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require 'dotenv'
$definable_thread_group ||= ThreadGroup.new
module Live
# offers typed constant defintions with default value, by using lots of introspecting...
module Definable
MAIN_CSS = 'app/assets/stylesheets/application.css'.freeze # useful to trigger :reload_all from RailsLiveReload
def integer(default = 0) = define_type_from_callee(caller[0], :integer, default)
def boolean(default = true) = define_type_from_callee(caller[0], :boolean, default) # rubocop:disable Style/OptionalBooleanParameter
def string(default = '') = define_type_from_callee(caller[0], :string, default)
def reload_from_env
logger.debug('reload from env')
changes = []
new_env_values = env_values(cached: false)
new_env_keys = new_env_values.keys
new_env_values.each_pair { |constant, raw| changes << override(constant, raw) }
definitions.except(*new_env_keys).each_pair { |constant, definition| changes << restore(constant, definition) }
changes.compact!
trigger_rolling_event(changes) if changes.any?
end
private
def trigger_rolling_event(changes)
ActiveSupport::Notifications.instrument('rolling.live_constant', changes:)
FileUtils.touch(MAIN_CSS) if defined?(RailsLiveReload) # triggering RailsLiveReload
rescue StandardError => e
logger.error(e)
end
def override(constant, raw)
return unless definitions.include?(constant)
type = definitions[constant][:type]
new_value = typed_value(type, raw, definitions[constant][:default])
old_value = definitions[constant][:value]
return if new_value == old_value
define_value(constant, new_value)
logger.warn "Constant overriden from environment:#{Semantic::AnsiColors::CLEAR} #{constant} = #{new_value.ai}"
{ kind: :overriden, constant:, type:, old_value:, new_value: }
end
def restore(constant, definition)
new_value = definition[:default]
old_value = definition[:value]
return if old_value == new_value
type = definition[:type]
define_value(constant, new_value)
logger.warn "Constant restored:#{Semantic::AnsiColors::CLEAR} #{constant} = #{new_value.ai}"
{ kind: :restored, constant:, type:, old_value:, new_value: }
end
def env_values(cached: true)
return @env_values if @env_values && cached
@env_values = Dotenv.parse(*Dotenv::Rails.files)
end
def logger = @logger ||= SemanticLogger[self]
def definitions = @definitions ||= {}
def define_value(constant, value)
definitions[constant][:value] = value
remove_const(constant)
const_set(constant, value)
end
# origin (or caller[0]) helps fetching the constant name from source code introspection
def define_type_from_callee(origin, type, default)
@@class_origin ||= self # rubocop:disable Style/ClassVars
@listener ||= start_listener
file, line = origin.split(':')
constant = introspect_constant_from_file(file, line.to_i - 1)
raw_value = env_values.fetch(constant, nil)
value = typed_value(type, raw_value, default)
definitions[constant] = { type:, default:, value: }
# logger.debug('new definitions', definitions)
value
end
def start_listener
$definable_thread_group.list.each(&:kill)
$definable_thread_group.add(Thread.new do
listener = Listen.to(Rails.root, only: /^\.env\.?/) do
@@class_origin.reload_from_env
rescue StandardError
nil
end
listener.start
end)
end
def typed_value(type, raw, default)
return default if raw.nil?
case type
when :integer then raw.to_i
when :boolean then raw.upcase == 'TRUE'
else raw
end
end
# returns current directory of this source code
def dir_source_location
return @dir_source_location if defined?(@dir_source_location)
*paths, _ = Live.const_source_location(:Definable).first.split('/')
@dir_source_location = paths.join('/')
end
def introspect_constant_from_file(file, line)
*dir_file, _ = file.split('/')
dir_file = dir_file.join('/')
raise "unexpected directory: #{dir_file} != #{dir_source_location}" unless dir_file == dir_source_location
@lines ||= File.readlines(file) # cached source code
@lines[line].match(/\s*(.\w+)/)[1] # TODO: should be uppercase!
end
end
end