ComputerDetailViewController.swift

//
//  ComputerDetailViewController.swift
//  Computers
//
//  Created by Гоша Бодров on 24.07.2018.
//  Copyright © 2018 Гоша Бодров. All rights reserved.
//

import UIKit

class ComputerDetailViewController: UIViewController {
    
    @IBOutlet weak var scrollView: UIScrollView!
    
    @IBOutlet weak var similarComputer0: UIButton!
    @IBOutlet weak var similarComputer1: UIButton!
    @IBOutlet weak var similarComputer2: UIButton!
    
    @IBOutlet weak var detailLabelHeightConstraintCompany: NSLayoutConstraint!
    @IBOutlet weak var detailLabelHeightConstraintDate: NSLayoutConstraint!
    @IBOutlet weak var detailLabelTopConstraintDiscription: NSLayoutConstraint!
    @IBOutlet weak var detailLabelTopConstraintDate: NSLayoutConstraint!
    
    @IBOutlet weak var detailHeightImage: NSLayoutConstraint!
    @IBOutlet weak var detailTopConstraintImage: NSLayoutConstraint!
    
    @IBOutlet weak var detailImageView: UIImageView!
    @IBOutlet weak var detailLabelCompany: UILabel!
    @IBOutlet weak var detailLabelDate: UILabel!
    @IBOutlet weak var detailLabelDescription: UILabel!
    @IBOutlet weak var detailLabelHeightDescription: NSLayoutConstraint!
    
    private let urlString = "http://testwork.nsd.naumen.ru/rest/computers/"
    
    var computerId: Int = 0
    var companyName: String = ""
    
    var similarComputers: [Computer] = []
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        scrollView.delegate = self
        
        self.navigationItem.title = companyName
        
        fetchDetailComputers(forId: computerId)
        fetchSimilarComputers(forId: computerId)
    }
    
    private func fetchDetailComputers(forId id: Int) {
        guard let url = url(forPage: computerId) else {return}
        
        URLSession.shared.dataTask(with: url) { (data, response, error) in
            guard error == nil else { print(NetworkError.failInternetError)
                return }
            guard let data = data else { print("No similar computers")
                return }
            guard error == nil else { return }
            
            do {
                let dataAboutDetailComputerParsing = try JSONDecoder().decode(DetailAboutComputer.self, from: data)
                print(dataAboutDetailComputerParsing)
                DispatchQueue.main.async{
                    
                    
                    print("Begin of code")
                    if dataAboutDetailComputerParsing.imageUrl != nil{
                        if let url = URL(string: dataAboutDetailComputerParsing.imageUrl!) {
                            self.downloadImage(url: url)
                            self.detailImageView.contentMode = .scaleAspectFit
                            self.setTopConstraintImage(isHidden: false)
                            self.setHeightImage(isHidden: false)
                        } else {
                            self.clearImage()
                        }
                    } else {
                        self.clearImage()
                    }
                    
                    print("End of code. The image will continue downloading in the background and it will be loaded when it ends.")
                    
                    if dataAboutDetailComputerParsing.company?.name != nil{
                        self.setCompanyLabel(isHidden: false)
                        self.setTopConstraintDateLabel(isHidden: false)
                        self.detailLabelCompany.text = dataAboutDetailComputerParsing.company?.name
                    } else {
                        self.setCompanyLabel(isHidden: true)
                        self.setTopConstraintDateLabel(isHidden: true)
                    }
                    
                    if dataAboutDetailComputerParsing.introduced != nil{
                        self.setDateLabel(isHidden: false)
                        self.setTopConstraintDiscriptionLabel(isHidden: false)
                        self.detailLabelDate.text = dataAboutDetailComputerParsing.introduced
                    } else {
                        self.setDateLabel(isHidden: true)
                        self.setTopConstraintDiscriptionLabel(isHidden: true)
                    }
                    
                    if dataAboutDetailComputerParsing.description != nil {
                        self.setDescriptionLabel(isHidden: false)
                        self.detailLabelDescription.text = dataAboutDetailComputerParsing.description
                    } else {
                        self.setDescriptionLabel(isHidden: true)
                    }
                }
                
            } catch let error {
                print(error)
            }
            }.resume()
    }
    
    private func fetchSimilarComputers(forId id: Int) {
        guard let url = urlForSimilar(forPage: id) else {return}
        
