#!/bin/sh
# Full system backup script
# Backs up entire system except excluded directories

set -e

# Config
CONFIG_FILE="/etc/backup.conf"
LOG_DIR="${HOME}/.local/var/log"
LOG_FILE="${LOG_DIR}/backup.log"
LOCK_FILE="/tmp/backup-full.lock"

# Ensure log directory exists
mkdir -p "$LOG_DIR"

# Colors
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m'

log() {
  echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*" >> "$LOG_FILE"
  echo "$*"
}

error() {
  printf "${RED}✖${NC} %s\n" "$1"
  log "ERROR: $1"
}

info() {
  printf "${BLUE}ℹ${NC} %s\n" "$1"
  log "INFO: $1"
}

success() {
  printf "${GREEN}✓${NC} %s\n" "$1"
  log "SUCCESS: $1"
}

# Load config
if [ ! -f "$CONFIG_FILE" ]; then
  error "Configuration file not found: $CONFIG_FILE"
  exit 1
fi

# shellcheck source=/dev/null
. "$CONFIG_FILE"

# Create lock file
if [ -f "$LOCK_FILE" ]; then
  error "Backup already running (lock file exists: $LOCK_FILE)"
  exit 1
fi

trap 'rm -f "$LOCK_FILE"' EXIT
touch "$LOCK_FILE"

# Check cooldown
if [ -f "$LAST_BACKUP_FILE" ]; then
  LAST_BACKUP=$(cat "$LAST_BACKUP_FILE")
  NOW=$(date +%s)
  ELAPSED=$((NOW - LAST_BACKUP))

  if [ "$ELAPSED" -lt "$BACKUP_COOLDOWN" ]; then
    REMAINING=$((BACKUP_COOLDOWN - ELAPSED))
    error "Backup cooldown active. Wait ${REMAINING}s before next backup"
    exit 0
  fi
fi

# Start backup
log "=========================================="
log "Starting FULL SYSTEM BACKUP"
log "=========================================="

# Check NAS connectivity
info "Checking NAS connectivity..."
if ! ping -c 1 -W 2 "$NAS_HOST" >/dev/null 2>&1; then
  error "NAS host $NAS_HOST is not reachable"
  exit 1
fi

if ! ssh -p "$NAS_PORT" -o ConnectTimeout=5 -o BatchMode=yes \
     "${NAS_USER}@${NAS_HOST}" "echo test" >/dev/null 2>&1; then
  error "SSH connection to NAS failed"
  exit 1
fi

success "NAS is reachable"

# Create backup directory name with timestamp
BACKUP_NAME="full-$(date +%Y%m%d-%H%M%S)"
BACKUP_DEST="${NAS_USER}@${NAS_HOST}:${NAS_PATH}/${BACKUP_NAME}"

info "Backup destination: ${BACKUP_DEST}"

# Build exclude arguments for rsync
EXCLUDE_ARGS=""
for pattern in "${EXCLUDE_PATTERNS[@]}"; do
  EXCLUDE_ARGS="$EXCLUDE_ARGS --exclude=$pattern"
done

# Run rsync backup
info "Starting rsync (this may take a while)..."

# shellcheck disable=SC2086
if rsync -avz --delete --numeric-ids \
  --rsync-path="mkdir -p ${NAS_PATH}/${BACKUP_NAME} && rsync" \
  -e "ssh -p ${NAS_PORT}" \
  $EXCLUDE_ARGS \
  / \
  "$BACKUP_DEST" >> "$LOG_FILE" 2>&1; then

  success "Backup completed successfully!"

  # Update last backup timestamp
  LAST_BACKUP_FILE="${HOME}/.local/var/backup/last-backup"
  mkdir -p "$(dirname "$LAST_BACKUP_FILE")"
  date +%s > "$LAST_BACKUP_FILE"

  # Log backup size
  BACKUP_SIZE=$(ssh -p "$NAS_PORT" "${NAS_USER}@${NAS_HOST}" \
    "du -sh '${NAS_PATH}/${BACKUP_NAME}' 2>/dev/null | cut -f1" || echo "unknown")
  info "Backup size: $BACKUP_SIZE"

  # Clean up old backups (keep last N)
  info "Cleaning up old backups (keeping last ${RETENTION_COUNT})..."
  ssh -p "$NAS_PORT" "${NAS_USER}@${NAS_HOST}" \
    "cd '${NAS_PATH}' && ls -t | grep '^full-' | tail -n +$((RETENTION_COUNT + 1)) | xargs -r rm -rf" \
    >> "$LOG_FILE" 2>&1 || true

else
  error "Backup failed! Check $LOG_FILE for details"
  exit 1
fi

log "=========================================="
log "Backup completed at $(date)"
log "=========================================="