introduce setup command and centralize client cred storage

related to #29

lib/calendar_assistant/authorizer.rb

@@ -27,7 +27,7 @@ class UnauthorizedError < CalendarAssistant::BaseException ; end
 
     OOB_URI = 'urn:ietf:wg:oauth:2.0:oob'.freeze
     APPLICATION_NAME = "Flavorjones Calendar Assistant".freeze
-    CREDENTIALS_PATH = 'credentials.json'.freeze
+    CREDENTIALS_PATH = File.join ENV["HOME"], ".calendar-assistant.client"
     SCOPE = Google::Apis::CalendarV3::AUTH_CALENDAR
 
     attr_reader :profile_name, :config_token_store
@@ -77,9 +77,10 @@ def prompt_user_for_authorization
     def authorizer
       @authorizer ||= begin
                         if ! File.exists?(CREDENTIALS_PATH)
-                          raise NoCredentials, "No credentials found. Please run `calendar-assistant help authorize` for help"
+                          raise NoCredentials, "No credentials found. Please run `calendar-assistant help setup` for instructions"
                         end
 
+                        FileUtils.chmod 0600, CREDENTIALS_PATH
                         client_id = Google::Auth::ClientId.from_file(CREDENTIALS_PATH)
                         Google::Auth::UserAuthorizer.new(client_id, SCOPE, config_token_store)
                       end

lib/calendar_assistant/cli.rb

@@ -38,6 +38,47 @@ def config
     end
 
 
+    desc "setup",
+         "Link your local calendar-assistant installation to a Google API Client"
+    long_desc <<~EOD
+      This command will walk you through setting up a Google Cloud
+      Project, enabling the Google Calendar API, and saving the
+      credentials necessary to access the API on behalf of users.
+
+      If you already have downloaded client credentials, you don't
+      need to run this command. Instead, rename the downloaded JSON
+      file to `#{CalendarAssistant::Authorizer::CREDENTIALS_PATH}`
+    EOD
+    def setup
+      out = CLIHelpers::Out.new
+      if File.exist? CalendarAssistant::Authorizer::CREDENTIALS_PATH
+        out.puts sprintf("Credentials already exist in %s",
+                         CalendarAssistant::Authorizer::CREDENTIALS_PATH)
+        exit 0
+      end
+
+      out.launch "https://developers.google.com/calendar/quickstart/ruby"
+      sleep 1
+      out.puts <<~EOT
+        Please click on "ENABLE THE GOOGLE CALENDAR API" and either create a new project or select an existing project.
+
+        (If you create a new project, name it something like "yourname-calendar-assistant" so you remember why it exists.)
+
+        Then click "DOWNLOAD CLIENT CONFIGURATION" to download the credentials to local disk.
+
+        Finally, paste the contents of the downloaded file here (it should be a complete JSON object):
+      EOT
+
+      json = out.prompt "Paste JSON here"
+      File.open(CalendarAssistant::Authorizer::CREDENTIALS_PATH, "w") do |f|
+        f.write json
+      end
+      FileUtils.chmod 0600, CalendarAssistant::Authorizer::CREDENTIALS_PATH
+
+      out.puts "\nOK! Your next step is to run `calendar-assistant authorize`."
+    end
+
+
     desc "authorize PROFILE_NAME",
          "create (or validate) a profile named NAME with calendar access"
     long_desc <<~EOD

lib/calendar_assistant/cli_helpers.rb

@@ -59,6 +59,22 @@ def puts *args
         io.puts(*args)
       end
 
+      def prompt query, default=nil
+        loop do
+          message = query
+          message += " [#{default}]" if default
+          message += ": "
+          print Rainbow(message).bold
+          answer = STDIN.gets.chomp.strip
+          if answer.empty?
+            return default if default
+            puts Rainbow("Please provide an answer.").red
+          else
+            return answer
+          end
+        end
+      end
+
       def print_now! ca, event, printed_now
         return true if printed_now
         return false if event.start_date != Date.today

spec/calendar_assistant/cli_helpers_spec.rb

@@ -170,6 +170,10 @@
       end
     end
 
+    describe "#prompt" do
+      it "should have tests"
+    end
+
     describe "#print_now!" do
       freeze_time