define "Methadone D.DE555":
  [MedicationRequest] MR
        where MR.intent = 'order'
        and MR.medication ~ ConceptsCustom."methadone"

/*
@dataElement: HIV.D.DE555 - Methadone
@activity: HIV.D8 Capture or update client history
@description: Opioid substitution to treat opioid dependence
*/
define "Methadone D.DE555":
  Elements."Methadone D.DE555" MR
        where MR.status = 'completed'
        and MR.MedicationRequestPeriod() during "Measurement Period"

define "Buprenorphine D.DE552":
  [MedicationRequest] MR
        where MR.intent = 'order'
        and MR.medication ~ ConceptsCustom."buprenorphine"

/* End of Enhanced adherence counselling provided */

/*
@dataElement: HIV.D.DE552 - Buprenorphine
@activity: HIV.D8 Capture or update client history
@description: Opioid substitution to treat opioid dependence
*/

define "Buprenorphine D.DE552":
  Elements."Buprenorphine D.DE552" MR
        where MR.status = 'completed'
        and MR.MedicationRequestPeriod() during "Measurement Period"

/**
 * Numerator
 * 
 * Definition: Number of people, at a specified date, maintained on methadone or buprenorphine receiving recommended minimum maintenance dose (WHO guidance recommends doses of ≥60 mg of methadone or ≥8 mg of buprenorphine*)
 * Calculation: COUNT of clients with ("Medications prescribed"='Methadone' AND "Dose of medications prescribed" GREATER THAN OR EQUAL TO 60mg) OR ("Medications prescribed"='Buprenorphine' AND "Dose of medications prescribed" GREATER THAN OR EQUAL TO 8mg) for a specified "Reporting date"
 */

define "Numerator":
  First(HIE."Methadone D.DE555").dailyDose() >= System.Quantity{ value: 60, unit: 'mg' }
  or First(HIE."Buprenorphine D.DE552").dailyDose() >= System.Quantity{ value: 8, unit: 'mg' }

/**
 * Denominator
 *
 * Definition: Number of people receiving maintenance dose of methadone or buprenorphine at a specified date, excluding: a) individuals currently being inducted on OAMT and yet to reach the maintenance dose and b) individuals on reducing doses of OAMT.
 * Calculation: COUNT of clients with "Medications prescribed" IN 'Methadone', 'Buprenorphine' for a specified "Reporting date"
 */

define "Denominator":
  Exists(HIE."Methadone D.DE555") or Exists(HIE."Buprenorphine D.DE552")

/* Populations */

/*
 *Initial Population
 */

define "Initial Population":
  true

//define function "GetMedicationDailyDose"(dosage Quantity, dosesPerDay Decimal):
  //dosage * Quantity { value: dosesPerDay, unit: '/d' }


define fluent function dailyDose(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: System.Quantity { value: timing.repeat.period, unit: timing.repeat.periodUnit.value },
      doseRange: doseAndRate.dose as Range,
      doseQuantity: doseAndRate.dose as SimpleQuantity,
      dose: Coalesce(doseRange.high, doseQuantity),
      dosesPerDay: Coalesce(ToDaily(frequency, period), Count(timing.repeat.timeOfDay), 1.0),
      quantity: R.dispenseRequest.quantity
    return
      quantity / (dose * dosesPerDay)

define function ToDecimal(value decimal): value.value

//System.Integer
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 null
  end

define function ToInteger(value integer): value.value

define function ToQuantity(quantity FHIR.Quantity):
    case
        when quantity is null then null
        when quantity.value is null then null
        when quantity.comparator is not null then
            Message(null, true, 'FHIRHelpers.ToQuantity.ComparatorQuantityNotSupported', 'Error', 'FHIR Quantity value has a comparator and cannot be converted to a System.Quantity value.')
        when quantity.system is null or quantity.system.value = 'http://unitsofmeasure.org'
              or quantity.system.value = 'http://hl7.org/fhirpath/CodeSystem/calendar-units' then
            System.Quantity { value: quantity.value.value, unit: ToCalendarUnit(Coalesce(quantity.code.value, quantity.unit.value, '1')) }
        else
            Message(null, true, 'FHIRHelpers.ToQuantity.InvalidFHIRQuantity', 'Error', 'Invalid FHIR Quantity code: ' & quantity.unit.value & ' (' & quantity.system.value & '|' & quantity.code.value & ')')
    end

define function ToCalendarUnit(unit System.String):
    case unit
        when 'ms' then 'millisecond'
        when 's' then 'second'
        when 'min' then 'minute'
        when 'h' then 'hour'
        when 'd' then 'day'
        when 'wk' then 'week'
        when 'mo' then 'month'
        when 'a' then 'year'
        else unit
    end

define function ToString(value MedicationRequestIntent): value.value

define function ToConcept(concept FHIR.CodeableConcept):
    if concept is null then
        null
    else
        System.Concept {
            codes: concept.coding C return ToCode(C),
            display: concept.text.value
        }

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
        }

define function ToString(value MedicationRequestStatus): value.value

define fluent function MedicationRequestPeriod(Request MedicationRequest):
  Request R
    let
      dosage: singleton from R.dosageInstruction,
      doseAndRate: singleton from dosage.doseAndRate,
      doseRange: doseAndRate.dose as Range,
      doseQuantity: doseAndRate.dose as SimpleQuantity,
      dose: Coalesce(end of doseRange, doseQuantity),
      timing: dosage.timing,
      frequency: Coalesce(timing.repeat.frequencyMax, timing.repeat.frequency),
      period: System.Quantity { value: timing.repeat.period, unit: timing.repeat.periodUnit.value },
      dosesPerDay: Coalesce(ToDaily(FHIRHelpers.ToInteger(frequency), period), Count(timing.repeat.timeOfDay), 1.0),
      boundsPeriod: timing.repeat.bounds as Period,
      daysSupply: R.dispenseRequest.expectedSupplyDuration,
      quantity: R.dispenseRequest.quantity,
      refills: Coalesce(R.dispenseRequest.numberOfRepeatsAllowed, 0),
      startDate:
        Coalesce(
          start of boundsPeriod,
          start of R.dispenseRequest.validityPeriod,
          R.authoredOn
        )
    return
      if HasEnd(boundsPeriod) then
        Interval[startDate, end of boundsPeriod]
      else
        (
          Coalesce(daysSupply, quantity / (dose * dosesPerDay))
            * (1 + refills)
        ) durationInDays
          return Interval[startDate, startDate + durationInDays]

define function ToInterval(range FHIR.Range):
    if range is null then
        null
    else
        Interval[ToQuantity(range.low), ToQuantity(range.high)]

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]

define function ToDateTime(value dateTime): value.value

define function "HasEnd"(period Interval<DateTime> ):
  not (end of period is null
    or end of period = maximum DateTime
)