define "Initial Population":
  AgeInYearsAt(date from "IPSD") >= 18
    and "Has IPSD and Major Depression Diagnosis"
    and exists "Qualifying Encounters"

define "Denominator":
  "Initial Population"

define "Denominator Exclusions":
  Hospice."Has Hospice Services"
    or exists ( ( ( [MedicationRequest: "Antidepressant Medication"] ).isMedicationActive ( ) ) ActiveAntidepressant
        where "IPSD" is not null
          and CQMCommon.ToDateInterval ( ActiveAntidepressant.medicationRequestPeriod ( ) ) overlaps Interval["IPSD" - 105 days, "IPSD" )
    )

define "Numerator 1":
  "Cumulative Medication Duration Greater Than or Equal to 84 Days"

define "Initial Population":
  AgeInYearsAt(date from "IPSD") >= 18
    and "Has IPSD and Major Depression Diagnosis"
    and exists "Qualifying Encounters"

define "Denominator":
  "Initial Population"

define "Denominator Exclusions":
  Hospice."Has Hospice Services"
    or exists ( ( ( [MedicationRequest: "Antidepressant Medication"] ).isMedicationActive ( ) ) ActiveAntidepressant
        where "IPSD" is not null
          and CQMCommon.ToDateInterval ( ActiveAntidepressant.medicationRequestPeriod ( ) ) overlaps Interval["IPSD" - 105 days, "IPSD" )
    )

define "Numerator 2":
  "Cumulative Medication Duration Greater Than or Equal to 180 Days"

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 "SDE Sex":
  case
    when Patient.sex = '248153007' then "Male (finding)"
    when Patient.sex = '248152002' then "Female (finding)"
    else null
  end

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

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

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

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

define "May 1 of the Year Prior to the Measurement Period":
  DateTime((year from start of "Measurement Period" - 1), 5, 1, 0, 0, 0, 0, 0)

define "April 30 of the Measurement Period":
  DateTime((year from start of "Measurement Period"), 4, 30, 23, 59, 59, 0, 0)

define "Intake Period":
  Interval["May 1 of the Year Prior to the Measurement Period", "April 30 of the Measurement Period"]

define "IPSD":
  First((([MedicationDispense: "Antidepressant Medication"]).isMedicationDispensed()) Antidepressant
      where start of Antidepressant.medicationDispensePeriod() in day of "Intake Period"
      return {
        AntidepressantDate: date from start of Antidepressant.medicationDispensePeriod()
      }
      sort by AntidepressantDate
  ).AntidepressantDate

define "Has IPSD and Major Depression Diagnosis":
  exists ( ( ( [ConditionProblemsHealthConcerns: "Major Depression"]
        union [ConditionEncounterDiagnosis: "Major Depression"]
    ).verified ( ) ) MajorDepression
      where "IPSD" is not null
        and date from start of MajorDepression.prevalenceInterval ( ) within 60 days of "IPSD"
  )

define "Qualifying Encounters":
  ( ( [Encounter: "Office Visit"]
      union [Encounter: "Preventive Care Services Established Office Visit, 18 and Up"]
      union [Encounter: "Preventive Care Services Initial Office Visit, 18 and Up"]
      union [Encounter: "Home Healthcare Services"]
      union [Encounter: "Annual Wellness Visit"]
      union [Encounter: "Nursing Facility Visit"]
      union [Encounter: "Psych Visit Diagnostic Evaluation"]
      union [Encounter: "Psych Visit Psychotherapy"]
      union [Encounter: "Telephone Visits"]
      union [Encounter: "Virtual Encounter"]
  ).isEncounterPerformed ( ) ) ValidEncounter
    where date from start of ValidEncounter.period within 60 days of "IPSD"

define "Initial Population":
  AgeInYearsAt(date from "IPSD") >= 18
    and "Has IPSD and Major Depression Diagnosis"
    and exists "Qualifying Encounters"

define "Denominator":
  "Initial Population"

define "Antidepressant Medication Period Between IPSD and 114 Days After IPSD":
  ( ( [MedicationDispense: "Antidepressant Medication"] ).isMedicationDispensed ( ) ) Antidepressant
    let MedicationPeriod: Antidepressant.medicationDispensePeriod ( )
    return MedicationPeriod
      intersect Interval["IPSD", "IPSD" + 114 days]

define "Cumulative Medication Duration Greater Than or Equal to 84 Days":
  ( "Antidepressant Medication Period Between IPSD and 114 Days After IPSD".cumulativeDuration ( ) ) >= 84

define "Numerator 1":
  "Cumulative Medication Duration Greater Than or Equal to 84 Days"

