//
//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
//

#import "OWSFailedMessagesJob.h"
#import "TSMessage.h"
#import "TSOutgoingMessage.h"
#import "TSStorageManager.h"
#import <YapDatabase/YapDatabaseConnection.h>
#import <YapDatabase/YapDatabaseQuery.h>
#import <YapDatabase/YapDatabaseSecondaryIndex.h>

NS_ASSUME_NONNULL_BEGIN

static NSString *const OWSFailedMessagesJobMessageStateColumn = @"message_state";
static NSString *const OWSFailedMessagesJobMessageStateIndex = @"index_outoing_messages_on_message_state";

@interface OWSFailedMessagesJob ()

@property (nonatomic, readonly) TSStorageManager *storageManager;

@end

@implementation OWSFailedMessagesJob

- (instancetype)initWithStorageManager:(TSStorageManager *)storageManager
{
    self = [super init];
    if (!self) {
        return self;
    }

    _storageManager = storageManager;

    return self;
}

- (NSArray<NSString *> *)fetchAttemptingOutMessageIds:(YapDatabaseConnection *)dbConnection
{
    NSMutableArray<NSString *> *messageIds = [NSMutableArray new];

    NSString *formattedString = [NSString stringWithFormat:@"WHERE %@ == %d",
                                          OWSFailedMessagesJobMessageStateColumn,
                                          (int)TSOutgoingMessageStateAttemptingOut];
    YapDatabaseQuery *query = [YapDatabaseQuery queryWithFormat:formattedString];
    [dbConnection readWithBlock:^(YapDatabaseReadTransaction *_Nonnull transaction) {
        [[transaction ext:OWSFailedMessagesJobMessageStateIndex]
            enumerateKeysMatchingQuery:query
                            usingBlock:^void(NSString *collection, NSString *key, BOOL *stop) {
                                [messageIds addObject:key];
                            }];
    }];

    return [messageIds copy];
}

- (void)enumerateAttemptingOutMessagesWithBlock:(void (^_Nonnull)(TSOutgoingMessage *message))block
{
    YapDatabaseConnection *dbConnection = [self.storageManager newDatabaseConnection];

    // Since we can't directly mutate the enumerated "attempting out" expired messages, we store only their ids in hopes
    // of saving a little memory and then enumerate the (larger) TSMessage objects one at a time.
    for (NSString *expiredMessageId in [self fetchAttemptingOutMessageIds:dbConnection]) {
        TSOutgoingMessage *_Nullable message = [TSOutgoingMessage fetchObjectWithUniqueID:expiredMessageId];
        if ([message isKindOfClass:[TSOutgoingMessage class]]) {
            block(message);
        } else {
            DDLogError(@"%@ unexpected object: %@", self.tag, message);
        }
    }
}

- (void)run
{
    __block uint count = 0;
    [self enumerateAttemptingOutMessagesWithBlock:^(TSOutgoingMessage *message) {
        // sanity check
        OWSAssert(message.messageState == TSOutgoingMessageStateAttemptingOut);
        if (message.messageState != TSOutgoingMessageStateAttemptingOut) {
            DDLogError(@"%@ Refusing to mark as unsent message with state: %d", self.tag, (int)message.messageState);
            return;
        }

        DDLogDebug(@"%@ marking message as unsent", self.tag);
        message.messageState = TSOutgoingMessageStateUnsent;
        [message save];
        count++;
    }];

    DDLogDebug(@"%@ Marked %u messages as unsent", self.tag, count);
}

#pragma mark - YapDatabaseExtension

- (YapDatabaseSecondaryIndex *)indexDatabaseExtension
{
    YapDatabaseSecondaryIndexSetup *setup = [YapDatabaseSecondaryIndexSetup new];
    [setup addColumn:OWSFailedMessagesJobMessageStateColumn withType:YapDatabaseSecondaryIndexTypeInteger];

    YapDatabaseSecondaryIndexHandler *handler =
        [YapDatabaseSecondaryIndexHandler withObjectBlock:^(YapDatabaseReadTransaction *transaction,
            NSMutableDictionary *dict,
            NSString *collection,
            NSString *key,
            id object) {
            if (![object isKindOfClass:[TSOutgoingMessage class]]) {
                return;
            }
            TSOutgoingMessage *message = (TSOutgoingMessage *)object;

            dict[OWSFailedMessagesJobMessageStateColumn] = @(message.messageState);
        }];

    return [[YapDatabaseSecondaryIndex alloc] initWithSetup:setup handler:handler];
}

// Useful for tests, don't use in app startup path because it's slow.
- (void)blockingRegisterDatabaseExtensions
{
    [self.storageManager.database registerExtension:[self indexDatabaseExtension]
                                           withName:OWSFailedMessagesJobMessageStateIndex];
}

- (void)asyncRegisterDatabaseExtensions
{
    [self.storageManager.database asyncRegisterExtension:[self indexDatabaseExtension]
                                                withName:OWSFailedMessagesJobMessageStateIndex
                                         completionBlock:^(BOOL ready) {
                                             if (ready) {
                                                 DDLogDebug(@"%@ completed registering extension async.", self.tag);
                                             } else {
                                                 DDLogError(@"%@ failed registering extension async.", self.tag);
                                             }
                                         }];
}

#pragma mark - Logging

+ (NSString *)tag
{
    return [NSString stringWithFormat:@"[%@]", self.class];
}

- (NSString *)tag
{
    return self.class.tag;
}

@end

NS_ASSUME_NONNULL_END