// Copyright 2015-present 650 Industries. All rights reserved.

#import "EXAnalytics.h"
#import "EXAppState.h"
#import "EXAppViewController.h"
#import "EXBuildConstants.h"
#import "EXFrame.h"
#import "EXKernel.h"
#import "EXKernelAppRecord.h"
#import "EXKernelModule.h"
#import "EXKernelLinkingManager.h"
#import "EXLinkingManager.h"
#import "EXVersions.h"

#import <React/RCTBridge+Private.h>
#import <React/RCTEventDispatcher.h>
#import <React/RCTModuleData.h>
#import <React/RCTUtils.h>

NS_ASSUME_NONNULL_BEGIN

NSString *kEXKernelErrorDomain = @"EXKernelErrorDomain";
NSNotificationName kEXKernelJSIsLoadedNotification = @"EXKernelJSIsLoadedNotification";
NSNotificationName kEXKernelAppDidDisplay = @"EXKernelAppDidDisplay";
NSString *kEXKernelShouldForegroundTaskEvent = @"foregroundTask";
NSString * const kEXDeviceInstallUUIDKey = @"EXDeviceInstallUUIDKey";
NSString * const kEXKernelClearJSCacheUserDefaultsKey = @"EXKernelClearJSCacheUserDefaultsKey";
NSString * const EXKernelDisableNuxDefaultsKey = @"EXKernelDisableNuxDefaultsKey";

@interface EXKernel () <EXKernelAppRegistryDelegate>

@end

@implementation EXKernel

+ (instancetype)sharedInstance
{
  static EXKernel *theKernel;
  static dispatch_once_t once;
  dispatch_once(&once, ^{
    if (!theKernel) {
      theKernel = [[EXKernel alloc] init];
    }
  });
  return theKernel;
}

- (instancetype)init
{
  if (self = [super init]) {
    // init app registry: keep track of RN bridges we are running
    _appRegistry = [[EXKernelAppRegistry alloc] init];
    _appRegistry.delegate = self;

    // init service registry: classes which manage shared resources among all bridges
    _serviceRegistry = [[EXKernelServiceRegistry alloc] init];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_onKernelJSLoaded) name:kEXKernelJSIsLoadedNotification object:nil];
    for (NSString *name in @[UIApplicationDidBecomeActiveNotification,
                             UIApplicationDidEnterBackgroundNotification,
                             UIApplicationDidFinishLaunchingNotification,
                             UIApplicationWillResignActiveNotification,
                             UIApplicationWillEnterForegroundNotification]) {
      
      [[NSNotificationCenter defaultCenter] addObserver:self
                                               selector:@selector(_handleAppStateDidChange:)
                                                   name:name
                                                 object:nil];
    }
    NSLog(@"Expo iOS Runtime Version %@", [EXBuildConstants sharedInstance].expoRuntimeVersion);
  }
  return self;
}

- (void)dealloc
{
  [[NSNotificationCenter defaultCenter] removeObserver:self];
}

- (void)_onKernelJSLoaded
{
  // used by appetize: optionally disable nux
  // TODO: ben: audit
  BOOL disableNuxDefaultsValue = [[NSUserDefaults standardUserDefaults] boolForKey:EXKernelDisableNuxDefaultsKey];
  if (disableNuxDefaultsValue) {
    [self dispatchKernelJSEvent:@"resetNuxState" body:@{ @"isNuxCompleted": @YES } onSuccess:nil onFailure:nil];
    [[NSUserDefaults standardUserDefaults] removeObjectForKey:EXKernelDisableNuxDefaultsKey];
  }
}

#pragma mark - Misc

+ (NSString *)deviceInstallUUID
{
  NSString *uuid = [[NSUserDefaults standardUserDefaults] stringForKey:kEXDeviceInstallUUIDKey];
  if (!uuid) {
    uuid = [[NSUUID UUID] UUIDString];
    [[NSUserDefaults standardUserDefaults] setObject:uuid forKey:kEXDeviceInstallUUIDKey];
    [[NSUserDefaults standardUserDefaults] synchronize];
  }
  return uuid;
}

#pragma mark - bridge registry delegate

- (void)appRegistry:(EXKernelAppRegistry *)registry didRegisterAppRecord:(EXKernelAppRecord *)appRecord
{
  // forward to service registry
  [_serviceRegistry appRegistry:registry didRegisterAppRecord:appRecord];
}

- (void)appRegistry:(EXKernelAppRegistry *)registry willUnregisterAppRecord:(EXKernelAppRecord *)appRecord
{
  // forward to service registry
  [_serviceRegistry appRegistry:registry willUnregisterAppRecord:appRecord];
}