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

define "Antidepressant Medication Period Between IPSD and 231 Days After IPSD":
  ( ( [MedicationDispense: "Antidepressant Medication"] ).isMedicationDispensed ( ) ) Antidepressant
    let MedicationPeriod: Antidepressant.medicationDispensePeriod ( )
    return MedicationPeriod
      intersect Interval["IPSD", "IPSD" + 231 days]

define "Cumulative Medication Duration Greater Than or Equal to 180 Days":
  ( "Antidepressant Medication Period Between IPSD and 231 Days After IPSD".cumulativeDuration ( ) ) >= 180

define "Numerator 2":
  "Cumulative Medication Duration Greater Than or Equal to 180 Days"

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

define "Denominator Exclusions":
  Hospice."Has Hospice Services"
    or exists ( ( ( [MedicationRequest: "Antidepressant Medication"] ).isMedicationActive ( ) ) ActiveAntidepressant
        where "IPSD" is not null
          and CQMCommon.ToDateInterval ( ActiveAntidepressant.medicationRequestPeriod ( ) ) overlaps Interval["IPSD" - 105 days, "IPSD" )
    )

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

define function ToString(value uri): value.value

/*
@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]

/*
@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
        }

/*
@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

//Medication, Dispensed
define fluent function isMedicationDispensed(Med List<MedicationDispense>):
  Med M
    where M.status in { 'completed', 'in-progress', 'on-hold' }

//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"
      )

//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'

//Medication, Active
define fluent function isMedicationActive(MedicationRequest List<MedicationRequest>):
  MedicationRequest M
    where M.status = 'active'
      and M.intent in {'order', 'original-order', 'reflex-order', 'filler-order', 'instance-order'}

/*
@description: Returns an interval of date values extracted from the input interval of date-time values
@comment: This function returns an interval constructed using the `date from` extractor on the start
and end values of the input date-time interval. Note that using a precision specifier such as `day of`
as part of a timing phrase is preferred to communicate intent to perform day-level comparison, as well
as for general readability.
*/
define function "ToDateInterval"(period Interval<DateTime>):
  Interval[date from start of period, date from end of period]

/*
Calculates Medication Period for a given MedicationDispense
MedicationDispense instances provided to this function are expected
to conform to the [TODO: MMEMedicationDispense](http://build.fhir.org/ig/cqframework/opioid-mme-r4/StructureDefinition-mmemedicationdispense.html)
profile, which expects:
* 1 and only 1 dosageInstruction, multiple dosageInstruction elements will result in an error
* 1 and only 1 doseAndRate, multiple doseAndRate elements will result in an error
* 1 timing with 1 repeat, missing timing or repeat elements will result in a null
* frequency, frequencyMax, defaulting to 1
* period, periodUnit, defaulting to 1 'd'
* timeOfDay
* doseQuantity or doseRange, missing doseQuantity and doseRange will result in a null
* whenHandedOver or whenPrepared, if missing both whenHandedOver and whenPrepared will result in a null
Note that MedicationDispense status is not considered by this calculation, as the
list of MedicationDispense instances provided to this function should already have
considered appropriate statuses, depending on the use case, typically `completed`,
especially since whenHandedOver would be expected to be present for a completed
MedicationDispense.
Note also that the dosage information recorded in a dispense is expected to be a copy of the
dispense information from the related medication request. As such, the boundsPeriod would be expected
to cover the entire range, and should _not_ be used for timing of the event.
There is also active discussion in the Pharmacy WG about what date should be used if whenPrepared/whenHandedOver is not present.
This may take the form of an "original creation date", but may also be a "status change date" for dispense events that are updating
status of an existing dispense. That discussion is ongoing, so until that is resolved, this logic will return
null if whenPrepared/whenHandedOver are not available.
*/
define fluent function medicationDispensePeriod(Dispense "MedicationDispense"):
  Dispense D
    let
      dosage: singleton from D.dosageInstruction,
      doseAndRate: singleton from dosage.doseAndRate,
      timing: dosage.timing,
      frequency: Coalesce(timing.repeat.frequencyMax, timing.repeat.frequency),
      period: Quantity(timing.repeat.period, timing.repeat.periodUnit),
      doseRange: doseAndRate.dose,
      doseQuantity: doseAndRate.dose,
      dose: Coalesce(end of doseRange, doseQuantity),
      daysSupply: (convert D.daysSupply to days).value,
      dosesPerDay: Coalesce(ToDaily(frequency, period), Count(timing.repeat.timeOfDay), 1.0),
      startDate:
        Coalesce(
          date from D.whenHandedOver,
          date from D.whenPrepared
        ),
      totalDaysSupplied: Coalesce(daysSupply, D.quantity.value / (dose.value * dosesPerDay))
    return
      if startDate is not null and totalDaysSupplied is not null then
        Interval[startDate, startDate + Quantity(totalDaysSupplied - 1, 'day')]
      else
        null

