#!/bin/bash
# =============================================================================
# plugin/sbin/podman-storage.sh
#
# "Container Storage erstellen" — creates, mounts, and unmounts the
# podman.img loopback filesystem that backs Podman's overlay storage graph
# (images, containers, named volumes). See docs/ARCHITECTURE.md section 4.3
# for why this needs to be a real mounted filesystem (XFS with ftype=1, on a
# cache pool or dedicated disk) rather than a directory under /mnt/user —
# the FUSE (shfs) layer behind /mnt/user does not reliably support the
# overlay storage driver's filesystem requirements (d_type, etc).
#
# Usage:
#   podman-storage.sh create   # create podman.img if it doesn't exist yet
#   podman-storage.sh mount    # mount it at $PODMAN_GRAPHROOT (idempotent)
#   podman-storage.sh unmount  # cleanly unmount
#   podman-storage.sh status   # report existence/mount/usage
# =============================================================================

set -eu

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
# shellcheck source=./podman-common.sh
. "$SCRIPT_DIR/podman-common.sh"

podman_load_cfg

# -----------------------------------------------------------------------------
# cmd_create
#
# Creates podman.img at the configured size if it doesn't already exist,
# and formats it XFS with ftype=1 (required for the overlay storage driver
# to see correct directory entry types — without it, podman's overlay
# backend silently falls back to a slower/less-capable mode or fails
# outright, depending on version). Does nothing (and exits 0) if the image
# already exists — this script is meant to be safe to call on every boot.
# -----------------------------------------------------------------------------
cmd_create() {
  if ! podman_storage_path_is_safe "$STORAGE_PATH"; then
    return 1
  fi

  if [ -f "$PODMAN_STORAGE_IMAGE" ]; then
    podman_log "storage: $PODMAN_STORAGE_IMAGE already exists, not recreating"
    return 0
  fi

  if [ ! -d "$STORAGE_PATH" ]; then
    podman_log_error "storage: $STORAGE_PATH does not exist or is not mounted."
    podman_log_error "storage: check that the configured cache pool/disk is present before starting podman."
    return 1
  fi

  # Free space check: refuse to create an image bigger than what's actually
  # available, with a small safety margin, rather than letting truncate
  # silently create a sparse file that will fail unpredictably later once
  # it's actually written to (see docs/ARCHITECTURE.md section 16.2).
  local available_kb required_kb
  available_kb=$(df --output=avail -k "$STORAGE_PATH" | tail -n1 | tr -d '[:space:]')
  required_kb=$((STORAGE_IMAGE_SIZE_GB * 1024 * 1024))
  if [ "$available_kb" -lt "$required_kb" ]; then
    podman_log_error "storage: not enough free space on $STORAGE_PATH (need ${STORAGE_IMAGE_SIZE_GB}G, have $((available_kb / 1024 / 1024))G)"
    podman_notify "Podman storage creation failed" \
      "Not enough free space on $STORAGE_PATH for a ${STORAGE_IMAGE_SIZE_GB}G podman.img." \
      "alert"
    return 1
  fi

  podman_log "storage: creating ${STORAGE_IMAGE_SIZE_GB}G image at $PODMAN_STORAGE_IMAGE"
  mkdir -p "$STORAGE_PATH"

  # Sparse file: only actually consumes disk space as data is written,
  # matching Docker-for-Unraid's docker.img behavior that users already
  # understand.
  truncate -s "${STORAGE_IMAGE_SIZE_GB}G" "$PODMAN_STORAGE_IMAGE"

  podman_require_command mkfs.xfs
  # -n ftype=1 is the whole reason this has to be a purpose-made image
  # rather than a plain directory — see file header comment.
  mkfs.xfs -n ftype=1 -q "$PODMAN_STORAGE_IMAGE"

