module Searchlogic
  module RailsHelpers
    # Creates a link that alternates between acending and descending. It basically
    # alternates between calling 2 named scopes: "ascend_by_*" and "descend_by_*"
    #
    # By default Searchlogic gives you these named scopes for all of your columns, but
    # if you wanted to create your own, it will work with those too.
    #
    # Examples:
    #
    #   order @search, :by => :username
    #   order @search, :by => :created_at, :as => "Created"
    #
    # This helper accepts the following options:
    #
    # * <tt>:by</tt> - the name of the named scope. This helper will prepend this value with "ascend_by_" and "descend_by_"
    # * <tt>:as</tt> - the text used in the link, defaults to whatever is passed to :by
    # * <tt>:ascend_scope</tt> - what scope to call for ascending the data, defaults to "ascend_by_:by"
    # * <tt>:descend_scope</tt> - what scope to call for descending the data, defaults to "descend_by_:by"
    # * <tt>:params_scope</tt> - the name of the params key to scope the order condition by, defaults to :search
    def order(search, options = {}, html_options = {})
      options[:params_scope] ||= :search
      options[:as] ||= options[:by].to_s.humanize
      options[:ascend_scope] ||= "ascend_by_#{options[:by]}"
      options[:descend_scope] ||= "descend_by_#{options[:by]}"
      ascending = search.order.to_s == options[:ascend_scope]
      new_scope = ascending ? options[:descend_scope] : options[:ascend_scope]
      selected = [options[:ascend_scope], options[:descend_scope]].include?(search.order.to_s)
      if selected
        css_classes = html_options[:class] ? html_options[:class].split(" ") : []
        if ascending
          options[:as] = "&#9650;&nbsp;#{options[:as]}"
          css_classes << "ascending"
        else
          options[:as] = "&#9660;&nbsp;#{options[:as]}"
          css_classes << "descending"
        end
        html_options[:class] = css_classes.join(" ")
      end
      link_to options[:as], url_for(options[:params_scope] => search.conditions.merge( { :order => new_scope } ) ), html_options
    end

    # Automatically makes the form method :get if a Searchlogic::Search and sets
    # the params scope to :search
    def form_for(*args, &block)
      if search_obj = args.find { |arg| arg.is_a?(Searchlogic::Search) }
        options = args.extract_options!
        options[:html] ||= {}
        options[:html][:method] ||= :get
        options[:url] ||= url_for
        args.unshift(:search) if args.first == search_obj
        args << options
      end
      super
    end
    
    # Automatically adds an "order" hidden field in your form to preserve how the data 
    # is being ordered.
    def fields_for(*args, &block)
      if search_obj = args.find { |arg| arg.is_a?(Searchlogic::Search) }
        args.unshift(:search) if args.first == search_obj
        concat(hidden_field_tag("#{args.first}[order]", search_obj.order) + "\n")
        super
      else
        super
      end
    end
  end
end