//
//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
//

#import "OWSBlockingManager.h"
#import "AppContext.h"
#import "AppReadiness.h"
#import "NSNotificationCenter+OWS.h"
#import "OWSPrimaryStorage.h"
#import "SSKEnvironment.h"
#import "TSContactThread.h"
#import "TSGroupThread.h"
#import "YapDatabaseConnection+OWS.h"
#import <SessionMessagingKit/SessionMessagingKit-Swift.h>
#import <SessionUtilitiesKit/SessionUtilitiesKit-Swift.h>

NS_ASSUME_NONNULL_BEGIN

NSString *const kNSNotificationName_BlockListDidChange = @"kNSNotificationName_BlockListDidChange";

NSString *const kOWSBlockingManager_BlockListCollection = @"kOWSBlockingManager_BlockedPhoneNumbersCollection";

// These keys are used to persist the current local "block list" state.
NSString *const kOWSBlockingManager_BlockedPhoneNumbersKey = @"kOWSBlockingManager_BlockedPhoneNumbersKey";
NSString *const kOWSBlockingManager_BlockedGroupMapKey = @"kOWSBlockingManager_BlockedGroupMapKey";

// These keys are used to persist the most recently synced remote "block list" state.
NSString *const kOWSBlockingManager_SyncedBlockedPhoneNumbersKey = @"kOWSBlockingManager_SyncedBlockedPhoneNumbersKey";
NSString *const kOWSBlockingManager_SyncedBlockedGroupIdsKey = @"kOWSBlockingManager_SyncedBlockedGroupIdsKey";

@interface OWSBlockingManager ()

@property (nonatomic, readonly) YapDatabaseConnection *dbConnection;

// We don't store the phone numbers as instances of PhoneNumber to avoid
// consistency issues between clients, but these should all be valid e164
// phone numbers.
@property (atomic, readonly) NSMutableSet<NSString *> *blockedPhoneNumberSet;
@property (atomic, readonly) NSMutableDictionary<NSData *, TSGroupModel *> *blockedGroupMap;

@end

#pragma mark -

@implementation OWSBlockingManager

+ (instancetype)sharedManager
{
    return SSKEnvironment.shared.blockingManager;
}

- (instancetype)initWithPrimaryStorage:(OWSPrimaryStorage *)primaryStorage
{
    self = [super init];

    if (!self) {
        return self;
    }

    _dbConnection = primaryStorage.newDatabaseConnection;

    return self;
}

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

- (void)observeNotifications
{
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(applicationDidBecomeActive:)
                                                 name:OWSApplicationDidBecomeActiveNotification
                                               object:nil];
}

#pragma mark -

- (BOOL)isThreadBlocked:(TSThread *)thread
{
    if ([thread isKindOfClass:[TSContactThread class]]) {
        TSContactThread *contactThread = (TSContactThread *)thread;
        return [self isRecipientIdBlocked:contactThread.contactSessionID];
    } else if ([thread isKindOfClass:[TSGroupThread class]]) {
        TSGroupThread *groupThread = (TSGroupThread *)thread;
        return [self isGroupIdBlocked:groupThread.groupModel.groupId];
    } else {
        return NO;
    }
}

#pragma mark - Contact Blocking

- (void)addBlockedPhoneNumber:(NSString *)phoneNumber
{
    @synchronized(self)
    {
        [self ensureLazyInitialization];

        if ([_blockedPhoneNumberSet containsObject:phoneNumber]) {
            // Ignore redundant changes.
            return;
        }

        [_blockedPhoneNumberSet addObject:phoneNumber];
    }

    [self handleUpdate];
}

- (void)removeBlockedPhoneNumber:(NSString *)phoneNumber
{
    @synchronized(self)
    {
        [self ensureLazyInitialization];

        if (![_blockedPhoneNumberSet containsObject:phoneNumber]) {
            // Ignore redundant changes.
            return;
        }

        [_blockedPhoneNumberSet removeObject:phoneNumber];
    }

    [self handleUpdate];
}

- (void)setBlockedPhoneNumbers:(NSArray<NSString *> *)blockedPhoneNumbers sendSyncMessage:(BOOL)sendSyncMessage
{
    @synchronized(self)
    {
        [self ensureLazyInitialization];

        NSSet *newSet = [NSSet setWithArray:blockedPhoneNumbers];
        if ([_blockedPhoneNumberSet isEqualToSet:newSet]) {
            return;
        }

        _blockedPhoneNumberSet = [newSet mutableCopy];
    }

    [self handleUpdate:sendSyncMessage];
}

- (NSArray<NSString *> *)blockedPhoneNumbers
{
    @synchronized(self)
    {
        [self ensureLazyInitialization];

        return [_blockedPhoneNumberSet.allObjects sortedArrayUsingSelector:@selector(compare:)];
    }
}

- (BOOL)isRecipientIdBlocked:(NSString *)recipientId
{
    return [self.blockedPhoneNumbers containsObject:recipientId];
}

#pragma mark - Group Blocking

- (NSArray<NSData *> *)blockedGroupIds
{
    @synchronized(self) {
        [self ensureLazyInitialization];
        return self.blockedGroupMap.allKeys;
    }
}

- (NSArray<TSGroupModel *> *)blockedGroups
{
    @synchronized(self) {
        [self ensureLazyInitialization];
        return self.blockedGroupMap.allValues;
    }
}

- (BOOL)isGroupIdBlocked:(NSData *)groupId
{
    return self.blockedGroupMap[groupId] != nil;
}

- (nullable TSGroupModel *)cachedGroupDetailsWithGroupId:(NSData *)groupId
{
    @synchronized(self) {
        return self.blockedGroupMap[groupId];
    }
}

