//
//  AVSettingsView.m
//  AVDemo
//

#import "AVSettingsView.h"
#import "AVConstants.h"

@interface AVSettingsView () <UITextFieldDelegate>
@property (nonatomic, copy) AVSettingsViewCallback callback;
@property (nonatomic, strong) AVVideoConfiguration *tempConfig;
@property (nonatomic, assign) AVSettingsFieldMask fieldsMask;

@property (nonatomic, strong) UIView *containerView;
@property (nonatomic, strong) UIScrollView *scrollView;
@property (nonatomic, strong) UIView *contentView;
@property (nonatomic, strong) UITextField *streamIdField;
@property (nonatomic, strong) UITextField *nicknameField;
@property (nonatomic, strong) UISegmentedControl *codecSegment;
@property (nonatomic, strong) UISegmentedControl *resolutionSegment;
@property (nonatomic, strong) UITextField *fpsField;
@property (nonatomic, strong) UITextField *maxBitrateField;
@property (nonatomic, strong) UITextField *minBitrateField;

@property (nonatomic, strong) NSLayoutConstraint *containerCenterYConstraint;
@property (nonatomic, weak) UITextField *activeTextField; // 当前激活的输入框
@end

@implementation AVSettingsView

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        // UI will be setup when showing
        
        // 监听键盘通知
        [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(keyboardWillShow:)
                                                     name:UIKeyboardWillShowNotification
                                                   object:nil];
        [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(keyboardWillHide:)
                                                     name:UIKeyboardWillHideNotification
                                                   object:nil];
    }
    return self;
}

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

- (void)setupUI {
    self.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.5];

    // 在方法开始时统一计算屏幕尺寸和方向，避免重复定义
    CGFloat screenHeight = CGRectGetHeight([UIScreen mainScreen].bounds);
    CGFloat screenWidth = CGRectGetWidth([UIScreen mainScreen].bounds);
    BOOL isLandscape = screenWidth > screenHeight;

    _containerView = [[UIView alloc] init];
    _containerView.backgroundColor = [UIColor systemBackgroundColor];
    _containerView.layer.cornerRadius = 12;
    _containerView.layer.masksToBounds = YES;
    [self addSubview:_containerView];

    _containerView.translatesAutoresizingMaskIntoConstraints = NO;
    _containerCenterYConstraint = [_containerView.centerYAnchor constraintEqualToAnchor:self.centerYAnchor];
    
    // 根据屏幕方向动态调整容器高度
    CGFloat maxHeight = isLandscape ? (screenHeight * 0.85) : 600; // 横屏时使用屏幕高度的85%
    
    [NSLayoutConstraint activateConstraints:@[
        [_containerView.leadingAnchor constraintEqualToAnchor:self.leadingAnchor constant:20],
        [_containerView.trailingAnchor constraintEqualToAnchor:self.trailingAnchor constant:-20],
        _containerCenterYConstraint,
        [_containerView.heightAnchor constraintLessThanOrEqualToConstant:maxHeight]
    ]];

    // Add dismiss button
    UIButton *dismissButton = [UIButton buttonWithType:UIButtonTypeSystem];
    [dismissButton setTitle:@"×" forState:UIControlStateNormal];
    dismissButton.titleLabel.font = [UIFont systemFontOfSize:30];
    [dismissButton addTarget:self action:@selector(dismiss) forControlEvents:UIControlEventTouchUpInside];
    [_containerView addSubview:dismissButton];

    dismissButton.translatesAutoresizingMaskIntoConstraints = NO;
    [NSLayoutConstraint activateConstraints:@[
        [dismissButton.topAnchor constraintEqualToAnchor:_containerView.topAnchor constant:10],
        [dismissButton.trailingAnchor constraintEqualToAnchor:_containerView.trailingAnchor constant:-10],
        [dismissButton.widthAnchor constraintEqualToConstant:44],
        [dismissButton.heightAnchor constraintEqualToConstant:44]
    ]];

