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

import UIKit

class AllCoursesViewController: UITableViewController {

    var tempData = [Course]()

    var allCourses = [Course]()
    var ownedCourses = [Course]()
    var displayCourses = [Course]()
    var mycourse: Course!

    let retrieveAllCoursesDG = DispatchGroup()
    let retrieveOwnedCoursesDG = DispatchGroup()

    override func viewDidLoad() {
        super.viewDidLoad()
        // Get all courses once we've checked authentication.
        print("Get All Courses")
        self.getAllCourses(endpoint: "courses", stateDG: self.retrieveAllCoursesDG)
        // Get owned courses once we've got all courses.
        retrieveAllCoursesDG.notify(queue: .main) {
            print("Get Owned Courses")
            self.allCourses = self.tempData.copy()
            self.getAllCourses(endpoint: "courses/my", stateDG: self.retrieveOwnedCoursesDG)
        }

        // Do the thing where we check courses against owned or whatever.
        retrieveOwnedCoursesDG.notify(queue: .main) {
            print("Filter Courses")
            self.ownedCourses = self.tempData.copy()
            for i in 0 ..< self.ownedCourses.count {
                self.ownedCourses[i].owned = true
            }

            var idArray = [Int]()
            for course in self.ownedCourses {
                idArray.append(course.id)
            }
            for var course in self.allCourses {
                course.owned = idArray.contains(course.id)
                self.displayCourses.append(course)
            }
            self.tableView.reloadData()
        }

    }

    func getAllCourses(endpoint: String, stateDG: DispatchGroup) {
        stateDG.enter()
        let url = URL(string: "\(ServHandler.connectProtocol)://\(ServHandler.baseURL)/\(endpoint)")
        let task = URLSession.shared.dataTask(with: url!) {(data, response, error) in
            guard error == nil else {
                print("Error!")
                return
            }
            guard let content = data else {
                print("There is no data!")
                return
            }

            let decoder = JSONDecoder()
            do {
                for course in try decoder.decode([Course].self, from: content) {
                    self.tempData.append(course)
                }
                stateDG.leave()
                return
            } catch {
                print(error.localizedDescription)
                print(error)
                return
            }
        }
        task.resume()
    }


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


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


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

        if (selectedCourse.owned == true) {
            // Load the subjects for this course
            performSegue(withIdentifier: "courseToSubjectSegue", sender: self)
        }
        else {
            // Trigger an alert to buy the course
            let alert = UIAlertController(title: "Purhcase Course?", message: "You do not own this course. Do you wish to purchase it?", preferredStyle: .alert)

            alert.addAction(UIAlertAction(title: "Yes", style: .default, handler: { action in
                print("RUN IAP CODE BOI")
            }))
            alert.addAction(UIAlertAction(title: "No", style: .cancel, handler: nil))

            self.present(alert, animated: true)
        }
    }

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