//
// Copyright (c) 2019 Google Inc.
//
// 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 "MainViewController.h"
#import "NSDate+Format.h"
#import "UITextView+Placeholder.h"
@import Firebase;
@import MaterialComponents;

NS_ASSUME_NONNULL_BEGIN

@interface UIView (Constraints)
- (void)addConstraintsWithFormat:(NSString *)format views:(NSArray<UIView *> *)views;
@end

@implementation UIView (Constraints)
- (void)addConstraintsWithFormat:(NSString *)format views:(NSArray<UIView *> *)views {
 NSMutableDictionary *viewsDictionary = [[NSMutableDictionary alloc] initWithCapacity:views.count];
 for (int i = 0; i < views.count; i++) {
 UIView *view = views[i];
 NSString *key = [NSString stringWithFormat:@"v%d", i];
 view.translatesAutoresizingMaskIntoConstraints = false;
 viewsDictionary[key] = view;
 }
 [self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:format
 options:0
 metrics:nil
 views:viewsDictionary]];
}
@end

@interface MainViewController ()
@property(strong, nonatomic) NSMutableArray<FIRTextMessage *> *messages;
@property(nonatomic) BOOL isLocalUser;
@property(strong, nonatomic) NSLayoutConstraint *bottomConstraint;
@property(strong, nonatomic) NSLayoutConstraint *heightConstraint;
@property(strong, nonatomic) NSLayoutConstraint *inputBottomConstraint;
@property(strong, nonatomic) NSLayoutConstraint *sendBottomConstraint;
@property(nonatomic) BOOL isKeyboardShown;
@property(strong, nonatomic) UIView *messageInputContainerView;

@property(strong, nonatomic) FIRSmartReply *smartReply;

@property(nonatomic) CGFloat bottomAreaInset;

@property(strong, nonatomic) UITextView *inputTextView;
@property(strong, nonatomic) UIStackView *smartReplyView;
@property(strong, nonatomic) UILabel *updatedLabel;
@property(strong, nonatomic) MDCFloatingButton *sendButton;
@property(nonatomic, strong) UIAlertController *moreAlert;
@end

@implementation MainViewController

- (UIAlertController *)moreAlert {
 if (_moreAlert == nil) {
 _moreAlert = [UIAlertController alertControllerWithTitle:nil
 message:nil
 preferredStyle:UIAlertControllerStyleActionSheet];
 [_moreAlert addAction:[UIAlertAction actionWithTitle:@"Generate basic history"
 style:UIAlertActionStyleDefault
 handler:^(UIAlertAction *action) {
 [self generateChatHistoryBasic];
 }]];
 [_moreAlert addAction:[UIAlertAction actionWithTitle:@"Generate history with sensitive content"
 style:UIAlertActionStyleDefault
 handler:^(UIAlertAction *action) {
 [self generateChatHistoryWithSensitiveContent];
 }]];
 [_moreAlert addAction:[UIAlertAction actionWithTitle:@"Clear chat history"
 style:UIAlertActionStyleDestructive
 handler:^(UIAlertAction *action) {
 self.messages = [NSMutableArray new];
 [self updateReplies];
 [self.collectionView reloadData];
 }]];
 [_moreAlert addAction:[UIAlertAction actionWithTitle:@"Cancel"
 style:UIAlertActionStyleCancel
 handler:nil]];
 }
 return _moreAlert;
}

- (void)viewDidLoad {
 [super viewDidLoad];
 self.messages = [NSMutableArray new];
 self.isLocalUser = YES;
 self.messageInputContainerView = [UIView new];
 _messageInputContainerView.backgroundColor = UIColor.whiteColor;
 self.smartReply = [[FIRNaturalLanguage naturalLanguage] smartReply];
 self.bottomAreaInset = 0;
 self.inputTextView = [[UITextView alloc] initWithPlaceholder:@"Write a message"];
 _inputTextView.font = [UIFont preferredFontForTextStyle:UIFontTextStyleCallout];
 _inputTextView.scrollEnabled = NO;
 self.smartReplyView = [UIStackView new];
 _smartReplyView.distribution = UIStackViewDistributionEqualSpacing;


 for (int i = 0; i < 3; i++) {
 MDCChipView *chipView = [MDCChipView new];
 chipView.hidden = YES;
 [chipView setTitleColor:UIColor.redColor forState:UIControlStateSelected];
 NSLayoutConstraint *widthConstraint = [chipView.widthAnchor constraintEqualToConstant:0];
 widthConstraint.identifier = @"width";
 widthConstraint.active = YES;
 [chipView addTarget:self
 action:@selector(replySelected:)
 forControlEvents:UIControlEventTouchUpInside];
 [_smartReplyView addArrangedSubview:chipView];
 }


