#!/usr/bin/env bash
# rotate-snapshots.sh — create today's daily snapshot + prune snapshots
# older than N days. Idempotent: safe to run repeatedly on the same day.
#
# Snapshots created by this script are named `daily-YYYY-MM-DD`. Only
# snapshots matching that prefix are candidates for pruning — hand-created
# snapshots (release-anchor, pre-migration, etc.) are never touched.
#
# Env / args:
#   CLAWSTOR_BIN     path to claw-store binary (default: ~/clawstor-deploy/claw-store)
#   CLAWSTOR_CONFIG  path to config.toml     (default: ~/clawstor-deploy/config.toml)
#   RETAIN_DAYS      snapshots older than this many days get pruned (default: 30)
#   DRY_RUN=1        print what would happen, no side effects

set -euo pipefail

CLAWSTOR_BIN=${CLAWSTOR_BIN:-$HOME/clawstor-deploy/claw-store}
CLAWSTOR_CONFIG=${CLAWSTOR_CONFIG:-$HOME/clawstor-deploy/config.toml}
RETAIN_DAYS=${RETAIN_DAYS:-30}
DRY_RUN=${DRY_RUN:-0}

if [ ! -x "$CLAWSTOR_BIN" ]; then
  echo "error: $CLAWSTOR_BIN not executable" >&2
  exit 1
fi

CS="$CLAWSTOR_BIN --config $CLAWSTOR_CONFIG"
TODAY=$(date +%Y-%m-%d)
NAME="daily-$TODAY"

echo "── rotate-snapshots ────────────────────────────────"
echo "today:      $NAME"
echo "retention:  $RETAIN_DAYS days"

# Create today's snapshot. Idempotent: `cluster-snapshot-create` errors
# if the name already exists — we treat that as success.
if [ "$DRY_RUN" = "1" ]; then
  echo "dry-run: would create snapshot $NAME"
else
  if $CS cluster-snapshot-create --name "$NAME" 2>&1 | tail -6; then
    echo "created:    $NAME"
  else
    echo "already exists (idempotent): $NAME"
  fi
fi

# Compute cutoff — POSIX date arithmetic (no GNU date extensions needed
# because we do the math on the epoch integer).
NOW_EPOCH=$(date +%s)
CUTOFF_EPOCH=$((NOW_EPOCH - RETAIN_DAYS * 86400))

# Snapshot list format:
#   CREATED_AT           NAME                 BLOBS      SIZE
#   1784046443           daily-2026-07-14     4          224
# So awk field 1 = epoch, field 2 = name.
PRUNE_LIST=$($CS cluster-snapshot-list 2>/dev/null | awk -v cutoff="$CUTOFF_EPOCH" '
    NR > 4 && $2 ~ /^daily-/ && $1 < cutoff { print $2 }
')

echo
if [ -z "$PRUNE_LIST" ]; then
  echo "nothing to prune"
else
  echo "prune candidates (older than $RETAIN_DAYS days):"
  echo "$PRUNE_LIST" | sed 's/^/  /'
  if [ "$DRY_RUN" = "1" ]; then
    echo "dry-run: no snapshots deleted"
  else
    echo "$PRUNE_LIST" | while read -r snap; do
      $CS cluster-snapshot-delete --name "$snap" 2>&1 | tail -1
    done
  fi
fi
echo "────────────────────────────────────────────────────"