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 HBsAg test date D.DE161 */


/*
@dataElement: HIV.D.DE162 - HBsAg test result
@activity: HIV.D12 Determine recommended screenings and tests
@description: Hepatitis B virus test result (HBsAg)
*/

define "HBsAg test result D.DE162":
  [Observation: Concepts."HBsAg test result - HIV.D.DE162"] O
    where O.status in { 'final', 'amended', 'corrected' }

/* End of HBsAg test result D.DE162 */

/*
@dataElement: HIV.D.DE163 - Positive
@activity: HIV.D12 Determine recommended screenings and tests
@description: HBsAg test result was positive
*/

define "Positive D.DE163":
  "HBsAg test result D.DE162" O
  where O.value ~ Concepts."Positive - HIV.D.DE163"

/* 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 Terfenadine */

/*
@dataElement: HIV.D.DE912 - TDF
@activity: HIV.D21 Determine regimen and treatment options
@description: TDF currently being taken by, or considered for, client
*/

define "TDF D.DE912":
  [MedicationStatement] MS
    where MS.medication ~ Concepts."TDF - HIV.D.DE912"

/* End of Direct acting antivirals */

/*
@dataElement: HIV.D.DE185 - Currently on TDF-based ART
@activity: HIV.D12 Determine recommended screenings and tests
@description: Client is currently on TDF-based ART regimen
*/

define "Currently on TDF-based ART":
  "TDF D.DE912" MS where exists(MS.reasonCode C where C ~ Concepts."Currently on TDF-based ART")

/* End of Indeterminate D.DE165 */

/*
@dataElement: HIV.D.DE167 - HBV treatment TDF start date
@activity: HIV.D12 Determine recommended screenings and tests
@description: Date when client started treatment (TDF) for hepatitis B virus (HBV)
*/

define "HBV treatment TDF start date":
  "Currently on TDF-based ART" MS
  sort by start of effective.toInterval()

/**
 * Numerator
 * 
 * Definition: Number of people newly started on HBV treatment (TDF) during the reporting period  | plus | Number of people living with HIV who are already on TDF-based ART
 * Calculation: COUNT of clients with "HIV status"='HIV-positive' AND "HBsAg test date" in the reporting period AND "HBsAg test result"=' HBsAg positive' AND "HBV treatment (TDF) start date" in the reporting period | + | COUNT of clients with "HIV status"='HIV-positive' AND "HBsAg test date" in the reporting period AND "HBsAg test result"=' HBsAg positive' AND "Currently on TDF-based ART"
 */

define "Numerator":
  HIE."Has HIV-positive Status" and
  exists(HE."Positive D.DE163" G
  with HE."HBsAg test date D.DE161" P
  such that G.partOf.references(P) and P.performed.toInterval() during "Measurement Period") and
  (exists(HE."HBV treatment TDF start date" MS where start of MS.effective.toInterval() during "Measurement Period") or
  exists(HE."HBV treatment TDF start date" MS where  MS.effective.toInterval() overlaps "Measurement Period")
  )

/**
 * Denominator
 *
 * Definition: Number of people living with HIV who were diagnosed with HBV
 * Calculation: COUNT of clients with "HIV status"='HIV-positive' AND "HBsAg test date" in the reporting period AND "HBsAg test result"='HBsAg positive'
 */

define "Denominator":
  HIE."Has HIV-positive Status" and
  exists(HE."Positive D.DE163" G
  with HE."HBsAg test date D.DE161" P
  such that G.partOf.references(P) and P.performed.toInterval() during "Measurement Period")

/* 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

/*
@description: Returns true if any of the given references are to the given resource
@comment: Returns true if the `id` element of the given resource exactly equals the tail of any of the given references.
NOTE: This function assumes resources from the same source server.
*/
define fluent function references(references List<FHIR.Reference>, resource FHIR.Resource):
  exists (references R where R.references(resource))

/*
@description: Returns true if the given reference is to the given resource
@comment: Returns true if the `id` element of the given resource exactly equals the tail of the given reference.
NOTE: This function assumes resources from the same source server.
*/
define fluent function references(reference FHIR.Reference, resource FHIR.Resource):
  resource.id = Last(Split(reference.reference, '/'))

define function ToString(value string): value.value