class ActiveStorage::Service::S3Service

def delete(key)
  instrument :delete, key: key do
    object_for(key).delete
  end
end

def delete_prefixed(prefix)
  instrument :delete_prefixed, prefix: prefix do
    bucket.objects(prefix: prefix).batch_delete!
  end
end

def download(key, &block)
  if block_given?
    instrument :streaming_download, key: key do
      stream(key, &block)
    end
  else
    instrument :download, key: key do
      object_for(key).get.body.string.force_encoding(Encoding::BINARY)
    end
  end
end

def download_chunk(key, range)
  instrument :download_chunk, key: key, range: range do
    object_for(key).get(range: "bytes=#{range.begin}-#{range.exclude_end? ? range.end - 1 : range.end}").body.read.force_encoding(Encoding::BINARY)
  end
end

def exist?(key)
  instrument :exist, key: key do |payload|
    answer = object_for(key).exists?
    payload[:exist] = answer
    answer
  end
end

def headers_for_direct_upload(key, content_type:, checksum:, **)
  { "Content-Type" => content_type, "Content-MD5" => checksum }
end

def initialize(bucket:, upload: {}, **options)
  @client = Aws::S3::Resource.new(**options)
  @bucket = @client.bucket(bucket)
  @upload_options = upload
end

def object_for(key)
  bucket.object(key)
end

def stream(key)
  object = object_for(key)
  chunk_size = 5.megabytes
  offset = 0
  while offset < object.content_length
    yield object.get(range: "bytes=#{offset}-#{offset + chunk_size - 1}").body.read.force_encoding(Encoding::BINARY)
    offset += chunk_size
  end
end

def upload(key, io, checksum: nil, **)
  instrument :upload, key: key, checksum: checksum do
    begin
      object_for(key).put(upload_options.merge(body: io, content_md5: checksum))
    rescue Aws::S3::Errors::BadDigest
      raise ActiveStorage::IntegrityError
    end
  end
end

def url(key, expires_in:, filename:, disposition:, content_type:)
  instrument :url, key: key do |payload|
    generated_url = object_for(key).presigned_url :get, expires_in: expires_in.to_i,
      response_content_disposition: content_disposition_with(type: disposition, filename: filename),
      response_content_type: content_type
    payload[:url] = generated_url
    generated_url
  end
end

def url_for_direct_upload(key, expires_in:, content_type:, content_length:, checksum:)
  instrument :url, key: key do |payload|
    generated_url = object_for(key).presigned_url :put, expires_in: expires_in.to_i,
      content_type: content_type, content_length: content_length, content_md5: checksum,
      whitelist_headers: ['content-length']
    payload[:url] = generated_url
    generated_url
  end
end