SOLR_DOCUMENT_ID = "id" unless defined?(SOLR_DOCUMENT_ID)

module ActiveFedora
  # = ActiveFedora
  # This module mixes various methods into the including class,
  # much in the way ActiveRecord does.  
  module Model 
    DEFAULT_NS = 'afmodel'

    def self.included(klass) # :nodoc:
      klass.extend(ClassMethods)
    end
    
    # Takes a Fedora URI for a cModel and returns classname, namespace
    def self.classname_from_uri(uri)
      local_path = uri.split('/')[1]
      parts = local_path.split(':')
      return parts[-1].gsub('_','/').classify, parts[0]
    end

    # Takes a Fedora URI for a cModel, and returns a 
    # corresponding Model if available
    # This method should reverse ClassMethods#to_class_uri
    def self.from_class_uri(uri)
      model_value, pid_ns = classname_from_uri(uri)
      raise "model URI incorrectly formatted: #{uri}" unless model_value

      unless class_exists?(model_value)
        logger.warn "#{model_value} is not a real class"
        return false
      end
      if model_value.include?("::")
        result = eval(model_value)
      else
        result = Kernel.const_get(model_value)
      end
      unless result.nil?
        model_ns = (result.respond_to? :pid_namespace) ? result.pid_namespace : DEFAULT_NS
        if model_ns != pid_ns
          logger.warn "Model class namespace '#{model_ns}' does not match uri: '#{uri}'"
        end
      end
      result
    end

    def add_metadata
    end

    def datastream
    end


    #
    # =Class Methods
    # These methods are mixed into the inheriting class.
    #
    # Accessor and mutator methods are dynamically generated based 
    # on the contents of the @@field_spec hash, which stores the 
    # field specifications recorded during invocation of has_metadata.
    #
    # Each metadata field will generate 3 methods:
    #
    #   fieldname_values
    #     *returns the current values array for this field
    #   fieldname_values=(val) 
    #     *store val as the values array. val 
    #     may be a single string, or an array of strings 
    #     (single items become single element arrays).
    #   fieldname_append(val)
    #     *appends val to the values array.
    module ClassMethods

      # Retrieve the Fedora object with the given pid and deserialize it as an instance of the current model
      # Note that you can actually pass a pid into this method, regardless of Fedora model type, and
      # ActiveFedora will try to parse the results into the current type of self, which may or may not be what you want.
      #
      # @param [String] pid of the object to load
      #
      # @example this will return an instance of Book, even if the object hydra:dataset1 asserts that it is a Dataset
      #   Book.load_instance("hydra:dataset1") 
      def load_instance(pid)
        RubydoraConnection.instance.find_model(pid, self)
      end
      
      # Returns a suitable uri object for :has_model
      # Should reverse Model#from_class_uri
      ### TODO: shouldn't this reverse ContentModel.pid_from_ruby_class
      def to_class_uri
        ns = (self.respond_to? :pid_namespace) ? self.pid_namespace : Model::DEFAULT_NS
        pid = self.name.gsub(/::/,'_')
        "info:fedora/#{ns}:#{pid}"
      end
      
      # Takes :all or a pid as arguments
      # Returns an Array of objects of the Class that +find+ is being 
      # called on
      def find(args, opts={})
        opts = {:rows=>25}.merge(opts)
        return_multiple = false
        if args == :all
          return_multiple = true
          escaped_class_uri = SolrService.escape_uri_for_query(self.to_class_uri)
          q = "#{ActiveFedora::SolrService.solr_name(:has_model, :symbol)}:#{escaped_class_uri}"
        elsif args.class == String
          escaped_id = args.gsub(/(:)/, '\\:')
          q = "#{SOLR_DOCUMENT_ID}:#{escaped_id}"
        end
        if return_multiple == true
          hits = SolrService.instance.conn.query(q, :rows=>opts[:rows]).hits 
        else
          hits = SolrService.instance.conn.query(q).hits 
        end
        if return_multiple
          return hits.map do |hit|
             RubydoraConnection.instance.find_model(hit[SOLR_DOCUMENT_ID], self)
          end
        else
          return RubydoraConnection.instance.find_model(hits.first[SOLR_DOCUMENT_ID], self) if hits.first
        end
      end

      # Get a count of the number of objects from solr
      # Takes :conditions as an argument
      def count(args = {})
          escaped_class_uri = SolrService.escape_uri_for_query(self.to_class_uri)
          q = "#{ActiveFedora::SolrService.solr_name(:has_model, :symbol)}:#{escaped_class_uri}"
          q << " AND #{args[:conditions]}" if args[:conditions]
          SolrService.instance.conn.query(q, :rows=>0).total_hits
      end

      #Sends a query directly to SolrService
      def solr_search(query, args={})
        SolrService.instance.conn.query(query, args)
      end


