# FriendlyId is a comprehensive Ruby library for ActiveRecord permalinks and
# slugs.
# @author Norman Clarke
module FriendlyId

  autoload :Slugged, "friendly_id/slugged"
  autoload :Scoped,  "friendly_id/scoped"

  # Class methods that will be added to ActiveRecord::Base.
  module Base
    extend self

    def has_friendly_id(*args)
      options = args.extract_options!
      base = args.shift
      friendly_id_config.set options.merge(:base => base)
      include Model
      # @NOTE: AR-specific code here
      validates_exclusion_of base, :in => Configuration::DEFAULTS[:reserved_words]
      before_save do |record|
        record.instance_eval {@_current_friendly_id = friendly_id}
      end
    end

    def friendly_id_config
      @friendly_id_config ||= Configuration.new(self)
    end

    def uses_friendly_id?
      !! @friendly_id_config
    end
  end

  # Instance methods that will be added to all classes using FriendlyId.
  module Model

    # Convenience method for accessing the class method of the same name.
    def friendly_id_config
      self.class.friendly_id_config
    end

    # Get the instance's friendly_id.
    def friendly_id
      send friendly_id_config.query_field
    end

    # Either the friendly_id, or the numeric id cast to a string.
    def to_param
      (friendly_id or id).to_s
    end
  end

  # The configuration paramters passed to +has_friendly_id+ will be stored
  # in this object.
  class Configuration
    attr_accessor :base
    attr_reader   :klass

    DEFAULTS = {
      :config_error_message => 'FriendlyId has no such config option "%s"',
      :reserved_words       => ["new", "edit"]
    }

    def initialize(klass, values = nil)
      @klass = klass
      set values
    end

    def method_missing(symbol, *args, &block)
      option = symbol.to_s.gsub(/=\z/, '')
      raise ArgumentError, DEFAULTS[:config_error_message] % option
    end

    def set(values)
      values and values.each {|name, value| self.send "#{name}=", value}
    end

    def query_field
      base
    end
  end

  # Utility methods that are in Object because it's impossible to predict what
  # kinds of objects get passed into FinderMethods#find_one and
  # Model#normalize_friendly_id.
  module ObjectUtils

    # True is the id is definitely friendly, false if definitely unfriendly,
    # else nil.
    def friendly_id?
      if kind_of?(Integer) or kind_of?(Symbol) or self.class.respond_to? :friendly_id_config
        false
      elsif to_i.to_s != to_s
        true
      end
    end

    # True if the id is definitely unfriendly, false if definitely friendly,
    # else nil.
    def unfriendly_id?
      val = friendly_id? ; !val unless val.nil?
    end
  end

  # These methods will override the finder methods in ActiveRecord::Relation.
  module FinderMethods

    protected

    # @NOTE AR-specific code here
    def find_one(id)
      return super if !@klass.uses_friendly_id? or id.unfriendly_id?
      where(@klass.friendly_id_config.query_field => id).first or super
    end

  end
end

ActiveRecord::Base.extend FriendlyId::Base
ActiveRecord::Relation.send :include, FriendlyId::FinderMethods
Object.send :include, FriendlyId::ObjectUtils