1 files changed, 148 insertions, 0 deletions
diff --git a/lib/gitlab/legacy_github_import/client.rb b/lib/gitlab/legacy_github_import/client.rb
new file mode 100644
index 00000000000..53c910d44bd
--- /dev/null
+++ b/lib/gitlab/legacy_github_import/client.rb
@@ -0,0 +1,148 @@
+module Gitlab
+  module LegacyGithubImport
+    class Client
+      GITHUB_SAFE_REMAINING_REQUESTS = 100
+      GITHUB_SAFE_SLEEP_TIME = 500
+
+      attr_reader :access_token, :host, :api_version
+
+      def initialize(access_token, host: nil, api_version: 'v3')
+        @access_token = access_token
+        @host = host.to_s.sub(%r{/+\z}, '')
+        @api_version = api_version
+        @users = {}
+
+        if access_token
+          ::Octokit.auto_paginate = false
+        end
+      end
+
+      def api
+        @api ||= ::Octokit::Client.new(
+          access_token: access_token,
+          api_endpoint: api_endpoint,
+          # If there is no config, we're connecting to github.com and we
+          # should verify ssl.
+          connection_options: {
+            ssl: { verify: config ? config['verify_ssl'] : true }
+          }
+        )
+      end
+
+      def client
+        unless config
+          raise Projects::ImportService::Error,
+            'OAuth configuration for GitHub missing.'
+        end
+
+        @client ||= ::OAuth2::Client.new(
+          config.app_id,
+          config.app_secret,
+          github_options.merge(ssl: { verify: config['verify_ssl'] })
+        )
+      end
+
+      def authorize_url(redirect_uri)
+        client.auth_code.authorize_url({
+          redirect_uri: redirect_uri,
+          scope: "repo, user, user:email"
+        })
+      end
+
+      def get_token(code)
+        client.auth_code.get_token(code).token
+      end
+
+      def method_missing(method, *args, &block)
+        if api.respond_to?(method)
+          request(method, *args, &block)
+        else
+          super(method, *args, &block)
+        end
+      end
+
+      def respond_to?(method)
+        api.respond_to?(method) || super
+      end
+
+      def user(login)
+        return nil unless login.present?
+        return @users[login] if @users.key?(login)
+
+        @users[login] = api.user(login)
+      end
+
+      private
+
+      def api_endpoint
+        if host.present? && api_version.present?
+          "#{host}/api/#{api_version}"
+        else
+          github_options[:site]
+        end
+      end
+
+      def config
+        Gitlab.config.omniauth.providers.find { |provider| provider.name == "github" }
+      end
+
+      def github_options
+        if config
+          config["args"]["client_options"].deep_symbolize_keys
+        else
+          OmniAuth::Strategies::GitHub.default_options[:client_options].symbolize_keys
+        end
+      end
+
+      def rate_limit
+        api.rate_limit!
+      # GitHub Rate Limit API returns 404 when the rate limit is
+      # disabled. In this case we just want to return gracefully
+      # instead of spitting out an error.
+      rescue Octokit::NotFound
+        nil
+      end
+
+      def has_rate_limit?
+        return @has_rate_limit if defined?(@has_rate_limit)
+
+        @has_rate_limit = rate_limit.present?
+      end
+
+      def rate_limit_exceed?
+        has_rate_limit? && rate_limit.remaining <= GITHUB_SAFE_REMAINING_REQUESTS
+      end
+
+      def rate_limit_sleep_time
+        rate_limit.resets_in + GITHUB_SAFE_SLEEP_TIME
+      end
+
+      def request(method, *args, &block)
+        sleep rate_limit_sleep_time if rate_limit_exceed?
+
+        data = api.__send__(method, *args) # rubocop:disable GitlabSecurity/PublicSend
+        return data unless data.is_a?(Array)
+
+        last_response = api.last_response
+
+        if block_given?
+          yield data
+          # api.last_response could change while we're yielding (e.g. fetching labels for each PR)
+          # so we cache our own last response
+          each_response_page(last_response, &block)
+        else
+          each_response_page(last_response) { |page| data.concat(page) }
+          data
+        end
+      end
+
+      def each_response_page(last_response)
+        while last_response.rels[:next]
+          sleep rate_limit_sleep_time if rate_limit_exceed?
+          last_response = last_response.rels[:next].get
+          yield last_response.data if last_response.data.is_a?(Array)
+        end
+      end
+    end
+  end
+end