CoreStore/Sources/CoreStoreError.swift

//
//  CoreStoreError.swift
//  CoreStore
//
//  Copyright © 2014 John Rommel Estropia
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in all
//  copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
//  SOFTWARE.
//

import Foundation
import CoreData


// MARK: - CoreStoreError

/**
 All errors thrown from CoreStore are expressed in `CoreStoreError` enum values.
 */
public enum CoreStoreError: Error, CustomNSError, Hashable {
    
    /**
     A failure occured because of an unknown error.
     */
    case unknown
    
    /**
     The `NSPersistentStore` could not be initialized because another store existed at the specified `NSURL`.
     */
    case differentStorageExistsAtURL(existingPersistentStoreURL: URL)
    
    /**
     An `NSMappingModel` could not be found for a specific source and destination model versions.
     */
    case mappingModelNotFound(localStoreURL: URL, targetModel: NSManagedObjectModel, targetModelVersion: String)
    
    /**
     Progressive migrations are disabled for a store, but an `NSMappingModel` could not be found for a specific source and destination model versions.
     */
    case progressiveMigrationRequired(localStoreURL: URL)
    
    /**
     An internal SDK call failed with the specified `NSError`.
     */
    case internalError(NSError: NSError)
    
    
    // MARK: CustomNSError
    
    public static var errorDomain: String {
        
        return CoreStoreErrorDomain
    }
    
    public var errorCode: Int {
    
        switch self {
            
        case .unknown:
            return CoreStoreErrorCode.unknownError.rawValue
            
        case .differentStorageExistsAtURL:
            return CoreStoreErrorCode.differentStorageExistsAtURL.rawValue
            
        case .mappingModelNotFound:
            return CoreStoreErrorCode.mappingModelNotFound.rawValue
            
        case .progressiveMigrationRequired:
            return CoreStoreErrorCode.progressiveMigrationRequired.rawValue
            
        case .internalError:
            return CoreStoreErrorCode.internalError.rawValue
        }
    }
    
    public var errorUserInfo: [String : Any] {
        
        switch self {
            
        case .unknown:
            return [:]
            
        case .differentStorageExistsAtURL(let existingPersistentStoreURL):
            return [
                "existingPersistentStoreURL": existingPersistentStoreURL
            ]
            
        case .mappingModelNotFound(let localStoreURL, let targetModel, let targetModelVersion):
            return [
                "localStoreURL": localStoreURL,
                "targetModel": targetModel,
                "targetModelVersion": targetModelVersion
            ]
            
        case .progressiveMigrationRequired(let localStoreURL):
            return [
                "localStoreURL": localStoreURL
            ]
            
        case .internalError(let NSError):
            return [
                "NSError": NSError
            ]
        }
    }
    
    
    // MARK: Hashable
    
    public var hashValue: Int {
        
        let code = self._code
        switch self {
            
        case .unknown:
            return code.hashValue
            
        case .differentStorageExistsAtURL(let existingPersistentStoreURL):
            return code.hashValue ^ existingPersistentStoreURL.hashValue
            
        case .mappingModelNotFound(let localStoreURL, let targetModel, let targetModelVersion):
            return code.hashValue ^ localStoreURL.hashValue ^ targetModel.hashValue ^ targetModelVersion.hashValue
            
        case .progressiveMigrationRequired(let localStoreURL):
            return code.hashValue ^ localStoreURL.hashValue
            
        case .internalError(let NSError):
            return code.hashValue ^ NSError.hashValue
        }
    }
    
    
    // MARK: Internal
    
    internal init(_ error: Error?) {
        
        self = error.flatMap { $0.bridgeToSwift } ?? .unknown
    }
}


// MARK: - CoreStoreError: Equatable

public func == (lhs: CoreStoreError, rhs: CoreStoreError) -> Bool {
    
    switch (lhs, rhs) {
        
    case (.unknown, .unknown):
        return true
        
    case (.differentStorageExistsAtURL(let url1), .differentStorageExistsAtURL(let url2)):
        return url1 == url2
        
    case (.mappingModelNotFound(let url1, let model1, let version1), .mappingModelNotFound(let url2, let model2, let version2)):
        return url1 == url2 && model1 == model2 && version1 == version2
        
    case (.progressiveMigrationRequired(let url1), .progressiveMigrationRequired(let url2)):
        return url1 == url2
        
    case (.internalError(let NSError1), .internalError(let NSError2)):
        return NSError1 == NSError2
        
    default:
        return false
    }
}


// MARK: - CoreStoreErrorDomain

/**
 The `NSError` error domain string for `CSError`.
 */
@nonobjc
public let CoreStoreErrorDomain = "com.corestore.error"


// MARK: - CoreStoreErrorCode

/**
 The `NSError` error codes for `CoreStoreErrorDomain`.
 */
public enum CoreStoreErrorCode: Int {
    
    /**
     A failure occured because of an unknown error.
     */
    case unknownError
    
    /**
     The `NSPersistentStore` could note be initialized because another store existed at the specified `NSURL`.
     */
    case differentStorageExistsAtURL
    
    /**
     An `NSMappingModel` could not be found for a specific source and destination model versions.
     */
    case mappingModelNotFound
    
    /**
     Progressive migrations are disabled for a store, but an `NSMappingModel` could not be found for a specific source and destination model versions.
     */
    case progressiveMigrationRequired
    
    /**
     An internal SDK call failed with the specified "NSError" userInfo key.
     */
    case internalError
}


// MARK: - NSError

public extension NSError {
    
    // MARK: Internal
    
    internal var isCoreDataMigrationError: Bool {
        
        let code = self.code
        return (code == NSPersistentStoreIncompatibleVersionHashError
            || code == NSMigrationMissingSourceModelError
            || code == NSMigrationError)
            && self.domain == NSCocoaErrorDomain
    }
}