    // Title
    UILabel *titleLabel = [[UILabel alloc] init];
    titleLabel.text = @"设置";
    titleLabel.font = [UIFont systemFontOfSize:20 weight:UIFontWeightBold];
    [_containerView addSubview:titleLabel];

    titleLabel.translatesAutoresizingMaskIntoConstraints = NO;
    [NSLayoutConstraint activateConstraints:@[
        [titleLabel.topAnchor constraintEqualToAnchor:_containerView.topAnchor constant:20],
        [titleLabel.centerXAnchor constraintEqualToAnchor:_containerView.centerXAnchor]
    ]];

    UIScrollView *scrollView = [[UIScrollView alloc] init];
    scrollView.keyboardDismissMode = UIScrollViewKeyboardDismissModeInteractive; // 允许滑动关闭键盘
    [_containerView addSubview:scrollView];
    _scrollView = scrollView;

    // 动态调整 scrollView 和按钮之间的间距
    CGFloat buttonAreaHeight = isLandscape ? 64 : 80; // 横屏时减小按钮区域高度
    
    scrollView.translatesAutoresizingMaskIntoConstraints = NO;
    [NSLayoutConstraint activateConstraints:@[
        [scrollView.topAnchor constraintEqualToAnchor:titleLabel.bottomAnchor constant:20],
        [scrollView.leadingAnchor constraintEqualToAnchor:_containerView.leadingAnchor],
        [scrollView.trailingAnchor constraintEqualToAnchor:_containerView.trailingAnchor],
        [scrollView.bottomAnchor constraintEqualToAnchor:_containerView.bottomAnchor constant:-buttonAreaHeight]
    ]];

    UIView *contentView = [[UIView alloc] init];
    [scrollView addSubview:contentView];
    _contentView = contentView; // 保存引用

    contentView.translatesAutoresizingMaskIntoConstraints = NO;
    [NSLayoutConstraint activateConstraints:@[
        [contentView.topAnchor constraintEqualToAnchor:scrollView.topAnchor],
        [contentView.leadingAnchor constraintEqualToAnchor:scrollView.leadingAnchor],
        [contentView.trailingAnchor constraintEqualToAnchor:scrollView.trailingAnchor],
        [contentView.bottomAnchor constraintEqualToAnchor:scrollView.bottomAnchor],
        [contentView.widthAnchor constraintEqualToAnchor:scrollView.widthAnchor]
    ]];

    // Add form elements (similar to settings VC)
    CGFloat topOffset = 10;
    CGFloat spacing = 20;

    // Stream ID (conditional)
    if (self.fieldsMask & AVSettingsFieldStreamId) {
        UILabel *streamIdLabel = [[UILabel alloc] init];
        streamIdLabel.text = @"Stream ID";
        streamIdLabel.font = [UIFont systemFontOfSize:14 weight:UIFontWeightMedium];
        [contentView addSubview:streamIdLabel];
        streamIdLabel.translatesAutoresizingMaskIntoConstraints = NO;
        [NSLayoutConstraint activateConstraints:@[
            [streamIdLabel.leadingAnchor constraintEqualToAnchor:contentView.leadingAnchor constant:20],
            [streamIdLabel.topAnchor constraintEqualToAnchor:contentView.topAnchor constant:topOffset]
        ]];
        topOffset += 20;

        _streamIdField = [[UITextField alloc] init];
        _streamIdField.placeholder = @"请输入Stream ID";
        _streamIdField.borderStyle = UITextBorderStyleRoundedRect;
        _streamIdField.delegate = self;
        _streamIdField.returnKeyType = UIReturnKeyDone;
        [contentView addSubview:_streamIdField];
        _streamIdField.translatesAutoresizingMaskIntoConstraints = NO;
        [NSLayoutConstraint activateConstraints:@[
            [_streamIdField.leadingAnchor constraintEqualToAnchor:contentView.leadingAnchor constant:20],
            [_streamIdField.trailingAnchor constraintEqualToAnchor:contentView.trailingAnchor constant:-20],
            [_streamIdField.topAnchor constraintEqualToAnchor:contentView.topAnchor constant:topOffset],
            [_streamIdField.heightAnchor constraintEqualToConstant:40]
        ]];
        topOffset += 40 + spacing;
    }

