elpha-ios/elpha-ios/InstancesDataManager.swift

//
//  InstancesDataManager.swift
//  elpha-ios
//
//  Created by Dwayne Harris on 9/18/18.
//  Copyright © 2018 Elpha. All rights reserved.
//

import CoreData
import Foundation
import UIKit

class InstancesDataManager {
    static let shared = InstancesDataManager()
    
    let instanceRequestCount = 20
    var instances: [ISInstanceMO] = []
    var finished = false
    var nextID: String? = nil
    
    static func upsertLanguage(string: String) -> ISLanguageMO? {
        let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
        let request = NSFetchRequest<ISLanguageMO>(entityName: "ISLanguage")
        request.predicate = NSPredicate(format: "id == %@", string)
        
        do {
            let results: [ISLanguageMO] = try context.fetch(request)
            switch results.count {
            case 0:
                let language = ISLanguageMO(context: context)
                language.id = string
                try context.save()
                
                return language
            case 1:
                return results.first
            default:
                print("Duplicate ISLanguage entity")
                return nil
            }
        } catch {
            print("\(error)")
            return nil
        }
    }
    
    static func upsertCategory(string: String) -> ISCategoryMO? {
        let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
        let request = NSFetchRequest<ISCategoryMO>(entityName: "ISCategory")
        request.predicate = NSPredicate(format: "id == %@", string)
        
        do {
            let results: [ISCategoryMO] = try context.fetch(request)
            switch results.count {
            case 0:
                let category = ISCategoryMO(context: context)
                category.id = string
                try context.save()
                
                return category
            case 1:
                return results.first
            default:
                print("Duplicate ISCategory entity")
                return nil
            }
        } catch {
            print("\(error)")
            return nil
        }
    }
    
    static func setAttributes(on i: ISInstanceMO, attributes: [String: Any]) {
        guard let id = attributes["id"] as? String, let name = attributes["name"] as? String else {
            print("Error")
            return
        }
        
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZ"
        dateFormatter.locale = Locale(identifier: "en_US_POSIX")
        
        i.id = id
        i.name = name
        i.url = URL(string: "https://\(name)")!
        i.uptime = attributes["uptime"] as! Int32
        i.up = attributes["up"] as! Bool
        i.dead = attributes["dead"] as! Bool
        i.version = attributes["version"] as? String
        i.ipv6 = attributes["ipv6"] as! Bool
        i.users = Int64(attributes["users"] as! String)!
        i.statuses = Int64(attributes["statuses"] as! String)!
        i.connections = Int64(attributes["connections"] as! String)!
        i.openRegistrations = attributes["open_registrations"] as! Bool
        
        if let activeUsers = attributes["active_users"] as? Int64 {
            i.activeUsers = activeUsers
        }
        
        if let updatedAt = attributes["updated_at"] as? String {
            i.updatedAt = dateFormatter.date(from: updatedAt)
        }
        
        if let checkedAt = attributes["checked_at"] as? String {
            i.checkedAt = dateFormatter.date(from: checkedAt)
        }
        
        if let thumbnail = attributes["thumbnail"] as? String {
            i.thumbnail = URL(string: thumbnail)!
        }
        
        if let info = attributes["info"] as? [String: Any] {
            i.shortDesc = info["short_description"] as? String
            i.fullDescription = info["full_description"] as? String
            i.topic = info["topic"] as? String
            
            for language in info["languages"] as! [String] {
                if let l = upsertLanguage(string: language) {
                    i.mutableSetValue(forKey: "languages").add(l)
                }
            }
            
            for category in info["categories"] as! [String] {
                if let c = upsertCategory(string: category) {
                    i.mutableSetValue(forKey: "categories").add(c)
                }
            }
        }
    }
    
    func reloadInstances(completion: @escaping (Error?) -> Void) {
        finished = false
        nextID = nil
        loadInstances(completion: completion)
    }
    
    func loadInstances(completion: @escaping (Error?) -> Void) {
        var params = [
            "count=\(instanceRequestCount)",
            "sort_by=users",
            "sort_order=desc",
            "include_closed=true",
            "include_down=false",
            ]
        
        if let nextID = nextID {
            params.append("min_id=\(nextID)")
        }
        
        let requestURL = "\(Config.instancesServiceUrl)\(Config.instancesServiceEndpoint)?\(params.joined(separator: "&"))"
        print("loading instances: requestURL: \(requestURL)")
        
        var request = URLRequest(url: URL(string: requestURL)!)
        request.addValue("Bearer \(Config.instancesServiceSecret)", forHTTPHeaderField: "Authorization")
        
        URLSession.shared.dataTask(with: request) { data, response, error in
            guard error == nil else {
                completion(error)
                return
            }
            
            guard let response = response as? HTTPURLResponse else {
                print("No HTTP response")
                completion(NSError())
                return
            }
            
            switch response.statusCode {
            case 200..<300:
                guard let data = data else {
                    print("No HTTP response")
                    completion(NSError())
                    return
                }
                
                DispatchQueue.main.async {
                    do {
                        let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
                        let instancesResult = try JSONSerialization.jsonObject(with: data) as! [String: Any]
                        
                        if let pagination = instancesResult["pagination"] as? [String: Any] {
                            if let nextID = pagination["next_id"] as? String {
                                self.nextID = nextID
                            } else {
                                self.nextID = nil
                                self.finished = true
                            }
                        }
                        
                        if let instances = instancesResult["instances"] as? [Any] {
                            for case let instance as [String: Any] in instances {
                                if let id = instance["id"] as? String {
                                    let request = NSFetchRequest<ISInstanceMO>(entityName: "ISInstance")
                                    request.predicate = NSPredicate(format: "id == %@", id)
                                    
                                    let results: [ISInstanceMO] = try context.fetch(request)
                                    
                                    switch results.count {
                                    case 0:
                                        let i = ISInstanceMO(context: context)
                                        InstancesDataManager.setAttributes(on: i, attributes: instance)
                                    case 1:
                                        if let i = results.first {
                                            InstancesDataManager.setAttributes(on: i, attributes: instance)
                                        }
                                    default:
                                        print("Duplicate Instance entity")
                                    }
                                }
                            }
                            
                            do {
                                try context.save()
                            } catch {
                                completion(error)
                                return
                            }
                        }
                        
                        completion(nil)
                    } catch {
                        completion(error)
                        return
                    }
                }
            case 400:
                print("instances.social: 400")
                completion(NSError())
            default:
                completion(nil)
                return
            }
        }.resume()
    }
}