class RuboCop::Cop::Style::StringLiterals

def accept_child_double_quotes?(nodes)
  nodes.any? do |n|
    n.dstr_type? || double_quotes_required?(n.source)
  end
end

def all_string_literals?(nodes)
  nodes.all? { |n| n.str_type? || n.dstr_type? }
end

def check_multiline_quote_style(node, quote)
  range = node.source_range
  children = node.children
  if unexpected_single_quotes?(quote)
    add_offense(node, range) if children.all? { |c| wrong_quotes?(c) }
  elsif unexpected_double_quotes?(quote) &&
        !accept_child_double_quotes?(children)
    add_offense(node, range)
  end
end

def consistent_multiline?
  cop_config['ConsistentQuotesInMultiline']
end

def detect_quote_styles(node)
  styles = node.children.map { |c| c.loc.begin }
  # For multi-line strings that only have quote marks
  # at the beginning of the first line and the end of
  # the last, the begin and end region of each child
  # is nil. The quote marks are in the parent node.
  return [node.loc.begin.source] if styles.all?(&:nil?)
  styles.map(&:source).uniq
end

def message(*)
  if style == :single_quotes
    "Prefer single-quoted strings when you don't need string " \
    'interpolation or special symbols.'
  else
    'Prefer double-quoted strings unless you need single quotes to ' \
    'avoid extra backslashes for escaping.'
  end
end

def offense?(node)
  # If it's a string within an interpolation, then it's not an offense
  # for this cop.
  return false if inside_interpolation?(node)
  wrong_quotes?(node)
end

def on_dstr(node)
  # Strings which are continued across multiple lines using \
  # are parsed as a `dstr` node with `str` children
  # If one part of that continued string contains interpolations,
  # then it will be parsed as a nested `dstr` node
  return unless consistent_multiline?
  return if node.loc.is_a?(Parser::Source::Map::Heredoc)
  children = node.children
  return unless all_string_literals?(children)
  quote_styles = detect_quote_styles(node)
  if quote_styles.size > 1
    add_offense(node, :expression, MSG_INCONSISTENT)
  else
    check_multiline_quote_style(node, quote_styles[0])
  end
  ignore_node(node)
end

def unexpected_double_quotes?(quote)
  quote == '"' && style == :single_quotes
end

def unexpected_single_quotes?(quote)
  quote == "'" && style == :double_quotes
end