    // Nickname (conditional)
    if (self.fieldsMask & AVSettingsFieldNickname) {
        UILabel *nicknameLabel = [[UILabel alloc] init];
        nicknameLabel.text = @"用户昵称";
        nicknameLabel.font = [UIFont systemFontOfSize:14 weight:UIFontWeightMedium];
        [contentView addSubview:nicknameLabel];
        nicknameLabel.translatesAutoresizingMaskIntoConstraints = NO;
        [NSLayoutConstraint activateConstraints:@[
            [nicknameLabel.leadingAnchor constraintEqualToAnchor:contentView.leadingAnchor constant:20],
            [nicknameLabel.topAnchor constraintEqualToAnchor:contentView.topAnchor constant:topOffset]
        ]];
        topOffset += 20;

        _nicknameField = [[UITextField alloc] init];
        _nicknameField.placeholder = @"请输入昵称";
        _nicknameField.borderStyle = UITextBorderStyleRoundedRect;
        _nicknameField.delegate = self;
        _nicknameField.returnKeyType = UIReturnKeyDone;
        [contentView addSubview:_nicknameField];
        _nicknameField.translatesAutoresizingMaskIntoConstraints = NO;
        [NSLayoutConstraint activateConstraints:@[
            [_nicknameField.leadingAnchor constraintEqualToAnchor:contentView.leadingAnchor constant:20],
            [_nicknameField.trailingAnchor constraintEqualToAnchor:contentView.trailingAnchor constant:-20],
            [_nicknameField.topAnchor constraintEqualToAnchor:contentView.topAnchor constant:topOffset],
            [_nicknameField.heightAnchor constraintEqualToConstant:40]
        ]];
        topOffset += 40 + spacing;
    }

    // Video parameters (conditional)
    if (self.fieldsMask & AVSettingsFieldVideoParams) {
        // Resolution
        UILabel *resolutionLabel = [[UILabel alloc] init];
        resolutionLabel.text = @"分辨率";
        resolutionLabel.font = [UIFont systemFontOfSize:14 weight:UIFontWeightMedium];
        [contentView addSubview:resolutionLabel];
        resolutionLabel.translatesAutoresizingMaskIntoConstraints = NO;
        [NSLayoutConstraint activateConstraints:@[
            [resolutionLabel.leadingAnchor constraintEqualToAnchor:contentView.leadingAnchor constant:20],
            [resolutionLabel.topAnchor constraintEqualToAnchor:contentView.topAnchor constant:topOffset]
        ]];
        topOffset += 20;

        _resolutionSegment = [[UISegmentedControl alloc] initWithItems:@[@"360p", @"480p", @"540p", @"720p"]];
        [contentView addSubview:_resolutionSegment];
        _resolutionSegment.translatesAutoresizingMaskIntoConstraints = NO;
        [NSLayoutConstraint activateConstraints:@[
            [_resolutionSegment.leadingAnchor constraintEqualToAnchor:contentView.leadingAnchor constant:20],
            [_resolutionSegment.trailingAnchor constraintEqualToAnchor:contentView.trailingAnchor constant:-20],
            [_resolutionSegment.topAnchor constraintEqualToAnchor:contentView.topAnchor constant:topOffset],
            [_resolutionSegment.heightAnchor constraintEqualToConstant:32]
        ]];
        topOffset += 32 + spacing;

        // FPS
        UILabel *fpsLabel = [[UILabel alloc] init];
        fpsLabel.text = @"帧率 (FPS)";
        fpsLabel.font = [UIFont systemFontOfSize:14 weight:UIFontWeightMedium];
        [contentView addSubview:fpsLabel];
        fpsLabel.translatesAutoresizingMaskIntoConstraints = NO;
        [NSLayoutConstraint activateConstraints:@[
            [fpsLabel.leadingAnchor constraintEqualToAnchor:contentView.leadingAnchor constant:20],
            [fpsLabel.topAnchor constraintEqualToAnchor:contentView.topAnchor constant:topOffset]
        ]];
        topOffset += 20;

