require 'rrb/script'

module RRB

  class RenameGlobalVarVisitor < Visitor

    def initialize(old_var, new_var )
      @old_var = old_var
      @new_var = new_var
      @result = []
    end

    attr_reader :result

    def visit_node( namespace, node)
      node.global_vars.find_all(){|id| id.name == @old_var}.each do |id|
        @result << Replacer.new_from_id(id, @new_var)
      end
    end
  end

  class RenameGlobalVarCheckVisitor < Visitor
    
    def initialize(old_var, new_var )
      @old_var = old_var
      @new_var = new_var
      @result = true
    end

    attr_reader :result

    def visit_node( namespace, node )
      if node.global_vars.find{|i| i.name == @new_var} then
        @error_message = "#{@new_var}: already used"
	@result = false
      end
    end
    
  end

  class ScriptFile
    
    def rename_global_var(old_var, new_var )
      visitor = RenameGlobalVarVisitor.new( old_var, new_var )
      @tree.accept( visitor )
      @new_script = RRB.replace_str( @input, visitor.result )
    end

    def rename_global_var?(old_var, new_var )

      visitor = RenameGlobalVarCheckVisitor.new( old_var, new_var )
      @tree.accept( visitor )
      @error_message = visitor.error_message unless visitor.result
      return visitor.result
    end

  end

  class Script
    def rename_global_var(old_var, new_var )
      @files.each do |scriptfile|
	scriptfile.rename_global_var(old_var, new_var )
      end
    end

    def rename_global_var?(old_var, new_var )
      unless RRB.valid_global_var?( new_var )
        @error_message = "#{new_var}: not a valid name for global variables"
        return false
      end

      @files.each do |scriptfile|
        unless scriptfile.rename_global_var?(old_var, new_var )
          @error_message = scriptfile.error_message
          return false
        end
      end

      return true
    end

  end
end