Request.swift

//
//  Request.swift
//  SMARTMarkers
//
//  Created by Raheel Sayeed on 3/1/19.
//  Copyright © 2019 Boston Children's Hospital. All rights reserved.
//

import Foundation
import SMART

/**
 PGHD Request Protocol
 Fetches and Manages `FHIR` request resource
 */
public protocol Request:  DomainResource {
    
    
    /// Request identifier
    var rq_identifier: String { get }
    
    /// Title Representation of the Request
    var rq_title: String? { get }
    
    /// Person requesting the PRO
    var rq_requesterName: String? { get }
    
    /// Requested activity code
    var rq_code: Coding? { get }
    
    /// Entity requesting the PRO
    var rq_requesterEntity: String? { get }
    
    /// Date of Request
    var rq_requestDate: Date? { get }
    
    /// Primary identifying Request Code
    var rq_categoryCode: String? { get }
    
    /// Schedule
    var rq_schedule: TaskSchedule? { get set }

    /// Fetch Parameters
    static var rq_fetchParameters: [String: String]? { get }

    /// Embedded Questionnaire URL
    var rq_instrumentMetadataQuestionnaireReferenceURL: URL? { get }

    /// Notifies request has been updated
    func rq_updated(_ completed: Bool, callback: @escaping ((_ success: Bool) -> Void))
    
    /// Requested Instrument
    func rq_resolveInstrument(callback: @escaping ((_ instrument: Instrument?, _ error: Error?) -> Void))
    
    /// Resolve FHIR References if needed;
    func rq_resolveReferences(callback: @escaping ((Bool) -> Void))
    
    /// Call for the receiver to configure itself with the instrument, scheduling, subject (patient) and practitioner
    func rq_configureNew(for instrument: Instrument, schedule: TaskSchedule?, patient: Patient?, practitioner: Practitioner?) throws
    
}

public extension Request {
    
    var description : String {
        return "Request: \(rq_identifier)"
    }
}


public extension Request {
    
    static func rq_create() -> Self? {
        //TODO: Swift 5.1 should replace this!
        return ServiceRequest() as? Self
    }
    
    static func PGHDRequests(from server: Server, for patient: Patient?, options: [String:String]?, callback: @escaping ((_ requestResources: [Self]?, _ error: Error?) -> Void)) {
        
        var searchParams =  rq_fetchParameters ?? [String:String]()
        
        if let patientFHIRID = patient?.id?.string {
            searchParams["subject"] = patientFHIRID
        }
        
        if let options = options {
            for (k,v) in options {
                searchParams[k] = v
            }
        }
        
        PGHDRequests(from: server, options: searchParams, callback: callback)
    }

    
    static func PGHDRequests(from server: Server, options: [String:String]?, callback: @escaping ((_ requestResources: [Self]?, _ error: Error?) -> Void)) {
        let search = Self.search(options as Any)
        search.pageCount = 100
        search.perform(server) { (bundle, error) in
            if let bundle = bundle {
                let resources = bundle.entry?.filter { $0.resource is Self }.map { $0.resource as! Self }
                let group = DispatchGroup()
                for r in resources ?? [] {
                    group.enter()
                    r.rq_resolveReferences(callback: { (_ ) in
                        group.leave()
                    })
                }
                
                group.notify(queue: .global(qos: .userInteractive), execute: {
                    callback(resources, nil)
                })

            }
            else {
                callback(nil, error)
            }
        }
    }
    
    var asFHIR : DomainResource? {
        return self 
    }

    
    func asRelativeReference() throws -> Reference {
        return try self.asRelativeReference()
    }
}