define "HIV Status Positive Condition":
  [Condition: Concepts."HIV-positive - HIV.B.DE116"] C
    where C.clinicalStatus ~ ConceptsCustom."active"
      and exists(C.category CC where CC ~ ConceptsCustom."encounter-diagnosis")
    sort by start of onset.toInterval()

define "HIV Status Positive Condition":
  Elements."HIV Status Positive Condition" C
  where C.onset before end of "Measurement Period"

/* End of HIV-inconclusive */

/*
@dataElement: HIV.B.DE115 - HIV status
@activity: HIV.B7 Test for HIV using testing algorithm
@description: HIV status reported after applying the national HIV testing algorithm. No single HIV test can provide an HIV-positive diagnosis.
*/
define "HIV Status Observation":
  [Observation: Concepts."HIV status"] O
    where O.status in { 'final', 'amended', 'corrected' }

define "HIV Status Positive Observation":
"HIV Status Observation" O
    where O.value ~ Concepts."HIV-positive - HIV.B.DE116"
      sort by start of effective.toInterval()

define "HIV Status Positive Observation":
  Elements."HIV Status Positive Observation" O
  where O.issued before end of "Measurement Period"
  or O.effective.toInterval() starts before end of "Measurement Period"

define "Has HIV-positive Status":
  exists "HIV Status Positive Condition"
  or exists "HIV Status Positive Observation"

/* End of STI testing and treatment D.DE160 */

/*
@dataElement: HIV.D.DE161 - HBsAg test date
@activity: HIV.D12 Determine recommended screenings and tests
@description: Date client was tested for hepatitis B virus (HBV)
*/

define "HBsAg test date D.DE161":
  [Procedure] P
  where P.status = 'completed'
  and P.code ~ ConceptsCustom."HBsAg test"

/* End of Current ART regimen */

/*
@dataElement: HIV.D.DE161 - HBsAg test date
@activity: HIV.D12 Determine recommended screenings and tests
@description: Date client was tested for hepatitis B virus (HBV)
*/
//TODO - verify
define "HBsAg test date D.DE161":
  exists(Elements."HBsAg test date D.DE161" P
    where P.performed.toInterval() during "Measurement Period")

/**
 * Numerator
 * 
 * Definition: Number of people living with HIV tested for HBsAg during the reporting period
 * Calculation: COUNT of clients with "HIV status"='HIV-positive' AND with "HBsAg test date" in the reporting period
 */

define "Numerator":
  HIE."Has HIV-positive Status" and HIE."HBsAg test date D.DE161"

/* End of Viral load test result SRV.DE13 */

/*
@dataElement: HIV.SRV.DE15 - Visit date
@activity: HIV.A2 Gather client details
@description: The date and time of the client's visit
*/

define "Visit date SRV.DE15":
  [Encounter] E
  return E.period

/* End of Viral load test result SRV.DE13 */

/*
@dataElement: HIV.SRV.DE15 - Visit date
@activity: HIV.A2 Gather client details
@description: The date and time of the client's visit
*/

define "Visit date SRV.DE15":
  exists(Elements."Visit date SRV.DE15" E
    where start of E during "Measurement Period")

/**
 * Denominator
 *
 * Definition: Number of people living with HIV attending HIV care and treatment services during the reporting period
 * Calculation: COUNT of clients with "HIV status"='HIV-positive' AND with a "Visit date" in the reporting period
 */

define "Denominator":
  HIE."Has HIV-positive Status"
  and HIE."Visit date SRV.DE15"

/* 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 ToDateTime(value dateTime): value.value

define function ToString(value ObservationStatus): value.value

define function ToDateTime(value instant): value.value

define function ToString(value ProcedureStatus): 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]