//
//  BrowseViewController.swift
//  AltStore
//
//  Created by Riley Testut on 7/15/19.
//  Copyright © 2019 Riley Testut. All rights reserved.
//

import UIKit

import minimuxer
import AltStoreCore
import Roxas

import Nuke

class BrowseViewController: UICollectionViewController, PeekPopPreviewing
{
    // Nil == Show apps from all sources.
    var source: Source?
    
    private lazy var dataSource = self.makeDataSource()
    private lazy var placeholderView = RSTPlaceholderView(frame: .zero)
    
    private let prototypeCell = AppCardCollectionViewCell(frame: .zero)
    
    private var loadingState: LoadingState = .loading {
        didSet {
            self.update()
        }
    }
    
    init?(source: Source?, coder: NSCoder)
    {
        self.source = source
        
        super.init(coder: coder)
    }
    
    required init?(coder: NSCoder)
    {
        super.init(coder: coder)
    }
    
    private var cachedItemSizes = [String: CGSize]()
    
    @IBOutlet private var sourcesBarButtonItem: UIBarButtonItem!
    
    override func viewDidLoad()
    {
        super.viewDidLoad()
        
        self.collectionView.backgroundColor = .altBackground
        
        #if BETA
        self.dataSource.searchController.searchableKeyPaths = [#keyPath(InstalledApp.name)]
        self.navigationItem.searchController = self.dataSource.searchController
        #endif
        
        self.prototypeCell.contentView.translatesAutoresizingMaskIntoConstraints = false
        
        self.collectionView.register(AppCardCollectionViewCell.self, forCellWithReuseIdentifier: RSTCellContentGenericCellIdentifier)
        
        self.collectionView.dataSource = self.dataSource
        self.collectionView.prefetchDataSource = self.dataSource
        
        let collectionViewLayout = self.collectionViewLayout as! UICollectionViewFlowLayout
        collectionViewLayout.minimumLineSpacing = 30
        
        (self as PeekPopPreviewing).registerForPreviewing(with: self, sourceView: self.collectionView)
        
        if let source = self.source
        {
            let tintColor = source.effectiveTintColor ?? .altPrimary
            self.view.tintColor = tintColor
            
            let appearance = NavigationBarAppearance()
            appearance.configureWithTintColor(tintColor)
            appearance.configureWithDefaultBackground()
            
            let edgeAppearance = appearance.copy()
            edgeAppearance.configureWithTransparentBackground()
            
            self.navigationItem.standardAppearance = appearance
            self.navigationItem.scrollEdgeAppearance = edgeAppearance
        }
        
        self.update()
    }
    
    override func viewWillAppear(_ animated: Bool)
    {
        super.viewWillAppear(animated)
        
        self.fetchSource()
        
        self.update()
    }
}

private extension BrowseViewController
{
    func makeDataSource() -> RSTFetchedResultsCollectionViewPrefetchingDataSource<StoreApp, UIImage>
    {
        let fetchRequest = StoreApp.fetchRequest() as NSFetchRequest<StoreApp>
        fetchRequest.sortDescriptors = [NSSortDescriptor(keyPath: \StoreApp.sourceIdentifier, ascending: true),
                                        NSSortDescriptor(keyPath: \StoreApp.sortIndex, ascending: true),
                                        NSSortDescriptor(keyPath: \StoreApp.name, ascending: true),
                                        NSSortDescriptor(keyPath: \StoreApp.bundleIdentifier, ascending: true)]
        fetchRequest.returnsObjectsAsFaults = false
        
        let predicate = StoreApp.visibleAppsPredicate
        
        if let source = self.source
        {
            let filterPredicate = NSPredicate(format: "%K == %@", #keyPath(StoreApp._source), source)
            fetchRequest.predicate = NSCompoundPredicate(andPredicateWithSubpredicates: [filterPredicate, predicate])
        }
        else
        {
            fetchRequest.predicate = predicate
        }
        
        let context = self.source?.managedObjectContext ?? DatabaseManager.shared.viewContext
        let dataSource = RSTFetchedResultsCollectionViewPrefetchingDataSource<StoreApp, UIImage>(fetchRequest: fetchRequest, managedObjectContext: context)
        dataSource.cellConfigurationHandler = { (cell, app, indexPath) in
            let cell = cell as! AppCardCollectionViewCell
            cell.layoutMargins.left = self.view.layoutMargins.left
            cell.layoutMargins.right = self.view.layoutMargins.right
            
            cell.configure(for: app)
            
            cell.bannerView.iconImageView.image = nil
            cell.bannerView.iconImageView.isIndicatingActivity = true
            
            cell.bannerView.button.addTarget(self, action: #selector(BrowseViewController.performAppAction(_:)), for: .primaryActionTriggered)
            cell.bannerView.button.activityIndicatorView.style = .medium
            cell.bannerView.button.activityIndicatorView.color = .white
            
