/*
 * Copyright 2017 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 <Foundation/Foundation.h>

#import <FirebaseCore/FIRAppInternal.h>
#import <FirebaseCore/FIRLogger.h>

#import "FIRDatabase.h"
#import "FIRDatabase_Private.h"
#import "FIRDatabaseQuery_Private.h"
#import "FRepoManager.h"
#import "FValidation.h"
#import "FIRDatabaseConfig_Private.h"
#import "FRepoInfo.h"
#import "FIRDatabaseConfig.h"
#import "FIRDatabaseReference_Private.h"
#import <FirebaseCore/FIROptions.h>

@interface FIRDatabase ()
@property (nonatomic, strong) FRepoInfo *repoInfo;
@property (nonatomic, strong) FIRDatabaseConfig *config;
@property (nonatomic, strong) FRepo *repo;
@end

@implementation FIRDatabase

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

// The STR and STR_EXPAND macro allow a numeric version passed to he compiler driver
// with a -D to be treated as a string instead of an invalid floating point value.
#define STR(x) STR_EXPAND(x)
#define STR_EXPAND(x) #x
static const char *FIREBASE_SEMVER = (const char *)STR(FIRDatabase_VERSION);

+ (void)load {
  NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
  [center addObserverForName:kFIRAppDeleteNotification
                      object:nil
                       queue:nil
                  usingBlock:^(NSNotification * _Nonnull note) {
      NSString *appName = note.userInfo[kFIRAppNameKey];
      if (appName == nil) { return; }

      FIRDatabaseDictionary* instances = [self instances];
      @synchronized (instances) {
          NSMutableDictionary<FRepoInfo *, FIRDatabase *> *databaseInstances = instances[appName];
          if (databaseInstances) {
              // 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 [databaseInstances allValues]) {
                  [FRepoManager disposeRepos:database.config];
              }
              [instances removeObjectForKey:appName];
          }
      }
  }];
}

/**
 * A static NSMutableDictionary of FirebaseApp name and FRepoInfo to
 * FirebaseDatabase instance. To ensure thread-safety, it should only be
 * accessed in databaseForApp:URL:, which is synchronized.
 *
 * TODO: This serves a duplicate purpose as RepoManager.  We should clean up.
 * TODO: We should maybe be conscious of leaks and make this a weak map or
 * similar but we have a lot of work to do to allow FirebaseDatabase/Repo etc.
 * to be GC'd.
 */
+ (FIRDatabaseDictionary *)instances {
    static dispatch_once_t pred = 0;
    static FIRDatabaseDictionary *instances;
    dispatch_once(&pred, ^{
        instances = [NSMutableDictionary dictionary];
    });
    return instances;
}

+ (FIRDatabase *)database {
    if (![FIRApp isDefaultAppConfigured]) {
        [NSException raise:@"FIRAppNotConfigured"
                    format:@"Failed to get default Firebase Database instance. Must call `[FIRApp "
                           @"configure]` (`FirebaseApp.configure()` in Swift) before using "
                           @"Firebase Database."];
    }
    FIRApp *app = [FIRApp defaultApp];
    return [FIRDatabase databaseForApp:app];
}

+ (FIRDatabase *)databaseWithURL:(NSString *)url {
    FIRApp *app = [FIRApp defaultApp];
    if (app == nil) {
        [NSException raise:@"FIRAppNotConfigured"
                    format:@"Failed to get default Firebase Database instance. "
                           @"Must call `[FIRApp configure]` (`FirebaseApp.configure()` in Swift) "
                           @"before using Firebase Database."];
    }
    return [FIRDatabase databaseForApp:app URL:url];
}

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

    return [FIRDatabase databaseForApp:app URL:app.options.databaseURL];
}

+ (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) {
        NSMutableDictionary<FRepoInfo *, FIRDatabase *> *urlInstanceMap =
            instances[app.name];
        if (!urlInstanceMap) {
            urlInstanceMap = [NSMutableDictionary dictionary];
            instances[app.name] = urlInstanceMap;
        }

        FParsedUrl *parsedUrl = [FUtilities parseUrl:databaseUrl.absoluteString];
        FIRDatabase *database = urlInstanceMap[parsedUrl.repoInfo];
        if (!database) {
            id<FAuthTokenProvider> authTokenProvider = [FAuthTokenProvider authTokenProviderForApp:app];

