//

//  EmailListViewController.swift

//  pEpForiOS

//

//  Created by Dirk Zimmermann on 16/04/16.

//  Copyright © 2016 p≡p Security S.A. All rights reserved.

//

import UIKit

import MessageModel

class EmailListViewController: BaseTableViewController {

    private var _folderToShow: Folder?

    var folderToShow: Folder? {

        set {

            if newValue === _folderToShow {

                return

            }

            if newValue == nil {

                model = nil

                _folderToShow = newValue

                return

            }

            _folderToShow = newValue

            // Update the model to data of new folder/filter

            resetModel()

        }

        get {

            Log.shared.errorAndCrash(component: #function,

                                     errorString: "Use only the folderToShow from model (model?folderToShow).")

            return _folderToShow

        }

    }

    func updateLastLookAt() {

        guard let saveFolder = model?.folderToShow else {

            return

        }

        saveFolder.updateLastLookAt()

    }

    private var model: EmailListViewModel?

    private let queue: OperationQueue = {

        let createe = OperationQueue()

        createe.qualityOfService = .userInteractive

        createe.maxConcurrentOperationCount = 10

        return createe

    }()

    private var operations = [IndexPath:Operation]()

    public static let storyboardId = "EmailListViewController"

    fileprivate var lastSelectedIndexPath: IndexPath?

    let searchController = UISearchController(searchResultsController: nil)

    // MARK: - Outlets

    @IBOutlet weak var enableFilterButton: UIBarButtonItem!

    @IBOutlet weak var textFilterButton: UIBarButtonItem!

    @IBOutlet var showFoldersButton: UIBarButtonItem!

    // MARK: - Life Cycle

    override func viewDidLoad() {

        super.viewDidLoad()

        title = NSLocalizedString("Inbox", comment: "General name for (unified) inbox")

        UIHelper.emailListTableHeight(self.tableView)

        self.textFilterButton.isEnabled = false

        addSearchBar()

    }

    override func viewWillAppear(_ animated: Bool) {

        super.viewWillAppear(animated)

        self.navigationController?.setToolbarHidden(false, animated: true)

        if MiscUtil.isUnitTest() {

            return

        }

        //BUFF: TODO

        if let vm = model {

            self.textFilterButton.isEnabled = vm.isFilterEnabled

            updateFilterText()

        } else {

            self.textFilterButton.isEnabled = false

        }

        setDefaultColors()

        setup()

        updateView()

        // Mark this folder as having been looked at by the user

        updateLastLookAt()

        setupFoldersBarButton()

    }

    // MARK: - NavigationBar

    private func hideFoldersNavigationBarButton() {

        self.showFoldersButton.isEnabled = false

        self.showFoldersButton.tintColor = UIColor.clear

    }

    private func showFoldersNavigationBarButton() {

        self.showFoldersButton.isEnabled = true

        self.showFoldersButton.tintColor = nil

    }

    private func resetModel() {

        if _folderToShow != nil {

            model = EmailListViewModel(delegate: self, folderToShow: _folderToShow)

        }

    }

    private func setup() {

        // We have not been created to show a specific folder, thus we show unified inbox

        if model?.folderToShow == nil {

            folderToShow = UnifiedInbox()

        }

        if noAccountsExist() {

            performSegue(withIdentifier:.segueAddNewAccount, sender: self)

        }

        self.title = realNameOfFolderToShow()

    }

    private func noAccountsExist() -> Bool {

        return Account.all().isEmpty

    }

    private func setupFoldersBarButton() {

        if let size = navigationController?.viewControllers.count, size > 1 {

            hideFoldersNavigationBarButton()

        } else {

            showFoldersNavigationBarButton()

        }

    }

    private func addSearchBar() {

        searchController.searchResultsUpdater = self

        searchController.dimsBackgroundDuringPresentation = false

        searchController.delegate = self

        definesPresentationContext = true

        tableView.tableHeaderView = searchController.searchBar

        tableView.setContentOffset(CGPoint(x: 0.0, y: 40.0), animated: false)

    }

    // MARK: - Other

    private func realNameOfFolderToShow() -> String? {

        return model?.folderToShow?.realName

    }

    private func configure(cell: EmailListViewCell, for indexPath: IndexPath) {

        // Configure lightweight stuff on main thread ...

        guard let saveModel = model else {

            return

        }

        guard let row = saveModel.row(for: indexPath) else {

            Log.shared.errorAndCrash(component: #function, errorString: "We should have a row here")

            return

        }

        cell.senderLabel.text = row.from

        cell.subjectLabel.text = row.subject

        cell.summaryLabel.text = row.bodyPeek

        cell.isFlagged = row.isFlagged

        cell.isSeen = row.isSeen

        cell.hasAttachment = row.showAttchmentIcon

        cell.dateLabel.text = row.dateText

        // Set image from cache if any

        cell.setContactImage(image: row.senderContactImage)

        let op = BlockOperation() { [weak self] in

            // ... and expensive computations in background

            guard let strongSelf = self else {

                // View is gone, nothing to do.

                return

            }

            var senderImage: UIImage?

            if row.senderContactImage == nil {

                // image for identity has not been cached yet, get and cache it

                senderImage = strongSelf.model?.senderImage(forCellAt: indexPath)

            }

            // Set data on cell on main queue.

