#!/usr/bin/env bash
#
# Delete files older than a defined number of days.
#
# This is a simple and practical maintenance script for temporary folders,
# export directories, application cache folders, and backup staging areas.
#
# Usage:
#   bash cleanup_old_files.sh --path /var/tmp/app --days 30 --dry-run
#   bash cleanup_old_files.sh --path /var/tmp/app --days 30 --delete
#
# Options:
#   --path DIR    Directory to scan.
#   --days N      Delete files older than N days.
#   --delete      Actually delete files.
#   --dry-run     Show what would be deleted. This is the default behavior.
#   --help        Show this help message.

set -Eeuo pipefail

target_path=""
days=""
delete_files=false

usage() {
  sed -n '2,18p' "$0" | sed 's/^# \{0,1\}//'
}

log() {
  printf '[%s] %s\n' "$(date '+%Y-%m-%d %H:%M:%S')" "$*"
}

while [[ "$#" -gt 0 ]]; do
  case "$1" in
    --path)
      target_path="${2:-}"
      shift 2
      ;;
    --days)
      days="${2:-}"
      shift 2
      ;;
    --delete)
      delete_files=true
      shift
      ;;
    --dry-run)
      delete_files=false
      shift
      ;;
    --help|-h)
      usage
      exit 0
      ;;
    *)
      printf 'ERROR: unknown option: %s\n' "$1" >&2
      usage >&2
      exit 1
      ;;
  esac
done

[[ -d "$target_path" ]] || { printf 'ERROR: directory not found: %s\n' "$target_path" >&2; exit 1; }
[[ "$days" =~ ^[0-9]+$ ]] || { printf 'ERROR: --days must be a positive number.\n' >&2; exit 1; }

log "Scanning '${target_path}' for files older than ${days} days."

if [[ "$delete_files" == true ]]; then
  log "Delete mode enabled."
  find "$target_path" -type f -mtime "+${days}" -print -delete
  log "Cleanup finished."
else
  log "Dry-run mode enabled. No files will be deleted."
  find "$target_path" -type f -mtime "+${days}" -print
  log "Dry-run finished."
fi