module QME

  module MapReduce

    # Computes the value of quality measures based on the current set of patient
    # records in the database
    class Executor

      include DatabaseAccess
      SUPPLEMENTAL_DATA_ELEMENTS = {QME::QualityReport::RACE => "$value.race.code",
                                    QME::QualityReport::ETHNICITY => "$value.ethnicity.code",
                                    QME::QualityReport::SEX => "$value.gender",
                                    QME::QualityReport::PAYER => "$value.payer.code"}
      # Create a new Executor for a specific measure, effective date and patient population.
      # @param [String] measure_id the measure identifier
      # @param [String] sub_id the measure sub-identifier or null if the measure is single numerator
      # @param [Hash] parameter_values a hash that may contain the following keys: 'effective_date' the measurement period end date, 'test_id' an identifier for a specific set of patients
      def initialize(measure_id, sub_id, parameter_values)
        @measure_id = measure_id
        @sub_id = sub_id
        @parameter_values = parameter_values
        @measure_def = QualityMeasure.new(@measure_id, @sub_id, parameter_values['bundle_id']).definition
        determine_connection_information()
      end

      def build_query
        pipeline = []

        filters = @parameter_values['filters']

        
        match = {'value.measure_id' => @measure_id, 
                 'value.sub_id'           => @sub_id,
                 'value.effective_date'   => @parameter_values['effective_date'],
                 'value.test_id'          => @parameter_values['test_id'],
                 'value.manual_exclusion' => {'$in' => [nil, false]}}

        if(filters)
          if (filters['races'] && filters['races'].size > 0)
            match['value.race.code'] = {'$in' => filters['races']}
          end
          if (filters['ethnicities'] && filters['ethnicities'].size > 0)
            match['value.ethnicity.code'] = {'$in' => filters['ethnicities']}
          end
          if (filters['genders'] && filters['genders'].size > 0)
            match['value.gender'] = {'$in' => filters['genders']}
          end
          if (filters['providers'] && filters['providers'].size > 0)
            providers = filters['providers'].map { |pv| {'providers' => Moped::BSON::ObjectId(pv) } }
            pipeline.concat [{'$project' => {'value' => 1, 'providers' => "$value.provider_performances.provider_id"}}, 
                             {'$unwind' => '$providers'}, 
                             {'$match' => {'$or' => providers}},
                             {'$group' => {"_id" => "$_id", "value" => {"$first" => "$value"}}}]
          end
          if (filters['languages'] && filters['languages'].size > 0)
            languages = filters['languages'].map { |l| {'languages' => l } }
            pipeline.concat  [{'$project' => {'value' => 1, 'languages' => "$value.languages"}},
                              {'$unwind' => "$languages"},
                              {'$project' => {'value' => 1, 'languages' => {'$substr' => ['$languages', 0, 2]}}},
                              {'$match' => {'$or' => languages}},
                              {'$group' => {"_id" => "$_id", "value" => {"$first" => "$value"}}}]
          end
        end

        pipeline.unshift({'$match' => match})

        pipeline
      end


      #Calculate all of the supoplemental data elements 
      def calculate_supplemental_data_elements

        match = {'value.measure_id' => @measure_id, 
                 'value.sub_id'           => @sub_id,
                 'value.effective_date'   => @parameter_values['effective_date'],
                 'value.test_id'          => @parameter_values['test_id'],
                 'value.manual_exclusion' => {'$in' => [nil, false]}}    
       
        keys = @measure_def["population_ids"].keys - [QME::QualityReport::OBSERVATION, "stratification"]
        supplemental_data = Hash[*keys.map{|k| [k,{QME::QualityReport::RACE => {},
                                                   QME::QualityReport::ETHNICITY => {},
                                                   QME::QualityReport::SEX => {},
                                                   QME::QualityReport::PAYER => {}}]}.flatten]
                                                 
        keys.each do |pop_id|
          _match = match.clone
          _match["value.#{pop_id}"] = {"$gt" => 0}
          SUPPLEMENTAL_DATA_ELEMENTS.each_pair do |supp_element,location|
            group1 = {"$group" => { "_id" => { "id" => "$_id", "val" => location}}} 
            group2 = {"$group" => {"_id" => "$_id.val", "val" =>{"$sum" => 1} }}
            pipeline = [{"$match" =>_match},group1,group2]
            aggregate = get_db.command(:aggregate => 'patient_cache', :pipeline => pipeline)

            v = {}
            (aggregate["result"] || []).each  do |entry| 
              code  = entry["_id"].nil? ? "UNK" : entry["_id"]
              v[code] = entry["val"]
            end
            supplemental_data[pop_id] ||= {}
            supplemental_data[pop_id][supp_element] = v
           end
        end
        supplemental_data
      end


      # Examines the patient_cache collection and generates a total of all groups
      # for the measure. The totals are placed in a document in the query_cache
      # collection.
      # @return [Hash] measure groups (like numerator) as keys, counts as values
      def count_records_in_measure_groups
        pipeline = build_query

        pipeline << {'$group' => {
          "_id" => "$value.measure_id", # we don't really need this, but Mongo requires that we group 
          QME::QualityReport::POPULATION => {"$sum" => "$value.#{QME::QualityReport::POPULATION}"}, 
          QME::QualityReport::DENOMINATOR => {"$sum" => "$value.#{QME::QualityReport::DENOMINATOR}"},
          QME::QualityReport::NUMERATOR => {"$sum" => "$value.#{QME::QualityReport::NUMERATOR}"},
          QME::QualityReport::ANTINUMERATOR => {"$sum" => "$value.#{QME::QualityReport::ANTINUMERATOR}"},
          QME::QualityReport::EXCLUSIONS => {"$sum" => "$value.#{QME::QualityReport::EXCLUSIONS}"},
          QME::QualityReport::EXCEPTIONS => {"$sum" => "$value.#{QME::QualityReport::EXCEPTIONS}"},
          QME::QualityReport::MSRPOPL => {"$sum" => "$value.#{QME::QualityReport::MSRPOPL}"},
          QME::QualityReport::CONSIDERED => {"$sum" => 1}
        }}

