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 Serodiscordant partner D.DE37 */

/*
@dataElement: HIV.D.DE38 - On ART
@activity: HIV.D8 Capture or update client history
@description: Client is currently taking ART
*/

define "On ART D.DE38":
    [MedicationStatement] MS
    where exists(MS.reasonCode C where C ~ Concepts."On ART - HIV.D.DE38")
    sort by start of effective.toInterval()

define "First On ART":
  (First("On ART D.DE38"))

/* End of HIV test result SRV.DE2 */

/*
@dataElement: HIV.SRV.DE3 - Baseline CD4 count
@activity: HIV.D20 Diagnostics
@description: CD4 count performed at HIV diagnosis
*/

define "Baseline CD4 count SRV.DE3":
  [Observation: Concepts."Baseline CD4 count - HIV.SRV.DE3"] O
    where O.status in { 'final', 'amended', 'corrected' }

/**
 * Numerator
 * 
 * Definition: Number of people living with HIV initiating ART during the reporting period with a baseline CD4 count of <200 cells/mm3
 * Calculation: COUNT of clients with "HIV status"='HIV-positive' AND "ART start date" within the reporting period AND "Date of baseline CD4 count test" within the reporting period AND "Baseline CD4 count" LESS THAN 200 cells/mm^3
 */

define "Numerator":
    HIE."Has HIV-positive Status" 
   and (date from start of HE."First On ART".effective.toInterval() during "Measurement Period")
   and exists(HE."Baseline CD4 count SRV.DE3" O
   where O.effective.toInterval() during "Measurement Period"
   and O.value < 200)

/**
 * Denominator
 *
 * Definition: Number of people living with HIV initiating ART during the reporting period who have a baseline CD4 cell count
 * Calculation: COUNT of clients with "HIV status"='HIV-positive' AND "ART start date" within the reporting period AND "Date of baseline CD4 count test" within the reporting period
 */

define "Denominator":
 HIE."Has HIV-positive Status" 
   and (date from start of HE."First On ART".effective.toInterval() during "Measurement Period")
   and exists(HE."Baseline CD4 count SRV.DE3" O
   where O.effective.toInterval() during "Measurement Period")

/* Populations */

/*
 *Initial Population
 */

define "Initial Population":
  true

/*
@dataElement: HIV.A.DE18 - Gender
@activity: HIV.A6.1 Review sociodemographic data with client | HIV.A5 Create new client record
@description: Gender of the client
*/

/*
 * By Administrative Gender of Patient Stratifier
 * Need to expand codes
 */

define "By Administrative Gender Stratifier":
  case 
      when Patient.gender = 'male' then Concepts."Male"
      when Patient.gender = 'female' then Concepts."Female"
      when Patient.gender = 'transgender female' then Concepts."Transgender female"
      when Patient.gender = 'transgender male' then Concepts."Transgender male"
      else Concepts."Other - HIV.A.DE23"
  end

/* End of Visit date A.DE3 */

/*
@dataElement: HIV.A.DE17 - Age
@activity: HIV.A6.1 Review sociodemographic data with client | HIV.A5 Create new client record
@description: Calculated age (number of years) of the client based on date of birth
*/
define "Age In Years":
  AgeInYearsAt(start of "Measurement Period")

/*
 * By Age Stratifiers
 * Age (0–4, 5–9, 10–14, 15–19, 20–24, 25–49, 50+ years)
 * 
 */
define "By Age Stratifier 2":
  case 
      when "Age In Years" <= 4 then '0-4'
      when "Age In Years" <= 9 then '5-9'
      when "Age In Years" <= 14 then '10–14'
      when "Age In Years" <= 19 then '15–19'
      when "Age In Years" <= 24 then '20–24'
      when "Age In Years" <= 49 then '25–49'
      when "Age In Years" >= 50 then '50+'
      else null
  end

// Geographic Region
define "By Geographic Region Stratifier":
    First(Patient.address A where A.use in { 'home' }).state

/* End of Key population member B.DE49 */

/*
@dataElement: HIV.B.DE50 - Key population member type
@activity: HIV.B6 Capture or update client history
@description: The type of key population that the client is included in
*/
define "Key population member type Observation":
  [Observation: Concepts."Key population member - HIV.B.DE49"] O
    where O.status in { 'final', 'amended', 'corrected' }
    and exists(O.category OC where OC ~ ConceptsCustom."social-history")

define "Key population member type Observation":
  Elements."Key population member type Observation" O
    where O.effective.toInterval() before end of "Measurement Period"
    or O.issued before end of "Measurement Period"

// Stratifier
define patientGroups:
  "Key population member type Observation" O
  return Combine(O.code.coding.code, ':')

define "Stratification":
 HIE."By Administrative Gender Stratifier".code 
  + ':' + HIE."By Age Stratifier 2"
+ ':' + HIE."By Geographic Region Stratifier"
+ Combine(HIE.patientGroups, ':')

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 ToInteger(value integer): value.value

define function ToString(value AdministrativeGender): value.value

define function ToString(value string): value.value

define function ToString(value AddressUse): value.value