define "Digoxin Prescription":
  ContextPrescriptions P
    where P.medication in "Digoxin"
    return P.medication as CodeableConcept

define "Is Context medication digoxin":
  exists ("Digoxin Prescription")

define "Digoxin Rx":
    (
      [MedicationRequest: "Digoxin"] MR
        where MR.authoredOn.toInterval() during Interval[Today() - 100 days, null]
        return MR.medication as CodeableConcept
    )
    union (
      [MedicationAdministration: "Digoxin"] MA
        where MA.effective.toInterval() overlaps Interval[Today() - 100 days, null]
        return MA.medication as CodeableConcept
    )
    union (
      [MedicationDispense: "Digoxin"] MD
        where MD.whenHandedOver.toInterval() during Interval[Today() - 100 days, null]
        return MD.medication as CodeableConcept
    )
    union (
      [MedicationStatement: "Digoxin"] MS
        where MS.effective.toInterval() overlaps Interval[Today() - 100 days, null]
        return MS.medication as CodeableConcept
    )

define "Is digoxin in prefetch":
  exists ("Digoxin Rx")

define "Is continuation order for digoxin":
  "Is Context medication digoxin"
      and "Is digoxin in prefetch"

define "Cyclosporine Prescription":
  ContextPrescriptions P
    where P.medication in "Cyclosporine"
    return P.medication as CodeableConcept

define "Is Context medication cyclosporine":
  exists ("Cyclosporine Prescription")

define "Cyclosporine Rx":
    (
      [MedicationRequest: "Cyclosporine"] MR
        where MR.authoredOn.toInterval() during Interval[Today() - 100 days, null]
        return MR.medication as CodeableConcept
    )
    union (
      [MedicationAdministration: "Cyclosporine"] MA
        where MA.effective.toInterval() overlaps Interval[Today() - 100 days, null]
        return MA.medication as CodeableConcept
    )
    union (
      [MedicationDispense: "Cyclosporine"] MD
        where MD.whenHandedOver.toInterval() during Interval[Today() - 100 days, null]
        return MD.medication as CodeableConcept
    )
    union (
      [MedicationStatement: "Cyclosporine"] MS
        where MS.effective.toInterval() overlaps Interval[Today() - 100 days, null]
        return MS.medication as CodeableConcept
    )

define "Is cyclosporine in prefetch":
  exists ("Cyclosporine Rx")

define "Is continuation order for cyclosporine":
  "Is Context medication cyclosporine"
      and "Is cyclosporine in prefetch"

define "Normal Digoxin Observation":
	Last (
    [Observation: "Digoxin LOINC"] O
      where O.effective.toInterval() during Interval[Today() - 30 days, null]
        and O.value < 0.9 'ng/mL'
      sort by start of effective.toInterval()
  )

define "Is there a normal digoxin level in prefetch":
  "Normal Digoxin Observation" is not null

define "Aldosterone Antagonists Rx":
    (
      [MedicationRequest: "Aldosterone Antagonists"] MR
        where MR.authoredOn.toInterval() during Interval[Today() - 100 days, null]
        return MR.medication as CodeableConcept
    )
    union (
      [MedicationAdministration: "Aldosterone Antagonists"] MA
        where MA.effective.toInterval() overlaps Interval[Today() - 100 days, null]
        return MA.medication as CodeableConcept
    )
    union (
      [MedicationDispense: "Aldosterone Antagonists"] MD
        where MD.whenHandedOver.toInterval() during Interval[Today() - 100 days, null]
        return MD.medication as CodeableConcept
    )
    union (
      [MedicationStatement: "Aldosterone Antagonists"] MS
        where MS.effective.toInterval() overlaps Interval[Today() - 100 days, null]
        return MS.medication as CodeableConcept
    )

