define "Initial Population":
  AgeInYearsAt(date from start of "Measurement Period") in Interval[1, 20]
    and exists ( "Qualifying Encounters" )

define "Denominator":
  "Initial Population"

define "Denominator Exclusions":
  Hospice."Has Hospice Services"

define "Numerator":
  Count((([Procedure: "Fluoride Varnish Application for Children"]).isProcedurePerformed()) FluorideApplication
      where FluorideApplication.performed.toInterval() ends during day of "Measurement Period"
      return distinct date from 
      end of FluorideApplication.performed.toInterval()
  ) >= 2

define "Initial Population":
  AgeInYearsAt(date from start of "Measurement Period") in Interval[1, 20]
    and exists ( "Qualifying Encounters" )

define "Initial Population":
  AgeInYearsAt(date from start of "Measurement Period") in Interval[1, 20]
    and exists ( "Qualifying Encounters" )

define "Initial Population":
  AgeInYearsAt(date from start of "Measurement Period") in Interval[1, 20]
    and exists ( "Qualifying Encounters" )

define "Has Hospice Services":
  exists ((([Encounter: "Encounter Inpatient"]).isEncounterPerformed()) InpatientEncounter
      where (InpatientEncounter.hospitalization.dischargeDisposition ~ "Discharge to home for hospice care (procedure)"
          or InpatientEncounter.hospitalization.dischargeDisposition ~ "Discharge to healthcare facility for hospice care (procedure)"
      )
        and InpatientEncounter.period ends during day of "Measurement Period"
  )
    or exists ((([Encounter: "Hospice Encounter"]).isEncounterPerformed()) HospiceEncounter
        where HospiceEncounter.period overlaps day of "Measurement Period"
    )
    or exists ((([ObservationScreeningAssessment: "Hospice care [Minimum Data Set]"]).isAssessmentPerformed()) HospiceAssessment
        where HospiceAssessment.value ~ "Yes (qualifier value)"
          and HospiceAssessment.effective.toInterval() overlaps day of "Measurement Period"
    )
    or exists ((([ServiceRequest: "Hospice Care Ambulatory"]).isInterventionOrder()) HospiceOrder
        where HospiceOrder.authoredOn during day of "Measurement Period"
    )
    or exists ((([Procedure: "Hospice Care Ambulatory"]).isInterventionPerformed()) HospicePerformed
        where HospicePerformed.performed.toInterval() overlaps day of "Measurement Period"
    )
    or exists ((([ConditionProblemsHealthConcerns: "Hospice Diagnosis"]
        union [ConditionEncounterDiagnosis: "Hospice Diagnosis"]).verified()) HospiceCareDiagnosis
        where HospiceCareDiagnosis.prevalenceInterval() overlaps day of "Measurement Period"
    )

define "Numerator":
  Count((([Procedure: "Fluoride Varnish Application for Children"]).isProcedurePerformed()) FluorideApplication
      where FluorideApplication.performed.toInterval() ends during day of "Measurement Period"
      return distinct date from 
      end of FluorideApplication.performed.toInterval()
  ) >= 2

define "Qualifying Encounters":
  ( ( [Encounter: "Clinical Oral Evaluation"] ).isEncounterPerformed ( ) ) ValidEncounter
    where ValidEncounter.period during day of "Measurement Period"

define "Initial Population":
  AgeInYearsAt(date from start of "Measurement Period") in Interval[1, 20]
    and exists ( "Qualifying Encounters" )

define "Denominator":
  "Initial Population"

define "Denominator Exclusions":
  Hospice."Has Hospice Services"

