// When self.username changes, log the new name to the console.
//
// RACAble(self.username) creates a new RACSignal that sends a new value
// whenever the username changes. -subscribeNext: will execute the block
// whenever the signal sends a value.
[RACAble(self.username) subscribeNext:^(NSString *newName) {
    NSLog(@"%@", newName);
}];

// Only log names that start with "j".
//
// -filter returns a new RACSignal that only sends a new value when its block
// returns YES.
[[RACAble(self.username)
   filter:^(NSString *newName) {
       return [newName hasPrefix:@"j"];
   }]
   subscribeNext:^(NSString *newName) {
       NSLog(@"%@", newName);
   }];

// Create a one-way binding so that self.createEnabled will be
// true whenever self.password and self.passwordConfirmation
// are equal.
//
// RAC() is a macro that makes the binding look nicer.
// 
// +combineLatest:reduce: takes an array of signals, executes the block with the
// latest value from each signal whenever any of them changes, and returns a new
// RACSignal that sends the return value of that block as values.
RAC(self.createEnabled) = [RACSignal 
    combineLatest:@[ RACAble(self.password), RACAble(self.passwordConfirmation) ] 
    reduce:^(NSString *password, NSString *passwordConfirm) {
        return @([passwordConfirm isEqualToString:password]);
    }];

// Log a message whenever the button is pressed.
//
// RACCommand is a RACSignal subclass that represents UI actions.
//
// -rac_command is an addition to NSButton. The button will send itself on that
// command whenever it's pressed.
self.button.rac_command = [RACCommand command];
[self.button.rac_command subscribeNext:^(id _) {
    NSLog(@"button was pressed!");
}];

// Hook up a "Log in" button to log in over the network and log a message when
// it was successful.
//
// loginCommand does the actual work of logging in. loginResult sends a value
// whenever the async work is done.
self.loginCommand = [RACAsyncCommand command];

// This block will execute whenever the login command sends a value.
//
// -sequenceMany: will return a signal that represents the combination of all
// the signals returned from this block. In this case, the login result will
// send a value whenever a login attempt sends a value, completes, or errors
// out.
self.loginResult  = [self.loginCommand sequenceMany:^{
    // The hypothetical -logIn method returns a signal that sends a value when
    // the network request finishes.
    //
    // -materialize wraps up values, completions, and errors in RACEvents so errors won't
    // close the login result signal.
    return [[client logIn] materialize];
}];

[[self.loginResult 
    // Filter out everything but successful logins.
    filter:^(RACEvent *x) {
        return x.eventType == RACEventTypeCompleted;
    }]
    subscribeNext:^(id _) {
        NSLog(@"Logged in successfully!");
    }];

// Execute the login command when the button is pressed
self.loginButton.rac_command = self.loginCommand;

// Perform 2 network operations and log a message to the console when they are
// both completed.
//
// +merge: takes an array of signals and returns a new RACSignal that passes
// through the values of all of the signals and completes when all of the
// signals complete.
//
// -subscribeCompleted: will execute the block when the signal completes.
[[RACSignal 
    merge:@[ [client fetchUserRepos], [client fetchOrgRepos] ]] 
    subscribeCompleted:^{
        NSLog(@"They're both done!");
    }];

// Log in the user, then load any cached messages, then fetch the remaining
// messages from the server. After that's all done, log a message to the
// console.
//
// The hypothetical -logInUser methods returns a signal that completes after
// logging in.
//
// -flattenMap: will execute its block whenever the signal sends a value, and
// return a new RACSignal that merges all of the signals returned from the block
// into a single signal.
[[[[client 
    logInUser] 
    flattenMap:^(User *user) {
        // Return a signal that loads cached messages for the user.
        return [client loadCachedMessagesForUser:user];
    }]
    flattenMap:^(NSArray *messages) {
        // Return a signal that fetches any remaining messages.
        return [client fetchMessagesAfterMessage:messages.lastObject];
    }]
    subscribeCompleted:^{
        NSLog(@"Fetched all messages.");
    }];

// Create a one-way binding so that self.imageView.image will be set the user's
// avatar as soon as it's downloaded.
//
// The hypothetical -fetchUserWithUsername: method returns a signal which sends
// the user.
//
// -deliverOn: creates new signals that will do their work on other queues. In
// this example, it's used to move work to a background queue and then back to the main thread.
//
// -map: calls its block with each user that's fetched and returns a new
// RACSignal that sends values returned from the block.
RAC(self.imageView.image) = [[[[client 
    fetchUserWithUsername:@"joshaber"]
    deliverOn:[RACScheduler scheduler]]
    map:^(User *user) {
        // Download the avatar (this is done on a background queue).
        return [[NSImage alloc] initWithContentsOfURL:user.avatarURL];
    }]
    // Now the assignment will be done on the main thread.
    deliverOn:RACScheduler.mainThreadScheduler];