ZcashLightClientKit/Example/ZcashLightClientSample/ZcashLightClientSample/Derivation Tool/DerivationToolViewController.swift

//
//  DerivationToolViewController.swift
//  ZcashLightClientSample
//
//  Created by Francisco Gindre on 12/9/20.
//  Copyright © 2020 Electric Coin Company. All rights reserved.
//

import UIKit
import ZcashLightClientKit
import MnemonicSwift
class DerivationToolViewController: UIViewController {
    enum DerivationErrors: Error {
        case couldNotDeriveSpendingKeys(underlyingError: Error)
        case couldNotDeriveViewingKeys(underlyingError: Error)
        case unknown
    }

    @IBOutlet weak var seedTextView: UITextView!
    @IBOutlet weak var seedTextLabel: UILabel!
    @IBOutlet weak var shieldedAddressLabel: UILabel!
    @IBOutlet weak var transparentAddressLabel: UILabel!
    @IBOutlet weak var spendingKeyLabel: UILabel!
    @IBOutlet weak var extendedFullViewingKeyLabel: UILabel!
    @IBOutlet weak var deriveButton: UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()
        deriveButton.isEnabled = isValidSeed(seedTextView.text)
        updateValidationUI()
    }

    @IBAction func spendingKeyTapped(_ gesture: UIGestureRecognizer) {
        loggerProxy.event("spending key copied to clipboard")
        
        UIPasteboard.general.string = self.spendingKeyLabel.text
        
        let alert = UIAlertController(
            title: "",
            message: "Spending Key Copied to clipboard",
            preferredStyle: UIAlertController.Style.alert
        )

        alert.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))
        self.present(alert, animated: true, completion: nil)
    }
    
    @IBAction func viewingKeyTapped(_ gesture: UIGestureRecognizer) {
        loggerProxy.event("extended full viewing key copied to clipboard")
        
        UIPasteboard.general.string = self.extendedFullViewingKeyLabel.text
        
        let alert = UIAlertController(
            title: "",
            message: "extended full viewing key copied to clipboard",
            preferredStyle: UIAlertController.Style.alert
        )

        alert.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))
        self.present(alert, animated: true, completion: nil)
    }
    
    @IBAction func zAddressTapped(_ gesture: UIGestureRecognizer) {
        loggerProxy.event("zAddress copied to clipboard")

        UIPasteboard.general.string = self.shieldedAddressLabel.text
        let alert = UIAlertController(
            title: "",
            message: "zAddress Copied to clipboard",
            preferredStyle: UIAlertController.Style.alert
        )

        alert.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))
        self.present(alert, animated: true, completion: nil)
    }
    
    @IBAction func tAddressTapped(_ gesture: UIGestureRecognizer) {
        loggerProxy.event("tAddress copied to clipboard")

        UIPasteboard.general.string = self.transparentAddressLabel.text

        let alert = UIAlertController(
            title: "",
            message: "tAddress Copied to clipboard",
            preferredStyle: UIAlertController.Style.alert
        )

        alert.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))
        self.present(alert, animated: true, completion: nil)
    }
    
    @IBAction func deriveButtonTapped(_ sender: Any) {
        do {
            try deriveFrom(seedPhrase: seedTextView.text)
        } catch {
            fail(error)
            
            clearLabels()
        }
    }
    
    func deriveFrom(seedPhrase: String) throws {
        let seedBytes = try Mnemonic.deterministicSeedBytes(from: seedPhrase)
        let derivationTool = DerivationTool(networkType: kZcashNetwork.networkType)

        guard let spendingKey = try derivationTool.deriveSpendingKeys(seed: seedBytes, numberOfAccounts: 1).first else {
            throw DerivationErrors.couldNotDeriveSpendingKeys(underlyingError: DerivationErrors.unknown)
        }

        guard let viewingKey = try derivationTool.deriveUnifiedFullViewingKeysFromSeed(seedBytes, numberOfAccounts: 1).first else {
            throw DerivationErrors.couldNotDeriveViewingKeys(underlyingError: DerivationErrors.unknown)
        }
        
        let unifiedAddress = try derivationTool.deriveUnifiedAddress(from: viewingKey)
        
        let transparentAddress = try derivationTool.deriveTransparentAddress(seed: seedBytes)

        updateLabels(
            spendingKey: spendingKey.stringEncoded,
            viewingKey: viewingKey.stringEncoded,
            shieldedAddress: unifiedAddress.stringEncoded,
            transaparentAddress: transparentAddress.stringEncoded
        )
    }
    
    func updateLabels(
        spendingKey: String = "",
        viewingKey: String = "",
        shieldedAddress: String = "",
        transaparentAddress: String = ""
    ) {
        spendingKeyLabel.text = spendingKey
        extendedFullViewingKeyLabel.text = viewingKey
        shieldedAddressLabel.text = shieldedAddress
        transparentAddressLabel.text = transaparentAddress
    }
    
    func clearLabels() {
        updateLabels()
    }
    
    func fail(_ error: Error) {
        let alert = UIAlertController(title: "Error", message: "\(error)", preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))
        self.present(alert, animated: true, completion: nil)
    }
    
    func setValidSeed() {
        seedTextLabel.text = "This is a valid seed phrase"
        seedTextLabel.textColor = UIColor.systemGreen
    }
    
    func setInvalidSeed() {
        seedTextLabel.text = "Invalid seed phrase"
        seedTextLabel.textColor = UIColor.red
    }
    
    func isValidSeed(_ seed: String) -> Bool {
        do {
            try Mnemonic.validate(mnemonic: seed)
        } catch {
            return false
        }
        return true
    }
    
    func updateValidationUI() {
        guard isValidSeed(seedTextView.text)  else {
            setInvalidSeed()
            return
        }
        setValidSeed()
    }
}

extension DerivationToolViewController: UITextViewDelegate {
    func textViewDidEndEditing(_ textView: UITextView) {
        updateValidationUI()
    }
    
    func textViewDidChange(_ textView: UITextView) {
        deriveButton.isEnabled = isValidSeed(textView.text)
    }
}