            // 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];
            urlInstanceMap[parsedUrl.repoInfo] = database;
        }

        return database;
    }
}

+ (NSString *) buildVersion {
    // TODO: Restore git hash when build moves back to git
    return [NSString stringWithFormat:@"%s_%s", FIREBASE_SEMVER, __DATE__];
}

+ (FIRDatabase *)createDatabaseForTests:(FRepoInfo *)repoInfo config:(FIRDatabaseConfig *)config {
    FIRDatabase *db = [[FIRDatabase alloc] initWithApp:nil repoInfo:repoInfo config:config];
    [db ensureRepo];
    return db;
}


+ (NSString *) sdkVersion {
    return [NSString stringWithUTF8String:FIREBASE_SEMVER];
}

+ (void) setLoggingEnabled:(BOOL)enabled {
    [FUtilities setLoggingEnabled:enabled];
    FFLog(@"I-RDB024001", @"BUILD Version: %@", [FIRDatabase buildVersion]);
}


- (id)initWithApp:(FIRApp *)app repoInfo:(FRepoInfo *)info config:(FIRDatabaseConfig *)config {
    self = [super init];
    if (self != nil) {
        self->_repoInfo = info;
        self->_config = config;
        self->_app = app;
    }
    return self;
}

- (FIRDatabaseReference *)reference {
    [self ensureRepo];

    return [[FIRDatabaseReference alloc] initWithRepo:self.repo path:[FPath empty]];
}

- (FIRDatabaseReference *)referenceWithPath:(NSString *)path {
    [self ensureRepo];

    [FValidation validateFrom:@"referenceWithPath" validRootPathString:path];
    FPath *childPath = [[FPath alloc] initWith:path];
    return [[FIRDatabaseReference alloc] initWithRepo:self.repo path:childPath];
}

- (FIRDatabaseReference *)referenceFromURL:(NSString *)databaseUrl {
    [self ensureRepo];

    if (databaseUrl == nil) {
        [NSException raise:@"InvalidDatabaseURL" format:@"Invalid nil url passed to referenceFromURL:"];
    }
    FParsedUrl *parsedUrl = [FUtilities parseUrl:databaseUrl];
    [FValidation validateFrom:@"referenceFromURL:" validURL:parsedUrl];
    if (![parsedUrl.repoInfo.host isEqualToString:_repoInfo.host]) {
        [NSException raise:@"InvalidDatabaseURL" format:@"Invalid URL (%@) passed to getReference(). URL was expected "
            "to match configured Database URL: %@", databaseUrl, [self reference].URL];
    }
    return [[FIRDatabaseReference alloc] initWithRepo:self.repo path:parsedUrl.path];
}


- (void)purgeOutstandingWrites {
    [self ensureRepo];

    dispatch_async([FIRDatabaseQuery sharedQueue], ^{
        [self.repo purgeOutstandingWrites];
    });
}

- (void)goOnline {
    [self ensureRepo];

    dispatch_async([FIRDatabaseQuery sharedQueue], ^{
        [self.repo resume];
    });
}

- (void)goOffline {
    [self ensureRepo];

    dispatch_async([FIRDatabaseQuery sharedQueue], ^{
        [self.repo interrupt];
    });
}

- (void)setPersistenceEnabled:(BOOL)persistenceEnabled {
    [self assertUnfrozen:@"setPersistenceEnabled"];
    self->_config.persistenceEnabled = persistenceEnabled;
}

- (BOOL)persistenceEnabled {
    return self->_config.persistenceEnabled;
}

- (void)setPersistenceCacheSizeBytes:(NSUInteger)persistenceCacheSizeBytes {
    [self assertUnfrozen:@"setPersistenceCacheSizeBytes"];
    self->_config.persistenceCacheSizeBytes = persistenceCacheSizeBytes;
}

- (NSUInteger)persistenceCacheSizeBytes {
    return self->_config.persistenceCacheSizeBytes;
}

- (void)setCallbackQueue:(dispatch_queue_t)callbackQueue {
    [self assertUnfrozen:@"setCallbackQueue"];
    self->_config.callbackQueue = callbackQueue;
}

- (dispatch_queue_t)callbackQueue {
    return self->_config.callbackQueue;
}

- (void) assertUnfrozen:(NSString*)methodName {
    if (self.repo != nil) {
        [NSException raise:@"FIRDatabaseAlreadyInUse" format:@"Calls to %@ must be made before any other usage of "
                "FIRDatabase instance.", methodName];
    }
}

- (void) ensureRepo {
    if (self.repo == nil) {
        self.repo = [FRepoManager createRepo:self.repoInfo config:self.config database:self];
    }
}

@end