library EnrollPatient

using FHIR version '4.0.1'

include FHIRHelpers version '4.0.1'

codesystem "Activity Type": 'http://hl7.org/fhir/uv/cpg/CodeSystem/cpg-activity-type-cs'

code "Enrollment": 'enrollment' from "Activity Type"

parameter enrollInPathway String

context Patient

/* Recommendation to enroll a patient in a pathway */

/*
NOTE: This recommendation is dramatically simplified to illustrate the general
pattern for a positive recommendation to enroll a patient, with the ability
for users to reject the recommendation, and flexibility in how the recommendation
is achieved.

Specifically:
* There is no terminology, any task on any topic will do
* There is no timing, any task will do at any time
* There is no reference to participants other than the patient
* There is no relationship to a setting
* There is no relationship to an encounter or episode
* There is no relationship to a care plan

These simplifications allow the example to focus exclusively on the pattern for
recommending and for accepting/rejecting the proposal, as well as documenting
the completion, or explicit non-performance of the activity.
*/

/*
Positive recommendation:

If the patient meets the eligibility criteria
  If the patient is not enrolled
    If enrollment has not been planned or proposed
      Propose enrollment

Given a proposal, the user can:
  Accept the proposal
  Ignore the proposal
  Reject the proposal without reason
  Reject the proposal with reason

Scenario 1: No event, no plan or proposal, decision support should propose
Scenario 2: No event, incomplete proposal, decision support should not propose
Scenario 3: No event, rejected proposal, decision support should not propose
Scenario 4: Event, no proposal, decision support should not propose
Scenario 5: Event, completed proposal, decision support should not propose
Scenario 6: Event not done, no proposal, decision support should not propose
Scenario 7: Event not done, proposal, decision support should not propose

*/

define Tasks: [Task]
define EpisodesOfCare: [EpisodeOfCare]

define "Inclusion Criteria":
  Patient.active

define "Enrollment Task":
  [Task] C
    where C.code ~ "Enrollment"
      and enrollIn(C) = enrollInPathway
      and isUnenrollment(C) is not true
      and doNotPerform(C) is not true

define "Case":
  [EpisodeOfCare] E
    where enrolledIn(E) = enrollInPathway

define "Active or Completed Activity":
  "Enrollment Task" C
    where C.status in { 'in-progress', 'on-hold', 'completed' }

define "Activity Not Done":
  "Enrollment Task" C
    where C.status in { 'cancelled', 'failed' }

define "Activity Proposal":
  "Enrollment Task" R
    where R.status in { 'draft', 'requested', 'received', 'accepted', 'ready' }

define "Activity Proposal Rejected":
  "Enrollment Task" R
    where R.status in { 'rejected' }

define "Is Recommendation Applicable":
  "Inclusion Criteria"
    and not exists ("Case")
    and not exists (
      "Active or Completed Activity"
        union "Activity Not Done"
    )
    and not exists (
      "Activity Proposal"
        union "Activity Proposal Rejected"
    )

define function doNotPerform(task Task):
  singleton from (
    task.modifierExtension E
      where E.url = 'http://hl7.org/fhir/StructureDefinition/request-doNotPerform'
  ).value as boolean

define function isUnenrollment(task Task):
  singleton from (
    task.modifierExtension E
      where E.url = 'http://hl7.org/fhir/uv/cpg/StructureDefinition/cpg-isUnenrollment'
  ).value as boolean

define function enrollIn(task Task):
  singleton from (
    task.input I
      where I.type ~ "Enrollment"
  ).value as canonical

define function enrolledIn(episodeOfCare EpisodeOfCare):
  singleton from (
    episodeOfCare.extension E
      where E.url = 'http://hl7.org/fhir/uv/cpg/StructureDefinition/cpg-enrolledIn'
  ).value as canonical

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