#pragma mark - Interfacing with JS

- (void)sendUrl:(NSString *)urlString toAppRecord:(EXKernelAppRecord *)app
{
  // fire a Linking url event on this (possibly versioned) bridge
  EXReactAppManager *appManager = app.appManager;
  id linkingModule = [self nativeModuleForAppManager:appManager named:@"LinkingManager"];
  if (!linkingModule) {
    DDLogError(@"Could not find the Linking module to open URL (%@)", urlString);
  } else if ([linkingModule respondsToSelector:@selector(dispatchOpenUrlEvent:)]) {
    [linkingModule dispatchOpenUrlEvent:[NSURL URLWithString:urlString]];
  } else {
    DDLogError(@"Linking module doesn't support the API we use to open URL (%@)", urlString);
  }
  [self moveAppToVisible:app];
}

- (void)dispatchKernelJSEvent:(NSString *)eventName body:(NSDictionary *)eventBody onSuccess:(void (^_Nullable)(NSDictionary * _Nullable))success onFailure:(void (^_Nullable)(NSString * _Nullable))failure
{
  // TODO: ben: kill me
  /* EXKernelModule *kernelModule = [self nativeModuleForAppManager:_appRegistry.kernelAppManager named:@"ExponentKernel"];
  if (kernelModule) {
    [kernelModule dispatchJSEvent:eventName body:eventBody onSuccess:success onFailure:failure];
  } */
}

- (void)_dispatchJSEvent:(NSString *)eventName body:(NSDictionary *)eventBody onAppManager:(EXReactAppManager *)appManager
{
  [appManager.reactBridge enqueueJSCall:@"RCTDeviceEventEmitter.emit"
                                   args:eventBody ? @[eventName, eventBody] : @[eventName]];
}

- (id)nativeModuleForAppManager:(EXReactAppManager *)appManager named:(NSString *)moduleName
{
  id destinationBridge = appManager.reactBridge;

  if ([destinationBridge respondsToSelector:@selector(batchedBridge)]) {
    id batchedBridge = [destinationBridge batchedBridge];
    id moduleData = [batchedBridge moduleDataForName:moduleName];
    
    // React Native before SDK 11 didn't strip the "RCT" prefix from module names
    if (!moduleData && ![moduleName hasPrefix:@"RCT"]) {
      moduleData = [batchedBridge moduleDataForName:[@"RCT" stringByAppendingString:moduleName]];
    }
    
    if (moduleData) {
      return [moduleData instance];
    }
  } else {
    DDLogError(@"Bridge does not support the API we use to get its underlying batched bridge");
  }
  return nil;
}

/**
 *  If the bridge has a batchedBridge or parentBridge selector, posts the notification on that object as well.
 */
- (void)_postNotificationName: (NSNotificationName)name onAbstractBridge: (id)bridge
{
  [[NSNotificationCenter defaultCenter] postNotificationName:name object:bridge];
  if ([bridge respondsToSelector:@selector(batchedBridge)]) {
    [[NSNotificationCenter defaultCenter] postNotificationName:name object:[bridge batchedBridge]];
  } else if ([bridge respondsToSelector:@selector(parentBridge)]) {
    [[NSNotificationCenter defaultCenter] postNotificationName:name object:[bridge parentBridge]];
  }
}

- (void)sendNotification:(NSDictionary *)notifBody
      toExperienceWithId:(NSString *)destinationExperienceId
          fromBackground:(BOOL)isFromBackground
                isRemote:(BOOL)isRemote
{
  EXReactAppManager *destinationAppManager = _appRegistry.homeAppRecord.appManager; // TODO: BEN
  EXKernelAppRecord *recordWithExperienceId = [_appRegistry newestRecordWithExperienceId:destinationExperienceId];
  if (recordWithExperienceId && recordWithExperienceId.appManager) {
    destinationAppManager = recordWithExperienceId.appManager;
  }
  // if the notification came from the background, in most but not all cases, this means the user acted on an iOS notification
  // and caused the app to launch.
  // From SO:
  // > Note that "App opened from Notification" will be a false positive if the notification is sent while the user is on a different
  // > screen (for example, if they pull down the status bar and then receive a notification from your app).
  NSDictionary *bodyWithOrigin = @{
                                   @"origin": (isFromBackground) ? @"selected" : @"received",
                                   @"remote": @(isRemote),
                                   @"data": notifBody,
                                   };
  if (destinationAppManager) {
    if (destinationAppManager == _appRegistry.homeAppRecord.appManager) { // TODO: BEN
      // send both the body and the experience id, so we can open a new experience from the kernel
      [self _dispatchJSEvent:@"Exponent.notification"
                        body:@{
                               @"body": bodyWithOrigin,
                               @"experienceId": destinationExperienceId,
                               }
                onAppManager:_appRegistry.homeAppRecord.appManager]; // TODO: BEN
    } else {
      // send the body to the already-open experience
      [self _dispatchJSEvent:@"Exponent.notification" body:bodyWithOrigin onAppManager:destinationAppManager];
      // TODO [self _moveAppToVisible:TODO: BEN];
    }
  }
}

