#!/usr/bin/bash
set -euo pipefail
IFS=$'\n\t'

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
if [[ -d "${SCRIPT_DIR}/../../.git" ]] || [[ -f "${SCRIPT_DIR}/../../nodo/config/etc/mirrors.env" ]]; then
  REPO_ROOT="$(cd "${SCRIPT_DIR}/../.." && pwd)"
else
  REPO_ROOT="$(cd "${SCRIPT_DIR}/.." && pwd)"
fi

if [[ -f "${REPO_ROOT}/nodo/config/etc/mirrors.env" ]]; then
  # shellcheck source=/dev/null
  source "${REPO_ROOT}/nodo/config/etc/mirrors.env"
elif [[ -f "${REPO_ROOT}/config/etc/mirrors.env" ]]; then
  # shellcheck source=/dev/null
  source "${REPO_ROOT}/config/etc/mirrors.env"
elif [[ -f "${REPO_ROOT}/etc/mirrors.env" ]]; then
  # shellcheck source=/dev/null
  source "${REPO_ROOT}/etc/mirrors.env"
fi

STAGING_DIR="${MIRRORS_STAGING_DIR:-$HOME/ipfs/staging}"
SNAPSHOTS_DIR="${MIRRORS_SNAPSHOTS_DIR:-$HOME/ipfs/snapshots}"
mkdir -p "${STAGING_DIR}" "${SNAPSHOTS_DIR}"

# Definición canónica de módulos gestionados y sus rutas relativas en staging
declare -A MODULES=(
  ["fedora-iso-43"]="fedora/linux/releases/43/Server/x86_64/iso"
  ["fedora-iso-44"]="fedora/linux/releases/44/Server/x86_64/iso"
  ["fedora-iso-45"]="fedora/linux/development/45/Server/x86_64/iso"
  ["fedora-everything-43"]="fedora/linux/releases/43/Everything"
  ["fedora-everything-44"]="fedora/linux/releases/44/Everything"
  ["fedora-everything-45"]="fedora/linux/development/45/Everything"
  ["centos-baseos"]="centos-stream/10-stream/BaseOS"
  ["centos-appstream"]="centos-stream/10-stream/AppStream"
  ["centos-crb"]="centos-stream/10-stream/CRB"
  ["centos-ha"]="centos-stream/10-stream/HighAvailability"
  ["centos-nfv"]="centos-stream/10-stream/NFV"
  ["centos-rt"]="centos-stream/10-stream/RT"
  ["centos-extras"]="centos-stream/SIGs/10-stream/extras"
  ["centos-iso"]="centos-stream/10-stream/BaseOS/x86_64/iso"
  ["centos-sig-extras"]="centos-stream/SIGs/10-stream/extras"
  ["centos-sig-virt"]="centos-stream/SIGs/10-stream/virt"
  ["centos-sig-kmods"]="centos-stream/SIGs/10-stream/kmods"
  ["centos-sig-messaging"]="centos-stream/SIGs/10-stream/messaging"
  ["centos-sig-storage"]="centos-stream/SIGs/10-stream/storage"
  ["centos-sig-hyperscale"]="centos-stream/SIGs/10-stream/hyperscale"
)

# Orden de presentación consistente
MODULE_KEYS=(
  "fedora-iso-43"
  "fedora-iso-44"
  "fedora-iso-45"
  "fedora-everything-43"
  "fedora-everything-44"
  "fedora-everything-45"
  "centos-iso"
  "centos-baseos"
  "centos-appstream"
  "centos-crb"
  "centos-ha"
  "centos-nfv"
  "centos-rt"
  "centos-sig-extras"
  "centos-sig-virt"
  "centos-sig-kmods"
  "centos-sig-messaging"
  "centos-sig-storage"
  "centos-sig-hyperscale"
)

resolve_module_path() {
  local target="$1"
  if [[ -n "${MODULES[${target}]:-}" ]]; then
    echo "${STAGING_DIR}/${MODULES[${target}]}"
    return 0
  fi

