session-ios/SignalServiceKit/src/Messages/Interactions/TSMessage.m

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

#import "TSMessage.h"
#import "AppContext.h"
#import "NSDate+OWS.h"
#import "NSString+SSK.h"
#import "TSAttachment.h"
#import "TSAttachmentPointer.h"
#import "TSThread.h"
#import <YapDatabase/YapDatabase.h>
#import <YapDatabase/YapDatabaseTransaction.h>

NS_ASSUME_NONNULL_BEGIN

static const NSUInteger OWSMessageSchemaVersion = 4;

@interface TSMessage ()

@property (nonatomic, nullable) NSString *body;
@property (nonatomic) uint32_t expiresInSeconds;
@property (nonatomic) uint64_t expireStartedAt;

/**
 * The version of the model class's schema last used to serialize this model. Use this to manage data migrations during
 * object de/serialization.
 *
 * e.g.
 *
 *    - (id)initWithCoder:(NSCoder *)coder
 *    {
 *      self = [super initWithCoder:coder];
 *      if (!self) { return self; }
 *      if (_schemaVersion < 2) {
 *        _newName = [coder decodeObjectForKey:@"oldName"]
 *      }
 *      ...
 *      _schemaVersion = 2;
 *    }
 */
@property (nonatomic, readonly) NSUInteger schemaVersion;

// The timestamp property is populated by the envelope,
// which is created by the sender.
//
// We typically want to order messages locally by when
// they were received & decrypted, not by when they were sent.
@property (nonatomic) uint64_t receivedAtTimestamp;

@end

#pragma mark -

@implementation TSMessage

- (instancetype)initWithTimestamp:(uint64_t)timestamp
{
    return [self initWithTimestamp:timestamp inThread:nil messageBody:nil];
}

- (instancetype)initWithTimestamp:(uint64_t)timestamp inThread:(nullable TSThread *)thread
{
    return [self initWithTimestamp:timestamp inThread:thread messageBody:nil attachmentIds:@[]];
}

- (instancetype)initWithTimestamp:(uint64_t)timestamp
                         inThread:(nullable TSThread *)thread
                      messageBody:(nullable NSString *)body
{
    return [self initWithTimestamp:timestamp inThread:thread messageBody:body attachmentIds:@[]];
}

- (instancetype)initWithTimestamp:(uint64_t)timestamp
                         inThread:(nullable TSThread *)thread
                      messageBody:(nullable NSString *)body
                    attachmentIds:(NSArray<NSString *> *)attachmentIds
{
    return [self initWithTimestamp:timestamp
                          inThread:thread
                       messageBody:body
                     attachmentIds:attachmentIds
                  expiresInSeconds:0];
}

- (instancetype)initWithTimestamp:(uint64_t)timestamp
                         inThread:(nullable TSThread *)thread
                      messageBody:(nullable NSString *)body
                    attachmentIds:(NSArray<NSString *> *)attachmentIds
                 expiresInSeconds:(uint32_t)expiresInSeconds
{
    return [self initWithTimestamp:timestamp
                          inThread:thread
                       messageBody:body
                     attachmentIds:attachmentIds
                  expiresInSeconds:expiresInSeconds
                   expireStartedAt:0];
}

- (instancetype)initWithTimestamp:(uint64_t)timestamp
                         inThread:(nullable TSThread *)thread
                      messageBody:(nullable NSString *)body
                    attachmentIds:(NSArray<NSString *> *)attachmentIds
                 expiresInSeconds:(uint32_t)expiresInSeconds
                  expireStartedAt:(uint64_t)expireStartedAt
{
    self = [super initWithTimestamp:timestamp inThread:thread];

    if (!self) {
        return self;
    }

    _schemaVersion = OWSMessageSchemaVersion;

