# frozen_string_literal: true
#
# ronin-code-sql - A Ruby DSL for crafting SQL Injections.
#
# Copyright (c) 2007-2023 Hal Brodigan (postmodern.mod3 at gmail.com)
#
# ronin-code-sql is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# ronin-code-sql is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with ronin-code-sql.  If not, see <https://www.gnu.org/licenses/>.
#

require 'ronin/code/sql/operators'
require 'ronin/code/sql/emittable'

module Ronin
  module Code
    module SQL
      #
      # Represents a SQL column, table or database name.
      #
      # @api semipublic
      #
      class Field

        include Operators
        include Emittable

        # The name of the field.
        #
        # @return [String]
        attr_reader :name

        # The parent of the field name.
        #
        # @return [Field, nil]
        attr_reader :parent

        #
        # Initializes the new field.
        #
        # @param [String] name
        #   The name of the field.
        #
        # @param [Field, nil] parent
        #   The parent of the field.
        #
        def initialize(name,parent=nil)
          @name   = name.to_s
          @parent = parent
        end

        #
        # Parses a field.
        #
        # @param [String] name
        #
        # @return [Field]
        #   The parsed field.
        #
        def self.parse(name)
          names = name.to_s.split('.',3)
          field = nil

          names.each { |keyword| field = new(keyword,field) }

          return field
        end

        alias to_str to_s

        #
        # Determines if the field responds to the given method.
        #
        # @param [Symbol] name
        #   The method name.
        #
        # @return [Boolean]
        #   Will return false if the field already has two parents, otherwise
        #   will return true.
        #
        def respond_to_missing?(name)
          self.parent.nil? || self.parent.parent.nil?
        end

        protected

        #
        # Allows accessing columns from tables or tables from databases.
        #
        # @param [Symbol] name
        #   The sub-field name.
        #
        # @param [Array] arguments
        #   Additional method arguments.
        #
        # @return [Field]
        #   The sub-field for the given name.
        #
        # @raise [ArgumentError]
        #   The method missing call was given additional arguments.
        #
        # @raise [NoMethodError]
        #   Cannot access a column from another column.
        #
        # @example
        #   db.users
        #
        # @example
        #   users.id
        #
        def method_missing(name,*arguments)
          unless arguments.empty?
            raise(ArgumentError,"canot access columns or tables with arguments")
          end

          if (self.parent.nil? || self.parent.parent.nil?)
            Field.new(name,self)
          else
            raise(NoMethodError,"cannot access columns from other columns")
          end
        end

      end
    end
  end
end