module JSONAPI::Relationships::ActiveStorageRemoval

def extract_blob_id_from_identifier(identifier)
  type = RelationshipHelpers.extract_type_from_identifier(identifier)
  id = RelationshipHelpers.extract_id_from_identifier(identifier)
  validate_blob_type!(type)
  id.to_i
end

def extract_blob_ids(relationship_data)
  relationship_data.map { |identifier| extract_blob_id_from_identifier(identifier) }
end

def extract_single_blob_id(relationship_data)
  extract_blob_id_from_identifier(relationship_data)
end

def remove_active_storage_relationship(relationship_data)
  reflection = @resource.class.reflect_on_attachment(@relationship_name)
  if reflection&.macro == :has_many_attached
    remove_many_active_storage_attachments(relationship_data)
  else
    remove_one_active_storage_attachment(relationship_data)
  end
end

def remove_many_active_storage_attachments(relationship_data)
  raise ArgumentError, "Expected array for to-many relationship removal" unless relationship_data.is_a?(Array)
  return if relationship_data.empty?
  attachment_proxy = @resource.public_send(@relationship_name)
  return unless attachment_proxy.attached?
  blob_ids = extract_blob_ids(relationship_data)
  attachments = attachment_proxy.attachments.where(blob_id: blob_ids)
  attachments.each(&:purge)
end

def remove_one_active_storage_attachment(relationship_data)
  validate_single_removal_identifier!(relationship_data)
  return if relationship_data.nil?
  attachment_proxy = @resource.public_send(@relationship_name)
  return unless attachment_proxy.attached?
  blob_id = extract_single_blob_id(relationship_data)
  attachment = attachment_proxy.attachments.find_by(blob_id:)
  attachment&.purge
end

def validate_blob_type!(type)
  return if self.class.active_storage_blob_type?(type)
  raise ArgumentError, "Expected active_storage_blobs type, got #{type}"
end