  # Si el usuario suministró una ruta directa o relativa
  if [[ "${target}" = /* ]]; then
    echo "${target}"
  else
    echo "${STAGING_DIR}/${target}"
  fi
}

is_btrfs_fs() {
  local target_dir="$1"
  local parent_check="${target_dir}"
  while [[ ! -d "${parent_check}" && "${parent_check}" != "/" ]]; do
    parent_check="$(dirname "${parent_check}")"
  done
  local fstype
  fstype="$(stat -f -c %T "${parent_check}" 2>/dev/null || echo "unknown")"
  [[ "${fstype}" == "btrfs" ]]
}

is_subvolume() {
  local target_dir="$1"
  if [[ ! -d "${target_dir}" ]]; then
    return 1
  fi
  # En sistemas de archivos Btrfs, el inodo raíz de cualquier subvolumen es 256
  local inode
  inode="$(stat -c %i "${target_dir}" 2>/dev/null || echo "0")"
  [[ "${inode}" == "256" ]]
}

get_human_size() {
  local target_dir="$1"
  if [[ -d "${target_dir}" ]]; then
    du -sh "${target_dir}" 2>/dev/null | cut -f1
  else
    echo "0 B"
  fi
}

count_snapshots() {
  local mod_key="$1"
  find "${SNAPSHOTS_DIR}" -maxdepth 1 -mindepth 1 -name "${mod_key}-*" 2>/dev/null | wc -l
}

cmd_list() {
  echo "===================================================================================================="
  echo " Catálogo de Módulos y Estado de Subvolúmenes Btrfs"
  echo " Directorio raíz: ${STAGING_DIR}"
  echo " Directorio de instantáneas: ${SNAPSHOTS_DIR}"
  echo "===================================================================================================="
  printf "%-22s %-40s %-12s %-10s %s\n" "Identificador" "Ruta relativa" "Subvolumen" "Tamaño" "Instantáneas"
  echo "----------------------------------------------------------------------------------------------------"

  for key in "${MODULE_KEYS[@]}"; do
    local rel_path="${MODULES[${key}]}"
    local abs_path="${STAGING_DIR}/${rel_path}"
    local is_sub="no"
    if is_subvolume "${abs_path}"; then
      is_sub="sí (Btrfs)"
    elif [[ -d "${abs_path}" ]]; then
      is_sub="directorio"
    else
      is_sub="no existe"
    fi

    local sz
    sz="$(get_human_size "${abs_path}")"
    local snaps
    snaps="$(count_snapshots "${key}")"

    printf "%-22s %-40s %-12s %-10s %s\n" "${key}" "${rel_path}" "${is_sub}" "${sz}" "${snaps}"
  done
  echo "===================================================================================================="
}

init_single_subvolume() {
  local key="$1"
  local rel_path="${MODULES[${key}]:-${key}}"
  local target_path="${STAGING_DIR}/${rel_path}"

  if ! is_btrfs_fs "${target_path}"; then
    echo "ERROR: La ruta ${target_path} no reside sobre un sistema de archivos Btrfs." >&2
    return 1
  fi

  if is_subvolume "${target_path}"; then
    echo "==> Módulo '${key}': ya es un subvolumen Btrfs (${target_path})."
    return 0
  fi

  local parent_dir
  parent_dir="$(dirname "${target_path}")"
  mkdir -p "${parent_dir}"

  if [[ ! -e "${target_path}" ]]; then
    echo "==> Módulo '${key}': creando subvolumen Btrfs en ${target_path}..."
    btrfs subvolume create "${target_path}"
    return 0
  fi

  # Si existe como directorio convencional, migrar mediante copia por reflink CoW
  echo "==> Módulo '${key}': migrando directorio a subvolumen con CoW reflink (costo de almacenamiento cero)..."
  local temp_subvol="${target_path}.tmp_subvol_$$"
  btrfs subvolume create "${temp_subvol}"

  if [[ -n "$(ls -A "${target_path}" 2>/dev/null)" ]]; then
    echo "    Clonando metadatos y referencias de bloques..."
    cp -aT --reflink=always "${target_path}" "${temp_subvol}"
  fi

  local backup_old="${target_path}.old_dir_$$"
  mv "${target_path}" "${backup_old}"
  mv "${temp_subvol}" "${target_path}"

  echo "    Limpiando directorio antiguo..."
  rm -rf "${backup_old}"
  echo "==> Módulo '${key}': migración a subvolumen Btrfs completada exitosamente."
}

