MessagesVC: Paging and fix scrolling bug.

Reviewed-by: @FredericJacobs

Signal.xcodeproj/project.pbxproj

@@ -505,6 +505,7 @@
 		FC4FA0331A1D46AE00DA100A /* InitialViewController.m in Sources */ = {isa = PBXBuildFile; fileRef = FC4FA0321A1D46AE00DA100A /* InitialViewController.m */; };
 		FC5CDF391A3393DD00B47253 /* error_white@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = FC5CDF371A3393DD00B47253 /* error_white@2x.png */; };
 		FC5CDF3A1A3393DD00B47253 /* warning_white@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = FC5CDF381A3393DD00B47253 /* warning_white@2x.png */; };
+		FC7C7A961A581AF40091823B /* TSAdapterCacheManager.m in Sources */ = {isa = PBXBuildFile; fileRef = FC7C7A951A581AF40091823B /* TSAdapterCacheManager.m */; };
 		FC9120411A39EFB70074545C /* qr@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = FC91203F1A39EFB70074545C /* qr@2x.png */; };
 		FC9120431A39F9E00074545C /* qr_scan_fingerprint@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = FC9120421A39F9E00074545C /* qr_scan_fingerprint@2x.png */; };
 		FCA52AE61A2B676C00CCADFA /* call_canceled@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = FCA52ADE1A2B676C00CCADFA /* call_canceled@2x.png */; };
@@ -1211,6 +1212,8 @@
 		FC4FA0321A1D46AE00DA100A /* InitialViewController.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = InitialViewController.m; sourceTree = "<group>"; };
 		FC5CDF371A3393DD00B47253 /* error_white@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "error_white@2x.png"; sourceTree = "<group>"; };
 		FC5CDF381A3393DD00B47253 /* warning_white@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "warning_white@2x.png"; sourceTree = "<group>"; };
+		FC7C7A941A581AF40091823B /* TSAdapterCacheManager.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = TSAdapterCacheManager.h; sourceTree = "<group>"; };
+		FC7C7A951A581AF40091823B /* TSAdapterCacheManager.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = TSAdapterCacheManager.m; sourceTree = "<group>"; };
 		FC91203F1A39EFB70074545C /* qr@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "qr@2x.png"; sourceTree = "<group>"; };
 		FC9120421A39F9E00074545C /* qr_scan_fingerprint@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "qr_scan_fingerprint@2x.png"; sourceTree = "<group>"; };
 		FCA52ADE1A2B676C00CCADFA /* call_canceled@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "call_canceled@2x.png"; sourceTree = "<group>"; };
@@ -1833,6 +1836,8 @@
 				76EB04FD18170B33006006FC /* Zid.m */,
 				FCC81A961A44558300DFEC7D /* UIDevice+TSHardwareVersion.h */,
 				FCC81A971A44558300DFEC7D /* UIDevice+TSHardwareVersion.m */,
+				FC7C7A941A581AF40091823B /* TSAdapterCacheManager.h */,
+				FC7C7A951A581AF40091823B /* TSAdapterCacheManager.m */,
 			);
 			path = util;
 			sourceTree = "<group>";
@@ -3272,6 +3277,7 @@
 				7038632718F70C0700D4A43F /* CryptoTools.m in Sources */,
 				76EB058C18170B33006006FC /* DnsManager.m in Sources */,
 				B63AF5CB1A1F757900D01AAD /* TSRegisterPrekeysRequest.m in Sources */,
+				FC7C7A961A581AF40091823B /* TSAdapterCacheManager.m in Sources */,
 				B6FAAAE81A41BC6C007FEC1D /* TSAttachmentPointer.m in Sources */,
 				B6B096881A1D25ED008BFAA6 /* TSStorageManager+keyFromIntLong.m in Sources */,
 				B6B50AAB1A4192C500F8F607 /* TSMessagesManager+attachments.m in Sources */,

Signal/src/util/TSAdapterCacheManager.h

@@ -0,0 +1,27 @@
+//
+//  TSAdapterCacheManager.h
+//  Signal
+//
+//  Created by Dylan Bourgeois on 03/01/15.
+//  Copyright (c) 2015 Open Whisper Systems. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+@class TSMessageAdapter;
+
+@interface TSAdapterCacheManager : NSObject  {
+    NSCache * messageAdaptersCache;
+}
+
+@property (nonatomic, retain) NSCache *messageAdaptersCache;
+
++ (id)sharedManager;
+
+- (void)cacheAdapter:(TSMessageAdapter*)adapter forInteractionId:(NSString*)identifier;
+- (void)clearCacheEntryForInteractionId:(NSString*)identifier;
+- (TSMessageAdapter*)adapterForInteractionId:(NSString*)identifier;
+- (BOOL)containsCacheEntryForInteractionId:(NSString*)identifier;
+
+
+@end