define "Loop Diuretics Rx":
    (
      [MedicationRequest: "Loop Diuretics"] MR
        where MR.authoredOn.toInterval() during Interval[Today() - 100 days, null]
        return MR.medication as CodeableConcept
    )
    union (
      [MedicationAdministration: "Loop Diuretics"] MA
        where MA.effective.toInterval() overlaps Interval[Today() - 100 days, null]
        return MA.medication as CodeableConcept
    )
    union (
      [MedicationDispense: "Loop Diuretics"] MD
        where MD.whenHandedOver.toInterval() during Interval[Today() - 100 days, null]
        return MD.medication as CodeableConcept
    )
    union (
      [MedicationStatement: "Loop Diuretics"] MS
        where MS.effective.toInterval() overlaps Interval[Today() - 100 days, null]
        return MS.medication as CodeableConcept
    )

define "Are diuretics in prefetch":
  exists ("Aldosterone Antagonists Rx")
    or exists("Loop Diuretics Rx")

define "Normal Potassium Observation":
  Last (
    [Observation: "Potassium LOINC"] O
      where O.effective.toInterval() during Interval[Today() - 365 days, null]
        and O.value > 3.5 'meq/L'
        and O.value < 5.0 'meq/L'
      sort by start of effective.toInterval()
  )

define "Normal Magnesium Observation":
  Last (
    [Observation: "Magnesium LOINC"] O
      where O.effective.toInterval() during Interval[Today() - 365 days, null]
        and O.value > 0.7 'mmol/L'
        and O.value < 1.1 'mmol/L'
      sort by start of effective.toInterval()
  )

define "Normal Calcium Observation":
  Last (
    [Observation: "Calcium LOINC"] O
      where O.effective.toInterval() during Interval[Today() - 365 days, null]
        and O.value > 8.5 'mg/dL'
        and O.value < 10.2 'mg/dL'
      sort by start of effective.toInterval()
  )

define "Is there a normal electrolyte observation in prefetch":
  "Normal Potassium Observation" is not null
  and "Normal Magnesium Observation" is not null
  and "Normal Calcium Observation" is not null

define "Normal Renal Observation":
  Last (
    [Observation: "Renal LOINC"] O
      where O.effective.toInterval() during Interval[Today() - 365 days, null]
        and O.value > 0.6 'mg/dL'
        and O.value < 1.2 'mg/dL'
      sort by start of effective.toInterval()
  )

define "Is there a normal renal observation in prefetch":
  "Normal Renal Observation" is not null

define "Is there a normal electrolyte and renal observation in prefetch":
  "Is there a normal electrolyte observation in prefetch"
    and "Is there a normal renal observation in prefetch"

define "Are diuretics or abnormal electrolyte or abnormal renal observations in prefetch":
  "Are diuretics in prefetch"
    or not "Is there a normal electrolyte and renal observation in prefetch"

define "Get Base Indicator":
  if "Is continuation order for digoxin"
    or "Is continuation order for cyclosporine"
    then if "Is there a normal digoxin level in prefetch"
        then if "Are diuretics or abnormal electrolyte or abnormal renal observations in prefetch"
            then 'warning'
          else 'info'
      else 'warning'
  else 'warning'

define "Get Card 2 Summary":
  if "Is there a normal digoxin level in prefetch"
    then 'Patient has digoxin level within 30 days that is below 0.9 ng/mL (SI: 1.2 nmol/L)'
  else 'Patient does not have digoxin level on record within the last 30 days. '

/*
**
** Digoxin Cyclosporine CDS Recommendation
**
*/

define "Inclusion Criteria":
  (
    "Is Context medication cyclosporine"
      and "Is digoxin in prefetch"
  )
  or (
    "Is Context medication digoxin"
      and "Is cyclosporine in prefetch"
  )

define "Get Card 3 Summary":
  if "Is there a normal electrolyte and renal observation in prefetch"
    then 'Within 100 days, the patient has had electrolyte and serum creatinine levels checked, and they are not on a potassium sparing or loop diuretic.'
  else 'Within 100 days, the patient has not had an electrolyte panel. The patient does have serum creatinine level and is not on a potassium sparing or loop diuretic.'

