//
//  ViewController.swift
//  MVMCoreUI
//
//  Created by Scott Pfeil on 11/5/19.
//  Copyright © 2019 Verizon Wireless. All rights reserved.
//

import UIKit

@objc open class ViewController: UIViewController, MVMCoreViewControllerProtocol, MVMCoreViewManagerViewControllerProtocol, MoleculeDelegateProtocol, FormHolderProtocol, MVMCoreActionDelegateProtocol, UITextFieldDelegate, UITextViewDelegate, ObservingTextFieldDelegate {
    @objc public var pageType: String?
    @objc public var loadObject: MVMCoreLoadObject?
    public var pageModel: MVMControllerModelProtocol?
    
    /// Set if this page is containted in a manager.
    public var manager: (UIViewController & MVMCoreViewManagerProtocol)?
    
    /// A temporary iVar backer for delegateObject() until we change the protocol
    public lazy var delegateObjectIVar: MVMCoreUIDelegateObject = {
        return MVMCoreUIDelegateObject.create(withDelegateForAll: self)
    }()
    
    public func delegateObject() -> DelegateObject? {
        return delegateObjectIVar
    }
    
    public var formValidator: FormValidator?
    
    public var needsUpdateUI = false
    private var observingForResponses = false
    private var initialLoadFinished = false
    private var previousScreenSize = CGSize.zero
    
    public var selectedField: UIView?

    /// Checks if the screen width has changed
    open func screenSizeChanged() -> Bool {
        return !MVMCoreGetterUtility.cgfequalwiththreshold(previousScreenSize.width, view.bounds.size.width, 0.1)
    }
    
    // MARK: - Response handling
    open func observeForResponseJSONUpdates() {
        guard !observingForResponses,
            (pagesToListenFor()?.count ?? 0 > 0 || modulesToListenFor()?.count ?? 0 > 0) else { return }
        observingForResponses = true
        NotificationCenter.default.addObserver(self, selector: #selector(responseJSONUpdated(notification:)), name: NSNotification.Name(rawValue: NotificationResponseLoaded), object: nil)
    }
    
    open func stopObservingForResponseJSONUpdates() {
        guard observingForResponses else { return }
        NotificationCenter.default.removeObserver(self, name: NSNotification.Name(rawValue: NotificationResponseLoaded), object: nil)
        observingForResponses = false
    }
   
    open func pagesToListenFor() -> [String]? {
        guard let pageType = loadObject?.pageType else { return nil }
        return [pageType]
    }
    
    open func modulesToListenFor() -> [String]? {
        return loadObject?.requestParameters?.modules as? [String]
    }
    
    @objc open func responseJSONUpdated(notification: Notification) {
        // Checks for a page we are listening for.
        var newData = false
        if let pagesLoaded = notification.userInfo?.optionalDictionaryForKey(KeyPageMap),
            let pageType = pagesToListenFor()?.first(where: { (pageTypeListened) -> Bool in
                guard let page = pagesLoaded.optionalDictionaryForKey(pageTypeListened),
                    let pageType = page.optionalStringForKey(KeyPageType),
                    pageType == pageTypeListened else { return false }
                return true
            }) {
            newData = true
            loadObject?.pageJSON = pagesLoaded.optionalDictionaryForKey(pageType)
        }
        
        // Checks for modules we are listening for.
        if let modulesLoaded = notification.userInfo?.optionalDictionaryForKey(KeyModuleMap),
            let modulesListened = modulesToListenFor() {
            for moduleName in modulesListened {
                if let module = modulesLoaded.optionalDictionaryForKey(moduleName) {
                    newData = true
                    var currentModules = loadObject?.modulesJSON ?? [:]
                    currentModules.updateValue(module, forKey: moduleName)
                    loadObject?.modulesJSON = currentModules
                }
            }
        }
        
        guard newData else { return }
        do {
            try parsePageJSON()
            MVMCoreDispatchUtility.performBlock(onMainThread: {
                self.handleNewDataAndUpdateUI()
                // If the screen is showing, can update the navigation controller.
                if MVMCoreUIUtility.getCurrentVisibleController() == self.manager ?? self {
                    self.setNavigationController()
                }
            })
        } catch {
            if let coreError = MVMCoreErrorObject.createErrorObject(for: error, location: "updateJSON for pageType: \(String(describing: pageType))") {
                MVMCoreLoggingHandler.shared()?.addError(toLog: coreError)
            }
        }
    }
    
    open func shouldFinishProcessingLoad(_ loadObject: MVMCoreLoadObject, error: AutoreleasingUnsafeMutablePointer<MVMCoreErrorObject>) -> Bool {
        pageType = loadObject.pageType
        self.loadObject = loadObject
        