/*
@description: Normalizes a value that is a choice of timing-valued types to an equivalent interval
@comment: Normalizes a choice type of DateTime, Quanitty, Interval<DateTime>, or Interval<Quantity> types
to an equivalent interval. This selection of choice types is a superset of the majority of choice types that are used as possible
representations for timing-valued elements in QICore, allowing this function to be used across any resource.
The input can be provided as a DateTime, Quantity, Interval<DateTime> or Interval<Quantity>.
The intent of this function is to provide a clear and concise mechanism to treat single
elements that have multiple possible representations as intervals so that logic doesn't have to account
for the variability. More complex calculations (such as medication request period or dispense period
calculation) need specific guidance and consideration. That guidance may make use of this function, but
the focus of this function is on single element calculations where the semantics are unambiguous.
If the input is a DateTime, the result a DateTime Interval beginning and ending on that DateTime.
If the input is a Quantity, the quantity is expected to be a calendar-duration interpreted as an Age,
and the result is a DateTime Interval beginning on the Date the patient turned that age and ending immediately before one year later.
If the input is a DateTime Interval, the result is the input.
If the input is a Quantity Interval, the quantities are expected to be calendar-durations interpreted as an Age, and the result
is a DateTime Interval beginning on the date the patient turned the age given as the start of the quantity interval, and ending
immediately before one year later than the date the patient turned the age given as the end of the quantity interval.
If the input is a Timing, an error will be thrown indicating that Timing calculations are not implemented. Any other input will reslt in a null DateTime Interval
*/
define fluent function toInterval(choice Choice<DateTime, Quantity, Interval<DateTime>, Interval<Quantity>, Timing>):
  case
	  when choice is DateTime then
    	Interval[choice as DateTime, choice as DateTime]
		when choice is Interval<DateTime> then
  		choice as Interval<DateTime>
		when choice is Quantity then
		  Interval[Patient.birthDate + (choice as Quantity),
			  Patient.birthDate + (choice as Quantity) + 1 year)
		when choice is Interval<Quantity> then
		  Interval[Patient.birthDate + (choice.low as Quantity),
			  Patient.birthDate + (choice.high as Quantity) + 1 year)
		when choice is Timing then
      Message(null, true, 'NOT_IMPLEMENTED', 'Error', 'Calculation of an interval from a Timing value is not supported') as Interval<DateTime>
		else
			null as Interval<DateTime>
	end

/*
@description: Converts the given [Period](https://hl7.org/fhir/datatypes.html#Period)
value to a CQL DateTime Interval
@comment: If the start value of the given period is unspecified, the starting
boundary of the resulting interval will be open (meaning the start of the interval
is unknown, as opposed to interpreted as the beginning of time).
*/
define function ToInterval(period FHIR.Period):
    if period is null then
        null
    else
        if period."start" is null then
            Interval(period."start".value, period."end".value]
        else
            Interval[period."start".value, period."end".value]

//Procedure, Performed
define fluent function isProcedurePerformed(Proc List<Procedure>):
  Proc P
    where P.status ~ 'completed'

//Encounter, Performed
//General usage unless required otherwise by measure intent (e.g., follow-up encounters)
define fluent function isEncounterPerformed(Enc List<Encounter>):
  Enc E
    where E.status = 'finished'

//Assessment, Performed
define fluent function isAssessmentPerformed(Obs List<ObservationScreeningAssessment>):
  Obs O
    where O.status in { 'final', 'amended', 'corrected' }

//Intervention, Order
define fluent function isInterventionOrder(ServiceRequest List<ServiceRequest>):
  ServiceRequest S
    where S.status in { 'active', 'completed' }
      and S.intent in {'order', 'original-order', 'reflex-order', 'filler-order', 'instance-order'}

//Intervention, Performed
define fluent function isInterventionPerformed(Proc List<Procedure>):
  Proc P
    where P.status ~ 'completed'

//This library contains functions used to constrain FHIR resource elements for measures authored by NCQA, based on QICore 6.0.0 resources including IG and authoring patterns. The functions may appear similar to some QICoreCommon functions but differ in that they have constraints that are relevant for measures authored by NCQA.

//Condition
//Returns conditions in the given list that either have no verification status or have a verification status of confirmed, unconfirmed, provisional, or differential
define fluent function verified(conditions List<Choice<ConditionProblemsHealthConcerns, ConditionEncounterDiagnosis>>):
  conditions C
    where C.verificationStatus is not null implies
      (C.verificationStatus ~ "confirmed"
        or C.verificationStatus ~ "unconfirmed"
        or C.verificationStatus ~ "provisional"
        or C.verificationStatus ~ "differential"
      )