# frozen_string_literal: true

module CqmValidators
  class MeasureValidator
    include BaseValidator

    def initialize(template_oid)
      @template_oid = template_oid
    end

    def validate(file, data = {})
      @errors = []
      @doc = get_document(file)
      @doc.root.add_namespace_definition('cda', 'urn:hl7-org:v3')
      measure_ids = CQM::Measure.pluck(:hqmf_id)
      doc_measure_ids = @doc.xpath(measure_selector).map(&:value).map(&:upcase)
      # list of all of the set ids in the QRDA
      doc_neutral_ids = @doc.xpath(neutral_measure_selector).map(&:value).map(&:upcase).sort
      # list of all of the setids in the QRDA that are also in the bundle, includes duplicates if code appears twice in document
      bundle_neutral_ids = CQM::Measure.distinct(:hqmf_set_id)
      doc_bundle_neutral_ids = doc_neutral_ids - (doc_neutral_ids - bundle_neutral_ids)
      validate_measure_ids(doc_measure_ids, measure_ids, data)
      validate_set_ids(doc_neutral_ids, doc_bundle_neutral_ids, data)
      validate_measure_ids_set_ids_usage(doc_bundle_neutral_ids, doc_measure_ids, data) if validate_no_repeating_measure_population_ids(data)

      @errors
    end

    private

    # returns true if there are no repeating measures, check to see that the measure id usage is correct
    def validate_no_repeating_measure_population_ids(data = {})
      no_duplicate_measures = true
      doc_population_ids = @doc.xpath(measure_population_selector).map(&:value).map(&:upcase).sort
      duplicates = doc_population_ids.group_by { |e| e }.select { |_k, v| v.size > 1 }.map(&:first)
      duplicates.each do |duplicate|
        begin
          measure_id = @doc.xpath(find_measure_node_for_population(duplicate)).at_xpath("cda:reference/cda:externalDocument/cda:id[./@root='2.16.840.1.113883.4.738']/@extension")
          @errors << build_error("Population #{duplicate} for Measure #{measure_id.value} reported more than once", '/', data[:file_name])
        rescue
          @errors << build_error("Population #{duplicate} for reported more than once", '/', data[:file_name])
        end
        no_duplicate_measures = false
      end
      no_duplicate_measures
    end

    def validate_measure_ids(doc_measure_ids, measure_ids, data = {})
      (doc_measure_ids - measure_ids).map do |hqmf_id|
        @errors << build_error("Invalid HQMF ID Found: #{hqmf_id}", '/', data[:file_name])
      end
    end

    def validate_set_ids(doc_neutral_ids, doc_bundle_neutral_ids, data = {})
      # an error will be returned for all of the setids that are in the QRDA that aren't in the bundle
      (doc_neutral_ids - doc_bundle_neutral_ids).map do |hqmf_set_id|
        @errors << build_error("Invalid HQMF Set ID Found: #{hqmf_set_id}", '/', data[:file_name])
      end
    end

    # does not work if the same measure is reported more than once, nested under the repeating measures test
    def validate_measure_ids_set_ids_usage(doc_bundle_neutral_ids, doc_measure_ids, data = {})
      # for each of the setIds that are in the bundle, check that they are for the correct measure id
      entries_start_position = @doc.xpath(first_entry)
      previous = ''
      index = 1
      doc_bundle_neutral_ids.each do |hqmf_set_id|
        # selects the measure id that is in the same entry as the set id
        # iterates through multiple instances of the same setId
        index = if previous == hqmf_set_id
                  index + 1
                else
                  1
                end
        measure_id_entry = doc_measure_ids[(@doc.xpath(location_of_set_id(hqmf_set_id, index)) - entries_start_position)]
        previous = hqmf_set_id
        # queries database to see if there is a measure with the combindation of setId and measureId
        if CQM::Measure.where(hqmf_id: measure_id_entry, hqmf_set_id: hqmf_set_id).empty?
          @errors << build_error("Invalid HQMF Set ID Found: #{hqmf_set_id} for HQMF ID: #{measure_id_entry}", '/', data[:file_name])
        end
      end
    end

    def measure_selector
      '/cda:ClinicalDocument/cda:component/cda:structuredBody/cda:component/cda:section/cda:entry' \
        "/cda:organizer[./cda:templateId[@root='#{@template_oid}']]/cda:reference[@typeCode='REFR']" \
        "/cda:externalDocument[@classCode='DOC']/cda:id[@root='2.16.840.1.113883.4.738']/@extension"
    end

    # finds all of the setIds in the QRDA document
    def neutral_measure_selector
      '/cda:ClinicalDocument/cda:component/cda:structuredBody/cda:component/cda:section/cda:entry' \
        "/cda:organizer[./cda:templateId[@root='#{@template_oid}']]/cda:reference[@typeCode='REFR']" \
        "/cda:externalDocument[@classCode='DOC']/cda:setId/@root"
    end

    # finds the node index of the first entry element in the measure template
    def first_entry
      "count(//cda:entry[cda:organizer[./cda:templateId[@root='#{@template_oid}']]" \
        "/cda:reference[@typeCode='REFR']/cda:externalDocument[@classCode='DOC']" \
        "/cda:id[@root='2.16.840.1.113883.4.738']][1]/preceding-sibling::*)+1"
    end

    # finds the node index of the extry that the specified setId is in, index is used if the same setId appears twice
    def location_of_set_id(set_id, index)
      "count(//cda:entry[cda:organizer[./cda:templateId[@root='#{@template_oid}']]" \
        "/cda:reference[@typeCode='REFR']/cda:externalDocument[@classCode='DOC']" \
        "/cda:setId[@root[contains(translate(.,'abcdefghijklmnopqrstuvwxyz','ABCDEFGHIJKLOMNOPQRSTUVWXYZ')" \
        ",'#{set_id}')]]][#{index}]/preceding-sibling::*)+1"
    end

    def measure_population_selector
      '/cda:ClinicalDocument/cda:component/cda:structuredBody/cda:component/cda:section/cda:entry' \
        "/cda:organizer[./cda:templateId[@root='2.16.840.1.113883.10.20.27.3.1']]/cda:component" \
        "/cda:observation[./cda:templateId[@root='2.16.840.1.113883.10.20.27.3.5']]/cda:reference" \
        '/cda:externalObservation/cda:id/@root'
    end

    def find_measure_node_for_population(id)
      '/cda:ClinicalDocument/cda:component/cda:structuredBody/cda:component/cda:section/cda:entry' \
        "/cda:organizer[ ./cda:templateId[@root='2.16.840.1.113883.10.20.27.3.1']" \
        "and ./cda:component/cda:observation[./cda:templateId[@root='2.16.840.1.113883.10.20.27.3.5']]/cda:reference" \
        "/cda:externalObservation/cda:id[@root[contains(translate(.,'abcdefghijklmnopqrstuvwxyz','ABCDEFGHIJKLOMNOPQRSTUVWXYZ')" \
        ",'#{id.upcase}')]]]"
    end
  end
end