Signal/src/util/TSAdapterCacheManager.m

@@ -0,0 +1,58 @@
+//
+//  TSAdapterCacheManager.m
+//  Signal
+//
+//  Created by Dylan Bourgeois on 03/01/15.
+//  Copyright (c) 2015 Open Whisper Systems. All rights reserved.
+//
+
+#import "TSAdapterCacheManager.h"
+#import "TSMessageAdapter.h"
+
+@implementation TSAdapterCacheManager
+
+@synthesize messageAdaptersCache;
+
++ (id)sharedManager {
+    static TSAdapterCacheManager *sharedManager = nil;
+    static dispatch_once_t onceToken;
+    
+    dispatch_once(&onceToken, ^{
+        sharedManager = [[self alloc] init];
+    });
+    
+    return sharedManager;
+}
+
+- (id)init {
+    if (self = [super init]) {
+        messageAdaptersCache = [[NSCache alloc]init];
+    }
+    return self;
+}
+
+- (void)cacheAdapter:(TSMessageAdapter*)adapter forInteractionId:(NSString*)identifier
+{
+    NSParameterAssert(adapter);
+    NSParameterAssert(identifier);
+    [messageAdaptersCache setObject:adapter forKey:identifier];
+}
+
+-(void)clearCacheEntryForInteractionId:(NSString*)identifier
+{
+    NSParameterAssert(identifier);
+    [messageAdaptersCache removeObjectForKey:identifier];
+}
+
+-(TSMessageAdapter*)adapterForInteractionId:(NSString*)identifier
+{
+    NSParameterAssert(identifier);
+    return [messageAdaptersCache objectForKey:identifier];
+}
+
+-(BOOL)containsCacheEntryForInteractionId:(NSString*)identifier
+{
+    return [messageAdaptersCache objectForKey:identifier] != nil;
+}
+
+@end

Signal/src/view controllers/MessagesViewController.m

@@ -54,6 +54,12 @@
 #import "ContactsManager.h"
 #import "PreferencesUtil.h"
 
+#import "TSAdapterCacheManager.h"
+
+#define kYapDatabaseRangeLength 50
+#define kYapDatabaseRangeMaxLength 300
+#define kYapDatabaseRangeMinLength 20
+
 static NSTimeInterval const kTSMessageSentDateShowTimeInterval = 5 * 60;
 static NSString *const kUpdateGroupSegueIdentifier = @"updateGroupSegue";
 static NSString *const kFingerprintSegueIdentifier = @"fingerprintSegue";
@@ -82,6 +88,8 @@ typedef enum : NSUInteger {
 
 @property (nonatomic, retain) NSIndexPath *lastDeliveredMessageIndexPath;
 
+@property NSUInteger page;
+
 @end
 
 @implementation MessagesViewController
@@ -115,6 +123,7 @@ typedef enum : NSUInteger {
 
 - (void)viewDidLoad {
     [super viewDidLoad];
+    
     [self markAllMessagesAsRead];
     
     [self initializeBubbles];
@@ -122,14 +131,17 @@ typedef enum : NSUInteger {
     self.messageMappings = [[YapDatabaseViewMappings alloc] initWithGroups:@[self.thread.uniqueId]
                                                                       view:TSMessageDatabaseViewExtensionName];
     
+    self.page = 0;
+    
+    [self updateRangeOptionsForPage:self.page];
+    
     [self.uiDatabaseConnection readWithBlock:^(YapDatabaseReadTransaction *transaction) {
         [self.messageMappings updateWithTransaction:transaction];
     }];
-    
+
     [self initializeToolbars];
     [self initializeCollectionViewLayout];
     
-    
     self.senderId          = ME_MESSAGE_IDENTIFIER
     self.senderDisplayName = ME_MESSAGE_IDENTIFIER
     
@@ -142,8 +154,10 @@ typedef enum : NSUInteger {
 -(void)viewWillAppear:(BOOL)animated
 {
     [super viewWillAppear:animated];
-    self.automaticallyScrollsToMostRecentMessage = YES;
+    
-    [self scrollToBottomAnimated:NO];
+    NSIndexPath * lastCellIndexPath = [NSIndexPath indexPathForRow:(NSInteger)[self.messageMappings numberOfItemsInGroup:self.thread.uniqueId]-1 inSection:0];
+    [self.collectionView scrollToItemAtIndexPath:lastCellIndexPath atScrollPosition:UICollectionViewScrollPositionBottom animated:NO];
+
 }
 
 - (void)startReadTimer{
@@ -157,7 +171,6 @@ typedef enum : NSUInteger {
 - (void)viewDidAppear:(BOOL)animated{
     [super viewDidAppear:animated];
     [self startReadTimer];
-    [self scrollToBottomAnimated:YES];
 }
 
