RecoverWalletTableViewController.swift

//
//  RecoverWalletTableViewController.swift
//  Decred Wallet

// Copyright (c) 2018-2019 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
import UIKit

class RecoverWalletTableViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
    @IBOutlet var tableView : UITableView!
    @IBOutlet weak var wordSelectionDropDownContainer: UIView!
    
    @IBOutlet weak var tableViewFooter: UIStackView!
    @IBOutlet weak var tableViewFooterTopSpacingConstraint: NSLayoutConstraint!
    
    @IBOutlet weak var lblEnterAllSeeds: UILabel!
    @IBOutlet weak var btnConfirm: UIButton!
    
    var validSeedWords: [String] = []
    var userEnteredSeedWords = [String](repeating: "", count: 33)
    
    private var testSeed = "reform aftermath printer warranty gremlin paragraph beehive stethoscope regain disruptive regain Bradbury chisel October trouble forever Algol applicant island infancy physique paragraph woodlark hydraulic snapshot backwater ratchet surrender revenge customer retouch intention minnow"
    private var useTestSeed: Bool = false
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // load seed words
        let seedWordsPath = Bundle.main.path(forResource: "wordlist", ofType: "txt")
        let seedWords = try? String(contentsOfFile: seedWordsPath ?? "")
        validSeedWords = seedWords?.split{$0 == "\n"}.map(String.init) ?? []
        
        registerObserverForKeyboardNotification()
        self.hideKeyboardWhenTappedAround()
        
        // long press to proceed with test seed, only on testnet
        let isTestnet = Bool(infoForKey(GlobalConstants.Strings.IS_TESTNET)!)!
        if isTestnet {
            let longGesture = UILongPressGestureRecognizer(target: self, action: #selector(longPressConfirm))
            btnConfirm.addGestureRecognizer(longGesture)
        }
    }
    
    deinit {
        unregisterObserverForKeyboardNotification()
    }
    
    func registerObserverForKeyboardNotification() {
        NotificationCenter.default.addObserver(self, selector: #selector(onKeyboardWillShow), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(onKeyboardWillHide), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
    }
    
    func unregisterObserverForKeyboardNotification() {
        NotificationCenter.default.removeObserver(self, name:NSNotification.Name.UIKeyboardWillShow, object:nil)
        NotificationCenter.default.removeObserver(self, name:NSNotification.Name.UIKeyboardWillHide, object:nil)
    }
    
    @objc func onKeyboardWillShow(_ notification: Notification) {
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue,
            let window = self.view.window?.frame {
            // Minusing keyboard height from window height
            self.view.frame = CGRect(x: self.view.frame.origin.x,
                                     y: self.view.frame.origin.y,
                                     width: self.view.frame.width,
                                     height: window.origin.y + window.height - keyboardSize.height)
        }
    }
    
    @objc func onKeyboardWillHide(_ notification: Notification) {
        if let window = self.view.window?.frame {
            // Resize main view to window height
            self.view.frame = CGRect(x: self.view.frame.origin.x,
                                     y: self.view.frame.origin.y,
                                     width: self.view.frame.width,
                                     height: window.origin.y + window.height)
        }
    }
    
    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }
    
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 33
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let seedWordCell = tableView.dequeueReusableCell(withIdentifier: "seedWordCell", for: indexPath) as! RecoveryWalletSeedWordCell
        
        seedWordCell.lbSeedWordNum.text = "Word #\(indexPath.row + 1)"
        seedWordCell.seedWordAutoComplete.text = self.userEnteredSeedWords[indexPath.row]
        seedWordCell.seedWordAutoComplete.resignFirstResponder()
        
        seedWordCell.setupAutoComplete(for: indexPath.row,
                                       filter: self.validSeedWords,
                                       dropDownListPlaceholder: self.wordSelectionDropDownContainer,
                                       onSeedEntered: self.seedWordEntered)
        
        return seedWordCell
    }
    
    func seedWordEntered(for wordIndex: Int, seedWord: String, moveToNextField: Bool) {
        self.userEnteredSeedWords[wordIndex] = seedWord
        
        if wordIndex < 32 && moveToNextField {
            self.focusSeedWordInput(at: wordIndex + 1)
        } else {
            self.view.endEditing(true)
        }
        