        // Verifies all modules needed are loaded. TODO: change to ViewController
        guard ViewController.verifyRequiredModulesLoaded(for: loadObject, error: error) else { return false }
        
        // Parse the model for the page.
        do {
            try parsePageJSON()
            return true
        } catch let parsingError {
            // Log all parsing errors and fail load.
            if let errorObject = MVMCoreErrorObject.createErrorObject(for: parsingError, location: MVMCoreLoadHandler.sharedGlobal()?.errorLocation(forRequest: loadObject)) {
                errorObject.messageToDisplay = MVMCoreGetterUtility.hardcodedString(withKey: HardcodedErrorUnableToProcess)
                error.pointee = errorObject
            }
            return false
        }
    }
    
    open func parsePageJSON() throws {
    }

    open class func verifyRequiredModulesLoaded(for loadObject: MVMCoreLoadObject?, error: AutoreleasingUnsafeMutablePointer<MVMCoreErrorObject>) -> Bool {
        guard let pageType = loadObject?.pageType, var modulesRequired = MVMCoreUIViewControllerMappingObject.shared()?.modulesRequired(forPageType: pageType),
            !modulesRequired.isEmpty else { return true }

        guard let loadedModules = loadObject?.modulesJSON else { return false }

        for case let key as String in Array(loadedModules.keys) {
            guard modulesRequired.count > 0 else { break }
            if let index = modulesRequired.firstIndex(where: {($0 as? String) == key}) {
                modulesRequired.remove(at: index)
            }
        }

        guard modulesRequired.count == 0 else {
            if let errorObject = MVMCoreErrorObject(title: nil, message: MVMCoreGetterUtility.hardcodedString(withKey: HardcodedErrorCritical), messageToLog: modulesRequired.description, code: ErrorCode.requiredModuleNotPresent.rawValue, domain: ErrorDomainNative, location: MVMCoreLoadHandler.sharedGlobal()?.errorLocation(forRequest: loadObject!)) { 
                error.pointee = errorObject
            }
            return false
        }
        return true
    }
    
    /// Calls processNewData and then sets the ui to update with updateView
    open func handleNewDataAndUpdateUI() {
        handleNewData()
        needsUpdateUI = true
        view.setNeedsLayout()
    }

    /// Processes any new data. Called after the page is loaded the first time and on response updates for this page,
    open func handleNewData() {
        // TODO: remove legacy. Temporary, convert legacy to navigation model.
        var navigationModel = pageModel?.navigationItem ?? NavigationItemModel()
        navigationModel.title = pageModel?.screenHeading
        navigationModel.showLeftPanelButton = isMasterInitiallyAccessible()
        navigationModel.showRightPanelButton = isSupportInitiallyAccessible()
        if /*(self as? MVMCoreUITabBarPageControlViewController) != nil ||*/ manager != nil || loadObject?.requestParameters?.tabWasPressed ?? false == true {
            navigationModel.line = LineModel(type: .none)
        }
        pageModel?.navigationItem = navigationModel
        if formValidator == nil {
            let rules = pageModel?.formRules
            formValidator = FormValidator(rules)
        }

        if let backgroundColor = pageModel?.backgroundColor {
            view.backgroundColor = backgroundColor.uiColor
        }
    }
    
    // MARK: - Navigation Item (Move to model base)
    open func setNavigationController() {
        guard let navigationItemModel = pageModel?.navigationItem,
            let navigationController = manager?.navigationController ?? navigationController else {
            MVMCoreUISession.sharedGlobal()?.splitViewController?.parent?.setNeedsStatusBarAppearanceUpdate()
            return
        }
        let viewController = manager ?? self
        if navigationController == MVMCoreUISplitViewController.main()?.navigationController,
            navigationController.topViewController == viewController {
            MVMCoreUISession.sharedGlobal()?.splitViewController?.setupPanels()
            showBottomProgressBar()
        }
        NavigationController.set(navigationController: navigationController, navigationItemModel: navigationItemModel, viewController: viewController)
    }
    
    // Eventually will be moved to server
    open func isMasterInitiallyAccessible() -> Bool {
        if loadObject?.pageJSON?.boolForKey(KeyHideMainMenu) ?? false {
            return false
        }
        return MVMCoreUISession.sharedGlobal()?.launchAppLoadedSuccessfully ?? false
    }
    
