class RuboCop::Cop::Style::RedundantInterpolation

@var
# good if @var is already a String
@var.to_s
# good
“#{@var}”
# bad
@example
—-
y << ‘b’ # raise ‘FrozenError`.
y = x.to_s
y << ’b’ # return ‘ab’.
y = “#{x}”
x = ‘a’.freeze
x # return ‘ab’
y << ‘b’ # return ‘ab’
y = x.to_s
x # return ‘a’
y << ‘b’ # return ‘ab’
y = “#{x}”
x = ‘a’
—-
[source,ruby]

the resulting string may have different behavior or raise ‘FrozenError`.
Autocorrection is unsafe because when calling a destructive method to string,
@safety
Checks for strings that are just an interpolated expression.

def self.autocorrect_incompatible_with 

def self.autocorrect_incompatible_with
  [Style::LineEndConcatenation]
end

def autocorrect_other(corrector, embedded_node, node) 

def autocorrect_other(corrector, embedded_node, node)
  loc = node.loc
  embedded_loc = embedded_node.loc
  corrector.replace(loc.begin, '')
  corrector.replace(loc.end, '')
  corrector.replace(embedded_loc.begin, '(')
  corrector.replace(embedded_loc.end, ').to_s')
end

def autocorrect_single_variable_interpolation(corrector, embedded_node, node) 

def autocorrect_single_variable_interpolation(corrector, embedded_node, node)
  embedded_var = embedded_node.children.first
  source = if require_parentheses?(embedded_var)
             receiver = range_between(
               embedded_var.source_range.begin_pos, embedded_var.loc.selector.end_pos
             )
             arguments = embedded_var.arguments.map(&:source).join(', ')
             "#{receiver.source}(#{arguments})"
           else
             embedded_var.source
           end
  corrector.replace(node, "#{source}.to_s")
end

def autocorrect_variable_interpolation(corrector, embedded_node, node) 

def autocorrect_variable_interpolation(corrector, embedded_node, node)
  replacement = "#{embedded_node.source}.to_s"
  corrector.replace(node, replacement)
end

def embedded_in_percent_array?(node) 

def embedded_in_percent_array?(node)
  node.parent&.array_type? && percent_literal?(node.parent)
end

def implicit_concatenation?(node) 

def implicit_concatenation?(node)
  node.parent&.dstr_type?
end

def interpolation?(node) 

def interpolation?(node)
  variable_interpolation?(node) || node.begin_type?
end

def on_dstr(node) 

def on_dstr(node)
  return unless single_interpolation?(node)
  add_offense(node) do |corrector|
    embedded_node = node.children.first
    if variable_interpolation?(embedded_node)
      autocorrect_variable_interpolation(corrector, embedded_node, node)
    elsif single_variable_interpolation?(embedded_node)
      autocorrect_single_variable_interpolation(corrector, embedded_node, node)
    else
      autocorrect_other(corrector, embedded_node, node)
    end
  end
end

def require_parentheses?(node) 

def require_parentheses?(node)
  node.send_type? && !node.arguments.count.zero? && !node.parenthesized_call?
end

def single_interpolation?(node) 

def single_interpolation?(node)
  node.children.one? &&
    interpolation?(node.children.first) &&
    !implicit_concatenation?(node) &&
    !embedded_in_percent_array?(node)
end

def single_variable_interpolation?(node) 

def single_variable_interpolation?(node)
  return false unless node.children.one?
  first_child = node.children.first
  variable_interpolation?(first_child) ||
    (first_child.send_type? && !first_child.operator_method?)
end

def variable_interpolation?(node) 

def variable_interpolation?(node)
  node.variable? || node.reference?
end