#!/usr/bin/env bash
#
# VYNDR nightly database backup (security follow-up item 2).
#
# Supabase free tier has ZERO backups (no scheduled, no PITR) — the ledger and
# everything else have no safety net. This dumps the WHOLE database nightly via
# the direct connection string, keeps 14 days locally, pushes a weekly copy
# off-box, and pages ntfy on ANY failure. Runs on the Hetzner box via cron.
#
# REQUIRED env (set on the box / in the container that runs the cron):
#   SUPABASE_DB_URL   the Supabase DIRECT connection string (session mode, the
#                     db.<ref>.supabase.co:5432 URL — NOT the :6543 pooler;
#                     pg_dump needs a real session). Kev pastes this in Coolify.
# OPTIONAL env:
#   BACKUP_DIR        local dump dir            (default /var/backups/vyndr)
#   BACKUP_KEEP_DAYS  local retention           (default 14)
#   BACKUP_REMOTE     off-box rsync target for the weekly copy, e.g.
#                     u123456@u123456.your-storagebox.de:vyndr-backups/
#                     (empty = skip the off-box push; a WARN is paged)
#   NTFY_URL          (default https://ntfy.sh)
#   NTFY_TOPIC        (default vyndr-backups-kev2026)
#
set -Eeuo pipefail

BACKUP_DIR="${BACKUP_DIR:-/var/backups/vyndr}"
KEEP_DAYS="${BACKUP_KEEP_DAYS:-14}"
NTFY_URL="${NTFY_URL:-https://ntfy.sh}"
NTFY_TOPIC="${NTFY_TOPIC:-vyndr-backups-kev2026}"
STAMP="$(date -u +%Y%m%d-%H%M%S)"
DUMP="${BACKUP_DIR}/vyndr-${STAMP}.dump"
MIN_BYTES="${BACKUP_MIN_BYTES:-50000}"   # a real dump of this DB is far bigger; guards an empty/failed dump

notify() {  # notify <title> <priority> <message>
  curl -fsS --max-time 15 \
    -H "Title: ${1}" -H "Priority: ${2}" -H "Tags: floppy_disk" \
    -d "${3}" "${NTFY_URL}/${NTFY_TOPIC}" >/dev/null 2>&1 || true
}

fail() { notify "VYNDR backup FAILED" "urgent" "${1}"; echo "ERROR: ${1}" >&2; exit 1; }
trap 'fail "backup script errored near line ${LINENO}"' ERR

[ -n "${SUPABASE_DB_URL:-}" ] || fail "SUPABASE_DB_URL is not set — cannot back up"
command -v pg_dump >/dev/null 2>&1 || fail "pg_dump not installed (apt-get install postgresql-client)"
mkdir -p "${BACKUP_DIR}"

# 1. Dump the whole DB in custom format (-Fc: compressed, restorable with pg_restore).
pg_dump "${SUPABASE_DB_URL}" -Fc --no-owner --no-privileges -f "${DUMP}" \
  || fail "pg_dump failed"

# 2. Sanity: a real dump is not tiny. An empty/near-empty file is a silent failure.
SIZE="$(stat -c%s "${DUMP}" 2>/dev/null || echo 0)"
[ "${SIZE}" -ge "${MIN_BYTES}" ] || fail "dump is only ${SIZE} bytes (< ${MIN_BYTES}) — treating as a failed backup"

# 2b. Integrity fingerprint: a valid custom-format archive lists its objects via
#     pg_restore --list (no target DB needed). Confirm it parses AND contains the
#     ledger — proves it's a real, restorable archive, not just a file of bytes.
TOC="$(pg_restore --list "${DUMP}" 2>/dev/null)" || fail "pg_restore --list failed — dump is not a valid archive"
OBJECTS="$(printf '%s\n' "${TOC}" | grep -c ';' || true)"
printf '%s\n' "${TOC}" | grep -qi 'TABLE DATA public ledger_entries' \
  || fail "dump archive does not contain ledger_entries — refusing to trust it"
echo "backup validated: ${DUMP} (${SIZE} bytes, ${OBJECTS} archive objects, ledger_entries present)"

# 3. Rotate: drop local dumps older than KEEP_DAYS.
find "${BACKUP_DIR}" -name 'vyndr-*.dump' -type f -mtime "+${KEEP_DAYS}" -delete || true

# 3b. SSH key for the off-box push (Session 64).
#     The container filesystem is EPHEMERAL — a keypair generated inside it dies
#     on the next redeploy and the off-box push would silently start failing. So
#     the PRIVATE key is injected as an env var (Coolify secret) and written to a
#     0600 temp file per run. Hetzner Storage Box speaks full OpenSSH on PORT 23
#     (port 22 is SFTP-only, mod_sftp) — verified live; rsync must target 23.
SSH_KEY_FILE=""
cleanup_key() { [ -n "${SSH_KEY_FILE}" ] && rm -f "${SSH_KEY_FILE}" || true; }
trap cleanup_key EXIT
RSYNC_SSH="ssh -p ${BACKUP_SSH_PORT:-23} -o StrictHostKeyChecking=accept-new -o BatchMode=yes"
if [ -n "${BACKUP_SSH_KEY:-}" ]; then
  SSH_KEY_FILE="$(mktemp)"
  chmod 600 "${SSH_KEY_FILE}"
  # Accept the key with literal \n escapes (how env vars usually carry it).
  printf '%b\n' "${BACKUP_SSH_KEY}" | sed -e 's/[[:space:]]*$//' > "${SSH_KEY_FILE}"
  RSYNC_SSH="${RSYNC_SSH} -i ${SSH_KEY_FILE}"
fi

# 4. OFF-BOX COPY — every night, not only Sundays (Session 64).
#    A weekly push meant up to 6 days of dumps existed ONLY inside an ephemeral
#    container, which is the same as not existing. Off-box is the real backup.
if true; then
  if [ -n "${BACKUP_REMOTE:-}" ]; then
    if rsync -az --timeout=120 -e "${RSYNC_SSH}" "${DUMP}" "${BACKUP_REMOTE}"; then
      notify "VYNDR backup OK (+off-box)" "default" "Nightly dump ${STAMP} (${SIZE} bytes) pushed off-box to ${BACKUP_REMOTE%%:*}."
    else
      notify "VYNDR off-box push FAILED" "high" "Local dump ${STAMP} is fine (${SIZE} bytes) but the off-box rsync FAILED — the dump exists only in an ephemeral container."
    fi
  else
    notify "VYNDR off-box push SKIPPED" "high" "Local dump ${STAMP} OK but BACKUP_REMOTE is unset — the dump exists only in an ephemeral container."
  fi
else
  echo "backup ok: ${DUMP} (${SIZE} bytes)"
fi

exit 0