        _fpsField = [[UITextField alloc] init];
        _fpsField.placeholder = @"例如: 30";
        _fpsField.borderStyle = UITextBorderStyleRoundedRect;
        _fpsField.keyboardType = UIKeyboardTypeNumberPad;
        _fpsField.delegate = self;
        [self addDoneToolbarToTextField:_fpsField];
        [contentView addSubview:_fpsField];
        _fpsField.translatesAutoresizingMaskIntoConstraints = NO;
        [NSLayoutConstraint activateConstraints:@[
            [_fpsField.leadingAnchor constraintEqualToAnchor:contentView.leadingAnchor constant:20],
            [_fpsField.trailingAnchor constraintEqualToAnchor:contentView.trailingAnchor constant:-20],
            [_fpsField.topAnchor constraintEqualToAnchor:contentView.topAnchor constant:topOffset],
            [_fpsField.heightAnchor constraintEqualToConstant:40]
        ]];
        topOffset += 40 + spacing;

        // Max Bitrate
        UILabel *maxBitrateLabel = [[UILabel alloc] init];
        maxBitrateLabel.text = @"最大码率 (kbps)";
        maxBitrateLabel.font = [UIFont systemFontOfSize:14 weight:UIFontWeightMedium];
        [contentView addSubview:maxBitrateLabel];
        maxBitrateLabel.translatesAutoresizingMaskIntoConstraints = NO;
        [NSLayoutConstraint activateConstraints:@[
            [maxBitrateLabel.leadingAnchor constraintEqualToAnchor:contentView.leadingAnchor constant:20],
            [maxBitrateLabel.topAnchor constraintEqualToAnchor:contentView.topAnchor constant:topOffset]
        ]];
        topOffset += 20;

        _maxBitrateField = [[UITextField alloc] init];
        _maxBitrateField.placeholder = @"例如: 2000";
        _maxBitrateField.borderStyle = UITextBorderStyleRoundedRect;
        _maxBitrateField.keyboardType = UIKeyboardTypeNumberPad;
        _maxBitrateField.delegate = self;
        [self addDoneToolbarToTextField:_maxBitrateField];
        [contentView addSubview:_maxBitrateField];
        _maxBitrateField.translatesAutoresizingMaskIntoConstraints = NO;
        [NSLayoutConstraint activateConstraints:@[
            [_maxBitrateField.leadingAnchor constraintEqualToAnchor:contentView.leadingAnchor constant:20],
            [_maxBitrateField.trailingAnchor constraintEqualToAnchor:contentView.trailingAnchor constant:-20],
            [_maxBitrateField.topAnchor constraintEqualToAnchor:contentView.topAnchor constant:topOffset],
            [_maxBitrateField.heightAnchor constraintEqualToConstant:40]
        ]];
        topOffset += 40 + spacing;

        // Min Bitrate
        UILabel *minBitrateLabel = [[UILabel alloc] init];
        minBitrateLabel.text = @"最小码率 (kbps)";
        minBitrateLabel.font = [UIFont systemFontOfSize:14 weight:UIFontWeightMedium];
        [contentView addSubview:minBitrateLabel];
        minBitrateLabel.translatesAutoresizingMaskIntoConstraints = NO;
        [NSLayoutConstraint activateConstraints:@[
            [minBitrateLabel.leadingAnchor constraintEqualToAnchor:contentView.leadingAnchor constant:20],
            [minBitrateLabel.topAnchor constraintEqualToAnchor:contentView.topAnchor constant:topOffset]
        ]];
        topOffset += 20;

        _minBitrateField = [[UITextField alloc] init];
        _minBitrateField.placeholder = @"例如: 500";
        _minBitrateField.borderStyle = UITextBorderStyleRoundedRect;
        _minBitrateField.keyboardType = UIKeyboardTypeNumberPad;
        _minBitrateField.delegate = self;
        [self addDoneToolbarToTextField:_minBitrateField];
        [contentView addSubview:_minBitrateField];
        _minBitrateField.translatesAutoresizingMaskIntoConstraints = NO;
        [NSLayoutConstraint activateConstraints:@[
            [_minBitrateField.leadingAnchor constraintEqualToAnchor:contentView.leadingAnchor constant:20],
            [_minBitrateField.trailingAnchor constraintEqualToAnchor:contentView.trailingAnchor constant:-20],
            [_minBitrateField.topAnchor constraintEqualToAnchor:contentView.topAnchor constant:topOffset],
            [_minBitrateField.heightAnchor constraintEqualToConstant:40]
        ]];
        topOffset += 40 + spacing;
    }  // End of video parameters conditional block