            // In theory we want to set all data in *one* async call. But as pEpRatingColorImage takes

            // very long, we are setting the sender image seperatelly.

            DispatchQueue.main.async {

                if senderImage != nil {

                    cell.contactImageView.image  = senderImage

                }

            }

            let pEpRatingImage = strongSelf.model?.pEpRatingColorImage(forCellAt: indexPath)

            // Set data on cell on main queue, again ...

            DispatchQueue.main.async {

                if pEpRatingImage != nil {

                    cell.setPepRatingImage(image: pEpRatingImage)

                }

            }

        }

        queue(operation: op, for: indexPath)

    }

    // MARK: - Actions

    @IBAction func filterButtonHasBeenPressed(_ sender: UIBarButtonItem) {

        guard let vm = model else {

            Log.shared.errorAndCrash(component: #function, errorString: "We should have a model here")

            return

        }

        vm.isFilterEnabled = !vm.isFilterEnabled

        upadteFilterButtonView()

    }

    func upadteFilterButtonView() {

        guard let vm = model else {

            Log.shared.errorAndCrash(component: #function, errorString: "We should have a model here")

            return

        }

        textFilterButton.isEnabled = vm.isFilterEnabled

        if textFilterButton.isEnabled {

            enableFilterButton.image = UIImage(named: "unread-icon-active")

            updateFilterText()

        } else {

            textFilterButton.title = ""

            enableFilterButton.image = UIImage(named: "unread-icon")

        }

    }

    func updateFilterText() {

        if let vm = model, let txt = vm.activeFilter?.text {

            textFilterButton.title = "Filter by: " + txt

        }

    }

    // MARK: - UITableViewDataSource

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

        return model?.rowCount ?? 0

    }

    override func tableView(_ tableView: UITableView,

                            cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        guard let cell = tableView.dequeueReusableCell(withIdentifier: EmailListViewCell.storyboardId,

                                                       for: indexPath) as? EmailListViewCell

            else {

                Log.shared.errorAndCrash(component: #function, errorString: "Wrong cell!")

                return UITableViewCell()

        }

        configure(cell: cell, for: indexPath)

        return cell

    }

    // MARK: - UITableViewDelegate

    override func tableView(_ tableView: UITableView, editActionsForRowAt

        indexPath: IndexPath)-> [UITableViewRowAction]? {

        guard let flagAction = createFlagAction(forCellAt: indexPath),

            let deleteAction = createDeleteAction(forCellAt: indexPath),

            let moreAction = createMoreAction(forCellAt: indexPath) else {

                Log.shared.errorAndCrash(component: #function, errorString: "Error creating action.")

                return nil

        }

        return [deleteAction, flagAction, moreAction]

    }

    override func tableView(_ tableView: UITableView, didEndDisplaying cell: UITableViewCell, forRowAt indexPath: IndexPath) {

        cancelOperation(for: indexPath)

    }

    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

        lastSelectedIndexPath = indexPath

        tableView.selectRow(at: indexPath, animated: true, scrollPosition: .none)

        performSegue(withIdentifier: SegueIdentifier.segueShowEmail, sender: self)

    }

    // MARK: - Queue Handling

    private func queue(operation op:Operation, for indexPath: IndexPath) {

        operations[indexPath] = op

        queue.addOperation(op)

    }

    private func cancelOperation(for indexPath:IndexPath) {

        guard let op = operations.removeValue(forKey: indexPath) else {

            return

        }

        if !op.isCancelled  {

            op.cancel()

        }

    }

    override func didReceiveMemoryWarning() {

        model?.freeMemory()

    }

}

// MARK: - UISearchResultsUpdating, UISearchControllerDelegate

extension EmailListViewController: UISearchResultsUpdating, UISearchControllerDelegate {

    public func updateSearchResults(for searchController: UISearchController) {

        guard let vm = model, let searchText = searchController.searchBar.text else {

            return

        }

        vm.setSearchFilter(forSearchText: searchText)

    }

    func didDismissSearchController(_ searchController: UISearchController) {

        guard let vm = model else {

            return

        }

        vm.removeSearchFilter()

