define "Initial Population":
  AgeInYearsAt(date from start of "Measurement Period") >= 18
    and exists "Primary Open Angle Glaucoma Encounter"

define "Denominator":
  "Initial Population"

define "Numerator":
  exists "Cup to Disc Ratio Performed with Result"
    and exists "Optic Disc Exam Performed with Result"

define "Denominator Exceptions":
  exists "Medical Reason for Not Performing Cup to Disc Ratio"
    or exists "Medical Reason for Not Performing Optic Disc Exam"

define "SDE Sex":
  case
      when Patient.gender = 'male' then "M"
      when Patient.gender = 'female' then "F"
      else null
    end

define "SDE Sex":
  SDE."SDE Sex"

define "Qualifying Encounter During Measurement Period":
  ( ["Encounter": "Office Visit"]
    union ["Encounter": "Ophthalmological Services"]
    union ["Encounter": "Outpatient Consultation"]
    union ["Encounter": "Nursing Facility Visit"]
    union ["Encounter": "Care Services in Long-Term Residential Facility"] ) QualifyingEncounter
    where QualifyingEncounter.period during "Measurement Period"
      and QualifyingEncounter.class !~ "virtual"
      and QualifyingEncounter.class ~ "AMB"
      and QualifyingEncounter.status = 'finished'

define "Primary Open Angle Glaucoma Encounter":
  "Qualifying Encounter During Measurement Period" ValidQualifyingEncounter
    with ["Condition": "Primary Open-Angle Glaucoma"] PrimaryOpenAngleGlaucoma
      such that PrimaryOpenAngleGlaucoma.prevalenceInterval ( ) overlaps ValidQualifyingEncounter.period
        and PrimaryOpenAngleGlaucoma.isActive ( )
        and not ( PrimaryOpenAngleGlaucoma.verificationStatus ~ QICoreCommon."unconfirmed"
            or PrimaryOpenAngleGlaucoma.verificationStatus ~ QICoreCommon."refuted"
            or PrimaryOpenAngleGlaucoma.verificationStatus ~ QICoreCommon."entered-in-error"
        )

define "Cup to Disc Ratio Performed with Result":
  ["Observation": "Cup to Disc Ratio"] CupToDiscExamPerformed
    with "Primary Open Angle Glaucoma Encounter" EncounterWithPOAG
      such that CupToDiscExamPerformed.effective.toInterval ( ) during EncounterWithPOAG.period
    where CupToDiscExamPerformed.value is not null
      and CupToDiscExamPerformed.status in { 'final', 'amended', 'corrected' }

define "Optic Disc Exam Performed with Result":
  ["Observation": "Optic Disc Exam for Structural Abnormalities"] OpticDiscExamPerformed
    with "Primary Open Angle Glaucoma Encounter" EncounterWithPOAG
      such that OpticDiscExamPerformed.effective.toInterval ( ) during EncounterWithPOAG.period
    where OpticDiscExamPerformed.value is not null
      and OpticDiscExamPerformed.status in { 'final', 'amended', 'corrected' }

define "Numerator":
  exists "Cup to Disc Ratio Performed with Result"
    and exists "Optic Disc Exam Performed with Result"

define "Initial Population":
  AgeInYearsAt(date from start of "Measurement Period") >= 18
    and exists "Primary Open Angle Glaucoma Encounter"

define "Denominator":
  "Initial Population"

define "SDE Payer":
  [Coverage: type in "Payer Type"] Payer
    return {
      code: Payer.type,
      period: Payer.period
    }

define "SDE Payer":
  SDE."SDE Payer"

define "SDE Ethnicity":
  Patient.ethnicity E
    return Tuple {
      codes: { E.ombCategory } union E.detailed,
      display: E.text
    }

define "SDE Ethnicity":
  SDE."SDE Ethnicity"

define "SDE Race":
  Patient.race R
    return Tuple {
      codes: R.ombCategory union R.detailed,
      display: R.text
    }

define "SDE Race":
  SDE."SDE Race"

define "Medical Reason for Not Performing Cup to Disc Ratio":
  ["ObservationNotDone": "Cup to Disc Ratio"] CupToDiscExamNotPerformed
    with "Primary Open Angle Glaucoma Encounter" EncounterWithPOAG
      such that CupToDiscExamNotPerformed.issued.toInterval ( ) during EncounterWithPOAG.period
    where CupToDiscExamNotPerformed.status = 'cancelled'
      and CupToDiscExamNotPerformed.notDoneReason in "Medical Reason"

define "Medical Reason for Not Performing Optic Disc Exam":
  ["ObservationNotDone": "Optic Disc Exam for Structural Abnormalities"] OpticDiscExamNotPerformed
    with "Primary Open Angle Glaucoma Encounter" EncounterWithPOAG
      such that OpticDiscExamNotPerformed.issued.toInterval ( ) during EncounterWithPOAG.period
    where OpticDiscExamNotPerformed.status = 'cancelled'
      and OpticDiscExamNotPerformed.notDoneReason in "Medical Reason"

define "Denominator Exceptions":
  exists "Medical Reason for Not Performing Cup to Disc Ratio"
    or exists "Medical Reason for Not Performing Optic Disc Exam"

/*
@description: Returns an interval representing the normalized prevalence period of a given Condition.
@comment: Uses the ToInterval and ToAbatementInterval functions to determine the widest potential interval from
onset to abatement as specified in the given Condition. If the condition is active, the resulting interval will have
a closed ending boundary. If the condition is not active, the resulting interval will have an open ending boundary.
*/
define fluent function prevalenceInterval(condition Condition):
if condition.clinicalStatus ~ "active"
  or condition.clinicalStatus ~ "recurrence"
  or condition.clinicalStatus ~ "relapse" then
  Interval[start of condition.onset.toInterval(), end of condition.abatementInterval()]
else
  Interval[start of condition.onset.toInterval(), end of condition.abatementInterval())

/* Candidates for FHIRCommon */

/*
@description: Returns true if the given condition has a clinical status of active, recurrence, or relapse
*/
define fluent function isActive(condition Condition):
  condition.clinicalStatus ~ "active"
    or condition.clinicalStatus ~ "recurrence"
    or condition.clinicalStatus ~ "relapse"

/*
@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.
Any other input will reslt in a null DateTime Interval
*/
define fluent function toInterval(choice Choice<DateTime, Quantity, Interval<DateTime>, Interval<Quantity>>):
  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)
		else
			null as Interval<DateTime>
	end

define function ToString(value uri): value.value

/*
@description: Converts the given FHIR [Coding](https://hl7.org/fhir/datatypes.html#Coding) value to a CQL Code.
*/
define function ToCode(coding FHIR.Coding):
    if coding is null then
        null
    else
        System.Code {
          code: coding.code.value,
          system: coding.system.value,
          version: coding.version.value,
          display: coding.display.value
        }