    // Eventually will be moved to server
    open func isSupportInitiallyAccessible() -> Bool {
        if loadObject?.pageJSON?.boolForKey(KeyHideMainMenu) ?? false {
            return false
        }
        return (MVMCoreUISession.sharedGlobal()?.launchAppLoadedSuccessfully ?? false) || showRightPanelForScreenBeforeLaunchApp()
    }
    
    open func showRightPanelForScreenBeforeLaunchApp() -> Bool {
        return loadObject?.pageJSON?.lenientBoolForKey("showRightPanel") ?? false
    }

    // Eventually will be moved to separate button in navigation item model
    open func isOverridingRightButton() -> Bool {
        guard let rightPanelLink = loadObject?.pageJSON?.optionalDictionaryForKey("rightPanelButtonLink") else {
            return false
        }
        MVMCoreActionHandler.shared()?.handleAction(with: rightPanelLink, additionalData: nil, delegateObject: delegateObject())
        return true
    }

    // Eventually will be moved to separate button in navigation item model
    open func isOverridingLeftButton() -> Bool {
        guard let leftPanelLink = loadObject?.pageJSON?.optionalDictionaryForKey("leftPanelButtonLink") else {
            return false
        }
        MVMCoreActionHandler.shared()?.handleAction(with: leftPanelLink, additionalData: nil, delegateObject: delegateObject())
        return true
    }

    // Eventually will be moved to Model
    open func showBottomProgressBar() {
        if MVMCoreUISplitViewController.main()?.getCurrentVisibleController() == self,
            let progressString = loadObject?.pageJSON?.optionalStringForKey(KeyProgressPercent),
            let progress = Float(progressString) {
            MVMCoreUISplitViewController.main()?.setBottomProgressBarProgress(progress / Float(100))
        }
    }

    // MARK: - View lifecycle
    
    /// Called only once in viewDidLoad
    open func initialLoad() {
        observeForResponseJSONUpdates()
    }

    /// Called on screen size update.
    open func updateViews() {
        _ = formValidator?.validate()
    }

    override open func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        MVMCoreLoggingHandler.logDebugMessage(withDelegate: "View Controller Loaded : \(self)")

        // We use our own margins.
        viewRespectsSystemMinimumLayoutMargins = false

        // Presents from the bottom.
        modalPresentationStyle = MVMCoreGetterUtility.isOnIPad() ? .formSheet : .overCurrentContext
        
        // Do some initial loading.
        if !initialLoadFinished {
            initialLoadFinished = true
            initialLoad()
        }
        
        handleNewDataAndUpdateUI()
    }
    
    open override func viewDidLayoutSubviews() {
        // Add to fix a constraint bug where the width is zero and things get messed up.
        guard isViewLoaded, view.bounds.width > 1 else {
            super.viewDidLayoutSubviews()
            return
        }
        
        // First update should be explicit (hence the zero check)
        if needsUpdateUI || (previousScreenSize != .zero && screenSizeChanged()) {
            updateViews()
            needsUpdateUI = false
        }
        
        previousScreenSize = view.bounds.size;
        
        super.viewDidLayoutSubviews()
    }
    
    open override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        // Update the navigation bar ui when view is appearing. Can remove check in the future, see viewControllerReady
        if manager == nil {
            setNavigationController()
        }
    }
    
    open override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        
        if manager == nil {
            MVMCoreUISession.sharedGlobal()?.currentPageType = pageType
            MVMCoreUILoggingHandler.shared()?.defaultLogPageState(forController: self)
        }
    }
    
    deinit {
        stopObservingForResponseJSONUpdates()
        MVMCoreLoggingHandler.logDebugMessage(withDelegate: "View Controller Deallocated : \(self)")
    }

    open override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
        return MVMCoreGetterUtility.isOnIPad() ? UIInterfaceOrientationMask.all : UIInterfaceOrientationMask.portrait
    }
    
    open override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
        super.viewWillTransition(to: size, with: coordinator)
        
        // Updates the detail view width
        coordinator.animate(alongsideTransition: { (UIViewControllerTransitionCoordinatorContext) in
        }) { (UIViewControllerTransitionCoordinatorContext) in
            self.view.setNeedsLayout()
        }
    }
    
