#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

@class BTAPIClient, BTUI, BTPaymentRequest, BTPaymentMethodNonce;
@protocol BTDropInViewControllerDelegate;

/// A view controller that provides a quick and easy payment experience.
///
/// When initialized with a Braintree client, the Drop In will prompt a user for payment details,
/// based on your Gatweay configuration. The Drop In payment form supports cards and PayPal. When
/// using Drop In, you don't need to worry about which methods are already on file with Braintree;
/// newly created methods are saved as part of the Drop In flow as needed.
///
/// Upon successful form submission, you will receive a payment method nonce, which you can
/// transact with on your server. Client and validation errors are handled internally by Drop In;
/// other types of Errors are rare and generally irrecoverable.
///
/// The Drop In view controller delegates presentation and dismissal to the developer. It has been
/// most thoroughly tested in the context of a UINavigationController.
///
/// The Drop In can send success and cancelation messages to the developer via the
/// delegate. See `delegate` and `BTDropInViewControllerDelegate`.
///
/// You can customize Drop In in various ways, for example, you can change the primary Call To
/// Action button text. For visual customzation options see `theme` and `BTUI`. Like any
/// UIViewController, you can setup properties like `title` or `navigationBar.rightBarButtonItem`.
@interface BTDropInViewController : UIViewController

/// Initialize a new Drop-in view controller.
///
/// @param apiClient A BTAPIClient used for communicating with Braintree servers. Required.
///
/// @return A new Drop-in view controller that is ready to be presented.
- (instancetype)initWithAPIClient:(BTAPIClient *)apiClient;

/// The BTPaymentRequest that defines the Drop-in experience.
///
/// The properties of this payment request are used to customize Drop-in.
@property (nonatomic, strong, nullable) BTPaymentRequest *paymentRequest;

/// The array of `BTPaymentMethodNonce` payment method nonces on file. The payment method nonces may be in the Vault.
/// Most payment methods are automatically Vaulted if the client token was generated with a customer ID.
@property (nonatomic, strong) NSArray *paymentMethodNonces;

#pragma mark State Change Notifications

/// The delegate that, if set, is notified of success or failure.
@property (nonatomic, weak, nullable) id<BTDropInViewControllerDelegate> delegate;

#pragma mark Customization

/// The presentation theme to use for the Drop In.
@property (nonatomic, strong, nullable) BTUI *theme;

/// Fetches the customer's saved payment methods and populates Drop In with them.
///
/// @note For the best user experience, you should call this method as early as
///       possible (after initializing BTDropInViewController, before presenting it)
///       in order to avoid a loading spinner.
///
/// @param completionBlock A block that gets called on completion.
- (void)fetchPaymentMethodsOnCompletion:(void(^)())completionBlock;

/// The API Client used for communication with Braintree servers.
@property (nonatomic, strong) BTAPIClient *apiClient;

@end

/// A protocol for BTDropInViewController completion notifications.
@protocol BTDropInViewControllerDelegate <NSObject>

/// Informs the delegate when the user has successfully provided payment info that has been
/// successfully tokenized.
///
/// Upon receiving this message, you should dismiss Drop In.
///
/// @param viewController The Drop In view controller informing its delegate of success
/// @param tokenization The selected (and possibly newly created) tokenized payment information.
- (void)dropInViewController:(BTDropInViewController *)viewController didSucceedWithTokenization:(BTPaymentMethodNonce *)paymentMethodNonce;

/// Informs the delegate when the user has decided to cancel out of the Drop-in payment form.
///
/// Drop-in handles its own error cases, so this cancelation is user initiated and
/// irreversable. Upon receiving this message, you should dismiss Drop-in.
///
/// @param viewController The Drop-in view controller informing its delegate of failure or cancelation.
- (void)dropInViewControllerDidCancel:(BTDropInViewController *)viewController;

@optional

/// Informs the delegate when the Drop-in view controller has finished loading.
///
/// @param viewController The Drop-in view controller informing its delegate
- (void)dropInViewControllerDidLoad:(BTDropInViewController *)viewController;

/// Informs the delegate when the user has entered or selected payment information.
///
/// @param viewController The Drop-in view controller informing its delegate
- (void)dropInViewControllerWillComplete:(BTDropInViewController *)viewController;

@end

NS_ASSUME_NONNULL_END