- (void)addBlockedGroup:(TSGroupModel *)groupModel
{
    NSData *groupId = groupModel.groupId;

    @synchronized(self) {
        [self ensureLazyInitialization];

        if ([self isGroupIdBlocked:groupId]) {
            // Ignore redundant changes.
            return;
        }
        self.blockedGroupMap[groupId] = groupModel;
    }

    [self handleUpdate];
}

- (void)removeBlockedGroupId:(NSData *)groupId
{
    @synchronized(self) {
        [self ensureLazyInitialization];

        if (![self isGroupIdBlocked:groupId]) {
            // Ignore redundant changes.
            return;
        }

        [self.blockedGroupMap removeObjectForKey:groupId];
    }

    [self handleUpdate];
}


#pragma mark - Updates

// This should be called every time the block list changes.

- (void)handleUpdate
{
    // By default, always send a sync message when the block list changes.
    [self handleUpdate:YES];
}

// TODO label the `sendSyncMessage` param
- (void)handleUpdate:(BOOL)sendSyncMessage
{
    NSArray<NSString *> *blockedPhoneNumbers = [self blockedPhoneNumbers];

    [self.dbConnection setObject:blockedPhoneNumbers
                          forKey:kOWSBlockingManager_BlockedPhoneNumbersKey
                    inCollection:kOWSBlockingManager_BlockListCollection];

    NSDictionary *blockedGroupMap;
    @synchronized(self) {
        blockedGroupMap = [self.blockedGroupMap copy];
    }
    NSArray<NSData *> *blockedGroupIds = blockedGroupMap.allKeys;

    [self.dbConnection setObject:blockedGroupMap
                          forKey:kOWSBlockingManager_BlockedGroupMapKey
                    inCollection:kOWSBlockingManager_BlockListCollection];

    // Update the contact blocked state (so sync'ing won't be busted)
    NSMutableArray<SNContact *> *contactsToUpdate = [[NSMutableArray alloc] init];
    
    [[[LKStorage shared] getAllContacts] enumerateObjectsUsingBlock:^(SNContact * _Nonnull obj, BOOL * _Nonnull stop) {
        // If the blocked flag doesn't match then add it to the array to be saved
        BOOL contactInBlockedList = [blockedPhoneNumbers containsObject:obj.sessionID];
        
        if (obj.isBlocked != contactInBlockedList) {
            obj.isBlocked = contactInBlockedList;
            [contactsToUpdate addObject:obj];
        }
    }];
    
    if ([contactsToUpdate count] > 0) {
        [LKStorage writeWithBlock:^(YapDatabaseReadWriteTransaction * _Nonnull transaction) {
            [contactsToUpdate enumerateObjectsUsingBlock:^(SNContact * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
                [[LKStorage shared] setContact:obj usingTransaction:transaction];
            }];
        }];
    }
    
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        if (sendSyncMessage) {
            
        } else {
            // If this update came from an incoming block list sync message,
            // update the "synced blocked list" state immediately,
            // since we're now in sync.
            //
            // There could be data loss if both clients modify the block list
            // at the same time, but:
            //
            // a) Block list changes will be rare.
            // b) Conflicting block list changes will be even rarer.
            // c) It's unlikely a user will make conflicting changes on two
            //    devices around the same time.
            // d) There isn't a good way to avoid this.
            [self saveSyncedBlockListWithPhoneNumbers:blockedPhoneNumbers groupIds:blockedGroupIds];
        }

        [[NSNotificationCenter defaultCenter] postNotificationNameAsync:kNSNotificationName_BlockListDidChange
                                                                 object:nil
                                                               userInfo:nil];
    });
}

// This method should only be called from within a synchronized block.
- (void)ensureLazyInitialization
{
    if (_blockedPhoneNumberSet) {

        // already loaded
        return;
    }

    NSArray<NSString *> *blockedPhoneNumbers =
        [self.dbConnection objectForKey:kOWSBlockingManager_BlockedPhoneNumbersKey
                           inCollection:kOWSBlockingManager_BlockListCollection];
    _blockedPhoneNumberSet = [[NSMutableSet alloc] initWithArray:(blockedPhoneNumbers ?: [NSArray new])];

    NSDictionary<NSData *, TSGroupModel *> *storedBlockedGroupMap =
        [self.dbConnection objectForKey:kOWSBlockingManager_BlockedGroupMapKey
                           inCollection:kOWSBlockingManager_BlockListCollection];
    if ([storedBlockedGroupMap isKindOfClass:[NSDictionary class]]) {
        _blockedGroupMap = [storedBlockedGroupMap mutableCopy];
    } else {
        _blockedGroupMap = [NSMutableDictionary new];
    }

    [self observeNotifications];
}

/// Records the last block list which we successfully synced.
- (void)saveSyncedBlockListWithPhoneNumbers:(NSArray<NSString *> *)blockedPhoneNumbers
                                   groupIds:(NSArray<NSData *> *)blockedGroupIds
{
    [self.dbConnection setObject:blockedPhoneNumbers
                          forKey:kOWSBlockingManager_SyncedBlockedPhoneNumbersKey
                    inCollection:kOWSBlockingManager_BlockListCollection];

    [self.dbConnection setObject:blockedGroupIds
                          forKey:kOWSBlockingManager_SyncedBlockedGroupIdsKey
                    inCollection:kOWSBlockingManager_BlockListCollection];
}

#pragma mark - Notifications

- (void)applicationDidBecomeActive:(NSNotification *)notification
{
    
}

@end

NS_ASSUME_NONNULL_END