            // Explicitly set to false to ensure we're starting from a non-activity indicating state.
            // Otherwise, cell reuse can mess up some cached values.
            cell.bannerView.button.isIndicatingActivity = false
            
            let tintColor = app.tintColor ?? .altPrimary
            cell.tintColor = tintColor
            
            if app.installedApp == nil
            {
                let buttonTitle = NSLocalizedString("Free", comment: "")
                cell.bannerView.button.setTitle(buttonTitle.uppercased(), for: .normal)
                cell.bannerView.button.accessibilityLabel = String(format: NSLocalizedString("Download %@", comment: ""), app.name)
                cell.bannerView.button.accessibilityValue = buttonTitle
                
                let progress = AppManager.shared.installationProgress(for: app)
                cell.bannerView.button.progress = progress
                
                if let versionDate = app.latestSupportedVersion?.date, versionDate > Date()
                {
                    cell.bannerView.button.countdownDate = versionDate
                }
                else
                {
                    cell.bannerView.button.countdownDate = nil
                }
            }
            else
            {
                cell.bannerView.button.setTitle(NSLocalizedString("OPEN", comment: ""), for: .normal)
                cell.bannerView.button.accessibilityLabel = String(format: NSLocalizedString("Open %@", comment: ""), app.name)
                cell.bannerView.button.accessibilityValue = nil
                cell.bannerView.button.progress = nil
                cell.bannerView.button.countdownDate = nil
            }
        }
        dataSource.prefetchHandler = { (storeApp, indexPath, completionHandler) -> Foundation.Operation? in
            let iconURL = storeApp.iconURL
            
            return RSTAsyncBlockOperation() { (operation) in
                ImagePipeline.shared.loadImage(with: iconURL, progress: nil) { result in
                    guard !operation.isCancelled else { return operation.finish() }
                    
                    switch result
                    {
                    case .success(let response): completionHandler(response.image, nil)
                    case .failure(let error): completionHandler(nil, error)
                    }
                }
            }
        }
        dataSource.prefetchCompletionHandler = { (cell, image, indexPath, error) in
            let cell = cell as! AppCardCollectionViewCell
            cell.bannerView.iconImageView.isIndicatingActivity = false
            cell.bannerView.iconImageView.image = image
            
            if let error = error
            {
                print("Error loading image:", error)
            }
        }
        
        dataSource.placeholderView = self.placeholderView
        
        return dataSource
    }
    
    func updateDataSource()
    {
            self.dataSource.predicate = nil
    }
    
    func fetchSource()
    {
        self.loadingState = .loading
        
        AppManager.shared.fetchSources() { (result) in
            do
            {
                do
                {
                    let (_, context) = try result.get()
                    try context.save()
                    
                    DispatchQueue.main.async {
                        self.loadingState = .finished(.success(()))
                    }
                }
                catch let error as AppManager.FetchSourcesError
                {
                    try error.managedObjectContext?.save()
                    throw error
                }
                catch let mergeError as MergeError
                {
                    guard let sourceID = mergeError.sourceID else { throw mergeError }
                    
                    let sanitizedError = (mergeError as NSError).sanitizedForSerialization()
                    DatabaseManager.shared.persistentContainer.performBackgroundTask { context in
                        do
                        {
                            guard let source = Source.first(satisfying: NSPredicate(format: "%K == %@", #keyPath(Source.identifier), sourceID), in: context) else { return }
                            
                            source.error = sanitizedError
                            try context.save()
                        }
                        catch
                        {
                            print("[ALTLog] Failed to assign error \(sanitizedError.localizedErrorCode) to source \(sourceID).", error)
                        }
                    }
                    
                    throw mergeError
                }
            }
            catch var error as NSError
            {
                if error.localizedTitle == nil
                {
                    error = error.withLocalizedTitle(NSLocalizedString("Unable to Refresh Store", comment: ""))
                }
                                
                DispatchQueue.main.async {
                    if self.dataSource.itemCount > 0
                    {
                        let toastView = ToastView(error: error)
                        toastView.addTarget(nil, action: #selector(TabBarController.presentSources), for: .touchUpInside)
                        toastView.show(in: self)
                    }
                    
                    self.loadingState = .finished(.failure(error))
                }
            }
        }
    }
    
    func update()
    {
        switch self.loadingState
        {
        case .loading:
            self.placeholderView.textLabel.isHidden = true
            self.placeholderView.detailTextLabel.isHidden = false
            
            self.placeholderView.detailTextLabel.text = NSLocalizedString("Loading...", comment: "")
            
            self.placeholderView.activityIndicatorView.startAnimating()
            