define "Get Card 2 Detail":
  if "Is there a normal digoxin level in prefetch"
    then '(Digoxin: '
    + Common.GetLevelAndDate("Normal Digoxin Observation")
    + '). \nFor patients with a reliable plasma digoxin concentration in normal range, it is reasonable to anticipate an increase in plasma concentrations after the initiation of cyclosporine. Following initiation, close monitoring and adjusting the digoxin dose as needed is recommended'
  else 'Initiating cyclosporine is expected to increase digoxin levels. For patients without a reliable plasma digoxin concentration in normal range, use only if benefits outweight risks. Extreme caution and close monitoring is necessary.'

define "Is new order for digoxin":
  "Is Context medication digoxin"
      and not "Is digoxin in prefetch"

define "Get Card 3 Detail":
  if "Is there a normal electrolyte and renal observation in prefetch"
    then '(Potassium: '
    + Common.GetLevelAndDate("Normal Potassium Observation")
    + ')\n (Magnesium: '
    + Common.GetLevelAndDate("Normal Magnesium Observation")
    + ')\n (Calcium: '
    + Common.GetLevelAndDate("Normal Calcium Observation")
    + ')\n'
  else ''
  + '(Serum creatinine: '
  + Common.GetLevelAndDate("Normal Renal Observation")
  + ')\n Hypokalemia, hypomagnesemia, and hypercalcemia may potentiate digoxin toxicity. 50-70% of digoxin is excreted unchanged in the urine. Changing renal function may increase serum concentrations and risk of toxicity.'

// Card 3
define "Get Card 3 Indicator":
  if "Is there a normal electrolyte and renal observation in prefetch"
    then 'info'
  else 'warning'

define "Get Base Detail":
  'Increased risk of digoxin toxicity. Assess risk and take action if necessary. \nDigoxin toxicity is potentially serious. The clinical consequences may include anorexia, nausea, vomiting, visual changes, and cardiac arrhythmias. \nThe mechanism of this interaction appears to be mediated through P-glycoprotein inhibition by cyclosporine. P-glycoprotein is a major transporter for digoxin efflux. \nunknown. \nunknown.'

define "Need to reduce Digoxin dose":
  "Is Context medication cyclosporine"
    or not "Is there a normal digoxin level in prefetch"

define "Is new order for cyclosporine":
  "Is Context medication cyclosporine"
      and not "Is cyclosporine in prefetch"

// Card 2
define "Get Card 2 Indicator":
  if "Is new order for cyclosporine"
    then if "Is there a normal digoxin level in prefetch"
      then 'warning'
    else 'critical'
  else if "Is there a normal digoxin level in prefetch"
      then 'info'
    else 'warning'

// Card 1: Base
define "Get Base Summary":
  'Potential Drug-Drug Interaction between digoxin ('
    + (
      if "Is Context medication digoxin"
        then Common.GetDrugNames("Digoxin Prescription")
      else Common.GetDrugNames("Digoxin Rx")
    )
    + ') and cyclosporine ('
    + (
      if "Is Context medication cyclosporine"
        then Common.GetDrugNames("Cyclosporine Prescription")
      else Common.GetDrugNames("Cyclosporine Rx")
    )
    + ')'

/*
@description: Normalizes a value that is a choice of timing-valued types to an equivalent interval
@comment: Normalizes a choice type of FHIR.dateTime, FHIR.Period, FHIR.Timing, FHIR.instance, FHIR.string, FHIR.Age, or FHIR.Range types
to an equivalent interval. This selection of choice types is a superset of the majority of choice types that are used as possible
representations for timing-valued elements in FHIR, allowing this function to be used across any resource.

