_id=%s\nold_target=%s\nphase=%s\n' "$job_id" "$old_target" "$phase" > "$temporary"
  chmod 600 "$temporary"
  mv -Tf -- "$temporary" "$STATE_FILE"
}

clear_update_state() {
  [[ ! -L "$STATE_FILE" ]] || return 1
  rm -f -- "$STATE_FILE"
}

finalize_state_job() {
  local node=$1 status=$2 state_job=$3
  [[ "$state_job" =~ ^[0-9a-f-]{36}$ && -n "$node" ]] || return 1
  [[ -f "$CURRENT_LINK/dist/server/cli/update.js" ]] || return 1
  "$node" "$CURRENT_LINK/dist/server/cli/update.js" --finalize-job "$state_job" --finalize-status "$status" --message '新版本健康检查失败，已恢复上一版本' >/dev/null 2>&1
}

recover_stale_state() {
  local state_job state_old state_phase current_target recovery_node rollback_link state_mode state_uid
  [[ -f "$STATE_FILE" && ! -L "$STATE_FILE" ]] || die 'update state file is invalid'
  state_uid=$(stat -c '%u' "$STATE_FILE" 2>/dev/null || stat -f '%u' "$STATE_FILE")
  state_mode=$(stat -c '%a' "$STATE_FILE" 2>/dev/null || stat -f '%Lp' "$STATE_FILE")
  [[ "$state_uid" == 0 && "$state_mode" =~ ^[0-7]+$ && $((8#$state_mode & 077)) -eq 0 ]] || die 'update state file permissions are invalid'
  state_job=$(sed -n 's/^job_id=//p' "$STATE_FILE" | head -n 1)
  state_old=$(sed -n 's/^old_target=//p' "$STATE_FILE" | head -n 1)
  state_phase=$(sed -n 's/^phase=//p' "$STATE_FILE" | head -n 1)
  [[ "$state_job" =~ ^[0-9a-f-]{36}$ ]] || die 'update state job id is invalid'
  [[ "$state_old" == "$PREFIX/releases/"* && -d "$state_old" && ! -L "$state_old" ]] || die 'update state target is invalid'
  current_target=$(readlink -f -- "$CURRENT_LINK" 2>/dev/null || true)
  if [[ "$state_phase" == finalizing && "$current_target" != "$state_old" ]]; then
    recovery_node="$CURRENT_LINK/runtime/bin/node"
    [[ -x "$recovery_node" ]] || recovery_node=$(command -v node || true)
    for _ in 1 2 3; do
      if finalize_state_job "$recovery_node" completed "$state_job"; then
        rm -f -- "$REQUEST_FILE" 2>/dev/null || true
        clear_update_state || true
        return 10
      fi
      sleep 1
    done
    return 1
  fi
  if [[ "$current_target" != "$state_old" ]]; then
    rollback_link="$PREFIX/.current-recovery-$$-${RANDOM}.tmp"
    [[ ! -e "$rollback_link" && ! -L "$rollback_link" ]] || return 1
    ln -s -- "$state_old" "$rollback_link" || return 1
    if ! mv -Tf -- "$rollback_link" "$CURRENT_LINK"; then
      rm -f -- "$rollback_link" 2>/dev/null || true
      return 1
    fi
    recovery_node="$CURRENT_LINK/runtime/bin/node"
    [[ -x "$recovery_node" ]] || recovery_node=$(command -v node || true)
    if ! finalize_state_job "$recovery_node" failed "$state_job"; then
      # If the original queue is still present, retry it from the restored old
      # release; a crash before the CLI wrote its job row is recoverable this
      # way. Without a queue there is no safe operation to replay.
      if [[ -f "$REQUEST_FILE" && ! -L "$REQUEST_FILE" ]]; then
        clear_update_state || true
        return 0
      fi
      return 1
    fi
    rm -f -- "$REQUEST_FILE" 2>/dev/null || true
    clear_update_state || true
    return 11
  fi
  clear_update_state || true
  return 0
}

if [[ -e "$STATE_FILE" ]]; then
  recovery_result=0
  set +e
  recover_stale_state
  recovery_result=$?
  set -e
  case "$recovery_result" in
    10) if (( was_active )); then systemctl start "$SERVICE_NAME" || true; fi; exit 0 ;;
    11) if (( was_active )); then systemctl start "$SERVICE_NAME" || true; fi; exit 1 ;;
    0) : ;;
    *) if (( was_active )); then systemctl start "$SERVICE_NAME" || true; fi; exit 1 ;;
  esac
fi

