#!/usr/bin/env bash
# 005-mount-pgdata - Mount the dedicated 20G data disk (/dev/sdb, ext4)
# at /var/lib/postgresql so the PostgreSQL cluster lives on its own disk.
# Mounted by UUID (stable across device reordering), noatime for DB workload.
# up:   fstab entry + mount (idempotent; refuses if mountpoint holds data)
# down: unmount + remove fstab entry (data on the disk is preserved)
set -euo pipefail

DISK_UUID=d44ad362-947a-46de-acbf-5530f83e4506
MOUNTPOINT=/var/lib/postgresql
FSTAB_LINE="UUID=$DISK_UUID $MOUNTPOINT ext4 defaults,noatime 0 2"

case "${1:-}" in
  up)
    if findmnt -rn "$MOUNTPOINT" >/dev/null; then
      echo "    $MOUNTPOINT already mounted - skipping"
      exit 0
    fi
    dev=$(findfs UUID="$DISK_UUID") || {
      echo "disk with UUID=$DISK_UUID not found - is /dev/sdb attached?" >&2
      exit 1
    }
    # Never mount over existing data - it would be silently hidden
    if [[ -d $MOUNTPOINT ]] && find "$MOUNTPOINT" -mindepth 1 -print -quit | grep -q .; then
      echo "refusing to mount: $MOUNTPOINT exists and is not empty" >&2
      exit 1
    fi
    mkdir -p "$MOUNTPOINT"
    grep -q "^UUID=$DISK_UUID" /etc/fstab || echo "$FSTAB_LINE" >> /etc/fstab
    mount "$MOUNTPOINT"   # via fstab entry - also validates it
    echo "    $dev mounted at $MOUNTPOINT (noatime, fstab entry added)"
    ;;
  status)
    src=$(findmnt -rn -o SOURCE "$MOUNTPOINT" 2>/dev/null || true)
    want=$(readlink -f "/dev/disk/by-uuid/$DISK_UUID" 2>/dev/null || true)
    [[ -n $want ]] || { echo "? cannot resolve UUID=$DISK_UUID"; exit 2; }
    [[ -n $src ]] || { echo "DRIFT $MOUNTPOINT not mounted"; exit 1; }
    [[ $src == "$want" ]] || { echo "DRIFT $MOUNTPOINT mounted from $src (want $want)"; exit 1; }
    grep -q "^UUID=$DISK_UUID $MOUNTPOINT " /etc/fstab \
      || { echo "DRIFT fstab entry missing"; exit 1; }
    echo "OK $src at $MOUNTPOINT + fstab entry"
    ;;
  down)
    # sysmig rolls back in reverse order, so 006 (postgres) is already down
    if findmnt -rn "$MOUNTPOINT" >/dev/null; then umount "$MOUNTPOINT"; fi
    sed -i "\|^UUID=$DISK_UUID|d" /etc/fstab
    rmdir "$MOUNTPOINT" 2>/dev/null || true   # keep dir if data remains
    echo "    $MOUNTPOINT unmounted + fstab entry removed (disk data kept)"
    ;;
esac