    _body = body;
    _attachmentIds = attachmentIds ? [attachmentIds mutableCopy] : [NSMutableArray new];
    _expiresInSeconds = expiresInSeconds;
    _expireStartedAt = expireStartedAt;
    [self updateExpiresAt];
    _receivedAtTimestamp = [NSDate ows_millisecondTimeStamp];

    return self;
}

- (nullable instancetype)initWithCoder:(NSCoder *)coder
{
    self = [super initWithCoder:coder];
    if (!self) {
        return self;
    }

    if (_schemaVersion < 2) {
        // renamed _attachments to _attachmentIds
        if (!_attachmentIds) {
            _attachmentIds = [coder decodeObjectForKey:@"attachments"];
        }
    }

    if (_schemaVersion < 3) {
        _expiresInSeconds = 0;
        _expireStartedAt = 0;
        _expiresAt = 0;
    }

    if (_schemaVersion < 4) {
        // Wipe out the body field on these legacy attachment messages.
        //
        // Explantion: Historically, a message sent from iOS could be an attachment XOR a text message,
        // but now we support sending an attachment+caption as a single message.
        //
        // Other clients have supported sending attachment+caption in a single message for a long time.
        // So the way we used to handle receiving them was to make it look like they'd sent two messages:
        // first the attachment+caption (we'd ignore this caption when rendering), followed by a separate
        // message with just the caption (which we'd render as a simple independent text message), for
        // which we'd offset the timestamp by a little bit to get the desired ordering.
        //
        // Now that we can properly render an attachment+caption message together, these legacy "dummy" text
        // messages are not only unnecessary, but worse, would be rendered redundantly. For safety, rather
        // than building the logic to try to find and delete the redundant "dummy" text messages which users
        // have been seeing and interacting with, we delete the body field from the attachment message,
        // which iOS users have never seen directly.
        if (_attachmentIds.count > 0) {
            _body = nil;
        }
    }

    if (!_attachmentIds) {
        _attachmentIds = [NSMutableArray new];
    }

    if (_receivedAtTimestamp == 0) {
        // Upgrade from the older "receivedAtDate" and "receivedAt" properties if
        // necessary.
        NSDate *receivedAtDate = [coder decodeObjectForKey:@"receivedAtDate"];
        if (!receivedAtDate) {
            receivedAtDate = [coder decodeObjectForKey:@"receivedAt"];
        }
        if (receivedAtDate) {
            _receivedAtTimestamp = [NSDate ows_millisecondsSince1970ForDate:receivedAtDate];
        }
    }

    _schemaVersion = OWSMessageSchemaVersion;

    return self;
}

- (void)setExpiresInSeconds:(uint32_t)expiresInSeconds
{
    _expiresInSeconds = expiresInSeconds;
    [self updateExpiresAt];
}

- (void)setExpireStartedAt:(uint64_t)expireStartedAt
{
    _expireStartedAt = expireStartedAt;
    [self updateExpiresAt];
}

- (BOOL)shouldStartExpireTimer
{
    __block BOOL result;
    [self.dbReadConnection readWithBlock:^(YapDatabaseReadTransaction *_Nonnull transaction) {
        result = [self shouldStartExpireTimer:transaction];
    }];
    return result;
}

- (BOOL)shouldStartExpireTimer:(YapDatabaseReadTransaction *)transaction
{
    return self.isExpiringMessage;
}

// TODO a downloaded media doesn't start counting until download is complete.
- (void)updateExpiresAt
{
    if (_expiresInSeconds > 0 && _expireStartedAt > 0) {
        _expiresAt = _expireStartedAt + _expiresInSeconds * 1000;
    } else {
        _expiresAt = 0;
    }
}

- (BOOL)hasAttachments
{
    return self.attachmentIds ? (self.attachmentIds.count > 0) : NO;
}

- (nullable TSAttachment *)attachmentWithTransaction:(YapDatabaseReadTransaction *)transaction
{
    if (!self.hasAttachments) {
        return nil;
    }

    OWSAssert(self.attachmentIds.count == 1);
    return [TSAttachment fetchObjectWithUniqueID:self.attachmentIds.firstObject transaction:transaction];
}