The input can be provided as a dateTime, Period, Timing, instant, string, Age, or Range.
The intent of this function is to provide a clear and concise mechanism to treat single
elements that have multiple possible representations as intervals so that logic doesn't have to account
for the variability. More complex calculations (such as medication request period or dispense period
calculation) need specific guidance and consideration. That guidance may make use of this function, but
the focus of this function is on single element calculations where the semantics are unambiguous.
If the input is a dateTime, the result a DateTime Interval beginning and ending on that dateTime.
If the input is a Period, the result is a DateTime Interval.
If the input is a Timing, an error is raised indicating a single interval cannot be computed from a Timing.
If the input is an instant, the result is a DateTime Interval beginning and ending on that instant.
If the input is a string, an error is raised indicating a single interval cannot be computed from a string.
If the input is an Age, the result is a DateTime Interval beginning when the patient was the given Age,
and ending immediately prior to when the patient was the given Age plus one year.
If the input is a Range, the result is a DateTime Interval beginning when the patient was the Age given
by the low end of the Range, and ending immediately prior to when the patient was the Age given by the
high end of the Range plus one year.

NOTE: Due to the
complexity of determining a single interval from a Timing or String type, this function will throw a run-time exception if it is used
with a Timing or String.
*/
define fluent function toInterval(choice Choice<FHIR.dateTime, FHIR.Period, FHIR.Timing, FHIR.instant, FHIR.string, FHIR.Age, FHIR.Range>):
  case
    when choice is FHIR.dateTime then
      Interval[FHIRHelpers.ToDateTime(choice as FHIR.dateTime), FHIRHelpers.ToDateTime(choice as FHIR.dateTime)]
    when choice is FHIR.Period then
      FHIRHelpers.ToInterval(choice as FHIR.Period)
    when choice is FHIR.instant then
      Interval[FHIRHelpers.ToDateTime(choice as FHIR.instant), FHIRHelpers.ToDateTime(choice as FHIR.instant)]
    when choice is FHIR.Age then
      Interval[FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity(choice as FHIR.Age),
        FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity(choice as FHIR.Age) + 1 year)
    when choice is FHIR.Range then
      Interval[FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity((choice as FHIR.Range).low),
        FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity((choice as FHIR.Range).high) + 1 year)
    when choice is FHIR.Timing then
      Message(null as Interval<DateTime>, true, 'NOT_IMPLEMENTED', 'Error', 'Calculation of an interval from a Timing value is not supported')
    when choice 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
      null as Interval<DateTime>
  end

/*
@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 ToDateTime(value dateTime): value.value

/*
@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]

define function ToDateTime(value instant): value.value

define function ToDate(value date): value.value

/*
@description: Converts the given FHIR [Quantity](https://hl7.org/fhir/datatypes.html#Quantity) 
value to a CQL Quantity
@comment: If the given quantity has a comparator specified, a runtime error is raised. If the given quantity
has a system other than UCUM (i.e. `http://unitsofmeasure.org`) or CQL calendar units (i.e. `http://hl7.org/fhirpath/CodeSystem/calendar-units`)
an error is raised. For UCUM to calendar units, the `ToCalendarUnit` function is used.
@seealso: ToCalendarUnit
*/
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

/*
@description: Converts a UCUM definite duration unit to a CQL calendar duration
unit using conversions specified in the [quantities](https://cql.hl7.org/02-authorsguide.html#quantities) 
topic of the CQL specification.
@comment: Note that for durations above days (or weeks), the conversion is understood to be approximate
*/
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 GetLevelAndDate(observation Observation):
  if observation is not null
    then ToString(ToQuantity(observation.value as Quantity))
      + ' and ' 
      + ToString(observation.effective.value)
  else 'NA'

define function ToQuantity(quantity FHIR.Quantity):
  System.Quantity { value: quantity.value.value, unit: quantity.unit.value }

define function GetDrugNames(codes List<FHIR.CodeableConcept>):
  Combine(
    flatten(
      codes C
        return C.coding coding
          return ToCode(coding).display
    )
    ,', '
  )

define function ToCode(coding FHIR.Coding):
  System.Code {
    code: coding.code.value,
    system: coding.system.value,
    version: coding.version.value,
    display: coding.display.value
  }