ObjectStorage.swift

//
//  ObjectStorage.swift
//
//  Created by Soroush Khanlou on 9/20/16.
//

import Foundation

protocol ObjectStorageProtocol {
    
    associatedtype Stored
    
    init(location: StorageLocation)
    
    func save(object: Stored)
    
    func fetchObject() -> Stored?
    
    func deleteObject()

}

final class CodableObjectStorage<T: Codable>: ObjectStorageProtocol {
    
    private let fileManager = FileManager.default
    
    let storageLocation: StorageLocation
    
    init(location: StorageLocation) {
        self.storageLocation = location
    }
    
    func save(object: T) {
        guard let appStorageDirectory = appStorageDirectory else { return }
        do {
            try fileManager.createDirectory(at: appStorageDirectory, withIntermediateDirectories: true, attributes: nil)
            let encoder = PropertyListEncoder()
            let data = try encoder.encode(object)
            try data.write(to: storageURL.unwrap())
        } catch {
            Analytics.logEvent("Error writing the object.")
            print("Error writing the object.")
        }
    }
    
    func fetchObject() -> T? {
        do {
            let data = try Data(contentsOf: storageURL.unwrap())
            let decoder = PropertyListDecoder()
            return try decoder.decode(T.self, from: data)
        } catch {
            guard (error as NSError).code != NSFileReadNoSuchFileError else { return nil }
            Analytics.logEvent("Error reading the object.")
            print("Error reading the object.")
            return nil
        }
    }
    
    func deleteObject() {
        do {
            try fileManager.removeItem(at: storageURL.unwrap())
        } catch {
            guard (error as NSError).code != NSFileReadNoSuchFileError else { return }
            print("Error deleting cache file.")
        }
    }
    
    private var storageURL: URL? {
        return storageLocation.storageLocation
    }
    
    private var appStorageDirectory: URL? {
        return storageLocation.appStorageDirectory
    }
}


final class DisabledObjectStorage<T>: ObjectStorageProtocol {
    
    init(location: StorageLocation) {
        
    }
    
    func save(object: T) {
        
    }
    
    func fetchObject() -> T? {
        return nil
    }
        
    func deleteObject() {
        
    }
}

StorageLocation.swift

//
//  StorageLocation.swift
//
//  Created by Soroush Khanlou on 9/20/16.
//

import Foundation

enum StorageLocation {
    
    case cache(name: String)
    case userData(name: String)
    
    var name: String {
        switch self {
        case .cache(let name):
            return name
        case .userData(let name):
            return name
        }
    }
    
    var searchPathDirectory: FileManager.SearchPathDirectory {
        switch self {
        case .cache:
            return .cachesDirectory
        case .userData:
            return .libraryDirectory
        }
    }
    
    var fileExtension: String {
        switch self {
        case .cache:
            return ".cache"
        case .userData:
            return ".userData"
        }
    }
    
    var fileManager: FileManager {
        return FileManager.default
    }
    
    var path: String {
        return storageLocation?.path ?? ""
    }
    
    var storageLocation: URL? {
        return appStorageDirectory?.appendingPathComponent(filename)
    }
    
    var appStorageDirectory: URL? {
        return generalStoreDirectory?.appendingPathComponent("urbanarchive", isDirectory: true)
    }
    
    private var generalStoreDirectory: URL? {
        let URLs = fileManager.urls(for: searchPathDirectory, in: .userDomainMask)
        return URLs.first
    }
    
    private var filename: String {
        return sanitizedName + fileExtension
    }
    
    private var sanitizedName: String {
        let invalidFilenameCharacters = CharacterSet(charactersIn: ":/\\?%*|\"<>")
        let validName = name.components(separatedBy: invalidFilenameCharacters).joined()
        return validName.replacingOccurrences(of: " ", with: "-")
    }
    
}