Add ability to import PGP keys from the Files app

pass/Controllers/PGPKeyFileSettingTableViewController.swift

@@ -0,0 +1,106 @@
+//
+//  PGPKeyFileSettingTableViewController.swift
+//  pass
+//
+//  Created by Danny Moesch on 01.02.20.
+//  Copyright © 2020 Bob Sun. All rights reserved.
+//
+
+import passKit
+
+class PGPKeyFileSettingTableViewController: AutoCellHeightUITableViewController {
+
+    @IBOutlet weak var pgpPublicKeyFile: UITableViewCell!
+    @IBOutlet weak var pgpPrivateKeyFile: UITableViewCell!
+
+    private let passwordStore = PasswordStore.shared
+    private let keychain = AppKeychain.shared
+
+    private var publicKey: String? = nil
+    private var privateKey: String? = nil
+
+    private enum KeyType { case none, `private`, `public` }
+    private var currentlyPicking = KeyType.none
+
+    @IBAction func save(_ sender: Any) {
+        savePassphraseDialog()
+    }
+
+    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
+        let cell = tableView.cellForRow(at: indexPath)
+        let picker = UIDocumentPickerViewController(documentTypes: ["public.data"], in: .import)
+        if cell == pgpPublicKeyFile {
+            currentlyPicking = .public
+        } else if cell == pgpPrivateKeyFile {
+            currentlyPicking = .private
+        } else {
+            return
+        }
+        picker.delegate = self
+        if #available(iOS 13.0, *) {
+            picker.shouldShowFileExtensions = true
+        }
+        present(picker, animated: true, completion: nil)
+    }
+}
+
+extension PGPKeyFileSettingTableViewController: UIDocumentPickerDelegate {
+
+    func documentPicker(_: UIDocumentPickerViewController, didPickDocumentsAt url: [URL]) {
+        guard let url = url.first else {
+            return
+        }
+        let fileName = url.lastPathComponent
+        do {
+            let fileContent = try String(contentsOf: url, encoding: .ascii)
+            switch currentlyPicking {
+            case .none:
+                return
+            case .public:
+                publicKey = fileContent
+                pgpPublicKeyFile.textLabel?.text = fileName
+            case .private:
+                privateKey = fileContent
+                pgpPrivateKeyFile.textLabel?.text = fileName
+            }
+        } catch {
+            Utils.alert(title: "CannotImportFile".localize(), message: "FileCannotBeImported.".localize(fileName), controller: self)
+        }
+    }
+}
+
+extension PGPKeyFileSettingTableViewController: PGPKeyImporter {
+
+    static let keySource = PGPKeySource.files
+    static let label = "LoadFromFiles".localize()
+
+    func isReadyToUse() -> Bool {
+        return validate(key: publicKey) && validate(key: privateKey)
+    }
+
+    func importKeys() throws {
+        guard let publicKey = publicKey, let privateKey = privateKey else {
+            return
+        }
+        Defaults.pgpKeySource = Self.keySource
+
+        try KeyFileManager.PublicPgp.importKey(from: publicKey)
+        try KeyFileManager.PrivatePgp.importKey(from: privateKey)
+    }
+
+    func doAfterImport() {
+        Utils.alert(title: "RememberToRemoveKey".localize(), message: "RememberToRemoveKeyFromLocation.".localize(), controller: self)
+    }
+
+    func saveImportedKeys() {
+        self.performSegue(withIdentifier: "savePGPKeySegue", sender: self)
+    }
+
+    private func validate(key: String?) -> Bool {
+        guard key != nil else {
+            Utils.alert(title: "CannotSavePgpKey".localize(), message: "KeyFileNotSet.".localize(), controller: self)
+            return false
+        }
+        return true
+    }
+}