cmd_init() {
  local target="${1:-all}"
  if [[ "${target}" == "all" ]]; then
    echo "==> Inicializando todos los módulos como subvolúmenes Btrfs..."
    for key in "${MODULE_KEYS[@]}"; do
      init_single_subvolume "${key}"
    done
  elif [[ -n "${MODULES[${target}]:-}" ]]; then
    init_single_subvolume "${target}"
  else
    # Inicialización por ruta directa
    local mod_key="${target##*/}"
    init_single_subvolume "${mod_key}"
  fi
}

safe_delete_subvolume() {
  local target_subvol="$1"
  btrfs property set "${target_subvol}" ro false 2>/dev/null || true
  if ! btrfs subvolume delete "${target_subvol}" 2>/dev/null; then
    # shellcheck disable=SC2029
    ssh root@localhost btrfs subvolume delete "${target_subvol}"
  fi
}

cmd_delete() {
  local target="${1:-}"
  if [[ -z "${target}" ]]; then
    echo "ERROR: Debe especificar el módulo o subvolumen a eliminar." >&2
    echo "Uso: $0 delete <identificador-modulo|ruta>" >&2
    return 1
  fi

  local abs_path
  abs_path="$(resolve_module_path "${target}")"

  if [[ ! -e "${abs_path}" ]]; then
    echo "AVISO: La ruta ${abs_path} no existe en el sistema."
    return 0
  fi

  if is_subvolume "${abs_path}"; then
    echo "==> Eliminando subvolumen Btrfs de forma atómica e instantánea: ${abs_path}..."
    safe_delete_subvolume "${abs_path}"
    echo "==> Subvolumen eliminado exitosamente."
  else
    echo "AVISO: La ruta ${abs_path} es un directorio ordinario, no un subvolumen Btrfs."
    echo "==> Eliminando contenido mediante borrado recursivo..."
    rm -rf "${abs_path}"
    echo "==> Directorio eliminado."
  fi
}

cmd_snapshot() {
  local target="${1:-}"
  local tag="${2:-$(date -u +"%Y%m%d-%H%M%S")}"

  if [[ -z "${target}" ]]; then
    echo "ERROR: Debe especificar el módulo a respaldar mediante instantánea." >&2
    echo "Uso: $0 snapshot <identificador-modulo> [etiqueta]" >&2
    return 1
  fi

  local abs_path
  abs_path="$(resolve_module_path "${target}")"

  if ! is_subvolume "${abs_path}"; then
    echo "ERROR: La ruta ${abs_path} no es un subvolumen Btrfs activo." >&2
    echo "Ejecute previamente '$0 init ${target}' para convertirla en subvolumen." >&2
    return 1
  fi

  local snap_name="${target}-${tag}"
  local snap_dest="${SNAPSHOTS_DIR}/${snap_name}"

  echo "==> Creando instantánea de solo lectura con CoW (espacio adicional cero): ${snap_dest}..."
  btrfs subvolume snapshot -r "${abs_path}" "${snap_dest}"
  echo "==> Instantánea generada: ${snap_name}"
}

cmd_snapshots() {
  local filter="${1:-}"
  echo "===================================================================================================="
  echo " Instantáneas Btrfs en Almacén Local"
  echo " Directorio: ${SNAPSHOTS_DIR}"
  echo "===================================================================================================="
  printf "%-40s %-12s %s\n" "Nombre de Instantánea" "Tamaño" "Fecha de Creación"
  echo "----------------------------------------------------------------------------------------------------"

  local found=0
  for snap in "${SNAPSHOTS_DIR}"/*; do
    if [[ ! -d "${snap}" ]]; then
      continue
    fi
    local name
    name="$(basename "${snap}")"
    if [[ -n "${filter}" && "${name}" != *"${filter}"* ]]; then
      continue
    fi
    found=1
    local sz
    sz="$(get_human_size "${snap}")"
    local ctime
    ctime="$(stat -c '%y' "${snap}" 2>/dev/null | cut -d'.' -f1)"
    printf "%-40s %-12s %s\n" "${name}" "${sz}" "${ctime}"
  done

  if [[ "${found}" -eq 0 ]]; then
    echo "(No se encontraron instantáneas registradas)"
  fi
  echo "===================================================================================================="
}

cmd_rollback() {
  local target="${1:-}"
  local snap_name="${2:-}"

