define "Syndrome/STI diagnosed B.DE226 Condition":
  [Condition] C
    where C.code in Concepts."Syndrome/STI diagnosed - HIV.B.DE226 Choices"
      and C.verificationStatus.text = 'confirmed'

define "Syndrome/STI diagnosed B.DE226 Condition":
  Elements."Syndrome/STI diagnosed B.DE226 Condition" C
    where C.prevalenceInterval() overlaps "Measurement Period"

define "PrEP service date":
  [MedicationStatement] MS
    where exists(MS.reasonCode C where C ~ Concepts."PrEP for HIV prevention")
    return start of MS.effective.toInterval()

define "STI services date":
  [Procedure] P
  where P.status = 'completed'
  and P.code ~ Concepts."STI testing and treatment services"
  return start of P.performed.toInterval()

/* End of STI services */

/*
@dataElement: HIV.PRV.DE7 - VMMC
@activity: HIV.B6 Capture or update client history
@description: Client accessed voluntary medical male circumcision (VMMC) services
*/
// define "VMMC_done":
// [Procedure] P
//   where P.status = 'completed'
//   and P.code ~ Concepts."Voluntary medical male circumcision VMMC"


define "VMMC":
  [Procedure] P
  where P.status = 'completed'
  and P.code ~ Concepts."VMMC procedure"

define "VMMC date":
  "VMMC" P
  return start of P.performed.toInterval()

define "Other PRV.DE8 date":
  [Observation] O
    where O.status in {'final', 'amended'}
    and O.code ~ Concepts."HIV prevention intervention"
    and O.value ~ Concepts."Other - HIV.PRV.DE8"
  return start of O.effective.toInterval()

define "OAMT status date":
  [EpisodeOfCare] EOC
    where exists(EOC.type T where T ~ Concepts."OAMT")
    return start of EOC.period

/* End of Other PRV.DE8 */

/*
@dataElement: HIV.PRV.DE10 - Date accessed HIV prevention intervention
@activity: HIV.B6 Capture or update client history
@description: Date the client accessed HIV prevention intervention
*/
// TODO: NSP date requires fix to DeviceUseStatement support
define "Date accessed HIV prevention intervention": 
  flatten{"PrEP service date", /*"NSP date",*/ "STI services date", "VMMC date", "Other PRV.DE8 date","OAMT status date"}

/**
 * Numerator
 * 
 * Definition: Number of people attending HIV prevention services diagnosed with a particular STI syndrome two or more times during the reporting period
 * Calculation: COUNT of clients with "Any STI syndrome diagnosed"=True on multiple values of "Date accessed HIV prevention intervention" in reporting period
 */

define "Numerator":
  Count(
    (HIE."Syndrome/STI diagnosed B.DE226 Condition" C
    where exists (
      HE."Date accessed HIV prevention intervention" t
      where t = start of C.prevalenceInterval()
    ))
  ) > 1

/* End of Other PRV.DE8 */

/*
@dataElement: HIV.PRV.DE10 - Date accessed HIV prevention intervention
@activity: HIV.B6 Capture or update client history
@description: Date the client accessed HIV prevention intervention
*/

define "Date accessed HIV prevention intervention":
  Elements."Date accessed HIV prevention intervention" t where t included in "Measurement Period"

/**
 * Denominator
 *
 * Definition: Number of people attending HIV prevention services diagnosed with a particular STI syndrome during the reporting period
 * Calculation: COUNT of clients with "Date accessed HIV prevention intervention" in the reporting period
 */

define "Denominator":
  exists(HIE."Date accessed HIV prevention intervention")

/* Populations */

/*
 *Initial Population
 */

define "Initial Population":
  true

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 string): value.value

/*
@description: Returns an interval representing the normalized prevalence period of a given Condition resource.
@comment: Uses the toInterval and toAbatementInterval functions to determine the widest potential interval from
onset to abatement as specified in the given Condition.
*/
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
  (end of condition.abatementInterval()) abatementDate
    return 
	  if abatementDate is null then
        Interval[start of condition.onset.toInterval(), abatementDate)
      else
        Interval[start of condition.onset.toInterval(), abatementDate]

/*
@description: Returns an interval representing the normalized Abatement of a given Condition resource.
@comment: NOTE: Due to the complexity of determining an interval from a String, this function will throw
a run-time exception if used with a Condition instance that has a String as the abatement value.
*/
define fluent function abatementInterval(condition Condition):
  if condition.abatement is FHIR.dateTime then
    Interval[FHIRHelpers.ToDateTime(condition.abatement as FHIR.dateTime), FHIRHelpers.ToDateTime(condition.abatement as FHIR.dateTime)]
  else if condition.abatement is FHIR.Period then
    FHIRHelpers.ToInterval(condition.abatement as FHIR.Period)
  else if condition.abatement is FHIR.string then
    Message(null as Interval<DateTime>, true, 'NOT_IMPLEMENTED', 'Error', 'Calculation of an interval from a String value is not supported')
  else if condition.abatement is FHIR.Age then
    Interval[FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity(condition.abatement as FHIR.Age),
      FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity(condition.abatement as FHIR.Age) + 1 year)
  else if condition.abatement is FHIR.Range then
    Interval[FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity((condition.abatement as FHIR.Range).low),
      FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity((condition.abatement as FHIR.Range).high) + 1 year)
  else if condition.abatement is FHIR.boolean then
    Interval[end of condition.onset.toInterval(), condition.recordedDate)
  else 
    null

define function ToDateTime(value dateTime): value.value

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 ToDate(value date): 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 ProcedureStatus): value.value

define function ToString(value ObservationStatus): value.value