module Neo4j
  module Core
    module CypherTranslator
      # Cypher Helper
      def escape_value(value)
        if value.is_a?(String) || value.is_a?(Symbol)
          "'#{escape_quotes(sanitize_escape_sequences(value.to_s))}'"
        else
          value
        end
      end

      # Like escape_value but it does not wrap the value in quotes
      def create_escape_value(value)
        if value.is_a?(String) || value.is_a?(Symbol)
          "#{sanitize_escape_sequences(value.to_s)}"
        else
          value
        end
      end

      # Only following escape sequence characters are allowed in Cypher:
      #
      # \t Tab
      # \b Backspace
      # \n Newline
      # \r Carriage return
      # \f Form feed
      # \' Single quote
      # \" Double quote
      # \\ Backslash
      #
      # From:
      # http://docs.neo4j.org/chunked/stable/cypher-expressions.html#_note_on_string_literals
      SANITIZE_ESCAPED_REGEXP = /(?<!\\)\\(\\\\)*(?![futbnr'"\\])/
      EMPTY_PROPS = ''

      def sanitize_escape_sequences(s)
        s.gsub SANITIZE_ESCAPED_REGEXP, EMPTY_PROPS
      end

      def escape_quotes(s)
        s.gsub("'", %q(\\\'))
      end

      # Cypher Helper
      def cypher_prop_list(props)
        return nil unless props
        props.reject! { |_, v| v.nil? }
        {props: props.each { |k, v|  props[k] = create_escape_value(v) }}
      end

      # Stolen from keymaker
      # https://github.com/therubymug/keymaker/blob/master/lib/keymaker/parsers/cypher_response_parser.rb
      def self.translate_response(response_body, result)
        Hashie::Mash.new(Hash[sanitized_column_names(response_body).zip(result)])
      end

      def self.sanitized_column_names(response_body)
        response_body.columns.map { |column| column[/[^\.]+$/] }
      end

      def cypher_string(labels, props)
        "CREATE (n#{label_string(labels)} #{prop_identifier(props)}) RETURN ID(n)"
      end

      def label_string(labels)
        labels.empty? ? '' : ":#{labels.map { |k| "`#{k}`" }.join(':')}"
      end

      def prop_identifier(props)
        '{props}' unless props.nil?
      end
    end
  end
end