 - (void)viewWillDisappear:(BOOL)animated{
@@ -219,7 +232,7 @@ typedef enum : NSUInteger {
         self.collectionView.showsVerticalScrollIndicator = NO;
         self.collectionView.showsHorizontalScrollIndicator = NO;
         
-        self.automaticallyScrollsToMostRecentMessage = NO;
+        [self updateLoadEarlierVisible];
         
         self.collectionView.collectionViewLayout.incomingAvatarViewSize = CGSizeZero;
         self.collectionView.collectionViewLayout.outgoingAvatarViewSize = CGSizeZero;
@@ -426,7 +439,7 @@ typedef enum : NSUInteger {
 
 -(BOOL)shouldShowMessageStatusAtIndexPath:(NSIndexPath*)indexPath
 {
-    
+
     TSMessageAdapter *currentMessage = [self messageAtIndexPath:indexPath];
     if([self.thread isKindOfClass:[TSGroupThread class]]) {
         return currentMessage.messageType == TSIncomingMessageAdapter;
@@ -513,8 +526,7 @@ typedef enum : NSUInteger {
 {
     TSMessageAdapter *messageItem = [collectionView.dataSource collectionView:collectionView messageDataForItemAtIndexPath:indexPath];
     TSInteraction    *interaction = [self interactionAtIndexPath:indexPath];
-    
+
-    
     switch (messageItem.messageType) {
         case TSOutgoingMessageAdapter:
             if (messageItem.messageState == TSOutgoingMessageStateUnsent) {
@@ -558,6 +570,81 @@ typedef enum : NSUInteger {
     }
 }
 
+-(void)collectionView:(JSQMessagesCollectionView *)collectionView header:(JSQMessagesLoadEarlierHeaderView *)headerView didTapLoadEarlierMessagesButton:(UIButton *)sender
+{
+    if ([self shouldShowLoadEarlierMessages]) {
+        self.page++;
+    }
+    
+    NSInteger item = (NSInteger)[self scrollToItem];
+    
+    [self updateRangeOptionsForPage:self.page];
+    
+    [self.uiDatabaseConnection readWithBlock:^(YapDatabaseReadTransaction *transaction) {
+        [self.messageMappings updateWithTransaction:transaction];
+    }];
+    
+    [self updateLayoutForEarlierMessagesWithOffset:item];
+    
+}
+
+-(BOOL)shouldShowLoadEarlierMessages
+{
+    __block BOOL show = YES;
+    
+    [self.uiDatabaseConnection readWithBlock:^(YapDatabaseReadTransaction *transaction){
+        show = [self.messageMappings numberOfItemsInGroup:self.thread.uniqueId] < [[transaction ext:TSMessageDatabaseViewExtensionName] numberOfItemsInGroup:self.thread.uniqueId];
+    }];
+
+    return show;
+}
+
+-(NSUInteger)scrollToItem
+{
+    __block NSUInteger item = kYapDatabaseRangeLength*(self.page+1) - [self.messageMappings numberOfItemsInGroup:self.thread.uniqueId];
+    
+    [self.uiDatabaseConnection readWithBlock:^(YapDatabaseReadTransaction *transaction) {
+        
+        NSUInteger numberOfVisibleMessages = [self.messageMappings numberOfItemsInGroup:self.thread.uniqueId] ;
+        NSUInteger numberOfTotalMessages = [[transaction ext:TSMessageDatabaseViewExtensionName] numberOfItemsInGroup:self.thread.uniqueId] ;
+        NSUInteger numberOfMessagesToLoad =  numberOfTotalMessages - numberOfVisibleMessages ;
+        
+        BOOL canLoadFullRange = numberOfMessagesToLoad >= kYapDatabaseRangeLength;
+        
+        if (!canLoadFullRange) {
+            item = numberOfMessagesToLoad;
+        }
+    }];
+    
+    return item == 0 ? item : item - 1;
+}
+
+-(void)updateLoadEarlierVisible
+{
+    [self setShowLoadEarlierMessagesHeader:[self shouldShowLoadEarlierMessages]];
+}
+
+-(void)updateLayoutForEarlierMessagesWithOffset:(NSInteger)offset
+{
+    [self.collectionView.collectionViewLayout invalidateLayoutWithContext:[JSQMessagesCollectionViewFlowLayoutInvalidationContext context]];
+    [self.collectionView reloadData];
+    
+    [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:offset inSection:0] atScrollPosition:UICollectionViewScrollPositionTop animated:NO];
+    
+    [self updateLoadEarlierVisible];
+}
+
+-(void)updateRangeOptionsForPage:(NSUInteger)page
+{
+    YapDatabaseViewRangeOptions *rangeOptions = [YapDatabaseViewRangeOptions flexibleRangeWithLength:kYapDatabaseRangeLength*(page+1) offset:0 from:YapDatabaseViewEnd];
+    
+    rangeOptions.maxLength = kYapDatabaseRangeMaxLength;
+    rangeOptions.minLength = kYapDatabaseRangeMinLength;
+    
+    [self.messageMappings setRangeOptions:rangeOptions forGroup:self.thread.uniqueId];
+
+}
+
 #pragma mark Bubble User Actions
 