        if self.validateSeed().valid {
            self.activateConfirmButton()
        } else {
            self.deactivateConfirmButton()
        }
    }
    
    func focusSeedWordInput(at tableRowIndex: Int) {
        let tableIndexPath = IndexPath(row: tableRowIndex, section: 0)
        
        let nextSeedWordCell = self.tableView.cellForRow(at: tableIndexPath) as? RecoveryWalletSeedWordCell
        nextSeedWordCell?.seedWordAutoComplete.becomeFirstResponder()
        
        self.tableView.scrollToRow(at: tableIndexPath, at: .middle, animated: true)
    }
    
    func activateConfirmButton() {
        self.btnConfirm.backgroundColor = UIColor.DecredColors.Green
        self.lblEnterAllSeeds.isHidden = true
        
        // increase top spacing since warning label is now hidden so as to position button in center
        self.tableViewFooterTopSpacingConstraint.constant = 30
        UIView.animate(withDuration: 0.5) {
            self.tableViewFooter.layoutIfNeeded()
        }
    }
    
    func deactivateConfirmButton() {
        self.btnConfirm.backgroundColor = UIColor.LightGray
        self.lblEnterAllSeeds.isHidden = false
        
        if self.userEnteredSeedWords.contains("") {
            self.lblEnterAllSeeds.text = "Not all seeds are entered. Please, check input fields and enter all seeds."
        } else {
            self.lblEnterAllSeeds.text = "You entered an incorrect seed. Please check your words."
        }
        
        // reduce top spacing so that warning label and confirm button are centered in display
        self.tableViewFooterTopSpacingConstraint.constant = 10
        UIView.animate(withDuration: 0.5) {
            self.tableViewFooter.layoutIfNeeded()
        }
    }
    
    @IBAction func onConfirm() {
        if self.validSeedWords.contains("") || !self.validateSeed().valid {
            // all words have not been entered
            return
        }
        
        self.performSegue(withIdentifier: "confirmSeedSegue", sender: nil)
    }
    
    @objc func longPressConfirm() {
        if self.useTestSeed {
            return
        }
        self.useTestSeed = true
        self.performSegue(withIdentifier: "confirmSeedSegue", sender: nil)
    }
    
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "confirmSeedSegue" {
            var confirmSeedVC = segue.destination as? SeedCheckupProtocol
            if self.useTestSeed {
                confirmSeedVC?.seedToVerify = self.testSeed
            } else {
                confirmSeedVC?.seedToVerify = self.validateSeed().seed
            }
        }
    }
    
    private func validateSeed() -> (seed: String, valid: Bool) {
        let seed = self.userEnteredSeedWords.reduce("", {(word1, word2) in "\(word1!) \(word2)"})
        let seedValid = SingleInstance.shared.wallet?.verifySeed(seed)
        return (seed, seedValid!)
    }
    
    private func showError(_ error: String) {
        let alert = UIAlertController(title: "Wallet recovery error", message: error, preferredStyle: .alert)
        let okAction = UIAlertAction(title: "Try again", style: .default) { _ in
            alert.dismiss(animated: true, completion: nil)
            self.clearSeedInputs()
        }
        alert.addAction(okAction)
        self.present(alert, animated: true, completion: nil)
    }
    
    func clearSeedInputs() {
        self.userEnteredSeedWords = [String](repeating: "", count: 33)
        self.tableView.reloadData()
        self.tableView.scrollToRow(at: IndexPath(row: 0, section: 0), at: .top, animated: true)
    }
}

extension RecoverWalletTableViewController: UIScrollViewDelegate {
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        self.wordSelectionDropDownContainer.isHidden = true
    }
    
    func hideKeyboardWhenTappedAround() {
        let tap: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(self.handleTap(_:)))
        tap.cancelsTouchesInView = false
        view.addGestureRecognizer(tap)
    }
    
    @objc func handleTap(_ tap: UITapGestureRecognizer) {
        var tapPoint = tap.location(in: self.view)
        tapPoint = self.wordSelectionDropDownContainer.convert(tapPoint, from: self.view)
        if self.wordSelectionDropDownContainer.bounds.contains(tapPoint) {
            // ignore taps inside the autoselection dropdown
            return
        }
        
        view.endEditing(true)
        self.wordSelectionDropDownContainer.isHidden = true
    }
}