        case .finished(.failure(let error)):
            self.placeholderView.textLabel.isHidden = false
            self.placeholderView.detailTextLabel.isHidden = false
            
            self.placeholderView.textLabel.text = NSLocalizedString("Unable to Fetch Apps", comment: "")
            self.placeholderView.detailTextLabel.text = error.localizedDescription
            
            self.placeholderView.activityIndicatorView.stopAnimating()
            
        case .finished(.success):
            self.placeholderView.textLabel.isHidden = true
            self.placeholderView.detailTextLabel.isHidden = true
            
            self.placeholderView.activityIndicatorView.stopAnimating()
        }
    }
}

private extension BrowseViewController
{
    @IBAction func performAppAction(_ sender: PillButton)
    {
        let point = self.collectionView.convert(sender.center, from: sender.superview)
        guard let indexPath = self.collectionView.indexPathForItem(at: point) else { return }
        
        let app = self.dataSource.item(at: indexPath)
        
        if let installedApp = app.installedApp
        {
            self.open(installedApp)
        }
        else
        {
            self.install(app, at: indexPath)
        }
    }
    
    func install(_ app: StoreApp, at indexPath: IndexPath)
    {
        let previousProgress = AppManager.shared.installationProgress(for: app)
        guard previousProgress == nil else {
            previousProgress?.cancel()
            return
        }

        if !minimuxer.ready() {
            let toastView = ToastView(error: MinimuxerError.NoConnection)
            toastView.show(in: self)
            return
        }

        _ = AppManager.shared.install(app, presentingViewController: self) { (result) in
            DispatchQueue.main.async {
                switch result
                {
                case .failure(OperationError.cancelled): break // Ignore
                case .failure(let error):
                    let toastView = ToastView(error: error, opensLog: true)
                    toastView.show(in: self)
                
                case .success: print("Installed app:", app.bundleIdentifier)
                }
                
                self.collectionView.reloadItems(at: [indexPath])
            }
        }
        
        self.collectionView.reloadItems(at: [indexPath])
    }
    
    func open(_ installedApp: InstalledApp)
    {
        UIApplication.shared.open(installedApp.openAppURL)
    }
}

extension BrowseViewController: UICollectionViewDelegateFlowLayout
{
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize
    {
        let item = self.dataSource.item(at: indexPath)
        let itemID = item.globallyUniqueID ?? item.bundleIdentifier

        if let previousSize = self.cachedItemSizes[itemID]
        {
            return previousSize
        }
        
        self.dataSource.cellConfigurationHandler(self.prototypeCell, item, indexPath)
        
        let insets = (self.view.layoutMargins.left + self.view.layoutMargins.right)

        let widthConstraint = self.prototypeCell.contentView.widthAnchor.constraint(equalToConstant: collectionView.bounds.width - insets)
        widthConstraint.isActive = true
        defer { widthConstraint.isActive = false }

        // Manually update cell width & layout so we can accurately calculate screenshot sizes.
        self.prototypeCell.frame.size.width = widthConstraint.constant
        self.prototypeCell.layoutIfNeeded()
        
        let itemSize = self.prototypeCell.contentView.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize)
        self.cachedItemSizes[itemID] = itemSize
        return itemSize
    }
    
    override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath)
    {
        let app = self.dataSource.item(at: indexPath)
        
        let appViewController = AppViewController.makeAppViewController(app: app)
        self.navigationController?.pushViewController(appViewController, animated: true)
    }
}

extension BrowseViewController: UIViewControllerPreviewingDelegate
{
    @available(iOS, deprecated: 13.0)
    func previewingContext(_ previewingContext: UIViewControllerPreviewing, viewControllerForLocation location: CGPoint) -> UIViewController?
    {
        guard
            let indexPath = self.collectionView.indexPathForItem(at: location),
            let cell = self.collectionView.cellForItem(at: indexPath)
        else { return nil }
        
        previewingContext.sourceRect = cell.frame
        
        let app = self.dataSource.item(at: indexPath)
        
        let appViewController = AppViewController.makeAppViewController(app: app)
        return appViewController
    }
    
    @available(iOS, deprecated: 13.0)
    func previewingContext(_ previewingContext: UIViewControllerPreviewing, commit viewControllerToCommit: UIViewController)
    {
        self.navigationController?.pushViewController(viewControllerToCommit, animated: true)
    }
}

@available(iOS 17, *)
#Preview(traits: .portrait) {
    DatabaseManager.shared.startForPreview()
   
    let storyboard = UIStoryboard(name: "Main", bundle: .main)
    let browseViewController = storyboard.instantiateViewController(identifier: "browseViewController") { coder in
        BrowseViewController(source: nil, coder: coder)
    }
    
    let navigationController = UINavigationController(rootViewController: browseViewController)
    return navigationController
}