        URLSession.shared.dataTask(with: url) { [weak self](data, response, error) in
            guard let data = data else { return }
            guard error == nil else { return }
            
            do {
                let similarComputers = try JSONDecoder().decode([Computer].self, from: data)
                print(similarComputers)
                
                self?.similarComputers = similarComputers
                
                DispatchQueue.main.async {
                    // TODO: Show similar computers
                    self?.updateSimilarComputersButton(withComputers: similarComputers)
                }
            } catch let error {
                print(error)
            }
            }.resume()
    }
    
    func updateSimilarComputersButton(withComputers computers: [Computer]) {
        let number = computers.count
        
        if number >= 1 {
            similarComputer0.setTitle(computers[0].name, for: .normal)
            similarComputer0.isEnabled = true
        } else {
            similarComputer0.setTitle("", for: .normal)
            similarComputer0.isEnabled = false
        }
        
        if number >= 2 {
            similarComputer1.setTitle(computers[1].name, for: .normal)
            similarComputer1.isEnabled = true
        } else {
            similarComputer1.setTitle("", for: .normal)
            similarComputer1.isEnabled = false
        }
        
        if number >= 3 {
            similarComputer2.setTitle(computers[2].name, for: .normal)
            similarComputer2.isEnabled = true
        } else {
            similarComputer2.setTitle("", for: .normal)
            similarComputer2.isEnabled = false
        }
    }
    
    private func urlForSimilar(forPage page: Int) -> URL? {
        return URL(string: urlString+"\(page)"+"/similar")
    }
    
    private func url(forPage page: Int) -> URL? {
        return URL(string: urlString+"\(page)")
    }
    
    
    // Size constraint
    
    private func setCompanyLabel(isHidden: Bool) {
        detailLabelHeightConstraintCompany.constant = isHidden ? 0.0 : 41.0
        self.view.layoutIfNeeded()
    }
    private func setDateLabel(isHidden: Bool) {
        detailLabelHeightConstraintDate.constant = isHidden ? 0.0 : 41.0
        self.view.layoutIfNeeded()
    }
    private func setTopConstraintDateLabel(isHidden: Bool) {
        detailLabelTopConstraintDate.constant = isHidden ? 0.0 : 20.0
        self.view.layoutIfNeeded()
    }
    private func setDescriptionLabel(isHidden: Bool) {
        detailLabelHeightDescription.constant = isHidden ? 0.0 : 41.0
        self.view.layoutIfNeeded()
    }
    private func setTopConstraintDiscriptionLabel(isHidden: Bool) {
        detailLabelTopConstraintDiscription.constant = isHidden ? 0.0 : 20.0
        self.view.layoutIfNeeded()
    }
    private func setHeightImage(isHidden: Bool) {
        detailHeightImage.constant = isHidden ? 0.0 : 210.0
        self.view.layoutIfNeeded()
    }
    private func setTopConstraintImage(isHidden: Bool) {
        detailTopConstraintImage.constant = isHidden ? 0.0 : 35.0
        self.view.layoutIfNeeded()
    }
    
    // Download img from URL
    
    func getDataFromUrl(url: URL, completion: @escaping (Data?, URLResponse?, Error?) -> ()) {
        URLSession.shared.dataTask(with: url) { data, response, error in
            completion(data, response, error)
            }.resume()
    }
    
    func downloadImage(url: URL) {
        print("Download Started")
        getDataFromUrl(url: url) { data, response, error in
            guard let data = data, error == nil else {
                self.clearImage()
                return }
            print(response?.suggestedFilename ?? url.lastPathComponent)
            print("Download Finished")
            DispatchQueue.main.async() {
                if UIImage(data: data) != nil{
                    self.detailImageView.image = UIImage(data: data)
                } else {
                    self.clearImage()
                }
            }
        }
    }
    
    func clearImage(){
        DispatchQueue.main.async{
            self.detailImageView.image = nil
            self.setTopConstraintImage(isHidden: true)
            self.setHeightImage(isHidden: true)
            self.view.layoutIfNeeded()
        }
    }
    
    // Actions
    @IBAction func similarComputerTouched(_ sender: UIButton) {
        let index = sender.tag
        
        guard self.similarComputers.count > index else { return } // Количество элементов должно быть как минимум на 1 больше чем index (в массиве из 3-х элементов максимальный индекс 2)
        
        let computer = similarComputers[index]
        
        self.computerId = computer.id
        self.companyName = computer.name
        
        self.navigationItem.title = companyName
        clearImage()
        fetchDetailComputers(forId: computerId)
        fetchSimilarComputers(forId: computerId)
        
        DispatchQueue.main.async{
            print("Scroll to top")
            self.scrollView.setContentOffset(CGPoint.init(x: 0.0, y: -64.0), animated: true)
        }
    }
    
}

extension ComputerDetailViewController: UIScrollViewDelegate {
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
//        print("Scroll view content offset = \(scrollView.contentOffset)")
    }
}