SideStore/SideStoreApp/Sources/SideStoreAppKit/Authentication/Intents/IntentHandler.swift

//
//  IntentHandler.swift
//  AltStore
//
//  Created by Riley Testut on 7/6/20.
//  Copyright © 2020 Riley Testut. All rights reserved.
//

import Foundation
import SideStoreCore
import Intents
import os.log

@available(iOS 14, *)
public final class IntentHandler: NSObject, RefreshAllIntentHandling {
    private let queue = DispatchQueue(label: "io.altstore.IntentHandler")

    private var completionHandlers = [RefreshAllIntent: (RefreshAllIntentResponse) -> Void]()
    private var queuedResponses = [RefreshAllIntent: RefreshAllIntentResponse]()

    private var operations = [RefreshAllIntent: BackgroundRefreshAppsOperation]()

	public func confirm(intent: RefreshAllIntent, completion: @escaping (RefreshAllIntentResponse) -> Void) {
        // Refreshing apps usually, but not always, completes within alotted time.
        // As a workaround, we'll start refreshing apps in confirm() so we can
        // take advantage of some extra time before starting handle() timeout timer.

        completionHandlers[intent] = { response in
            if response.code != .ready {
                // Operation finished before confirmation "timeout".
                // Cache response to return it when handle() is called.
                self.queuedResponses[intent] = response
            }

            completion(RefreshAllIntentResponse(code: .ready, userActivity: nil))
        }

        // Give ourselves 9 extra seconds before starting handle() timeout timer.
        // 10 seconds or longer results in timeout regardless.
        queue.asyncAfter(deadline: .now() + 9.0) {
            self.finish(intent, response: RefreshAllIntentResponse(code: .ready, userActivity: nil))
        }

        if !DatabaseManager.shared.isStarted {
            DatabaseManager.shared.start { error in
                if let error = error {
                    self.finish(intent, response: RefreshAllIntentResponse.failure(localizedDescription: error.localizedDescription))
                } else {
                    self.refreshApps(intent: intent)
                }
            }
        } else {
            refreshApps(intent: intent)
        }
    }

	public func handle(intent: RefreshAllIntent, completion: @escaping (RefreshAllIntentResponse) -> Void) {
        completionHandlers[intent] = { response in
            // Ignore .ready response from confirm() timeout.
            guard response.code != .ready else { return }
            completion(response)
        }

        if let response = queuedResponses[intent] {
            queuedResponses[intent] = nil
            finish(intent, response: response)
        } else {
            queue.asyncAfter(deadline: .now() + 7.0) {
                if let operation = self.operations[intent] {
                    // We took too long to finish and return the final result,
                    // so we'll now present a normal notification when finished.
                    operation.presentsFinishedNotification = true
                }

                self.finish(intent, response: RefreshAllIntentResponse(code: .inProgress, userActivity: nil))
            }
        }
    }
}

@available(iOS 14, *)
private extension IntentHandler {
    func finish(_ intent: RefreshAllIntent, response: RefreshAllIntentResponse) {
        queue.async {
            if let completionHandler = self.completionHandlers[intent] {
                self.completionHandlers[intent] = nil
                completionHandler(response)
            } else if response.code != .ready && response.code != .inProgress {
                // Queue response in case refreshing finishes after confirm() but before handle().
                self.queuedResponses[intent] = response
            }
        }
    }

    func refreshApps(intent: RefreshAllIntent) {
        DatabaseManager.shared.persistentContainer.performBackgroundTask { context in
            let installedApps = InstalledApp.fetchActiveApps(in: context)
            let operation = AppManager.shared.backgroundRefresh(installedApps, presentsNotifications: false) { result in
                do {
                    let results = try result.get()

                    for (_, result) in results {
                        guard case let .failure(error) = result else { continue }
                        throw error
                    }

                    self.finish(intent, response: RefreshAllIntentResponse(code: .success, userActivity: nil))
                } catch RefreshError.noInstalledApps {
                    self.finish(intent, response: RefreshAllIntentResponse(code: .success, userActivity: nil))
                } catch let error as NSError {
                    os_log("Failed to refresh apps in background. %@", type: .error , error.localizedDescription)
                    self.finish(intent, response: RefreshAllIntentResponse.failure(localizedDescription: error.localizedFailureReason ?? error.localizedDescription))
                }

                self.operations[intent] = nil
            }

            self.operations[intent] = operation
        }
    }
}