#import <UIKit/UIKit.h>
#import <CoreData/CoreData.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext; // 数据管理器类，临时数据库
@property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel; // 数据模型器类，包含多个实体，实体中设置的属性，
　　实体名称等，可以认为是一个实体集合，相当于数据库中的表
@property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator; // 数据连接器类，
　　连接磁盘与内存中的临时数据库

- (void)saveContext;
- (NSURL *)applicationDocumentsDirectory;

@end

#pragma mark - Core Data stack

@synthesize managedObjectContext = _managedObjectContext;
@synthesize managedObjectModel = _managedObjectModel;
@synthesize persistentStoreCoordinator = _persistentStoreCoordinator;

// 这个方法的作用是获取Documents的路径，只不过这里的返回值是NSURl，而我们之前获取的路径是NSString，这个返回值在coreDate其他方法中当参数
- (NSURL *)applicationDocumentsDirectory {
    // The directory the application uses to store the Core Data store file. This code uses a directory named "lanou3g.CoreData" in the application‘s documents directory.
    return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}

// 需要用到此对象时才去加载，不需要时不加载，提高性能，增强对内存的有效使用
- (NSManagedObjectModel *)managedObjectModel {
    // The managed object model for the application. It is a fatal error for the application not to be able to find and load its model.
    if (_managedObjectModel != nil) {
        return _managedObjectModel;
    }
    NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"CoreData" withExtension:@"momd"];
    // 获取文件编译后的文件路径，数据模型器与CoreData.xcdatamodeld密切相关，CoreData.xcdatamodeld编译后形成的文件后缀名就是momd。
    
    _managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
    // 从得到的路径中加载数据模型器对象

    return _managedObjectModel;
}

// 持久存储助理，数据连接器类
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
    // The persistent store coordinator for the application. This implementation creates and return a coordinator, having added the store for the application to it.
    if (_persistentStoreCoordinator != nil) {
        return _persistentStoreCoordinator;
    }
    
    // Create the coordinator and store
    
    _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
    // 创建数据连接器对象，需要数据模型器作为参数，应为数据模型器决定了连接器从数据库文件中取得数据
    
    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"CoreData.sqlite"];
    // 找到磁盘中数据库存放的路径，连接操作需要知道源路径

    NSError *error = nil;
    NSString *failureReason = @"There was an error creating or loading the application‘s saved data.";
    
    NSDictionary *dic = @{NSMigratePersistentStoresAutomaticallyOption:@YES, NSInferMappingModelAutomaticallyOption:@YES}; // 支持版本迁移，支持数据迁移。
    
    if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:dic error:&error]) { //options参数是一个字典，这个字典保存的是coreData的默认设置，比如是否允许数据迁移，默认是不允许的，如果想要完成数据迁移，后期需要系应该这个参数
        // Report any error we got.
        
        // 下面创建的字典，就是保存错误信息的，如果数据连接器类连接失败，就会相应的将错误信息从字典中取出，打印出来
        NSMutableDictionary *dict = [NSMutableDictionary dictionary];
        dict[NSLocalizedDescriptionKey] = @"Failed to initialize the application‘s saved data";
        dict[NSLocalizedFailureReasonErrorKey] = failureReason;
        dict[NSUnderlyingErrorKey] = error;
        error = [NSError errorWithDomain:@"YOUR_ERROR_DOMAIN" code:9999 userInfo:dict];
        // Replace this with code to handle the error appropriately.
        // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort(); // 终止程序
    }
    
    return _persistentStoreCoordinator;
}

// 数据管理器类
- (NSManagedObjectContext *)managedObjectContext {
    // Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.)
    if (_managedObjectContext != nil) {
        return _managedObjectContext;
    }
    
    // 每一个数据管理器对象，都需要一个数据连接器
    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
    if (!coordinator) {
        return nil;
    }
    _managedObjectContext = [[NSManagedObjectContext alloc] init];
    [_managedObjectContext setPersistentStoreCoordinator:coordinator];
    return _managedObjectContext;
}

#pragma mark - Core Data Saving support

- (void)saveContext {
    NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
    if (managedObjectContext != nil) {
        NSError *error = nil;
        if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
            // 临时数据库(数据管理器类)对文件进行操作后，同步保存回磁盘时失败，那么此时打印失败信息，终止程序
            // Replace this implementation with code to handle the error appropriately.
            // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
            abort();
        }
    }
}