/**********************************************************************/
/* Functions in this region are copied from opioid-mme-r4             */
/**********************************************************************/

define function Quantity(value Decimal, unit String):
  if value is not null then
    System.Quantity { value: value, unit: unit }
  else
    null

/*
 Goal is to get to number of days
 Two broad approaches to the calculation:
  1) Based on supply and frequency, calculate the number of expected days the medication will cover/has covered
  2) Based on relevant period, determine a covered interval and calculate the length of that interval in days
This topic covers several use cases and illustrates how to calculate Cumulative
Medication Duration for each type of medication resource using the supply and
frequency approach.
*/

/*
  For the first approach, we need to get from frequency to a frequency/day
  So we define ToDaily
*/

/*
  Calculates daily frequency given frequency within a period
*/
define function ToDaily(frequency System.Integer, period System.Quantity):
  case period.unit
    when 'h' then frequency * (24.0 / period.value)
    when 'min' then frequency * (24.0 / period.value) * 60
    when 's' then frequency * (24.0 / period.value) * 60 * 60
    when 'd' then frequency * (24.0 / period.value) / 24
    when 'wk' then frequency * (24.0 / period.value) / (24 * 7)
    when 'mo' then frequency * (24.0 / period.value) / (24 * 30) /* assuming 30 days in month */
    when 'a' then frequency * (24.0 / period.value) / (24 * 365) /* assuming 365 days in year */
    when 'hour' then frequency * (24.0 / period.value)
    when 'minute' then frequency * (24.0 / period.value) * 60
    when 'second' then frequency * (24.0 / period.value) * 60 * 60
    when 'day' then frequency * (24.0 / period.value) / 24
    when 'week' then frequency * (24.0 / period.value) / (24 * 7)
    when 'month' then frequency * (24.0 / period.value) / (24 * 30) /* assuming 30 days in month */
    when 'year' then frequency * (24.0 / period.value) / (24 * 365) /* assuming 365 days in year */
    when 'hours' then frequency * (24.0 / period.value)
    when 'minutes' then frequency * (24.0 / period.value) * 60
    when 'seconds' then frequency * (24.0 / period.value) * 60 * 60
    when 'days' then frequency * (24.0 / period.value) / 24
    when 'weeks' then frequency * (24.0 / period.value) / (24 * 7)
    when 'months' then frequency * (24.0 / period.value) / (24 * 30) /* assuming 30 days in month */
    when 'years' then frequency * (24.0 / period.value) / (24 * 365) /* assuming 365 days in year */
    else Message(null, true, 'CMDLogic.ToDaily.UnknownUnit', ErrorLevel, 'Unknown unit ' & period.unit)
  end

/*
Now that we have functions for determining the medication period for individual
prescriptions, administrations, and dispenses, we can combine those using
an overall cumulative medication duration calculation.
There are two broad approaches to calculating cumulative duration, one that _collapses_
overlapping intervals so that calculations are not duplicated, and one that _rolls out_
overlapping intervals so that the durations are laid end-to-end.
First, we define a function that simply calculates CumulativeDuration of a set of
intervals:
*/
define fluent function cumulativeDuration(Intervals List<Interval<Date>>):
   if Intervals is not null then ( Sum((collapse Intervals per day)X
        return all(difference in days between start of X and 
          end of X
        )+ 1
    )
  ) 
    else null

define fluent function medicationRequestPeriod(Request "MedicationRequest"):
  Request R
    let
      dosage: singleton from R.dosageInstruction,
      doseAndRate: singleton from dosage.doseAndRate,
      timing: dosage.timing,
      frequency: Coalesce(timing.repeat.frequencyMax, timing.repeat.frequency),
      period: Quantity(timing.repeat.period, timing.repeat.periodUnit),
      doseRange: doseAndRate.dose,
      doseQuantity: doseAndRate.dose,
      dose: Coalesce(end of doseRange, doseQuantity),
      dosesPerDay: Coalesce(ToDaily(frequency, period), Count(timing.repeat.timeOfDay), 1.0),
      boundsPeriod: timing.repeat.bounds as Interval<DateTime>,
      daysSupply: (convert R.dispenseRequest.expectedSupplyDuration to days).value,
      quantity: R.dispenseRequest.quantity,
      refills: Coalesce(R.dispenseRequest.numberOfRepeatsAllowed, 0),
      startDate:
        Coalesce(
          date from start of boundsPeriod,
          date from R.authoredOn,
          date from start of R.dispenseRequest.validityPeriod
        ),
      totalDaysSupplied: Coalesce(daysSupply, quantity.value / (dose.value * dosesPerDay)) * (1 + refills)
    return
      if startDate is not null and totalDaysSupplied is not null then
        Interval[startDate, startDate + Quantity(totalDaysSupplied - 1, 'day') ]
      else if startDate is not null and boundsPeriod."high" is not null then
        Interval[startDate, date from end of boundsPeriod]
      else
        null