#!/bin/bash
set -euo pipefail

BACKUP_DIR="/opt/memento/backups"
SNAPSHOT_DIR="$BACKUP_DIR/snapshots"
PG_CONTAINER="memento-postgres"
PG_USER="${POSTGRES_USER:-memento}"
PG_DB="${POSTGRES_DB:-memento}"
LOG_FILE="$BACKUP_DIR/backup.log"

TELEGRAM_BOT_TOKEN="${TELEGRAM_BOT_TOKEN:-}"
TELEGRAM_CHAT_ID="${TELEGRAM_CHAT_ID:-}"

log() {
  echo "[$(date '+%Y-%m-%d %H:%M:%S')] $1" | tee -a "$LOG_FILE"
}

send_alert() {
  if [ -n "$TELEGRAM_BOT_TOKEN" ] && [ -n "$TELEGRAM_CHAT_ID" ]; then
    curl -s -X POST "https://api.telegram.org/bot${TELEGRAM_BOT_TOKEN}/sendMessage" \
      -d chat_id="$TELEGRAM_CHAT_ID" \
      -d text="$1" \
      -d parse_mode="HTML" >/dev/null 2>&1 || true
  fi
}

ISSUES=0

log "=== Backup verification ==="

LATEST_SNAPSHOT=$(ls -t "$SNAPSHOT_DIR"/*.sql.gz 2>/dev/null | head -1)
if [ -z "$LATEST_SNAPSHOT" ]; then
  log "CRITICAL: No snapshots found!"
  send_alert "🚨 MEMENTO: No database backups found! Data at risk!"
  exit 1
fi

SNAPSHOT_AGE=$(( ( $(date +%s) - $(stat -c%Y "$LATEST_SNAPSHOT") ) / 3600 ))
if [ "$SNAPSHOT_AGE" -gt 8 ]; then
  log "CRITICAL: Latest snapshot is ${SNAPSHOT_AGE}h old (> 8h threshold)"
  send_alert "🚨 MEMENTO: Latest DB backup is ${SNAPSHOT_AGE}h old! Backup cron may be broken!"
  ISSUES=$((ISSUES + 1))
else
  log "OK: Latest snapshot is ${SNAPSHOT_AGE}h old"
fi

SNAPSHOT_SIZE=$(stat -c%s "$LATEST_SNAPSHOT" 2>/dev/null || echo 0)
if [ "$SNAPSHOT_SIZE" -lt 1048576 ]; then
  log "CRITICAL: Snapshot is only $(( SNAPSHOT_SIZE / 1024 ))KB (< 1MB)"
  send_alert "🚨 MEMENTO: DB backup is suspiciously small ($(( SNAPSHOT_SIZE / 1024 ))KB)! Possible failure!"
  ISSUES=$((ISSUES + 1))
else
  log "OK: Snapshot size $(( SNAPSHOT_SIZE / 1024 ))KB"
fi

if ! gzip -t "$LATEST_SNAPSHOT" 2>/dev/null; then
  log "CRITICAL: Snapshot integrity check FAILED"
  send_alert "🚨 MEMENTO: DB backup integrity check FAILED! Backup is corrupted!"
  ISSUES=$((ISSUES + 1))
else
  log "OK: Snapshot integrity check passed"
fi

DB_NOTES=$(docker exec "$PG_CONTAINER" psql -U "$PG_USER" -d "$PG_DB" -t -c "SELECT COUNT(*) FROM \"Note\";" 2>/dev/null | tr -d ' ' || echo "ERROR")
DB_USERS=$(docker exec "$PG_CONTAINER" psql -U "$PG_USER" -d "$PG_DB" -t -c "SELECT COUNT(*) FROM \"User\";" 2>/dev/null | tr -d ' ' || echo "ERROR")

if [ "$DB_NOTES" = "ERROR" ] || [ "$DB_NOTES" = "0" ]; then
  log "CRITICAL: DB query returned $DB_NOTES notes"
  send_alert "🚨 MEMENTO: Database appears empty or unreachable! Notes count: $DB_NOTES"
  ISSUES=$((ISSUES + 1))
else
  log "OK: Database has $DB_NOTES notes, $DB_USERS users"
fi

APP_CODE=$(curl -s -o /dev/null -w "%{http_code}" --max-time 5 "http://localhost:3000/api/build-info" 2>/dev/null || echo "000")
if [ "$APP_CODE" = "000" ] || [ "$APP_CODE" -ge 500 ]; then
  log "CRITICAL: App health check failed (HTTP $APP_CODE)"
  send_alert "🚨 MEMENTO: App is down! Health check returned HTTP $APP_CODE"
  ISSUES=$((ISSUES + 1))
else
  log "OK: App is healthy (HTTP $APP_CODE)"
fi

DISK_PCT=$(df -h /opt/memento | awk 'NR==2{print $5}' | tr -d '%')
if [ "$DISK_PCT" -gt 85 ]; then
  log "WARNING: Disk usage at ${DISK_PCT}%"
  send_alert "⚠️ MEMENTO: Disk usage at ${DISK_PCT}%! Consider cleanup."
  ISSUES=$((ISSUES + 1))
else
  log "OK: Disk usage at ${DISK_PCT}%"
fi

if [ "$ISSUES" -eq 0 ]; then
  log "=== All checks PASSED ==="
else
  log "=== $ISSUES issue(s) found ==="
  exit 1
fi