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/* This Source Code Form is subject to the terms of the Mozilla
* License, v. 2.0. If a copy of the MPL was not distributed with this
import Foundation
import Glean
/**
* Instances of this class are useful for implementing a messaging service based upon
* Nimbus.
*
* The message helper is designed to help string interpolation and JEXL evalutaiuon against the context
* of the attrtibutes Nimbus already knows about.
*
* App-specific, additional context can be given at creation time.
*
* The helpers are designed to evaluate multiple messages at a time, however: since the context may change
* over time, the message helper should not be stored for long periods.
*/
public protocol NimbusMessagingProtocol {
func createMessageHelper() throws -> NimbusMessagingHelperProtocol
func createMessageHelper(additionalContext: [String: Any]) throws -> NimbusMessagingHelperProtocol
func createMessageHelper<T: Encodable>(additionalContext: T) throws -> NimbusMessagingHelperProtocol
var events: NimbusEventStore { get }
}
public protocol NimbusMessagingHelperProtocol: NimbusStringHelperProtocol, NimbusTargetingHelperProtocol {
/**
* Clear the JEXL cache
*/
func clearCache()
}
/**
* A helper object to make working with Strings uniform across multiple implementations of the messaging
* system.
*
* This object provides access to a JEXL evaluator which runs against the same context as provided by
* Nimbus targeting.
*
* It should also provide a similar function for String substitution, though this scheduled for EXP-2159.
*/
public class NimbusMessagingHelper: NimbusMessagingHelperProtocol {
private let targetingHelper: NimbusTargetingHelperProtocol
private let stringHelper: NimbusStringHelperProtocol
private var cache: [String: Bool]
public init(targetingHelper: NimbusTargetingHelperProtocol,
stringHelper: NimbusStringHelperProtocol,
cache: [String: Bool] = [:])
{
self.targetingHelper = targetingHelper
self.stringHelper = stringHelper
self.cache = cache
}
public func evalJexl(expression: String) throws -> Bool {
if let result = cache[expression] {
return result
} else {
let result = try targetingHelper.evalJexl(expression: expression)
cache[expression] = result
return result
}
}
public func clearCache() {
cache.removeAll()
}
public func getUuid(template: String) -> String? {
stringHelper.getUuid(template: template)
}
public func stringFormat(template: String, uuid: String?) -> String {
stringHelper.stringFormat(template: template, uuid: uuid)
}
}
// MARK: Dummy implementations
class AlwaysConstantTargetingHelper: NimbusTargetingHelperProtocol {
private let constant: Bool
public init(constant: Bool = false) {
self.constant = constant
}
public func evalJexl(expression _: String) throws -> Bool {
constant
}
}
class EchoStringHelper: NimbusStringHelperProtocol {
public func getUuid(template _: String) -> String? {
nil
}
public func stringFormat(template: String, uuid _: String?) -> String {
template
}
}