class EnvVarsValidator

# File lib/env_vars_validator.rb, line 4
def self.last_error
  @@last_error
end

# File lib/env_vars_validator.rb, line 8
def self.source_from_ruby_files(starting_dir)
  Dir.glob(File.join(starting_dir, '**', '*.rb')).
    reject { |file_path| file_path.include?('vendor') }.
    map { |file_path| File.read(file_path) }.
    join("\n")
end

# File lib/env_vars_validator.rb, line 15
def self.used_env_vars(starting_dir)
  source_from_ruby_files(starting_dir).
    scan(/ENV\[(?:'|")([^\]]+)(?:'|")\]/).
    flatten.
    uniq.
    sort
end

# File lib/env_vars_validator.rb, line 23
def self.validate(starting_dir)
  declared_env_vars = ENV.keys

  missing_env_vars = used_env_vars(starting_dir) - declared_env_vars

  unless missing_env_vars.empty?
    @@last_error = "The following env vars are required and have not been defined:\n  #{missing_env_vars.sort.join("\n  ")}"
    return false
  end

  true
end