        aggregate = get_db.command(:aggregate => 'patient_cache', :pipeline => pipeline)
        if aggregate['ok'] != 1
          raise RuntimeError, "Aggregation Failed"
        elsif aggregate['result'].size !=1
          raise RuntimeError, "Expected one group from patient_cache aggregation, got #{aggregate['result'].size}"
        end

        nqf_id = @measure_def['nqf_id'] || @measure_def['id']
        result = {:measure_id => @measure_id, :sub_id => @sub_id, :nqf_id => nqf_id, :population_ids => @measure_def["population_ids"],
                  :effective_date => @parameter_values['effective_date'],
                  :test_id => @parameter_values['test_id'], :filters => @parameter_values['filters']}

        if @measure_def['continuous_variable']
          aggregated_value = calculate_cv_aggregation 
          result[QME::QualityReport::OBSERVATION] = aggregated_value
        end

        result.merge!(aggregate['result'].first)
        result.reject! {|k, v| k == '_id'} # get rid of the group id the Mongo forced us to use
        # result['exclusions'] += get_db['patient_cache'].find(base_query.merge({'value.manual_exclusion'=>true})).count
        result.merge!(execution_time: (Time.now.to_i - @parameter_values['start_time'].to_i)) if @parameter_values['start_time']
        result[:supplemental_data] = self.calculate_supplemental_data_elements
        get_db()["query_cache"].insert(result)
        get_db().command({:getLastError => 1}) # make sure last insert finished before we continue
        result
      end

      # This method calculates the aggregated value for a CV measure.  It extracts all 
      # the values for patients in the MSRPOPL and uses the aggregator to combine those 
      # values into an aggregated value.  The currently supported aggregators are:
      #   MEDIAN
      #   MEAN
      def calculate_cv_aggregation
        cv_pipeline = build_query
        cv_pipeline.first['$match']["value.#{QME::QualityReport::MSRPOPL}"] = {'$gt'=>0}
        cv_pipeline << {'$unwind' => '$value.values'}
        cv_pipeline << {'$group' => {'_id' => '$value.values', 'count' => {'$sum' => 1}}}

        aggregate = get_db.command(:aggregate => 'patient_cache', :pipeline => cv_pipeline)

        raise RuntimeError, "Aggregation Failed" if aggregate['ok'] != 1

        frequencies = {}
        aggregate['result'].each do |freq_count_pair|
          frequencies[freq_count_pair['_id']] = freq_count_pair['count']
        end
        QME::MapReduce::CVAggregator.send(@measure_def['aggregator'].parameterize, frequencies)
      end


      # This method runs the MapReduce job for the measure which will create documents
      # in the patient_cache collection. These documents will state the measure groups
      # that the record belongs to, such as numerator, etc.
      def map_records_into_measure_groups
        measure = Builder.new(get_db(), @measure_def, @parameter_values)
        get_db().command(:mapReduce => 'records',
                         :map => measure.map_function,
                         :reduce => "function(key, values){return values;}",
                         :out => {:reduce => 'patient_cache'}, 
                         :finalize => measure.finalize_function,
                         :query => {:test_id => @parameter_values['test_id']})
        apply_manual_exclusions
      end
      
      # This method runs the MapReduce job for the measure and a specific patient.
      # This will create a document in the patient_cache collection. This document
      # will state the measure groups that the record belongs to, such as numerator, etc.
      def map_record_into_measure_groups(patient_id)
        measure = Builder.new(get_db(), @measure_def, @parameter_values)
        get_db().command(:mapReduce => 'records',
                         :map => measure.map_function,
                         :reduce => "function(key, values){return values;}",
                         :out => {:reduce => 'patient_cache'}, 
                         :finalize => measure.finalize_function,
                         :query => {:medical_record_number => patient_id, :test_id => @parameter_values['test_id']})
        apply_manual_exclusions
      end
      
      # This method runs the MapReduce job for the measure and a specific patient.
      # This will *not* create a document in the patient_cache collection, instead the
      # result is returned directly.
      def get_patient_result(patient_id)
        measure = Builder.new(get_db(), @measure_def, @parameter_values)
        result = get_db().command(:mapReduce => 'records',
                                  :map => measure.map_function,
                                  :reduce => "function(key, values){return values;}",
                                  :out => {:inline => true}, 
                                  :raw => true, 
                                  :finalize => measure.finalize_function,
                                  :query => {:medical_record_number => patient_id, :test_id => @parameter_values['test_id']})
        raise result['err'] if result['ok']!=1
        result['results'][0]['value']
      end
      
      # This collects the set of manual exclusions from the manual_exclusions collections
      # and sets a flag in each cached patient result for patients that have been excluded from the
      # current measure
      def apply_manual_exclusions
        exclusions = get_db()['manual_exclusions'].find({'measure_id'=>@measure_id, 'sub_id'=>@sub_id}).to_a.map do |exclusion|
          exclusion['medical_record_id']
        end
        get_db()['patient_cache'].find({'value.measure_id'=>@measure_id, 'value.sub_id'=>@sub_id, 'value.medical_record_id'=>{'$in'=>exclusions} })
          .update_all({'$set'=>{'value.manual_exclusion'=>true}})
      end
    end
  end
end