AllCoursesViewController.swift

//
//  AllCoursesViewController.swift
//  AeroBuddy
//
//  Created by Luke Collister on 01/09/2019.
//  Copyright © 2019 Luke Collister. All rights reserved.
//

import UIKit
import StoreKit

class AllCoursesViewController: UITableViewController {

    // MARK: - Properties
    var allCoursesArray = [Course]()
    var ownedCoursesArray = [Course]()
    var coursesToShow = [Course]()
    var IDArray = [Int]()
    var mycourse: Course!
    var IAPArray = [SKProduct]()

    let dispatchGroup = DispatchGroup()

    @IBAction func unwindToAllCourses(segue: UIStoryboardSegue) {
        DispatchQueue.main.async {
            self.performSegue(withIdentifier: "loginToAllCoursesSegue", sender: nil)
        }
    }

    override func viewWillAppear(_ animated: Bool) {
        let url = URL(string: "http://fe01.kilosierracharlie.me/user")
        let task = URLSession.shared.dataTask(with: url!) {(data, response, error) in
            guard error == nil else {
                print(error?.localizedDescription ?? "")
                return
            }

            if let httpStatus = response as? HTTPURLResponse {
                // check status code returned by the http server
                print("status code = \(httpStatus.statusCode)")
                // process result
                if httpStatus.statusCode == 200 {
                    // Do nada

                }
                else {
                    // Segue to Login screen
                    print("You need to log in")
                    DispatchQueue.main.async {
                        self.performSegue(withIdentifier: "allCoursesToLoginSegue", sender: self)
                    }
                }
            }
        }
        task.resume()
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Pull all owned courses, setting flags
        parseOwnedCoursesJSON()
        // Pull all courses
        parseAllCoursesJSON()

        dispatchGroup.notify(queue: .main) {
            // Merge both arrays, removing any duplicates where ID is present twice and flag is 0
            for cou in self.ownedCoursesArray {
                self.IDArray.append(cou.id)
            }
            for var cou in self.allCoursesArray {
                cou.owned = self.IDArray.contains(cou.id)
                self.coursesToShow.append(cou)
                print("COURSES TO SHOW ...")
                print(self.coursesToShow)
            }
            self.tableView.reloadData()
        }

        // IAP CODE
        //IAPHandler.shared.setProductIDs(IDs: self.productIDs)
        IAPHandler.shared.fetchAvailableProducts { [weak self](products)
            in
            guard let sSelf = self else {return}
            sSelf.IAPArray = products
        }
    }


    /*
     Determines data to be displayed
     1) Pull all courses
     2) Pull all purchased courses
     3) Loop through them, setting either an unlocked or locked flag/symbol
     4) Populate table view based off this
     */
    // PULL ALL COURSES AND FILL ARRAY
    func parseAllCoursesJSON() {
        dispatchGroup.enter()

        let url = URL(string: "http://fe01.kilosierracharlie.me/courses")
        let task = URLSession.shared.dataTask(with: url!) {(data, response, error) in

            // Check for errors
            guard error == nil else {
                print("There was an error")
                return
            }

            // Check for no data
            guard let content = data else {
                print("There is no data to show")
                return
            }

            // Using Codable, fill allCoursesArray
            let decoder = JSONDecoder()

            do {
                for cou in try decoder.decode([Course].self, from: content) {
                    self.allCoursesArray.append(cou)
                    print(cou)
                }
                self.dispatchGroup.leave()
                return
            }
            catch {
                print(error.localizedDescription)
                print(error)
                return
            }
        }
        task.resume()
    }


    // PULL ALL OWNED COURSES AND FILL THE ARRAY
    func parseOwnedCoursesJSON() {
        dispatchGroup.enter()

        let url = URL(string: "http://fe01.kilosierracharlie.me/courses/my")
        let task = URLSession.shared.dataTask(with: url!) {(data, response, error) in

            // Check for errors
            guard error == nil else {
                print("There was an error")
                return
            }

            // Check for no data
            guard let content = data else {
                print("There is no data to show")
                return
            }

            // Using Codable, fill ownedCoursesArray and set the owned flag to true
            let decoder = JSONDecoder()

            do {
                for cou in try decoder.decode([Course].self, from: content) {
                    self.ownedCoursesArray.append(cou)
                    print(cou)
                }
                for index in 0 ..< self.ownedCoursesArray.count {
                    self.ownedCoursesArray[index].owned = true
                }
                self.dispatchGroup.leave()
                return
            }
            catch {
                print(error.localizedDescription)
                print(error)
                return
            }
        }
        task.resume()
    }


    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return self.coursesToShow.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "CourseCell", for: indexPath) as! CourseCell
        cell.course = coursesToShow[indexPath.row]
        return cell
    }

    // When the cell is pressed
    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        // Determine which Course was selected
        let selectedCourse = coursesToShow[indexPath.row]
        mycourse = selectedCourse

        // Load the subjects for this course
        performSegue(withIdentifier: "courseToSubjectSegue", sender: self)
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "courseToSubjectSegue" {
            if let destinationVC = segue.destination as? SubjectsViewController {
                destinationVC.courseVar = mycourse
            }
        }
    }
}