NetNewsWire/Frameworks/Account/WebFeedMetadataFile.swift

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//
// WebFeedMetadataFile.swift
// Account
//
// Created by Maurice Parker on 9/13/19.
// Copyright © 2019 Ranchero Software, LLC. All rights reserved.
//
import Foundation
import os.log
import RSCore
final class WebFeedMetadataFile {
private var log = OSLog(subsystem: Bundle.main.bundleIdentifier!, category: "webFeedMetadataFile")
private let fileURL: URL
private let account: Account
private var isDirty = false {
didSet {
queueSaveToDiskIfNeeded()
}
}
private let saveQueue = CoalescingQueue(name: "Save Queue", interval: 0.5)
init(filename: String, account: Account) {
self.fileURL = URL(fileURLWithPath: filename)
self.account = account
}
func markAsDirty() {
isDirty = true
}
func load() {
let errorPointer: NSErrorPointer = nil
let fileCoordinator = NSFileCoordinator()
fileCoordinator.coordinate(readingItemAt: fileURL, options: [], error: errorPointer, byAccessor: { readURL in
if let fileData = try? Data(contentsOf: readURL) {
let decoder = PropertyListDecoder()
account.webFeedMetadata = (try? decoder.decode(Account.WebFeedMetadataDictionary.self, from: fileData)) ?? Account.WebFeedMetadataDictionary()
}
account.webFeedMetadata.values.forEach { $0.delegate = account }
})
if let error = errorPointer?.pointee {
os_log(.error, log: log, "Read from disk coordination failed: %@.", error.localizedDescription)
}
}
func save() {
guard !account.isDeleted else { return }
let feedMetadata = metadataForOnlySubscribedToFeeds()
let encoder = PropertyListEncoder()
encoder.outputFormat = .binary
let errorPointer: NSErrorPointer = nil
let fileCoordinator = NSFileCoordinator()
fileCoordinator.coordinate(writingItemAt: fileURL, options: [], error: errorPointer, byAccessor: { writeURL in
do {
let data = try encoder.encode(feedMetadata)
try data.write(to: writeURL)
} catch let error as NSError {
os_log(.error, log: log, "Save to disk failed: %@.", error.localizedDescription)
}
})
if let error = errorPointer?.pointee {
os_log(.error, log: log, "Save to disk coordination failed: %@.", error.localizedDescription)
}
}
}
private extension WebFeedMetadataFile {
func queueSaveToDiskIfNeeded() {
saveQueue.add(self, #selector(saveToDiskIfNeeded))
}
@objc func saveToDiskIfNeeded() {
if isDirty {
isDirty = false
save()
}
}
private func metadataForOnlySubscribedToFeeds() -> Account.WebFeedMetadataDictionary {
let webFeedIDs = account.idToWebFeedDictionary.keys
return account.webFeedMetadata.filter { (feedID: String, metadata: WebFeedMetadata) -> Bool in
return webFeedIDs.contains(metadata.webFeedID)
}
}
}