 self.sendButton = [[MDCFloatingButton alloc] initWithFrame:CGRectNull
 shape:MDCFloatingButtonShapeMini];
 [_sendButton setImage:[UIImage imageNamed:@"ic_send"] forState:UIControlStateNormal];
 _sendButton.tintColor = UIColor.blueColor;
 _sendButton.backgroundColor = UIColor.whiteColor;
 _sendButton.accessibilityLabel = @"Send";
 _sendButton.enabled = NO;
 [_sendButton addTarget:self
 action:@selector(enterPressed)
 forControlEvents:UIControlEventTouchUpInside];

 self.navigationController.navigationBar.barTintColor = UIColor.blueColor;
 [self.collectionView registerClass:MDCSelfSizingStereoCell.class
 forCellWithReuseIdentifier:@"cell"];
 if (@available(iOS 11, *)) {
 _bottomAreaInset = UIApplication.sharedApplication.keyWindow.safeAreaInsets.bottom;
 }
 self.isKeyboardShown = NO;

 _inputTextView.delegate = self;
 [NSNotificationCenter.defaultCenter addObserver:self
 selector:@selector(handleKeyboardNotification:)
 name:UIKeyboardWillShowNotification
 object:nil];
 [NSNotificationCenter.defaultCenter addObserver:self
 selector:@selector(handleKeyboardNotification:)
 name:UIKeyboardWillHideNotification
 object:nil];
 ((UICollectionViewFlowLayout *)self.collectionViewLayout).estimatedItemSize =
 CGSizeMake(self.collectionView.bounds.size.width, 52);
 [self.view addSubview:_messageInputContainerView];
 [self.view addConstraintsWithFormat:@"H:|[v0]|" views:@[ _messageInputContainerView ]];
 self.heightConstraint =
 [_messageInputContainerView.heightAnchor constraintEqualToConstant:88 + _bottomAreaInset];
 self.bottomConstraint = [NSLayoutConstraint constraintWithItem:_messageInputContainerView
 attribute:NSLayoutAttributeBottom
 relatedBy:NSLayoutRelationEqual
 toItem:self.view
 attribute:NSLayoutAttributeBottom
 multiplier:1
 constant:0];
 [self.view addConstraint:_bottomConstraint];
 [self.view addConstraint:_heightConstraint];
 [self setupInputComponents];
}

- (void)setupInputComponents {
 UIView *topBorderView = [UIView new];
 topBorderView.backgroundColor = [UIColor colorWithWhite:0.5 alpha:0.5];
 [_messageInputContainerView addSubview:_inputTextView];
 [_messageInputContainerView addSubview:_sendButton];
 [_messageInputContainerView addSubview:topBorderView];
 [_messageInputContainerView addSubview:_smartReplyView];

 [_messageInputContainerView addConstraintsWithFormat:@"H:|-8-[v0][v1(40)]-16-|"
 views:@[ _inputTextView, _sendButton ]];
 [_messageInputContainerView addConstraintsWithFormat:@"H:|[v0]|" views:@[ topBorderView ]];
 [_messageInputContainerView addConstraintsWithFormat:@"H:|-16-[v0]-16-|" views:@[ _smartReplyView ]];

 [_smartReplyView.topAnchor constraintEqualToAnchor:_messageInputContainerView.topAnchor
 constant:6]
 .active = YES;
 [_smartReplyView.bottomAnchor constraintEqualToAnchor:_inputTextView.topAnchor constant:-6]
 .active = YES;

 self.inputBottomConstraint =
 [_messageInputContainerView.bottomAnchor constraintEqualToAnchor:_inputTextView.bottomAnchor
 constant:_bottomAreaInset];
 _inputBottomConstraint.active = YES;

 self.sendBottomConstraint =
 [_messageInputContainerView.bottomAnchor constraintEqualToAnchor:_sendButton.bottomAnchor
 constant:_bottomAreaInset + 6];
 _sendBottomConstraint.active = YES;

 [_messageInputContainerView addConstraintsWithFormat:@"V:|[v0(0.5)]" views:@[ topBorderView ]];
}

- (void)viewWillAppear:(BOOL)animated {
 [super viewWillAppear:animated];
 [_inputTextView becomeFirstResponder];
}

- (void)viewWillDisappear:(BOOL)animated {
 [_inputTextView endEditing:YES];
 [super viewWillDisappear:animated];
}

