/**
 * Move validation utilities for S3 objects
 */

export interface IMoveValidation {
  valid: boolean;
  error?: string;
}

/**
 * Validates if a move operation is allowed
 * @param sourceKey The source object key (file or folder with trailing /)
 * @param destPrefix The destination prefix (folder)
 * @returns Validation result with error message if invalid
 */
export function validateMove(sourceKey: string, destPrefix: string): IMoveValidation {
  // Check: Moving folder into itself or a subfolder of itself
  if (sourceKey.endsWith('/')) {
    // It's a folder - check if destPrefix starts with sourceKey
    if (destPrefix.startsWith(sourceKey)) {
      return { valid: false, error: 'Cannot move a folder into itself' };
    }
  }

  // Check: Source and dest are the same location
  const sourceParent = getParentPrefix(sourceKey);
  if (sourceParent === destPrefix) {
    return { valid: false, error: 'Item is already in this location' };
  }

  return { valid: true };
}

/**
 * Gets the parent prefix (directory) of a given key
 * @param key The object key (file or folder)
 * @returns The parent prefix
 */
export function getParentPrefix(key: string): string {
  // "folder1/folder2/file.txt" -> "folder1/folder2/"
  // "folder1/folder2/" -> "folder1/"
  // "file.txt" -> ""
  // "folder/" -> ""
  const trimmed = key.endsWith('/') ? key.slice(0, -1) : key;
  const lastSlash = trimmed.lastIndexOf('/');
  return lastSlash >= 0 ? trimmed.substring(0, lastSlash + 1) : '';
}