  podman_log "storage: created and formatted $PODMAN_STORAGE_IMAGE"
}

# -----------------------------------------------------------------------------
# cmd_mount
#
# Idempotent: does nothing if $PODMAN_GRAPHROOT is already mounted from
# podman.img. Runs a read-only integrity check (xfs_repair -n) before
# mounting and refuses to proceed if it reports corruption — per
# docs/ARCHITECTURE.md section 16.1, this project does not auto-repair
# storage without the user's explicit action, to avoid silent data loss.
# -----------------------------------------------------------------------------
cmd_mount() {
  if mountpoint -q "$PODMAN_GRAPHROOT" 2> /dev/null; then
    podman_log "storage: $PODMAN_GRAPHROOT already mounted"
    return 0
  fi

  if [ ! -f "$PODMAN_STORAGE_IMAGE" ]; then
    podman_log_error "storage: $PODMAN_STORAGE_IMAGE does not exist — run 'podman-storage.sh create' first"
    return 1
  fi

  podman_require_command xfs_repair
  podman_log "storage: checking filesystem integrity of $PODMAN_STORAGE_IMAGE"
  if ! xfs_repair -n "$PODMAN_STORAGE_IMAGE" > /tmp/podman-xfs-repair.log 2>&1; then
    podman_log_error "storage: filesystem check failed for $PODMAN_STORAGE_IMAGE — refusing to mount."
    podman_log_error "storage: see /tmp/podman-xfs-repair.log. Run 'xfs_repair $PODMAN_STORAGE_IMAGE' manually to attempt repair, or restore from backup."
    podman_notify "Podman storage corruption detected" \
      "$PODMAN_STORAGE_IMAGE failed an integrity check and was not mounted. Manual recovery required — see plugin.log." \
      "alert"
    return 1
  fi

  mkdir -p "$PODMAN_GRAPHROOT"
  podman_log "storage: mounting $PODMAN_STORAGE_IMAGE at $PODMAN_GRAPHROOT"
  mount -o loop "$PODMAN_STORAGE_IMAGE" "$PODMAN_GRAPHROOT"

  # Runtime state (runroot) is tmpfs-backed and fine to live on RAM-root —
  # only the persistent graphroot needs the loopback filesystem.
  mkdir -p /var/run/containers/storage

  podman_log "storage: mounted"
}

# -----------------------------------------------------------------------------
# cmd_unmount
#
# Unmounts cleanly. Retries briefly if the mount is momentarily busy (a
# container process exiting can hold a reference for a few hundred ms),
# rather than immediately failing rc.podman's stop sequence.
# -----------------------------------------------------------------------------
cmd_unmount() {
  if ! mountpoint -q "$PODMAN_GRAPHROOT" 2> /dev/null; then
    podman_log "storage: $PODMAN_GRAPHROOT not mounted, nothing to do"
    return 0
  fi

  podman_log "storage: unmounting $PODMAN_GRAPHROOT"
  local attempt
  for attempt in 1 2 3 4 5; do
    if umount "$PODMAN_GRAPHROOT" 2> /dev/null; then
      podman_log "storage: unmounted"
      return 0
    fi
    sleep 1
  done

  podman_log_error "storage: failed to unmount $PODMAN_GRAPHROOT after 5 attempts (still busy?)"
  return 1
}

cmd_status() {
  echo "storage image:     $PODMAN_STORAGE_IMAGE"
  if [ -f "$PODMAN_STORAGE_IMAGE" ]; then
    echo "  exists:           yes ($(du -h "$PODMAN_STORAGE_IMAGE" | cut -f1) allocated / ${STORAGE_IMAGE_SIZE_GB}G nominal)"
  else
    echo "  exists:           no"
  fi

  echo "graphroot:          $PODMAN_GRAPHROOT"
  if mountpoint -q "$PODMAN_GRAPHROOT" 2> /dev/null; then
    echo "  mounted:          yes"
    df -h "$PODMAN_GRAPHROOT" | tail -n1 | awk '{print "  usage:            " $3 " used / " $2 " total (" $5 " full)"}'
  else
    echo "  mounted:          no"
  fi
}

case "${1:-}" in
  create)  cmd_create ;;
  mount)   cmd_mount ;;
  unmount) cmd_unmount ;;
  status)  cmd_status ;;
  *)
    echo "usage: $0 {create|mount|unmount|status}" >&2
    exit 1
    ;;
esac