    }

}

// MARK: - EmailListModelDelegate

extension EmailListViewController: EmailListViewModelDelegate {

    func emailListViewModel(viewModel: EmailListViewModel, didInsertDataAt indexPath: IndexPath) {

        tableView.beginUpdates()

        tableView.insertRows(at: [indexPath], with: .automatic)

        tableView.endUpdates()

    }

    func emailListViewModel(viewModel: EmailListViewModel, didRemoveDataAt indexPath: IndexPath) {

        tableView.beginUpdates()

        tableView.deleteRows(at: [indexPath], with: .automatic)

        tableView.endUpdates()

    }

    func emailListViewModel(viewModel: EmailListViewModel, didUpdateDataAt indexPath: IndexPath) {

        tableView.beginUpdates()

        tableView.reloadRows(at: [indexPath], with: .none)

        tableView.endUpdates()

    }

    func updateView() {

        self.tableView.reloadData()

    }

}

// MARK: - ActionSheet & ActionSheet Actions

extension EmailListViewController {

    func showMoreActionSheet(forRowAt indexPath: IndexPath) {

        lastSelectedIndexPath = indexPath

        let alertControler = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)

        alertControler.view.tintColor = .pEpGreen

        let cancelAction = createCancelAction()

        let replyAction = createReplyAction()

        let replyAllAction = createReplyAllAction()

        let forwardAction = createForwardAction()

        alertControler.addAction(cancelAction)

        alertControler.addAction(replyAction)

        alertControler.addAction(replyAllAction)

        alertControler.addAction(forwardAction)

        if let popoverPresentationController = alertControler.popoverPresentationController {

            popoverPresentationController.sourceView = tableView

        }

        present(alertControler, animated: true, completion: nil)

    }

    // MARK: Action Sheet Actions

    func createCancelAction() -> UIAlertAction {

        return  UIAlertAction(title: "Cancel", style: .cancel) { (action) in

            self.tableView.beginUpdates()

            self.tableView.setEditing(false, animated: true)

            self.tableView.endUpdates()

        }

    }

    func createReplyAction() ->  UIAlertAction {

        return UIAlertAction(title: "Reply", style: .default) { (action) in

            self.performSegue(withIdentifier: .segueReply, sender: self)

        }

    }

    func createReplyAllAction() ->  UIAlertAction {

        return UIAlertAction(title: "Reply All", style: .default) { (action) in

            self.performSegue(withIdentifier: .segueReplyAll, sender: self)

        }

    }

    func createForwardAction() -> UIAlertAction {

        return UIAlertAction(title: "Forward", style: .default) { (action) in

            self.performSegue(withIdentifier: .segueForward, sender: self)

        }

    }

}

// MARK: - TableViewCell Actions

extension EmailListViewController {

    private func createRowAction(image: UIImage?,

                                 action: @escaping (UITableViewRowAction, IndexPath) -> Void,

                                 title: String) -> UITableViewRowAction {

        let rowAction = UITableViewRowAction(style: .normal, title: title, handler: action)

        if let theImage = image {

            let iconColor = UIColor(patternImage: theImage)

            rowAction.backgroundColor = iconColor

        }

        return rowAction

    }

    func createFlagAction(forCellAt indexPath: IndexPath) -> UITableViewRowAction? {

        guard let row = model?.row(for: indexPath) else {

            Log.shared.errorAndCrash(component: #function, errorString: "No data for indexPath!")

            return nil

        }

        func action(action: UITableViewRowAction, indexPath: IndexPath) -> Void {

            if row.isFlagged {

                model?.unsetFlagged(forIndexPath: indexPath)

            } else {

                model?.setFlagged(forIndexPath: indexPath)

            }

            tableView.beginUpdates()

            tableView.setEditing(false, animated: true)

            tableView.reloadRows(at: [indexPath], with: .none)

            tableView.endUpdates()

        }

        let title: String

        if row.isFlagged{

            let unflagString = NSLocalizedString("Unflag", comment: "Message action (on swipe)")

            title = "\n\n\(unflagString)"

        } else {

            let flagString = NSLocalizedString("Flag", comment: "Message action (on swipe)")

            title = "\n\n\(flagString)"

        }

        return createRowAction(image: UIImage(named: "swipe-flag"), action: action, title: title)

    }

    func createDeleteAction(forCellAt indexPath: IndexPath) -> UITableViewRowAction? {

        func action(action: UITableViewRowAction, indexPath: IndexPath) -> Void {

            tableView.beginUpdates()

            model?.delete(forIndexPath: indexPath) // mark for deletion/trash

            tableView.deleteRows(at: [indexPath], with: .none)

            tableView.endUpdates()

