module Picky

  # = Picky Applications
  #
  # A Picky Application is where you configure the whole search engine.
  #
  # This is a step-by-step description on how to configure your Picky app.
  #
  # Start by subclassing Application:
  #   class MyGreatSearch < Application
  #     # Your configuration goes here.
  #   end
  # The generator
  #   $ picky generate unicorn_server project_name
  # will generate an example <tt>project_name/app/application.rb</tt> file for you
  # with some example code inside.
  #
  # == Indexes::Memory.new(name)
  #
  # Next, define where your data comes from, creating an <tt>Index</tt>. You use the <tt>Indexes::Memory.new</tt> method for that:
  #   my_index = Indexes::Memory.new :some_index_name
  # You give the index a name (or identifier), and a source (see Sources), where its data comes from. Let's do that:
  #   class MyGreatSearch < Application
  #
  #     books = Indexes::Memory.new :books do
  #       source Sources::CSV.new(:title, :author, :isbn, file:'app/library.csv')
  #     end
  #
  #   end
  # Now we have an index <tt>books</tt>.
  #
  # That on itself won't do much good.
  #
  # Note that a Redis index is also available: Indexes::Redis.new.
  #
  # == category(identifier, options = {})
  #
  # Picky needs us to define categories on the data.
  #
  # Categories help your user find data.
  # It's best if you look at an example yourself: http://floere.github.com/picky/examples.html
  #
  # Let's go ahead and define a category:
  #   class MyGreatSearch < Application
  #
  #     books = Indexes::Memory.new :books do
  #       source   Sources::CSV.new(:title, :author, :isbn, file:'app/library.csv')
  #       category :title
  #     end
  #
  #   end
  # Now we could already run the indexer:
  #   $ rake index
  #
  # (You can define similarity or partial search capabilities on a category, see http://github.com/floere/picky/wiki/Categories-configuration for info)
  #
  # So now we have indexed data (the title), but nobody to ask the index anything.
  #
  # == Search.new(*indexes, options = {})
  #
  # We need somebody who asks the index (a Query object, also see http://github.com/floere/picky/wiki/Queries-Configuration):
  #    books_search = Search.new books
  #
  # Now we have somebody we can ask about the index. But no external interface.
  #
  # == route(/regexp1/ => search1, /regexp2/ => search2, ...)
  #
  # Let's add a URL path (a Route, see http://github.com/floere/picky/wiki/Routing-configuration) to which we can send our queries. We do that with the route method:
  #   route %r{^/books$} => books_query
  # In full glory:
  #   class MyGreatSearch < Application
  #
  #     books = Indexes::Memory.new :books do
  #       source   Sources::CSV.new(:title, :author, :isbn, file:'app/library.csv')
  #       category :title
  #     end
  #
  #     route %r{^/books$} => Search.new(books)
  #
  #   end
  # That's it!
  #
  # Now run the indexer and server:
  #   $ rake index
  #   $ rake start
  # Run your first query:
  #   $ curl 'localhost:8080/books?query=hello server'
  #
  # Nice, right? Your first query!
  #
  # Maybe you don't find everything. We need to process the data before it goes into the index.
  #
  # == indexing(options = {})
  #
  # That's what the <tt>indexing</tt> method is for:
  #   indexing options
  # Read more about the options here: http://github.com/floere/picky/wiki/Indexing-configuration
  #
  # Same thing with the search text – we need to process that as well.
  #
  # == searching(options = {})
  #
  # Analog to the indexing method, we use the <tt>searching</tt> method.
  #   searching options
  # Read more about the options here: http://github.com/floere/picky/wiki/Searching-Configuration
  #
  # And that's all there is. It's incredibly powerful though, as you can combine, weigh, refine to the max.
  #
  # == Wiki
  #
  # Read more in the Wiki: http://github.com/floere/picky/wiki
  #
  # Have fun!
  #
  # == Full example
  #
  # Our example, fully fleshed out with indexing, querying, and weights:
  #   class MyGreatSearch < Application
  #
  #     indexing removes_characters: /[^a-zA-Z0-9\.]/,
  #              stopwords: /\b(and|or|in|on|is|has)\b/,
  #              splits_text_on: /\s/,
  #              removes_characters_after_splitting: /\./,
  #              substitutes_characters_with: CharacterSubstituters::WestEuropean.new,
  #              normalizes_words: [
  #                [/(.*)hausen/, 'hn'],
  #                [/\b(\w*)str(eet)?/, 'st']
  #              ]
  #
  #     searching removes_characters: /[^a-zA-Z0-9\s\/\-\,\&\"\~\*\:]/,
  #               stopwords: /\b(and|the|of|it|in|for)\b/,
  #               splits_text_on: /[\s\/\-\,\&]+/,
  #               removes_characters_after_splitting: /\./,
  #               substitutes_characters_with: CharacterSubstituters::WestEuropean.new,
  #               maximum_tokens: 4
  #
  #     books = Indexes::Memory.new :books do
  #       source   Sources::CSV.new(:title, :author, :isbn, file:'app/library.csv')
  #       category :title,
  #                qualifiers: [:t, :title, :titre],
  #                partial:    Partial::Substring.new(:from => 1),
  #                similarity: Similarity::DoubleMetaphone.new(2)
  #       category :author,
  #                partial: Partial::Substring.new(:from => -2)
  #       category :isbn
  #     end
  #
  #     route %r{^/books$} => Search.new(books) do
  #       boost [:title, :author] => +3, [:author, :title] => -1
  #     end
  #
  #   end
  # That's actually already a full-blown Picky App!
  #
  class Application