[[ -f "$REQUEST_FILE" && ! -L "$REQUEST_FILE" ]] || exit 0

rollback_current() {
  local current_target rollback_link
  current_target=$(readlink -f -- "$CURRENT_LINK" 2>/dev/null || true)
  [[ "$current_target" == "$old_target" ]] && return 0
  rollback_link="$PREFIX/.current-rollback-$$-${RANDOM}.tmp"
  [[ ! -e "$rollback_link" && ! -L "$rollback_link" ]] || return 1
  ln -s -- "$old_target" "$rollback_link" || return 1
  if ! mv -Tf -- "$rollback_link" "$CURRENT_LINK"; then
    rm -f -- "$rollback_link" 2>/dev/null || true
    return 1
  fi
  switched=0
}

finalize_failed_job() {
  [[ "$job_id" =~ ^[0-9a-f-]{36}$ ]] || return 0
  [[ -n "$old_node" && -f "$CURRENT_LINK/dist/server/cli/update.js" ]] || return 0
  "$old_node" "$CURRENT_LINK/dist/server/cli/update.js" --finalize-job "$job_id" --finalize-status failed --message '新版本健康检查失败，已恢复上一版本' >/dev/null 2>&1
}

finalize_completed_job() {
  [[ "$job_id" =~ ^[0-9a-f-]{36}$ ]] || return 0
  [[ -n "$final_node" ]] || return 1
  "$final_node" "$CURRENT_LINK/dist/server/cli/update.js" --finalize-job "$job_id" --finalize-status completed >/dev/null 2>&1
}

# shellcheck disable=SC2329 # invoked indirectly by the EXIT trap below
cleanup_after_update() {
  local result=$? rollback_ok=1
  if (( result != 0 && handled == 0 )); then
    if ! rollback_current; then rollback_ok=0; fi
    if (( rollback_ok == 1 && switched == 0 )); then
      if finalize_failed_job; then
        rm -f -- "$REQUEST_FILE"
        clear_update_state || true
      fi
    fi
  fi
  if (( was_active )); then
    systemctl start "$SERVICE_NAME" || true
  else
    systemctl stop "$SERVICE_NAME" || true
  fi
  return "$result"
}
trap cleanup_after_update EXIT

write_update_state running || exit 1
node_bin="$CURRENT_LINK/runtime/bin/node"
[[ -x "$node_bin" ]] || node_bin=$(command -v node || true)
[[ -n "$node_bin" ]] || die 'node runtime not found'
cli="$CURRENT_LINK/dist/server/cli/update.js"
[[ -f "$cli" ]] || die 'update CLI not found in current release'

set +e
"$node_bin" "$cli" --request-file "$REQUEST_FILE" --defer-completion
update_result=$?
set -e
if (( update_result != 0 )); then
  exit "$update_result"
fi

if [[ "$(readlink -f -- "$CURRENT_LINK" 2>/dev/null || true)" != "$old_target" ]]; then
  switched=1
fi
write_update_state health-check || exit 1

systemctl start "$SERVICE_NAME"
healthy=0
for _ in $(seq 1 30); do
  if curl --proto '=http' --max-time 2 --silent --show-error "http://$HEALTH_HOST:$PORT/health" >/dev/null 2>&1; then healthy=1; break; fi
  sleep 1
done

if (( healthy == 0 )); then
  systemctl stop "$SERVICE_NAME" || true
  rollback_current || die '无法恢复上一版本链接'
  if (( was_active )); then systemctl start "$SERVICE_NAME" || true; fi
  if ! finalize_failed_job; then
    exit 1
  fi
  rm -f -- "$REQUEST_FILE"
  clear_update_state || true
  handled=1
  trap - EXIT
  exit 1
fi

# Preserve an operator's intentionally stopped service after validating the
# new release in a temporary start.
if (( was_active == 0 )); then
  systemctl stop "$SERVICE_NAME"
fi

write_update_state finalizing || exit 1
final_node="$CURRENT_LINK/runtime/bin/node"
[[ -x "$final_node" ]] || final_node=$(command -v node || true)
if [[ "$job_id" =~ ^[0-9a-f-]{36}$ ]]; then
  finalized=0
  for _ in 1 2 3; do
    if finalize_completed_job; then finalized=1; break; fi
    sleep 1
  done
  (( finalized == 1 )) || exit 1
fi
rm -f -- "$REQUEST_FILE"
clear_update_state || true
handled=1
trap - EXIT
exit 0