- (void)enterPressed {
 NSString *text = _inputTextView.text;
 if (text.length > 0) {
 FIRTextMessage *message =
 [[FIRTextMessage alloc] initWithText:text
 timestamp:[NSDate date].timeIntervalSince1970
 userID:@""
 isLocalUser:_isLocalUser];
 [_messages addObject:message];
 [self.collectionView
 insertItemsAtIndexPaths:@[ [NSIndexPath indexPathForItem:_messages.count - 1
 inSection:0] ]];
 _inputTextView.text = nil;
 [_inputTextView textViewDidChange:_inputTextView];
 [self clearChips];
 }
 [_inputTextView endEditing:YES];
}

- (IBAction)didTapMore:(UIBarButtonItem *)sender {
 self.moreAlert.popoverPresentationController.barButtonItem = sender;
 [self presentViewController:self.moreAlert animated:YES completion:nil];
}

- (void)clearChips {
 for (UIView *view in self.smartReplyView.arrangedSubviews) {
 view.hidden = YES;
 }
}

- (void)updateReplies {
 // SmartReply for users' own messages is a non-use-case.
 FIRTextMessage *lastMessage = _messages.lastObject;
 if (lastMessage == nil || lastMessage.isLocalUser == _isLocalUser) {
 [self clearChips];
 return;
 }
 
 NSMutableArray<FIRTextMessage *> *chat = _messages;

 // Revert isLocalUser field in text messages to simulate the remote user for the sample.
 if (!_isLocalUser) {
 chat = [[NSMutableArray alloc] initWithCapacity:10];
 for (int i = (_messages.count <= 10 ? 0 : _messages.count - 10); i < _messages.count; i++) {
 FIRTextMessage *textMessage = _messages[i];
 textMessage = [[FIRTextMessage alloc] initWithText:textMessage.text
 timestamp:textMessage.timestamp
 userID:textMessage.userID
 isLocalUser:!textMessage.isLocalUser];
 [chat addObject:textMessage];
 }
 }

 [_smartReply
 suggestRepliesForMessages:chat
 completion:^(FIRSmartReplySuggestionResult *_Nullable result,
 NSError *_Nullable error) {
 if (error != nil || result == nil || result.suggestions.count == 0) {
 [self clearChips];
 return;
 }
 for (int i = 0; i < 3; i++) {
 MDCChipView *chip = self.smartReplyView.arrangedSubviews[i];
 chip.titleLabel.text = result.suggestions[i].text;
 [chip sizeToFit];
 chip.hidden = NO;
 for (NSLayoutConstraint *constraint in chip.constraints) {
 if ([constraint.identifier isEqualToString:@"width"]) {
 constraint.constant = chip.bounds.size.width;
 break;
 }
 }
 }
 }];
}

- (void)handleKeyboardNotification:(NSNotification *)notification {
 CGRect keyboardSize =
 ((NSValue *)notification.userInfo[UIKeyboardFrameEndUserInfoKey]).CGRectValue;
 BOOL isKeyboardShowing = notification.name == UIKeyboardWillShowNotification;
 if (_isKeyboardShown == isKeyboardShowing) {
 _bottomConstraint.constant = isKeyboardShowing ? -keyboardSize.size.height : 0;
 if (self.messages.count > 0) {
 NSIndexPath *indexPath = [NSIndexPath indexPathForItem:self.messages.count - 1
 inSection:0];
 [self.collectionView scrollToItemAtIndexPath:indexPath
 atScrollPosition:UICollectionViewScrollPositionTop
 animated:YES];
 }
 return;
 }
 _isKeyboardShown = isKeyboardShowing;
 _bottomConstraint.constant = isKeyboardShowing ? -keyboardSize.size.height : 0;
 double inset = isKeyboardShowing ? -_bottomAreaInset : _bottomAreaInset;
 _heightConstraint.constant += inset;
 _inputBottomConstraint.constant = isKeyboardShowing ? 0 : _bottomAreaInset;
 _sendBottomConstraint.constant = isKeyboardShowing ? 6 : (6 + _bottomAreaInset);
 NSTimeInterval animationDuration =
 ((NSNumber *)notification.userInfo[UIKeyboardAnimationDurationUserInfoKey]).doubleValue;
 [UIView animateWithDuration:animationDuration
 delay:0
 options:UIViewAnimationOptionCurveEaseOut
 animations:^{
 [self.view layoutIfNeeded];
 }
 completion:^(BOOL finished) {
 if (self.messages.count > 0) {
 NSIndexPath *indexPath = [NSIndexPath indexPathForItem:self.messages.count - 1
 inSection:0];
 [self.collectionView scrollToItemAtIndexPath:indexPath
 atScrollPosition:UICollectionViewScrollPositionTop
 animated:YES];
 }
 }];
}

