#!/bin/bash
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
cd "$SCRIPT_DIR"
[ -f "${SCRIPT_DIR}/env-mariadb" ]      && source "${SCRIPT_DIR}/env-mariadb"
[ -f "${SCRIPT_DIR}/_credentials.env" ] && source "${SCRIPT_DIR}/_credentials.env"

MARIADB_NAMESPACE="${MARIADB_NAMESPACE:-data}"
MARIADB_IMAGE="${MARIADB_IMAGE:-mariadb:12.2.2-ubi10}"
MARIADB_PORT="${MARIADB_PORT:-3306}"
MARIADB_DATA_DIR="${MARIADB_DATA_DIR:-/var/lib/mysql}"
MARIADB_STORAGE_CLASS="${MARIADB_STORAGE_CLASS:-longhorn-retain}"
MARIADB_STORAGE_SIZE="${MARIADB_STORAGE_SIZE:-4Gi}"
KUBECONFIG="${KUBECONFIG:-/etc/kubernetes/admin.conf}"

export KUBECONFIG

CMD_TSK="${CMD_TSK:-${1:-install}}"

_kubectl() {
  if command -v kubectl >/dev/null 2>&1; then
    command kubectl "$@"
  elif command -v k0s >/dev/null 2>&1; then
    k0s kubectl "$@"
  else
    echo "ERROR: no kubectl or k0s binary found" >&2; exit 127
  fi
}

_require_env() {
  local var="$1"
  if [ -z "${!var:-}" ]; then
    echo "ERROR: required variable $var is not set" >&2
    exit 1
  fi
}

_namespace_exists() {
  _kubectl get namespace "$MARIADB_NAMESPACE" >/dev/null 2>&1
}

_pod_name() {
  _kubectl get pod \
    --namespace "$MARIADB_NAMESPACE" \
    --selector "app.kubernetes.io/name=mariadb" \
    -o jsonpath='{.items[0].metadata.name}' 2>/dev/null
}

_wait_for_pod() {
  local timeout="${1:-180}"
  _kubectl wait pod \
    --namespace "$MARIADB_NAMESPACE" \
    --selector "app.kubernetes.io/name=mariadb" \
    --for=condition=Ready \
    --timeout="${timeout}s"
}

_do_install() {
  _require_env MARIADB_ROOT_PASSWORD

  if ! _namespace_exists; then
    _kubectl create namespace "$MARIADB_NAMESPACE"
  fi

  _kubectl create secret generic mariadb-credentials \
    --namespace "$MARIADB_NAMESPACE" \
    --from-literal=MARIADB_ROOT_PASSWORD="$MARIADB_ROOT_PASSWORD" \
    --dry-run=client -o yaml | _kubectl apply -f -

  for manifest in storageclass.yaml namespace.yaml pvc.yaml statefulset.yaml service.yaml; do
    local path="$SCRIPT_DIR/manifests/${manifest}"
    [ -f "$path" ] && _kubectl apply -f "$path"
  done

  echo "Waiting for MariaDB pod to be ready..."
  _wait_for_pod 180

  local post_install="$SCRIPT_DIR/manifests/post-install.sh"
  if [ -f "$post_install" ]; then
    bash "$post_install"
  fi

  echo "MariaDB installed in namespace $MARIADB_NAMESPACE"
}

_do_update() {
  _kubectl rollout restart statefulset/mariadb --namespace "$MARIADB_NAMESPACE"
  echo "Waiting for MariaDB to restart..."
  _wait_for_pod 120
  echo "MariaDB updated"
}

_do_delete() {
  if _namespace_exists; then
    _kubectl delete namespace "$MARIADB_NAMESPACE" --timeout=60s
    echo "Namespace $MARIADB_NAMESPACE deleted"
  else
    echo "Namespace $MARIADB_NAMESPACE does not exist, nothing to delete"
  fi
}

_do_backup() {
  _require_env BACKUP_DIR
  _require_env MARIADB_ROOT_PASSWORD
  local pod timestamp backup_file
  pod=$(_pod_name)
  timestamp=$(date +%Y%m%d_%H%M%S)
  backup_file="${BACKUP_DIR}/mariadb_${timestamp}.sql.gz"
  mkdir -p "$BACKUP_DIR"
  _kubectl exec --namespace "$MARIADB_NAMESPACE" "$pod" -- \
    mariadb-dump -u root --password="$MARIADB_ROOT_PASSWORD" --all-databases | gzip > "$backup_file"
  echo "Backup written to $backup_file"
}

_do_restore() {
  _require_env BACKUP_FILE
  _require_env MARIADB_ROOT_PASSWORD
  local pod
  pod=$(_pod_name)
  if [[ "$BACKUP_FILE" == *.gz ]]; then
    gunzip -c "$BACKUP_FILE" | _kubectl exec --stdin --namespace "$MARIADB_NAMESPACE" "$pod" -- \
      mariadb -u root --password="$MARIADB_ROOT_PASSWORD"
  else
    _kubectl exec --stdin --namespace "$MARIADB_NAMESPACE" "$pod" -- \
      mariadb -u root --password="$MARIADB_ROOT_PASSWORD" < "$BACKUP_FILE"
  fi
  echo "Restore completed from $BACKUP_FILE"
}

_do_health() {
  _require_env MARIADB_ROOT_PASSWORD
  local pod
  pod=$(_pod_name 2>/dev/null || true)
  if [ -z "$pod" ]; then
    echo "UNHEALTHY: no mariadb pod found in namespace $MARIADB_NAMESPACE" >&2
    exit 1
  fi
  if _kubectl exec --namespace "$MARIADB_NAMESPACE" "$pod" -- \
      mariadb -u root --password="$MARIADB_ROOT_PASSWORD" -e "SELECT 1" >/dev/null 2>&1; then
    echo "HEALTHY: mariadb is accepting queries"
  else
    echo "UNHEALTHY: mariadb did not respond to SELECT 1" >&2
    exit 1
  fi
}

_do_config() {
  _require_env MARIADB_ROOT_PASSWORD
  local pod
  pod=$(_pod_name)
  _kubectl exec --namespace "$MARIADB_NAMESPACE" "$pod" -- \
    mariadb -u root --password="$MARIADB_ROOT_PASSWORD" \
    -e "SHOW VARIABLES WHERE Variable_name IN ('max_connections','innodb_buffer_pool_size','innodb_log_file_size','character_set_server','collation_server');"
}

case "$CMD_TSK" in
  install) _do_install ;;
  update)  _do_update  ;;
  delete)  _do_delete  ;;
  backup)  _do_backup  ;;
  restore) _do_restore ;;
  health)  _do_health  ;;
  config)  _do_config  ;;
  *)
    echo "ERROR: unknown CMD_TSK='$CMD_TSK'. Valid: install|update|delete|backup|restore|health|config" >&2
    exit 1
    ;;
esac