# frozen_string_literal: true

module RuboCop
  module Cop
    module Style
      # This cop checks for usage of the %Q() syntax when %q() would do.
      #
      # @example EnforcedStyle: lower_case_q (default)
      #   # The `lower_case_q` style prefers `%q` unless
      #   # interpolation is needed.
      #   # bad
      #   %Q[Mix the foo into the baz.]
      #   %Q(They all said: 'Hooray!')
      #
      #   # good
      #   %q[Mix the foo into the baz]
      #   %q(They all said: 'Hooray!')
      #
      # @example EnforcedStyle: upper_case_q
      #   # The `upper_case_q` style requires the sole use of `%Q`.
      #   # bad
      #   %q/Mix the foo into the baz./
      #   %q{They all said: 'Hooray!'}
      #
      #   # good
      #   %Q/Mix the foo into the baz./
      #   %Q{They all said: 'Hooray!'}
      class PercentQLiterals < Base
        include PercentLiteral
        include ConfigurableEnforcedStyle
        extend AutoCorrector

        LOWER_CASE_Q_MSG = 'Do not use `%Q` unless interpolation is ' \
                           'needed. Use `%q`.'
        UPPER_CASE_Q_MSG = 'Use `%Q` instead of `%q`.'

        def on_str(node)
          process(node, '%Q', '%q')
        end

        private

        def on_percent_literal(node)
          return if correct_literal_style?(node)

          # Report offense only if changing case doesn't change semantics,
          # i.e., if the string would become dynamic or has special characters.
          ast = ProcessedSource.new(corrected(node.source), target_ruby_version).ast
          return if node.children != ast.children

          add_offense(node.loc.begin) do |corrector|
            corrector.replace(node, corrected(node.source))
          end
        end

        def correct_literal_style?(node)
          style == :lower_case_q && type(node) == '%q' ||
            style == :upper_case_q && type(node) == '%Q'
        end

        def message(_range)
          style == :lower_case_q ? LOWER_CASE_Q_MSG : UPPER_CASE_Q_MSG
        end

        def corrected(src)
          src.sub(src[1], src[1].swapcase)
        end
      end
    end
  end
end