Zeitwerk Inflector for full path -> Constant

our_inflector.rb

# frozen_string_literal: true

# Custom inflector for Zeitwerk
#
# The default inflector at ActiveSupport::Dependencies::ZeitwerkIntegration::Inflector only
# lets us override by `basename`, but we have both `Thing` and `THING` defined as constants
# in the app so that doesn't work for us. Rather than rename everything just now, work around it
# by letting us define overrides by _filepath_ (`abspath`) as well as `basename`.
#
# NB: Normally we'd subclass the default implementation, but it's a Module so can't do that.
#
# @see Zeitwerk::Inflector
# @see ActiveSupport::Dependencies::ZeitwerkIntegration::Inflector
#
class OurInflector
  def initialize
    @basename_overrides = {}
    @relpath_overrides = {}
  end

  # Override constant inflections based on the basename
  #
  # basename is just snake_case. Basically lets you override the same snake_case to SnakeCASE
  # across the app, no matter the namespace it's in.
  #
  # @param inflections [Hash{String => String}] mappings from base_name to BaseName
  # @return [void]
  def inflect_basename(inflections)
    @basename_overrides.merge!(inflections)
  end

  # Override constant inflections based on filename in app
  #
  # Where we have the same downcased string resolving to two different constant names within
  # the app we can't use `inflect_basename`. At that point we can define inflections on a file
  # by file basis to let us override in one case.
  #
  # @param inflections [Hash{String => String}] mappings from relative paths to Constants
  # @return [void]
  def inflect_relpath(inflections)
    @relpath_overrides.merge!(inflections)
  end

  # For a given basename & absolute path, return the expected constant
  #
  # We check for overrides in the following order:
  #   - path override
  #   - basename override
  #   - ActiveSupport camelize, which uses the app defined inflections
  #
  # @return [String] expected constant name as string
  def camelize(basename, abspath)
    relpath = abspath.sub("#{Rails.root}/", "") # rubocop:disable Rails/FilePath
    @relpath_overrides[relpath] || @basename_overrides[basename] || basename.camelize
  end
end