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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
import Kingfisher
import UIKit
import Common
// MARK: - Kingfisher wrappers
/// Image downloader wrapper around Kingfisher image downloader
/// Used in FaviconFetcher
protocol SiteImageDownloader: AnyObject {
/// Provides the KingFisher ImageDownloader with a Timeout in case the completion isn't called
var timeoutDelay: UInt64 { get }
var continuation: CheckedContinuation<any SiteImageLoadingResult, any Error>? { get set }
var logger: Logger { get }
@discardableResult
func downloadImage(
with url: URL,
completionHandler: ((Result<SiteImageLoadingResult, Error>) -> Void)?
) -> DownloadTask?
func downloadImage(with url: URL) async throws -> SiteImageLoadingResult
}
extension SiteImageDownloader {
func downloadImage(with url: URL) async throws -> SiteImageLoadingResult {
return try await withThrowingTaskGroup(of: SiteImageLoadingResult.self) { group in
// Use task groups to have a timeout when downloading an image from Kingfisher
group.addTask {
return try await self.handleImageDownload(url: url)
}
group.addTask {
try await self.handleTimeout()
}
// wait for the first task and cancel the other one
let result = try await group.next()
group.cancelAll()
guard let result = result else {
throw SiteImageError.unableToDownloadImage("Result not present")
}
return result
}
}
private func handleImageDownload(url: URL) async throws -> any SiteImageLoadingResult {
return try await withCheckedThrowingContinuation { continuation in
// Store a copy of the continuation to act on in the case the sleep finishes first
self.continuation = continuation
_ = self.downloadImage(with: url) { result in
guard let continuation = self.continuation else { return }
switch result {
case .success(let imageResult):
continuation.resume(returning: imageResult)
case .failure(let error):
continuation.resume(throwing: error)
}
self.continuation = nil
}
}
}
private func handleTimeout() async throws -> any SiteImageLoadingResult {
try await Task.sleep(nanoseconds: self.timeoutDelay * NSEC_PER_SEC)
try Task.checkCancellation()
let error = SiteImageError.unableToDownloadImage("Timeout reached")
self.continuation?.resume(throwing: error)
self.continuation = nil
self.logger.log("Timeout when downloading image reached",
level: .warning,
category: .images)
throw error
}
}
/// Image loading result wrapper for Kingfisher type so we have control when testing
/// Used in FaviconFetcher
protocol SiteImageLoadingResult {
var image: UIImage { get }
}
extension ImageLoadingResult: SiteImageLoadingResult {}