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

SCRIPT_NAME="$(basename "$0")"
SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
SKILL_ROOT="$(dirname "$SCRIPT_DIR")"

: "${OUTPUT_DIR:=$SKILL_ROOT/outputs}"
: "${BACKUP_DIR:=$OUTPUT_DIR/backups}"
: "${TEMPLATE_DIR:=$SKILL_ROOT/templates}"

log_info()  { echo "[INFO]  $(date -Iseconds) $*"; }
log_warn()  { echo "[WARN]  $(date -Iseconds) $*" >&2; }
log_error() { echo "[ERROR] $(date -Iseconds) $*" >&2; }

die() { log_error "$@"; exit 1; }

ensure_fail2ban() {
  if command -v fail2ban-client &>/dev/null; then
    return 0
  fi
  log_warn "fail2ban not found; attempting install (Debian/Ubuntu)"
  if command -v apt-get &>/dev/null; then
    sudo apt-get update -y
    sudo apt-get install -y fail2ban
  else
    die "fail2ban not installed and apt-get not available. Install manually."
  fi
}

render_jail() {
  local port="$1"
  sed "s/{{SSH_PORT}}/$port/g" "$TEMPLATE_DIR/fail2ban_jail.tpl"
}

main() {
  mkdir -p "$OUTPUT_DIR" "$BACKUP_DIR"

  local enabled="${FAIL2BAN_ENABLE:-true}"
  if [[ "$enabled" != "true" && "$enabled" != "1" ]]; then
    log_info "FAIL2BAN_ENABLE disabled; skipping"
    exit 0
  fi

  local dry="${DRY_RUN:-1}"
  [[ "$dry" == "0" ]] || die "Refusing to apply with DRY_RUN=$dry. Export DRY_RUN=0 to proceed."

  ensure_fail2ban

  local ssh_port="${SSH_PORT:-22}"

  if [[ -f /etc/fail2ban/jail.local ]]; then
    sudo cp -a /etc/fail2ban/jail.local "$BACKUP_DIR/jail.local.before"
  fi

  log_info "Writing /etc/fail2ban/jail.local"
  render_jail "$ssh_port" | sudo tee /etc/fail2ban/jail.local >/dev/null

  log_info "Enabling and restarting fail2ban"
  sudo systemctl enable fail2ban
  sudo systemctl restart fail2ban

  log_info "fail2ban setup complete"
}

[[ "${BASH_SOURCE[0]}" == "$0" ]] && main "$@"