- (void)textViewDidBeginEditing:(UITextView *)textView {
 [self textViewDidChange:textView];
}

- (void)collectionView:(UICollectionView *)collectionView
 didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
 [_inputTextView endEditing:YES];
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
 cellForItemAtIndexPath:(NSIndexPath *)indexPath {
 MDCSelfSizingStereoCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cell"
 forIndexPath:indexPath];
 FIRTextMessage *item = _messages[indexPath.item];
 cell.leadingImageView.image = [UIImage imageNamed:@"ic_account_circle_36pt"];
 cell.leadingImageView.tintColor = item.isLocalUser ? UIColor.blueColor : UIColor.redColor;
 cell.titleLabel.text = item.text;
 cell.detailLabel.text = [[NSDate dateWithTimeIntervalSince1970:item.timestamp] timeAgo];
 return cell;
}

- (void)replySelected:(MDCChipView *)reply {
 [_inputTextView insertText:reply.titleLabel.text];
}

- (IBAction)switchUser:(id)sender {
 self.isLocalUser = !_isLocalUser;
 UIColor *color = _isLocalUser ? UIColor.blueColor : UIColor.redColor;
 _sendButton.tintColor = color;
 self.navigationController.navigationBar.barTintColor = color;
 [self updateReplies];
}

- (void)generateChatHistoryBasic {
 NSDate *date = [NSCalendar.currentCalendar dateByAddingUnit:NSCalendarUnitDay
 value:-1
 toDate:[NSDate date]
 options:0];
 NSTimeInterval dateAfter = [NSCalendar.currentCalendar dateByAddingUnit:NSCalendarUnitMinute
 value:10
 toDate:date
 options:0]
 .timeIntervalSince1970;
 _messages =
 @[
 [[FIRTextMessage alloc] initWithText:@"Hello"
 timestamp:date.timeIntervalSince1970
 userID:@""
 isLocalUser:YES],
 [[FIRTextMessage alloc] initWithText:@"Hey" timestamp:dateAfter userID:@"" isLocalUser:NO]
 ]
 .mutableCopy;
 [self updateReplies];
 [self.collectionView reloadData];
}

- (void)generateChatHistoryWithSensitiveContent {
 NSDate *date = [NSCalendar.currentCalendar dateByAddingUnit:NSCalendarUnitDay
 value:-1
 toDate:[NSDate date]
 options:0];
 NSTimeInterval dateAfter = [NSCalendar.currentCalendar dateByAddingUnit:NSCalendarUnitMinute
 value:10
 toDate:date
 options:0]
 .timeIntervalSince1970;
 NSTimeInterval dateAfterAfter = [NSCalendar.currentCalendar dateByAddingUnit:NSCalendarUnitMinute
 value:20
 toDate:date
 options:0]
 .timeIntervalSince1970;
 _messages =
 @[
 [[FIRTextMessage alloc] initWithText:@"Hi"
 timestamp:date.timeIntervalSince1970
 userID:@""
 isLocalUser:NO],
 [[FIRTextMessage alloc] initWithText:@"How are you?"
 timestamp:dateAfter
 userID:@""
 isLocalUser:YES],
 [[FIRTextMessage alloc] initWithText:@"My cat died"
 timestamp:dateAfterAfter
 userID:@""
 isLocalUser:NO]
 ]
 .mutableCopy;
 [self updateReplies];
 [self.collectionView reloadData];
}

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
 return 1;
}

- (void)textViewDidEndEditing:(UITextView *)textView {
 _sendButton.enabled = NO;
 _heightConstraint.constant = 88 + _bottomAreaInset;
}

- (void)textViewDidChange:(UITextView *)textView {
 _sendButton.enabled = textView.text.length != 0;
 CGSize size = CGSizeMake(self.view.frame.size.width - 60, INFINITY);
 CGSize estimatedSize = [textView sizeThatFits:size];
 _heightConstraint.constant =
 estimatedSize.height + 54 + (self.isKeyboardShown ? 0 : _bottomAreaInset);
}

- (NSInteger)collectionView:(UICollectionView *)collectionView
 numberOfItemsInSection:(NSInteger)section {
 return _messages.count;
}

@end

NS_ASSUME_NONNULL_END