 - (void)handleUnsentMessageTap:(TSOutgoingMessage*)message{
@@ -823,48 +910,65 @@ typedef enum : NSUInteger {
                                                                          forNotifications:notifications
                                                                              withMappings:self.messageMappings];
     
+    __block BOOL containsInsertion = NO;
+    
     if (!messageRowChanges) {
         return;
     }
     
-    
     [self.collectionView performBatchUpdates:^{
-        
+
         for (YapDatabaseViewRowChange *rowChange in messageRowChanges)
         {
             switch (rowChange.type)
             {
                 case YapDatabaseViewChangeDelete :
                 {
+                    TSInteraction * interaction = [self interactionAtIndexPath:rowChange.indexPath];
+                    [[TSAdapterCacheManager sharedManager] clearCacheEntryForInteractionId:interaction.uniqueId];
                     [self.collectionView deleteItemsAtIndexPaths:@[ rowChange.indexPath ]];
                     break;
                 }
                 case YapDatabaseViewChangeInsert :
                 {
+                    TSInteraction * interaction = [self interactionAtIndexPath:rowChange.newIndexPath];
+                    [[TSAdapterCacheManager sharedManager] cacheAdapter:[TSMessageAdapter messageViewDataWithInteraction:interaction inThread:self.thread] forInteractionId:interaction.uniqueId];
                     [self.collectionView insertItemsAtIndexPaths:@[ rowChange.newIndexPath ]];
+                    containsInsertion = YES;
                     break;
                 }
                 case YapDatabaseViewChangeMove :
                 {
-                    [self.collectionView deleteItemsAtIndexPaths:@[ rowChange.indexPath]];
+                    [self.collectionView deleteItemsAtIndexPaths:@[ rowChange.indexPath ]];
-                    [self.collectionView insertItemsAtIndexPaths:@[ rowChange.newIndexPath]];
+                    [self.collectionView insertItemsAtIndexPaths:@[ rowChange.newIndexPath ]];
                     break;
                 }
                 case YapDatabaseViewChangeUpdate :
                 {
                     NSMutableArray *rowsToUpdate = [@[rowChange.indexPath] mutableCopy];
+
                     if (_lastDeliveredMessageIndexPath) {
                         [rowsToUpdate addObject:_lastDeliveredMessageIndexPath];
                     }
                     
+                    for (NSIndexPath* indexPath in rowsToUpdate) {
+                        TSInteraction * interaction = [self interactionAtIndexPath:indexPath];
+                        [[TSAdapterCacheManager sharedManager] cacheAdapter:[TSMessageAdapter messageViewDataWithInteraction:interaction inThread:self.thread] forInteractionId:interaction.uniqueId];
+                    }
+                    
                     [self.collectionView reloadItemsAtIndexPaths:rowsToUpdate];
                     break;
                 }
             }
         }
-        
+    } completion:^(BOOL success) {
-    } completion:^(BOOL finished) {
+        if (success) {
-        [self scrollToBottomAnimated:YES];
+            [self.collectionView.collectionViewLayout invalidateLayoutWithContext:[JSQMessagesCollectionViewFlowLayoutInvalidationContext context]];
+            [self.collectionView reloadData];
+        }
+        if (containsInsertion) {
+            [self scrollToBottomAnimated:YES];
+        }
     }];
 }
 
@@ -897,8 +1001,16 @@ typedef enum : NSUInteger {
 
 - (TSMessageAdapter*)messageAtIndexPath:(NSIndexPath *)indexPath {
     TSInteraction *interaction = [self interactionAtIndexPath:indexPath];
-    return [TSMessageAdapter messageViewDataWithInteraction:interaction inThread:self.thread];
+    TSAdapterCacheManager * manager = [TSAdapterCacheManager sharedManager];
+    
+    if (![manager containsCacheEntryForInteractionId:interaction.uniqueId]) {
+        [manager cacheAdapter:[TSMessageAdapter messageViewDataWithInteraction:interaction inThread:self.thread] forInteractionId:interaction.uniqueId];
+    }
+    
+    return [manager adapterForInteractionId:interaction.uniqueId];
 }
+
+
 #pragma mark group action view
 -(void)didPressGroupMenuButton:(UIButton *)sender
 {