# frozen_string_literal: true
module Gitlab
  module Lfs
    # Gitlab::Lfs::Client implements a simple LFS client, designed to talk to
    # LFS servers as described in these documents:
    #   * https://github.com/git-lfs/git-lfs/blob/master/docs/api/batch.md
    #   * https://github.com/git-lfs/git-lfs/blob/master/docs/api/basic-transfers.md
    class Client
      attr_reader :base_url

      def initialize(base_url, credentials:)
        @base_url = base_url
        @credentials = credentials
      end

      def batch(operation, objects)
        body = {
          operation: operation,
          transfers: ['basic'],
          # We don't know `ref`, so can't send it
          objects: objects.map { |object| { oid: object.oid, size: object.size } }
        }

        rsp = Gitlab::HTTP.post(
          batch_url,
          basic_auth: basic_auth,
          body: body.to_json,
          headers: { 'Content-Type' => 'application/vnd.git-lfs+json' }
        )

        raise BatchSubmitError unless rsp.success?

        # HTTParty provides rsp.parsed_response, but it only kicks in for the
        # application/json content type in the response, which we can't rely on
        body = Gitlab::Json.parse(rsp.body)
        transfer = body.fetch('transfer', 'basic')

        raise UnsupportedTransferError.new(transfer.inspect) unless transfer == 'basic'

        body
      end

      def upload(object, upload_action, authenticated:)
        file = object.file.open

        params = {
          body_stream: file,
          headers: {
            'Content-Length' => object.size.to_s,
            'Content-Type' => 'application/octet-stream'
          }.merge(upload_action['header'] || {})
        }

        params[:basic_auth] = basic_auth unless authenticated

        rsp = Gitlab::HTTP.put(upload_action['href'], params)

        raise ObjectUploadError unless rsp.success?
      ensure
        file&.close
      end

      private

      attr_reader :credentials

      def batch_url
        base_url + '/info/lfs/objects/batch'
      end

      def basic_auth
        return unless credentials[:auth_method] == "password"

        { username: credentials[:user], password: credentials[:password] }
      end

      class BatchSubmitError < StandardError
        def message
          "Failed to submit batch"
        end
      end

      class UnsupportedTransferError < StandardError
        def initialize(transfer = nil)
          super
          @transfer = transfer
        end

        def message
          "Unsupported transfer: #{@transfer}"
        end
      end

      class ObjectUploadError < StandardError
        def message
          "Failed to upload object"
        end
      end
    end
  end
end