      #  If query is :all, this method will query Solr for all instances
      #  of self.type (based on active_fedora_model_s as indexed
      #  by Solr). If the query is any other string, this method simply does
      #  a pid based search (id:query). 
      #
      #  Note that this method does _not_ return ActiveFedora::Model 
      #  objects, but rather an array of SolrResults.
      #
      #  Args is an options hash, which is passed into the SolrService 
      #  connection instance.
      def find_by_solr(query, args={})
        if query == :all
          escaped_class_name = self.name.gsub(/(:)/, '\\:')
          SolrService.instance.conn.query("#{ActiveFedora::SolrService.solr_name(:active_fedora_model, :symbol)}:#{escaped_class_name}", args)
        elsif query.class == String
          escaped_id = query.gsub(/(:)/, '\\:')          
          SolrService.instance.conn.query("#{SOLR_DOCUMENT_ID}:#{escaped_id}", args)
        end
      end

      # Find all ActiveFedora objects for this model that match arguments
      # passed in by querying Solr.  Like find_by_solr this returns a solr result.
      #
      # query_fields   a hash of object field names and values to filter on
      # opts           specifies options for the solr query
      #
      #   options may include:
      # 
      #   :sort             => array of hash with one hash per sort by field... defaults to [{system_create=>:descending}]
      #   :default_field, :rows, :filter_queries, :debug_query,
      #   :explain_other, :facets, :highlighting, :mlt,
      #   :operator         => :or / :and
      #   :start            => defaults to 0
      #   :field_list       => array, defaults to ["*", "score"]
      #
      def find_by_fields_by_solr(query_fields,opts={})
        #create solr_args from fields passed in, needs to be comma separated list of form field1=value1,field2=value2,...
        escaped_class_name = self.name.gsub(/(:)/, '\\:')
        query = "#{ActiveFedora::SolrService.solr_name(:active_fedora_model, :symbol)}:#{escaped_class_name}" 
        
        query_fields.each_pair do |key,value|
          unless value.nil?
            solr_key = key
            #convert to symbol if need be
            key = key.to_sym if !class_fields.has_key?(key)&&class_fields.has_key?(key.to_sym)
            #do necessary mapping with suffix in most cases, otherwise ignore as a solr field key that activefedora does not know about
            if class_fields.has_key?(key) && class_fields[key].has_key?(:type)
              type = class_fields[key][:type]
              type = :string unless type.kind_of?(Symbol)
              solr_key = ActiveFedora::SolrService.solr_name(key,type)
            end
            
            escaped_value = value.gsub(/(:)/, '\\:')
            #escaped_value = escaped_value.gsub(/ /, '\\ ')
            key = SOLR_DOCUMENT_ID if (key === :id || key === :pid)
            query = key.to_s.eql?(SOLR_DOCUMENT_ID) ? "#{query} AND #{key}:#{escaped_value}" : "#{query} AND #{solr_key}:#{escaped_value}"  
          end
        end
      
        query_opts = {}
        opts.each do |key,value|
          key = key.to_sym
          query_opts[key] = value
        end
      
        #set default sort to created date ascending
        unless query_opts.include?(:sort)
          query_opts.merge!({:sort=>[ActiveFedora::SolrService.solr_name(:system_create,:date)=>:ascending]}) 
        else
          #need to convert to solr names for all fields
          sort_array =[]
        
          opts[:sort].collect do |sort|
            sort_direction = :ascending
            if sort.respond_to?(:keys)
              key = sort.keys[0]
              sort_direction = sort[key]
              sort_direction =~ /^desc/ ? sort_direction = :descending : :ascending
            else
              key = sort.to_s
            end
            field_name = key
            
            if key.to_s =~ /^system_create/
              field_name = :system_create_date
              key = :system_create
            elsif key.to_s =~ /^system_mod/  
              field_name = :system_modified_date
              key = :system_modified
            end
         
            solr_name = field_name 
            if class_fields.include?(field_name.to_sym)
              solr_name = ActiveFedora::SolrService.solr_name(key,class_fields[field_name.to_sym][:type])
            end
            sort_array.push({solr_name=>sort_direction})
          end
        
          query_opts[:sort] = sort_array
        end

        logger.debug "Querying solr for #{self.name} objects with query: '#{query}'"
    	  results = ActiveFedora::SolrService.instance.conn.query(query,query_opts)
      end
    
      def class_fields
        #create dummy object that is empty by passing in fake pid
        object = self.new()#{:pid=>'FAKE'})
        fields = object.fields
        #reset id to nothing
        fields[:id][:values] = []
        return fields
      end

      #wrapper around instance_variable_set, sets @name to value
      def attribute_set(name, value)
        instance_variable_set("@#{name}", value)
      end

      #wrapper around instance_variable_get, returns current value of @name
      def attribute_get(name)
        instance_variable_get("@#{name}")
      end

    end
    def create_property_getter(property) # :nodoc:

      class_eval <<-END, __FILE__, __LINE__
          def #{property.name}
            attribute_get("#{property.name}")
          end
          END
    end

    def create_property_setter(property)# :nodoc:
      class_eval <<-END, __FILE__, __LINE__  
          def #{property.name}=(value)
            attribute_set("#{property.name}", value)
          end
          END
    end

    private 
    
    def self.class_exists?(class_name)
      klass = class_name.constantize
      return klass.is_a?(Class)
    rescue NameError
      return false
    end
    
  end
end