#!/bin/sh
set -eu

destination="${BACKUP_DESTINATION:-/backups}"
secondary="${BACKUP_SECONDARY_DESTINATION:-}"
interval="${BACKUP_INTERVAL_SECONDS:-86400}"
retention_days="${BACKUP_RETENTION_DAYS:-30}"
minimum_copies="${BACKUP_MINIMUM_COPIES:-7}"
restore_drill_interval="${BACKUP_RESTORE_DRILL_INTERVAL_SECONDS:-604800}"

case "$destination" in ""|"/"|".") echo "Unsafe backup destination: $destination" >&2; exit 1;; esac
case "$interval:$retention_days:$minimum_copies:$restore_drill_interval" in *[!0-9:]*|:*|*:) echo "Backup settings must be integers" >&2; exit 1;; esac
mkdir -p "$destination"
[ -z "$secondary" ] || mkdir -p "$secondary"

while true; do
  timestamp="$(date -u +%Y%m%dT%H%M%SZ)"
  target="$destination/mobilityops-$timestamp.dump"
  temporary="$target.partial"
  rm -f "$temporary"
  if pg_dump --format=custom --no-owner --no-acl \
      --host=db --username="$POSTGRES_USER" "$POSTGRES_DB" > "$temporary" \
      && pg_restore --list "$temporary" > /dev/null; then
    mv "$temporary" "$target"
    (cd "$destination" && sha256sum "$(basename "$target")" > "$(basename "$target").sha256")
    if [ -n "$secondary" ]; then
      cp "$target" "$target.sha256" "$secondary/"
      (cd "$secondary" && sha256sum -c "$(basename "$target.sha256")")
    fi
    date -u +%Y-%m-%dT%H:%M:%SZ > "$destination/latest-success"
    BACKUP_RETENTION_DAYS="$retention_days" BACKUP_MINIMUM_COPIES="$minimum_copies" \
      /opt/mobilityops/prune-postgres-backups.sh "$destination"
    if [ -n "$secondary" ]; then
      BACKUP_RETENTION_DAYS="$retention_days" BACKUP_MINIMUM_COPIES="$minimum_copies" \
        /opt/mobilityops/prune-postgres-backups.sh "$secondary"
    fi
    drill_minutes=$((restore_drill_interval / 60))
    if [ ! -f "$destination/latest-restore-drill" ] \
        || ! find "$destination/latest-restore-drill" -mmin "-$drill_minutes" -print -quit | grep -q .; then
      if /opt/mobilityops/restore-drill-postgres.sh "$target"; then
        date -u +%Y-%m-%dT%H:%M:%SZ > "$destination/latest-restore-drill"
      else
        echo "Restore drill failed for $target" >&2
      fi
    fi
    echo "Verified database backup: $target"
  else
    rm -f "$temporary"
    echo "Database backup failed at $timestamp" >&2
  fi
  sleep "$interval"
done