#!/usr/bin/env bash
# ==============================================================================
# nx9-wg Production Rollback Tool
# ==============================================================================
# PURPOSE:
#   Rolls back the active production binary (/usr/local/bin/nx9-wg) to the most
#   recent (or specified) backup binary created during previous deployments.
#
# PREREQUISITES:
#   - Root privileges (or sudo)
#   - At least one backup binary at /usr/local/bin/nx9-wg.backup.*
#
# SAFETY INVARIANTS:
#   - Never modifies or deletes the SQLite database.
#   - Restores executable permissions (0755) and root ownership.
#   - Confirms service restoration and binary version after rollback.
#
# USAGE:
#   sudo bash scripts/rollback.sh [OPTIONS] [SPECIFIC_BACKUP_PATH]
#
# OPTIONS:
#   -y, --yes       Skip confirmation prompt
#   -l, --list      List available backup binaries and exit
#   -h, --help      Show this help message
# ==============================================================================

set -euo pipefail

BIN_DIR="/usr/local/bin"
ACTIVE_BIN="${BIN_DIR}/nx9-wg"
ASSUME_YES=0
LIST_ONLY=0
SPECIFIED_BACKUP=""

usage() {
  cat <<EOF
nx9-wg Production Rollback Tool

Usage:
  sudo bash scripts/rollback.sh [OPTIONS] [BACKUP_FILE]

Options:
  -y, --yes       Skip interactive confirmation prompt
  -l, --list      List available backup binaries and exit
  -h, --help      Show this help message
EOF
  exit 0
}

while [[ $# -gt 0 ]]; do
  case "$1" in
    -y|--yes)
      ASSUME_YES=1
      shift
      ;;
    -l|--list)
      LIST_ONLY=1
      shift
      ;;
    -h|--help)
      usage
      ;;
    -*)
      echo "Unknown option: $1" >&2
      usage
      ;;
    *)
      SPECIFIED_BACKUP="$1"
      shift
      ;;
  esac
done

log() {
  echo -e "\033[1;34m[ROLLBACK]\033[0m \033[1;37m$*\033[0m"
}

success() {
  echo -e "\033[1;32m[SUCCESS]\033[0m $*"
}

warn() {
  echo -e "\033[1;33m[WARN]\033[0m $*"
}

error() {
  echo -e "\033[1;31m[ERROR]\033[0m $*" >&2
  exit 1
}

# 1. Privilege Verification (unless list only)
if [[ "${EUID}" -ne 0 && "${LIST_ONLY}" -eq 0 ]]; then
  error "Rollback must be run as root (or via sudo)."
fi

# 2. Discover Available Backups
BACKUPS=($(ls -1t "${ACTIVE_BIN}".backup.* 2>/dev/null || true))

if [[ "${#BACKUPS[@]}" -eq 0 ]]; then
  error "No backup binaries found in ${BIN_DIR} matching nx9-wg.backup.*"
fi

if [[ "${LIST_ONLY}" -eq 1 ]]; then
  echo "Available production backup binaries in ${BIN_DIR}:"
  for b in "${BACKUPS[@]}"; do
    SIZE="$(du -h "$b" | cut -f1)"
    DATE="$(date -r "$b" '+%Y-%m-%d %H:%M:%S')"
    echo "  $b (${SIZE}, ${DATE})"
  done
  exit 0
fi

# 3. Select Target Backup
TARGET_BACKUP=""
if [[ -n "${SPECIFIED_BACKUP}" ]]; then
  if [[ -f "${SPECIFIED_BACKUP}" ]]; then
    TARGET_BACKUP="${SPECIFIED_BACKUP}"
  elif [[ -f "${BIN_DIR}/${SPECIFIED_BACKUP}" ]]; then
    TARGET_BACKUP="${BIN_DIR}/${SPECIFIED_BACKUP}"
  else
    error "Specified backup file not found: ${SPECIFIED_BACKUP}"
  fi
else
  TARGET_BACKUP="${BACKUPS[0]}"
fi

log "Selected rollback target: ${TARGET_BACKUP}"
BACKUP_SIZE="$(du -h "${TARGET_BACKUP}" | cut -f1)"
BACKUP_DATE="$(date -r "${TARGET_BACKUP}" '+%Y-%m-%d %H:%M:%S')"
echo "  Size:      ${BACKUP_SIZE}"
echo "  Timestamp: ${BACKUP_DATE}"

# 4. Confirmation Prompt
if [[ "${ASSUME_YES}" -eq 0 ]]; then
  echo -e "\n\033[1;33mAre you sure you want to replace active binary ${ACTIVE_BIN} with ${TARGET_BACKUP}?\033[0m"
  read -r -p "Type 'yes' to proceed with rollback: " CONFIRM
  if [[ "${CONFIRM}" != "yes" ]]; then
    error "Rollback aborted by user."
  fi
fi

# 5. Execute Rollback
if command -v systemctl >/dev/null 2>&1; then
  if systemctl is-active --quiet nx9-wg 2>/dev/null; then
    log "Stopping nx9-wg service..."
    systemctl stop nx9-wg || true
  fi
fi

log "Restoring binary from ${TARGET_BACKUP} to ${ACTIVE_BIN}..."
install -m 0755 "${TARGET_BACKUP}" "${ACTIVE_BIN}"

# 6. Restart Service
if command -v systemctl >/dev/null 2>&1; then
  log "Starting nx9-wg service..."
  systemctl start nx9-wg || error "Failed to restart nx9-wg service after rollback."
  sleep 1

  if systemctl is-active --quiet nx9-wg; then
    success "nx9-wg.service is active and running."
  else
    warn "nx9-wg.service is not active. Checking logs:"
    journalctl -u nx9-wg -n 20 --no-pager || true
    error "Service failed to become active after rollback."
  fi
fi

# 7. Verify Restored Version
RESTORED_VER="$("${ACTIVE_BIN}" version | head -n 1)"
success "Rollback successful. Active binary version: ${RESTORED_VER}"

echo -e "\n================================================================="
echo -e "\033[1;32m PRODUCTION ROLLBACK COMPLETED SUCCESSFULLY!\033[0m"
echo -e "=================================================================\n"