define "Stratification 1" :
  "Inpatient Encounter" Encounter
    where not (PrincipalDiagnosis(Encounter).code in "Psychiatric/Mental Health Patient")

define "Stratification 2" :
  "Inpatient Encounter" Encounter
    where PrincipalDiagnosis(Encounter).code in "Psychiatric/Mental Health Patient"

define "Stratification 3" :
  "Inpatient Encounter" Encounter
    where PrincipalDiagnosis(Encounter) is null

/*
@description: Converts the given [Period](https://hl7.org/fhir/datatypes.html#Period)
value to a CQL DateTime Interval
@comment: If the start value of the given period is unspecified, the starting
boundary of the resulting interval will be open (meaning the start of the interval
is unknown, as opposed to interpreted as the beginning of time).
*/
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]

/*
@description: Converts the given FHIR [CodeableConcept](https://hl7.org/fhir/datatypes.html#CodeableConcept) value to a CQL Concept.
*/
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
        }

/*
@description: Converts the given FHIR [Coding](https://hl7.org/fhir/datatypes.html#Coding) value to a CQL Code.
*/
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

define function ToString(value EncounterStatus): value.value

define "Inpatient Encounter" :
  ["Encounter"] Encounter
    where LengthInDays(Encounter.period) <= 120
      and Encounter.period ends during "Measurement Period"

define "Stratification 3" :
  "Inpatient Encounter" Encounter
    where PrincipalDiagnosis(Encounter) is null

define "Stratification 2" :
  "Inpatient Encounter" Encounter
    where PrincipalDiagnosis(Encounter).code in "Psychiatric/Mental Health Patient"

define "Measure Population Exclusion" :
  "Inpatient Encounter" Encounter
    with ["Encounter" : "Emergency Department Visit"] ED
      such that ED.period ends 1 hour or less before start of Encounter.period
        and ED.status = 'finished'
        and ED.hospitalization.admitSource in "Hospital Settings"

define "Stratification 1" :
  "Inpatient Encounter" Encounter
    where not (PrincipalDiagnosis(Encounter).code in "Psychiatric/Mental Health Patient")

define "Initial Population" :
  "Inpatient Encounter" Encounter
    with ["Encounter" : "Emergency Department Visit"] ED
     such that ED.status = 'finished'
       and ED.period ends 1 hour or less before start of Encounter.period

define "Measure Population" :
  "Initial Population"

define function "LengthInDays"(Value Interval<DateTime>):
	difference in days between start of Value and end of Value

define function "PrincipalDiagnosis"(Encounter Encounter):
	(singleton from (Encounter.diagnosis D where D.use ~ ToConcept("Billing") and D.rank.value = 1)) PD
		return singleton from ([Condition: id in "GetId"(PD.condition.reference)])

define function "GetId"(uri String):
	Last(Split(uri, '/'))

define function "Measure Observation" (Encounter "Encounter" ) :
  duration in minutes of "Related ED Visit"(Encounter).period

//Measure Observation
define function "Related ED Visit" (Encounter "Encounter" ) :
  Last(["Encounter" : "Emergency Department Visit"] ED
    where ED.status = 'finished'
      and ED.period ends 1 hour or less before start of Encounter.period
    sort by start of period )