  if [[ -z "${target}" || -z "${snap_name}" ]]; then
    echo "ERROR: Argumentos insuficientes." >&2
    echo "Uso: $0 rollback <identificador-modulo> <nombre-instantanea>" >&2
    return 1
  fi

  local abs_path
  abs_path="$(resolve_module_path "${target}")"
  local snap_src="${SNAPSHOTS_DIR}/${snap_name}"

  if [[ ! -d "${snap_src}" ]]; then
    echo "ERROR: La instantánea ${snap_src} no existe." >&2
    return 1
  fi

  echo "==> Restaurando módulo '${target}' desde instantánea '${snap_name}'..."
  if is_subvolume "${abs_path}"; then
    echo "    Eliminando subvolumen actual..."
    safe_delete_subvolume "${abs_path}"
  elif [[ -d "${abs_path}" ]]; then
    echo "    Eliminando directorio actual..."
    rm -rf "${abs_path}"
  fi

  echo "    Creando subvolumen modificable derivado de la instantánea..."
  btrfs subvolume snapshot "${snap_src}" "${abs_path}"
  echo "==> Restauración completada exitosamente."
}

cmd_prune() {
  local target="${1:-}"
  local keep="${2:-3}"

  if [[ -z "${target}" ]]; then
    echo "ERROR: Debe especificar el módulo para podar instantáneas antiguas." >&2
    echo "Uso: $0 prune-snapshots <identificador-modulo> [cantidad-a-conservar]" >&2
    return 1
  fi

  local pattern="${target}-*"
  # shellcheck disable=SC2012
  local snaps
  mapfile -t snaps < <(find "${SNAPSHOTS_DIR}" -maxdepth 1 -mindepth 1 -name "${pattern}" 2>/dev/null | sort)
  local total="${#snaps[@]}"

  if [[ "${total}" -le "${keep}" ]]; then
    echo "==> Módulo '${target}': hay ${total} instantáneas (máximo permitido sin poda: ${keep}). No se requieren acciones."
    return 0
  fi

  local to_delete=$((total - keep))
  echo "==> Podando ${to_delete} instantáneas antiguas de '${target}' (conservando las últimas ${keep})..."

  for ((i = 0; i < to_delete; i++)); do
    local snap_del="${snaps[i]}"
    echo "    Eliminando instantánea: $(basename "${snap_del}")"
    safe_delete_subvolume "${snap_del}"
  done
  echo "==> Poda finalizada."
}

usage() {
  cat << EOF
Herramienta de Gestión de Módulos y Subvolúmenes Btrfs para Espejos MxOS

Uso:
  $0 list                                    Listar módulos, tamaño y estado de subvolúmenes
  $0 init [modulo|all]                       Inicializar o migrar módulos a subvolúmenes Btrfs
  $0 delete <modulo>                         Eliminar un módulo entero de forma instantánea y atómica
  $0 snapshot <modulo> [etiqueta]            Crear una instantánea de solo lectura con CoW
  $0 snapshots [filtro]                      Listar instantáneas almacenadas
  $0 rollback <modulo> <nombre-instantanea>  Restaurar un módulo a partir de una instantánea
  $0 prune-snapshots <modulo> [conservar]    Depurar instantáneas conservando las N más recientes

Módulos reconocidos:
  fedora-iso-43, fedora-iso-44, fedora-iso-45
  fedora-everything-43, fedora-everything-44, fedora-everything-45
  centos-baseos, centos-appstream, centos-crb, centos-ha, centos-nfv, centos-rt
  centos-sig-extras, centos-sig-virt, centos-sig-kmods, centos-sig-messaging, centos-sig-storage, centos-sig-hyperscale
EOF
}

main() {
  local action="${1:-list}"
  shift || true

  case "${action}" in
    list|status)
      cmd_list "$@"
      ;;
    init)
      cmd_init "$@"
      ;;
    delete|remove|rm)
      cmd_delete "$@"
      ;;
    snapshot|snap)
      cmd_snapshot "$@"
      ;;
    snapshots)
      cmd_snapshots "$@"
      ;;
    rollback)
      cmd_rollback "$@"
      ;;
    prune-snapshots|prune)
      cmd_prune "$@"
      ;;
    help|--help|-h)
      usage
      ;;
    *)
      echo "ERROR: Acción desconocida: ${action}" >&2
      usage >&2
      exit 1
      ;;
  esac
}

main "$@"