    class << self

      # API
      #

      # Returns a configured tokenizer that
      # is used for indexing by default.
      #
      def indexing options = {}
        Tokenizers::Index.default = Tokenizers::Index.new(options)
      end

      # Returns a configured tokenizer that
      # is used for querying by default.
      #
      def searching options = {}
        Tokenizers::Query.default = Tokenizers::Query.new(options)
      end

      # Routes.
      #
      delegate :route, :to => :rack_adapter

      # A Picky application implements the Rack interface.
      #
      # Delegates to its routing to handle a request.
      #
      def call env
        rack_adapter.call env
      end
      def rack_adapter # :nodoc:
        @rack_adapter || reset_rack_adapter
      end
      def reset_rack_adapter
        @rack_adapter = FrontendAdapters::Rack.new
      end

      # Reloads & finalizes the apps.
      #
      def reload
        Loader.load_user 'app'             # Sinatra app_file.
        Loader.load_user 'app/logging'     # Standard Picky logging.
        Loader.load_user 'app/application' # Standard Picky appfile.
        finalize_apps
        exclaim "Application #{apps.map(&:name).join(', ')} loaded."
      end

      # Finalize the subclass as soon as it
      # has finished loading.
      #
      attr_reader :apps # :nodoc:
      def initialize_apps # :nodoc:
        @apps ||= []
      end
      def inherited app # :nodoc:
        initialize_apps
        apps << app
      end
      def finalize_apps # :nodoc:
        initialize_apps
        apps.each &:finalize
      end
      # Finalizes the routes.
      #
      def finalize # :nodoc:
        check
        rack_adapter.finalize
      end
      # Checks app for missing things.
      #
      # Warns if something is missing.
      #
      def check # :nodoc:
        warnings = []
        warnings << check_external_interface
        warn "\n#{warnings.join(?\n)}\n\n" unless warnings.all? &:nil?
      end
      def check_external_interface
        "WARNING: No routes defined for application configuration in #{self.class}." if rack_adapter.empty?
      end

      def to_stats
        <<-APP
  \033[1mIndexing (default)\033[m:
  #{Tokenizers::Index.default.indented_to_s}

  \033[1mQuerying (default)\033[m:
  #{Tokenizers::Query.default.indented_to_s}

  \033[1mIndexes\033[m:
  #{Indexes.to_s.indented_to_s}

  \033[1mRoutes\033[m:
  #{to_routes.indented_to_s}
  APP
      end

      def to_routes
        rack_adapter.to_s
      end

      def to_s # :nodoc:
        self.name
      end

    end

  end

end