        }

        let title = NSLocalizedString("Delete", comment: "Message action (on swipe)")

        return createRowAction(image: UIImage(named: "swipe-trash"), action: action,

                               title: "\n\n\(title)")

    }

    func createMoreAction(forCellAt indexPath: IndexPath) -> UITableViewRowAction? {

        func action(action: UITableViewRowAction, indexPath: IndexPath) -> Void {

            self.showMoreActionSheet(forRowAt: indexPath)

        }

        let title = NSLocalizedString("More", comment: "Message action (on swipe)")

        return createRowAction(image: UIImage(named: "swipe-more"),

                               action: action,

                               title: "\n\n\(title)")

    }

}

// MARK: - SegueHandlerType

extension EmailListViewController: SegueHandlerType {

    enum SegueIdentifier: String {

        case segueAddNewAccount

        case segueShowEmail

        case segueCompose

        case segueReply

        case segueReplyAll

        case segueForward

        case segueFilter

        case segueFolderViews

        case noSegue

    }

    private func setup(composeViewController vc: ComposeTableViewController,

                       composeMode: ComposeTableViewController.ComposeMode = .normal,

                       originalMessage: Message? = nil) {

        vc.appConfig = appConfig

        vc.composeMode = composeMode

        vc.originalMessage = originalMessage

        vc.origin = model?.folderToShow?.account.user

    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

        switch segueIdentifier(for: segue) {

        case .segueReply:

            guard let nav = segue.destination as? UINavigationController,

                let destination = nav.topViewController as? ComposeTableViewController,

                let indexPath = lastSelectedIndexPath,

                let message = model?.message(representedByRowAt: indexPath) else {

                    Log.shared.errorAndCrash(component: #function, errorString: "Segue issue")

                    return

            }

            setup(composeViewController: destination, composeMode: .replyFrom,

                  originalMessage: message)

        case .segueReplyAll:

            guard let nav = segue.destination as? UINavigationController,

                let destination = nav.topViewController as? ComposeTableViewController,

                let indexPath = lastSelectedIndexPath,

                let message = model?.message(representedByRowAt: indexPath) else {

                    Log.shared.errorAndCrash(component: #function, errorString: "Segue issue")

                    return

            }

            setup(composeViewController: destination, composeMode: .replyAll,

                  originalMessage: message)

        case .segueShowEmail:

            guard let vc = segue.destination as? EmailViewController,

                let indexPath = lastSelectedIndexPath,

                let message = model?.message(representedByRowAt: indexPath) else { //BUFF: maybe remove message(representedByRowAt: and handle in dvc.

                    Log.shared.errorAndCrash(component: #function, errorString: "Segue issue")

                    return

            }

            vc.appConfig = appConfig

            vc.message = message

            vc.folderShow = model?.folderToShow

            vc.messageId = indexPath.row //that looks wrong

        case .segueForward:

            guard let nav = segue.destination as? UINavigationController,

                let destination = nav.topViewController as? ComposeTableViewController,

                let indexPath = lastSelectedIndexPath,

                let message = model?.message(representedByRowAt: indexPath) else {

                    Log.shared.errorAndCrash(component: #function, errorString: "Segue issue")

                    return

            }

            setup(composeViewController: destination, composeMode: .forward,

                  originalMessage: message)

        case .segueFilter:

            guard let destiny = segue.destination as? FilterTableViewController  else {

                Log.shared.errorAndCrash(component: #function, errorString: "Segue issue")

                return

            }

            destiny.appConfig = appConfig

            destiny.filterDelegate = model

            destiny.inFolder = false

            destiny.filterEnabled = model?.folderToShow?.filter?.clone()

            destiny.hidesBottomBarWhenPushed = true

        case .segueAddNewAccount:

            guard let vc = segue.destination as? LoginTableViewController  else {

                Log.shared.errorAndCrash(component: #function, errorString: "Segue issue")

                return

            }

            vc.appConfig = appConfig

            vc.hidesBottomBarWhenPushed = true

            break

        case .segueFolderViews:

            guard let vC = segue.destination as? FolderTableViewController  else {

                Log.shared.errorAndCrash(component: #function, errorString: "Segue issue")

                return

            }

            vC.appConfig = appConfig

            vC.hidesBottomBarWhenPushed = true

            break

        case .segueCompose:

            guard let nav = segue.destination as? UINavigationController,

                let destination = nav.rootViewController as? ComposeTableViewController else {

                    Log.shared.errorAndCrash(component: #function, errorString: "Segue issue")

                    return

            }

            setup(composeViewController: destination)

        default:

            Log.shared.errorAndCrash(component: #function, errorString: "Unhandled segue")

            break

        }

    }

    @IBAction func segueUnwindAccountAdded(segue: UIStoryboardSegue) {

        // nothing to do.

    }

}