/*

Copyright (C) 2016 Apple Inc. All Rights Reserved.

See LICENSE.txt for this sample’s licensing information

Abstract:

A view controller that shows a user's profile.

*/

import UIKit

class ProfileViewController: UIViewController {

    // MARK: Properties

    fileprivate var imageView: UIImageView?

    fileprivate var nameLabel: UILabel?

    fileprivate var conversationsLabel: UILabel?

    fileprivate var photosLabel: UILabel?

    // Holds the current constraints used to position the subviews.

    fileprivate var constraints = [NSLayoutConstraint]()

    let user: User

    var nameText: String {

        return user.name

    }

    var conversationsText: String {

        let conversationCount = user.conversations.count

        let localizedStringFormat = NSLocalizedString("%d conversations", comment: "X conversations")

        return String.localizedStringWithFormat(localizedStringFormat, conversationCount)

    }

    var photosText: String {

        let photoCount = user.conversations.reduce(0) { count, conversation in

            return count + conversation.photos.count

        }

        let localizedStringFormat = NSLocalizedString("%d photos", comment: "X photos")

        return String.localizedStringWithFormat(localizedStringFormat, photoCount)

    }

    // MARK: Initialization

    init(user: User) {

        self.user = user

        super.init(nibName: nil, bundle: nil)

        title = NSLocalizedString("Profile", comment: "Profile")

    }

    required init(coder aDecoder: NSCoder) {

        fatalError("init(coder:) has not been implemented")

    }

    // MARK: View Controller

    override func loadView() {

        let view = UIView()

        view.backgroundColor = UIColor.white

        // Create an image view

        let imageView = UIImageView()

        imageView.contentMode = .scaleAspectFit

        imageView.translatesAutoresizingMaskIntoConstraints = false

        self.imageView = imageView

        view.addSubview(imageView)

        // Create a label for the profile name

        let nameLabel = UILabel()

        nameLabel.font = UIFont.preferredFont(forTextStyle: UIFontTextStyle.headline)

        nameLabel.translatesAutoresizingMaskIntoConstraints = false

        self.nameLabel = nameLabel

        view.addSubview(nameLabel)

        // Create a label for the number of conversations

        let conversationsLabel = UILabel()

        conversationsLabel.font = UIFont.preferredFont(forTextStyle: UIFontTextStyle.body)

        conversationsLabel.translatesAutoresizingMaskIntoConstraints = false

        self.conversationsLabel = conversationsLabel

        view.addSubview(conversationsLabel)

        // Create a label for the number of photos

        let photosLabel = UILabel()

        photosLabel.font = UIFont.preferredFont(forTextStyle: UIFontTextStyle.body)

        photosLabel.translatesAutoresizingMaskIntoConstraints = false

        self.photosLabel = photosLabel

        view.addSubview(photosLabel)

        self.view = view

        // Update all of the visible information

        updateUser()

        updateConstraintsForTraitCollection(traitCollection)

    }

    override func willTransition(to newCollection: UITraitCollection, with coordinator: UIViewControllerTransitionCoordinator) {

        super.willTransition(to: newCollection, with: coordinator)

        // When the trait collection changes, change our views' constraints and animate the change

        coordinator.animate(alongsideTransition: { _ in

            self.updateConstraintsForTraitCollection(newCollection)

            self.view.setNeedsLayout()

        }, completion: nil)

    }

    // Applies the proper constraints to the subviews for the size class of the given trait collection.

    func updateConstraintsForTraitCollection(_ collection: UITraitCollection) {

        let views: [String: AnyObject] = [

            "topLayoutGuide":       topLayoutGuide,

            "imageView":            imageView!,

            "nameLabel":            nameLabel!,

            "conversationsLabel":   conversationsLabel!,

            "photosLabel":          photosLabel!

        ]

        // Make our new set of constraints for the current traits

        var newConstraints = [NSLayoutConstraint]()

        if collection.verticalSizeClass == .compact {

            // When we're vertically compact, show the image and labels side-by-side

            newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "|[imageView]-[nameLabel]-|", options: [], metrics: nil, views: views)

            newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "[imageView]-[conversationsLabel]-|", options: [], metrics: nil, views: views)

            newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "[imageView]-[photosLabel]-|", options: [], metrics: nil, views: views)

            newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "V:|[topLayoutGuide]-[nameLabel]-[conversationsLabel]-[photosLabel]", options: [], metrics: nil, views: views)

            newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "V:|[topLayoutGuide][imageView]|", options: [], metrics: nil, views: views)

            newConstraints += [

                NSLayoutConstraint(item: imageView!, attribute: .width, relatedBy: .equal, toItem: view, attribute: .width, multiplier: 0.5, constant: 0)

            ]

        }

        else {

            // When we're vertically compact, show the image and labels top-and-bottom

            newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "|[imageView]|", options: [], metrics: nil, views: views)

            newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "|-[nameLabel]-|", options: [], metrics: nil, views: views)

            newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "|-[conversationsLabel]-|", options: [], metrics: nil, views: views)

            newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "|-[photosLabel]-|", options: [], metrics: nil, views: views)

            newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "V:[topLayoutGuide]-[nameLabel]-[conversationsLabel]-[photosLabel]-20-[imageView]|", options: [], metrics: nil, views: views)

        }

        // Change to our new constraints

        NSLayoutConstraint.deactivate(constraints)

        constraints = newConstraints

        NSLayoutConstraint.activate(newConstraints)

    }

    // MARK: Convenience

    // Updates the user interface with the data from the current user object.

    func updateUser() {

        nameLabel?.text = nameText

        conversationsLabel?.text = conversationsText

        photosLabel?.text = photosText

        imageView?.image = user.lastPhoto?.image

    }

}