#pragma mark - App State

- (void)createNewAppWithUrl:(NSURL *)url
{
  NSString *recordId = [_appRegistry registerAppWithManifestUrl:url];
  EXKernelAppRecord *record = [_appRegistry recordForId:recordId];
  [self moveAppToVisible:record];
}

- (void)switchTasks
{
  if (!_browserController) {
    return;
  }
  
  if (_visibleApp != _appRegistry.homeAppRecord) {
    [EXUtil performSynchronouslyOnMainThread:^{
      [_browserController toggleMenu];
    }];
  } else {
    EXKernelAppRegistry *appRegistry = [EXKernel sharedInstance].appRegistry;
    for (NSString *recordId in appRegistry.appEnumerator) {
      EXKernelAppRecord *record = [appRegistry recordForId:recordId];
      // foreground the first thing we find
      [self moveAppToVisible:record];
    }
  }
}

- (void)moveAppToVisible:(EXKernelAppRecord *)appRecord
{
  if (_browserController) {
    [EXUtil performSynchronouslyOnMainThread:^{
      [_browserController moveAppToVisible:appRecord];
    }];
  }
}

- (void)appDidBecomeVisible:(EXKernelAppRecord *)appRecord
{
  EXKernelAppRecord *appRecordPreviouslyVisible = _visibleApp;
  if (appRecord != appRecordPreviouslyVisible) {
    if (appRecordPreviouslyVisible) {
      [appRecordPreviouslyVisible.viewController appDidBackground];
      [self _postNotificationName:kEXKernelBridgeDidBackgroundNotification onAbstractBridge:appRecordPreviouslyVisible.appManager.reactBridge];
      id appStateModule = [self nativeModuleForAppManager:appRecordPreviouslyVisible.appManager named:@"AppState"];
      if ([appStateModule respondsToSelector:@selector(setState:)]) {
        [appStateModule setState:@"background"];
      }
    }
    if (appRecord) {
      [appRecord.viewController appDidBecomeVisible];
      [self _postNotificationName:kEXKernelBridgeDidForegroundNotification onAbstractBridge:appRecord.appManager.reactBridge];
      id appStateModule = [self nativeModuleForAppManager:appRecord.appManager named:@"AppState"];
      if ([appStateModule respondsToSelector:@selector(setState:)]) {
        [appStateModule setState:@"active"];
      }
      _visibleApp = appRecord;
      [[EXAnalytics sharedInstance] logKernelAppVisibleEvent];
    } else {
      _visibleApp = nil;
    }
    
    if (_visibleApp && _visibleApp != _appRegistry.homeAppRecord) {
      [self _unregisterUnusedAppRecords];
    }
  }
}

- (void)_unregisterUnusedAppRecords
{
  for (NSString *recordId in _appRegistry.appEnumerator) {
    EXKernelAppRecord *record = [_appRegistry recordForId:recordId];
    if (record && record != _visibleApp) {
      [_appRegistry unregisterAppWithRecordId:recordId];
      break;
    }
  }
}

- (void)_handleAppStateDidChange:(NSNotification *)notification
{
  NSString *newState;
  
  if ([notification.name isEqualToString:UIApplicationWillResignActiveNotification]) {
    newState = @"inactive";
  } else if ([notification.name isEqualToString:UIApplicationWillEnterForegroundNotification]) {
    newState = @"background";
  } else {
    switch (RCTSharedApplication().applicationState) {
      case UIApplicationStateActive:
        newState = @"active";
        break;
      case UIApplicationStateBackground: {
        newState = @"background";
        break;
      }
      default: {
        newState = @"unknown";
        break;
      }
    }
  }
  
  if (_visibleApp) {
    EXReactAppManager *appManager = _visibleApp.appManager;
    id appStateModule = [self nativeModuleForAppManager:appManager named:@"AppState"];
    NSString *lastKnownState;
    if ([appStateModule respondsToSelector:@selector(lastKnownState)]) {
      lastKnownState = [appStateModule lastKnownState];
    }
    if ([appStateModule respondsToSelector:@selector(setState:)]) {
      [appStateModule setState:newState];
    }
    if (!lastKnownState || ![newState isEqualToString:lastKnownState]) {
      if ([newState isEqualToString:@"active"]) {
        [_visibleApp.viewController appDidBecomeVisible];
        [self _postNotificationName:kEXKernelBridgeDidForegroundNotification onAbstractBridge:appManager.reactBridge];
      } else if ([newState isEqualToString:@"background"]) {
        [_visibleApp.viewController appDidBackground];
        [self _postNotificationName:kEXKernelBridgeDidBackgroundNotification onAbstractBridge:appManager.reactBridge];
      }
    }
  }
}

@end

NS_ASSUME_NONNULL_END