    // MARK: - MVMCoreViewManagerViewControllerProtocol
    open func viewControllerReady(inManager manager: UIViewController & MVMCoreViewManagerProtocol) {
        // TODO: This check and set aren't technically needed anymore. The one in viewwillappear should be enough. However, there is a timing issue with the manager where the screen lays out before the menu shows, so the screen grows off the screen. Can fix in the future.
        if let _ = self.view {
            setNavigationController()
        }
        // Janky way to track current page.
        MVMCoreUISession.sharedGlobal()?.currentPageType = pageType
        MVMCoreUILoggingHandler.shared()?.defaultLogPageState(forController: self)
    }
    
    // MARK: - MVMCoreActionDelegateProtocol
    open func handleOpenPage(for requestParameters: MVMCoreRequestParameters, actionInformation: [AnyHashable: Any]?, additionalData: [AnyHashable: Any]?) {
        formValidator?.addFormParams(requestParameters: requestParameters)
        requestParameters.parentPageType = loadObject?.pageJSON?.optionalStringForKey("parentPageType")
        MVMCoreActionHandler.defaultHandleOpenPage(for: requestParameters, additionalData: additionalData, delegateObject: delegateObject())
    }
    
    open func logAction(withActionInformation actionInformation: [AnyHashable: Any]?, additionalData: [AnyHashable: Any]?) {
        MVMCoreUILoggingHandler.shared()?.defaultLogAction(forController: self, actionInformation: actionInformation, additionalData: additionalData)
    }
    
    // MARK: - MoleculeDelegateProtocol
    open func getModuleWithName(_ name: String?) -> [AnyHashable: Any]? {
        guard let name = name else { return nil }
        return loadObject?.modulesJSON?.optionalDictionaryForKey(name)
    }
    
    open func getModuleWithName(_ moleculeName: String) -> MoleculeModelProtocol? {
        guard let moduleJSON = loadObject?.modulesJSON?.optionalDictionaryForKey(moleculeName),
            let moleculeName = moduleJSON.optionalStringForKey("moleculeName"),
            let modelType = ModelRegistry.getType(for: moleculeName, with: MoleculeModelProtocol.self)
            else { return nil }
        do {
            return try modelType.decode(jsonDict: moduleJSON) as? MoleculeModelProtocol
        } catch {
            MVMCoreUILoggingHandler.logDebugMessage(withDelegate: "error: \(error)")
        }
        
        return nil
    }
    
    // Needed otherwise when subclassed, the extension gets called.
    open func moleculeLayoutUpdated(_ molecule: MoleculeViewProtocol) {}
    open func getIndexPath(for molecule: ListItemModelProtocol & MoleculeModelProtocol) -> IndexPath? { return nil }
    open func addMolecules(_ molecules: [ListItemModelProtocol & MoleculeModelProtocol], indexPath: IndexPath, animation: UITableView.RowAnimation) {}
    open func removeMolecules(_ molecules: [ListItemModelProtocol & MoleculeModelProtocol], animation: UITableView.RowAnimation) {}
    
    // MARK: - UITextFieldDelegate (Check if this is still needed)
    // To Remove TextFields Bug: Keyboard is not dismissing after reaching textfield max length limit
    open func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        textField.resignFirstResponder()
        return true
    }
        
    open func textFieldDidBeginEditing(_ textField: UITextField) {
        selectedField = textField
        
        // TODO: Make this into a protocol
        if UIAccessibility.isVoiceOverRunning {
            if let toolBar = textField.inputAccessoryView as? UIToolbar, let _ = toolBar.items?.last, let pickerView = textField.inputView as? UIPickerView {
                view.accessibilityElements = [pickerView, toolBar]
            }
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
                UIAccessibility.post(notification: .layoutChanged, argument: textField.inputView)
            }
        }
    }
    
    open func textFieldDidEndEditing(_ textField: UITextField, reason: UITextField.DidEndEditingReason) {
        if textField === selectedField {
            if UIAccessibility.isVoiceOverRunning {
                view.accessibilityElements = nil
                UIAccessibility.post(notification: .layoutChanged, argument: textField)
            }
            selectedField = nil
        }
    }
    
    @objc open func dismissFieldInput(_ sender: Any?) {
        selectedField?.resignFirstResponder()
    }
    
    // MARK: - UITextViewDelegate (Check if this is still needed)
    open func textViewDidBeginEditing(_ textView: UITextView) {
        selectedField = textView
    }
    
    open func textViewDidEndEditing(_ textView: UITextView) {
        if textView === selectedField {
            selectedField = nil
        }
    }
}