Chapter 11 - Chat App/ChatAppFinished/Pods/FirebaseDatabase/Firebase/Database/Api/FIRDatabaseComponent.m
/*
 * Copyright 2018 Google
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#import "FIRDatabaseComponent.h"

#import "FIRDatabase_Private.h"
#import "FIRDatabaseConfig_Private.h"
#import "FRepoManager.h"

#import <FirebaseAuthInterop/FIRAuthInterop.h>
#import <FirebaseCore/FIRAppInternal.h>
#import <FirebaseCore/FIRComponent.h>
#import <FirebaseCore/FIRComponentContainer.h>
#import <FirebaseCore/FIRDependency.h>
#import <FirebaseCore/FIRLibrary.h>
#import <FirebaseCore/FIROptions.h>

NS_ASSUME_NONNULL_BEGIN

/** A NSMutableDictionary of FirebaseApp name and FRepoInfo to FirebaseDatabase instance. */
typedef NSMutableDictionary<NSString *, FIRDatabase *> FIRDatabaseDictionary;

@interface FIRDatabaseComponent () <FIRComponentLifecycleMaintainer, FIRLibrary>
@property (nonatomic) FIRDatabaseDictionary *instances;
/// Internal intializer.
- (instancetype)initWithApp:(FIRApp *)app;
@end

@implementation FIRDatabaseComponent

#pragma mark - Initialization

- (instancetype)initWithApp:(FIRApp *)app {
  self = [super init];
  if (self) {
    _app = app;
    _instances = [NSMutableDictionary dictionary];
  }
  return self;
}

#pragma mark - Lifecycle

+ (void)load {
  [FIRApp registerInternalLibrary:(Class<FIRLibrary>)self
                         withName:@"fire-db"
                      withVersion:[FIRDatabase sdkVersion]];
}

#pragma mark - FIRComponentRegistrant

+ (NSArray<FIRComponent *> *)componentsToRegister {
  FIRDependency *authDep =
      [FIRDependency dependencyWithProtocol:@protocol(FIRAuthInterop) isRequired:NO];
  FIRComponentCreationBlock creationBlock =
      ^id _Nullable(FIRComponentContainer *container, BOOL *isCacheable) {
        *isCacheable = YES;
        return [[FIRDatabaseComponent alloc] initWithApp:container.app];
      };
  FIRComponent *databaseProvider =
      [FIRComponent componentWithProtocol:@protocol(FIRDatabaseProvider)
                      instantiationTiming:FIRInstantiationTimingLazy
                             dependencies:@[ authDep ]
                            creationBlock:creationBlock];
  return @[ databaseProvider ];
}

#pragma mark - Instance management.

- (void)appWillBeDeleted:(FIRApp *)app {
  NSString *appName = app.name;
  if (appName == nil) {
    return;
  }
  FIRDatabaseDictionary* instances = [self instances];
  @synchronized (instances) {
    // Clean up the deleted instance in an effort to remove any resources still in use.
    // Note: Any leftover instances of this exact database will be invalid.
    for (FIRDatabase * database in [instances allValues]) {
      [FRepoManager disposeRepos:database.config];
    }
    [instances removeAllObjects];
  }
}

#pragma mark - FIRDatabaseProvider Conformance


- (FIRDatabase *)databaseForApp:(FIRApp *)app URL:(NSString *)url {
  if (app == nil) {
    [NSException raise:@"InvalidFIRApp"
                format:@"nil FIRApp instance passed to databaseForApp."];
  }

  if (url == nil) {
    [NSException raise:@"MissingDatabaseURL"
                format:@"Failed to get FirebaseDatabase instance: "
     "Specify DatabaseURL within FIRApp or from your databaseForApp:URL: call."];
  }

  NSURL *databaseUrl = [NSURL URLWithString:url];

  if (databaseUrl == nil) {
    [NSException raise:@"InvalidDatabaseURL" format:@"The Database URL '%@' cannot be parsed. "
     "Specify a valid DatabaseURL within FIRApp or from your databaseForApp:URL: call.", databaseUrl];
  } else if (![databaseUrl.path isEqualToString:@""] && ![databaseUrl.path isEqualToString:@"/"]) {
    [NSException raise:@"InvalidDatabaseURL" format:@"Configured Database URL '%@' is invalid. It should point "
     "to the root of a Firebase Database but it includes a path: %@",databaseUrl, databaseUrl.path];
  }

  FIRDatabaseDictionary *instances = [self instances];
  @synchronized (instances) {
    FParsedUrl *parsedUrl = [FUtilities parseUrl:databaseUrl.absoluteString];
    NSString *urlIndex =
        [NSString stringWithFormat:@"%@:%@", parsedUrl.repoInfo.host, [parsedUrl.path toString]];
    FIRDatabase *database = instances[urlIndex];
    if (!database) {
      id<FAuthTokenProvider> authTokenProvider =
          [FAuthTokenProvider authTokenProviderWithAuth:
              FIR_COMPONENT(FIRAuthInterop, app.container)];

      // If this is the default app, don't set the session persistence key so that we use our
      // default ("default") instead of the FIRApp default ("[DEFAULT]") so that we
      // preserve the default location used by the legacy Firebase SDK.
      NSString *sessionIdentifier = @"default";
      if (![FIRApp isDefaultAppConfigured] || app != [FIRApp defaultApp]) {
        sessionIdentifier = app.name;
      }

      FIRDatabaseConfig *config =
          [[FIRDatabaseConfig alloc]  initWithSessionIdentifier:sessionIdentifier
                                              authTokenProvider:authTokenProvider];
      database = [[FIRDatabase alloc] initWithApp:app
                                         repoInfo:parsedUrl.repoInfo
                                           config:config];
      instances[urlIndex] = database;
    }

    return database;
  }
}

@end

NS_ASSUME_NONNULL_END
