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letro-ios/ElementX/Sources/AppCoordinatorStateMachine.swift
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Swift

//
// AppCoordinatorStateMachine.swift
// ElementX
//
// Created by Stefan Ceriu on 30/05/2022.
// Copyright © 2022 element.io. All rights reserved.
//
import Foundation
import SwiftState
class AppCoordinatorStateMachine {
/// States the AppCoordinator can find itself in
enum State: StateType {
/// The initial state, used before the AppCoordinator starts
case initial
/// Showing the login screen
case signedOut
/// Opening an existing session.
case restoringSession
/// Showing the home screen
case homeScreen
/// Showing a particular room's timeline
/// - Parameter roomId: that room's identifier
case roomScreen(roomId: String)
/// Showing the session verification flows
case sessionVerificationScreen
/// Showing the settings screen
case settingsScreen
/// Processing a sign out request
case signingOut
}
/// Events that can be triggered on the AppCoordinator state machine
enum Event: EventType {
/// Start the `AppCoordinator` by showing authentication.
case startWithAuthentication
/// Signing in succeeded
case succeededSigningIn
/// Start the `AppCoordinator` by restoring an existing account.
case startWithExistingSession
/// Restoring session succeeded.
case succeededRestoringSession
/// Restoring session failed.
case failedRestoringSession
/// Request sign out
case attemptSignOut
/// Signing out succeeded
case succeededSigningOut
/// Signing out failed
case failedSigningOut
/// Request presentation for a particular room
/// - Parameter roomId:the room identifier
case showRoomScreen(roomId: String)
/// The room screen has been dismissed
case dismissedRoomScreen
/// Request the start of the session verification flow
case showSessionVerificationScreen
/// Session verification has finished
case dismissedSessionVerificationScreen
/// Request settings screen presentation
case showSettingsScreen
/// The settings screen has been dismissed
case dismissedSettingsScreen
}
private let stateMachine: StateMachine<State, Event>
init() {
stateMachine = StateMachine(state: .initial) { machine in
machine.addRoutes(event: .startWithAuthentication, transitions: [.initial => .signedOut])
machine.addRoutes(event: .succeededSigningIn, transitions: [.signedOut => .homeScreen])
machine.addRoutes(event: .startWithExistingSession, transitions: [.initial => .restoringSession])
machine.addRoutes(event: .succeededRestoringSession, transitions: [.restoringSession => .homeScreen])
machine.addRoutes(event: .failedRestoringSession, transitions: [.restoringSession => .signedOut])
machine.addRoutes(event: .attemptSignOut, transitions: [.settingsScreen => .signingOut])
machine.addRoutes(event: .succeededSigningOut, transitions: [.signingOut => .signedOut])
machine.addRoutes(event: .failedSigningOut, transitions: [.signingOut => .settingsScreen])
machine.addRoutes(event: .showSettingsScreen, transitions: [.homeScreen => .settingsScreen])
machine.addRoutes(event: .dismissedSettingsScreen, transitions: [.settingsScreen => .homeScreen])
machine.addRoutes(event: .showSessionVerificationScreen, transitions: [.homeScreen => .sessionVerificationScreen])
machine.addRoutes(event: .dismissedSessionVerificationScreen, transitions: [.sessionVerificationScreen => .homeScreen])
// Transitions with associated values need to be handled through `addRouteMapping`
machine.addRouteMapping { event, fromState, _ in
switch (event, fromState) {
case (.showRoomScreen(let roomId), .homeScreen):
return .roomScreen(roomId: roomId)
case (.dismissedRoomScreen, .roomScreen):
return .homeScreen
default:
return nil
}
}
}
}
/// Attempt to move the state machine to another state through an event
/// It will either invoke the `transitionHandler` or the `errorHandler` depending on its current state
func processEvent(_ event: Event) {
stateMachine.tryEvent(event)
}
/// Registers a callback for processing state machine transitions
func addTransitionHandler(_ handler: @escaping StateMachine<State, Event>.Handler) {
stateMachine.addAnyHandler(.any => .any, handler: handler)
}
/// Registers a callback for processing state machine errors
func addErrorHandler(_ handler: @escaping StateMachine<State, Event>.Handler) {
stateMachine.addErrorHandler(handler: handler)
}
}