- (NSString *)debugDescription
{
    if ([self hasAttachments] && self.body.length > 0) {
        NSString *attachmentId = self.attachmentIds[0];
        return [NSString
            stringWithFormat:@"Media Message with attachmentId: %@ and caption: '%@'", attachmentId, self.body];
    } else if ([self hasAttachments]) {
        NSString *attachmentId = self.attachmentIds[0];
        return [NSString stringWithFormat:@"Media Message with attachmentId:%@", attachmentId];
    } else {
        return [NSString stringWithFormat:@"%@ with body: %@", [self class], self.body];
    }
}

// TODO: This method contains view-specific logic and probably belongs in NotificationsManager, not in SSK.
- (NSString *)previewTextWithTransaction:(YapDatabaseReadTransaction *)transaction
{
    NSString *_Nullable attachmentDescription = nil;
    if ([self hasAttachments]) {
        NSString *attachmentId = self.attachmentIds[0];
        TSAttachment *attachment = [TSAttachment fetchObjectWithUniqueID:attachmentId transaction:transaction];
        if (attachment) {
            attachmentDescription = attachment.description;
        } else {
            attachmentDescription = NSLocalizedString(@"UNKNOWN_ATTACHMENT_LABEL",
                @"In Inbox view, last message label for thread with corrupted attachment.");
        }
    }

    NSString *_Nullable bodyDescription = nil;
    if (self.body.length > 0) {
        // TODO: Filter this text using something like DisplayableText.
        bodyDescription = self.body;
    }

    if (attachmentDescription.length > 0 && bodyDescription.length > 0) {
        // Attachment with caption.
        if ([CurrentAppContext() isRTL]) {
            return [[bodyDescription stringByAppendingString:@": "] stringByAppendingString:attachmentDescription];
        } else {
            return [[attachmentDescription stringByAppendingString:@": "] stringByAppendingString:bodyDescription];
        }
    } else if (bodyDescription.length > 0) {
        return bodyDescription;
    } else if (attachmentDescription.length > 0) {
        return attachmentDescription;
    } else {
        OWSFail(@"%@ message has neither body nor attachment.", self.logTag);
        // TODO: We should do better here.
        return @"";
    }
}

// TODO deprecate this and implement something like previewTextWithTransaction: for all TSInteractions
- (NSString *)description
{
    __block NSString *result;
    [self.dbReadConnection readWithBlock:^(YapDatabaseReadTransaction *transaction) {
        result = [self previewTextWithTransaction:transaction];
    }];
    return result;
}

- (void)removeWithTransaction:(YapDatabaseReadWriteTransaction *)transaction
{
    [super removeWithTransaction:transaction];

    for (NSString *attachmentId in self.attachmentIds) {
        TSAttachment *attachment = [TSAttachment fetchObjectWithUniqueID:attachmentId transaction:transaction];
        [attachment removeWithTransaction:transaction];
    };

    // Updates inbox thread preview
    [self touchThreadWithTransaction:transaction];
}

- (void)touchThreadWithTransaction:(YapDatabaseReadWriteTransaction *)transaction
{
    [transaction touchObjectForKey:self.uniqueThreadId inCollection:[TSThread collection]];
}

- (BOOL)isExpiringMessage
{
    return self.expiresInSeconds > 0;
}

- (uint64_t)timestampForSorting
{
    if ([self shouldUseReceiptDateForSorting] && self.receivedAtTimestamp > 0) {
        return self.receivedAtTimestamp;
    } else {
        OWSAssert(self.timestamp > 0);
        return self.timestamp;
    }
}

- (BOOL)shouldUseReceiptDateForSorting
{
    return YES;
}

- (nullable NSString *)body
{
    return _body.filterStringForDisplay;
}

#pragma mark - Update With... Methods

- (void)updateWithExpireStartedAt:(uint64_t)expireStartedAt transaction:(YapDatabaseReadWriteTransaction *)transaction
{
    OWSAssert(expireStartedAt > 0);

    [self applyChangeToSelfAndLatestCopy:transaction
                             changeBlock:^(TSMessage *message) {
                                 [message setExpireStartedAt:expireStartedAt];
                             }];
}

@end

NS_ASSUME_NONNULL_END