// 封装一个插入学生的方法
- (void)insertStudentWithName:(NSString *)name gender:(NSString *)gender age:(NSNumber *)age {
    // 1、增加数据，插入数据
    /*
     NSManagedObjectModel *managedObjectModel =
     [[context persistentStoreCoordinator] managedObjectModel];
     
     NSEntityDescription *entity =
     [[managedObjectModel entitiesByName] objectForKey:entityName];
     
     NSManagedObject *newObject = [[NSManagedObject alloc]
     initWithEntity:entity insertIntoManagedObjectContext:context];
     
     return newObject;
     */
    Student *stu = [NSEntityDescription insertNewObjectForEntityForName:@"Student" inManagedObjectContext:self.managedObjectContext]; // 在临时数据库中，按照实体Student，加载出一个视图管理对象(数据模型)
    // 模型赋值有两种：KVC，属性点语法
    stu.name = name;
    [stu setValue:gender forKey:@"gender"];
    stu.age = age;
    // 数据管理类执行同步操作，将数据写入数据库
    [self.managedObjectContext save:nil];
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    // coreData完成增删改查
    // 1、增加数据，插入数据
    // 创建模型
//    [self insertStudentWithName:@"巴达" gender:@"雄" age:@20];
//    [self insertStudentWithName:@"大宝" gender:@"女" age:@10];
//    [self insertStudentWithName:@"秋香" gender:@"雌" age:@18];
    
    // 2、查询数据
    // 创建查询请求对象
//    NSFetchRequest *request = [[NSFetchRequest alloc] initWithEntityName:@"Student"]; // 这样的数据请求对象得到的是数据库中的所有记录
//    
//    // 让数据管理对象执行请求
//    NSArray *array =[self.managedObjectContext executeFetchRequest:request error:nil];
//    for (Student *stu in array) {
//        NSLog(@"name is %@, gender is %@, age is %@", stu.name, stu.gender, stu.age);
//    }
    
    // 为了更加方便的完成查询操作，查询请求可以添加谓词和排序
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    // 得到一个实体描述
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Student" inManagedObjectContext:self.managedObjectContext];
    request.entity = entity;

    // 添加谓词
//    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name like %@ or gender = %@", @"*香*", @"女"];
//    request.predicate = predicate;
//    NSArray *array = [self.managedObjectContext executeFetchRequest:request error:nil];
//    for (Student *stu in array) {
//        NSLog(@"name is %@, gender is %@, age is %@", stu.name, stu.gender, stu.age);
//    }
    
    // 添加排序
//    NSSortDescriptor *descripor = [[NSSortDescriptor alloc] initWithKey:@"age" ascending:YES]; // 创建按照年龄升序排列的排序条件
//    request.sortDescriptors =@[descripor];
//    NSArray *array = [self.managedObjectContext executeFetchRequest:request error:nil];
//    for (Student *stu in array) {
//        NSLog(@"name is %@, gender is %@, age is %@", stu.name, stu.gender, stu.age);
//    }
    
    // 3、修改数据
    // 首先找到要修改的数据，修改完成后，同步到数据库
//    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name = %@", @"中二"];
//    request.predicate = predicate;
//    NSArray *array = [self.managedObjectContext executeFetchRequest:request error:nil];
//    Student *student = [array objectAtIndex:0];
//    student.name = @"中小二";
//    student.gender = @"妖";
//    // 修改完成后执行save
//    [self.managedObjectContext save:nil];
//    
//    NSLog(@"name is %@, gender is %@, age is %@", student.name, student.gender, student.age);
    
    // 4、删除数据
    // 首先找到要删除的数据，然后让数据管理器对象执行delete方法
//    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name = %@", @"中小二"];
//        request.predicate = predicate;
//        NSArray *array = [self.managedObjectContext executeFetchRequest:request error:nil];
//    Student *student = [array objectAtIndex:0];
//    // 数据管理对象删除数据
//    [self.managedObjectContext deleteObject:student];
////    [self.managedObjectContext deletedObjects]; // 删除临时数据库中某个试题中的所有数据
//    [self.managedObjectContext save:nil];
    
    NSLog(@"%@", [self applicationDocumentsDirectory]);
    
    return YES;
}