    [NSLayoutConstraint activateConstraints:@[
        [contentView.heightAnchor constraintEqualToConstant:topOffset]
    ]];

    // Buttons
    UIButton *applyButton = [UIButton buttonWithType:UIButtonTypeSystem];
    [applyButton setTitle:@"应用" forState:UIControlStateNormal];
    applyButton.backgroundColor = [UIColor systemBlueColor];
    [applyButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
    applyButton.layer.cornerRadius = 8;
    [applyButton addTarget:self action:@selector(applyTapped) forControlEvents:UIControlEventTouchUpInside];
    [_containerView addSubview:applyButton];

    // 根据屏幕方向动态调整按钮高度和底部间距
    CGFloat buttonHeight = isLandscape ? 36 : 44; // 横屏时按钮更矮
    CGFloat buttonBottomMargin = isLandscape ? 12 : 20; // 横屏时减小底部边距
    
    applyButton.translatesAutoresizingMaskIntoConstraints = NO;
    [NSLayoutConstraint activateConstraints:@[
        [applyButton.leadingAnchor constraintEqualToAnchor:_containerView.leadingAnchor constant:20],
        [applyButton.trailingAnchor constraintEqualToAnchor:_containerView.trailingAnchor constant:-20],
        [applyButton.bottomAnchor constraintEqualToAnchor:_containerView.bottomAnchor constant:-buttonBottomMargin],
        [applyButton.heightAnchor constraintEqualToConstant:buttonHeight]
    ]];

    // Tap to dismiss
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(backgroundTapped:)];
    [self addGestureRecognizer:tap];
}

- (void)showInViewController:(UIViewController *)viewController
                  withConfig:(AVVideoConfiguration *)config
                  fieldsMask:(AVSettingsFieldMask)fieldsMask
                    callback:(AVSettingsViewCallback)callback {
    self.callback = callback;
    self.tempConfig = [config copy];
    self.fieldsMask = fieldsMask;

    // Setup UI now that we have fieldsMask
    [self setupUI];

    // Load config values
    if (_streamIdField) {
        // Generate random streamId if empty or default
        if (config.streamId.length == 0 || [config.streamId isEqualToString:@"stream"]) {
            // Generate random 3-digit number (100-999)
            NSInteger randomNumber = 100 + arc4random_uniform(900);
            _streamIdField.text = [NSString stringWithFormat:@"stream%ld", (long)randomNumber];
            // Update the temp config with the generated streamId
            self.tempConfig.streamId = _streamIdField.text;
        } else {
            _streamIdField.text = config.streamId;
        }
    }
    if (_nicknameField) {
        _nicknameField.text = config.nickname;
    }
    if (_resolutionSegment) {
        _resolutionSegment.selectedSegmentIndex = [config currentResolution];
    }
    if (_fpsField) {
        _fpsField.text = [NSString stringWithFormat:@"%ld", (long)config.videoFrameRate];
    }
    if (_maxBitrateField) {
        _maxBitrateField.text = [NSString stringWithFormat:@"%ld", (long)(config.videoBitRate / 1000)];
    }
    if (_minBitrateField) {
        _minBitrateField.text = [NSString stringWithFormat:@"%ld", (long)(config.videoMinBitRate / 1000)];
    }

    self.frame = viewController.view.bounds;
    self.alpha = 0;
    [viewController.view addSubview:self];

    [UIView animateWithDuration:0.3 animations:^{
        self.alpha = 1.0;
    }];
}

- (void)dismiss {
    [UIView animateWithDuration:0.3 animations:^{
        self.alpha = 0;
    } completion:^(BOOL finished) {
        [self removeFromSuperview];
    }];
}

- (void)applyTapped {
    // Update config with all field values
    if (_streamIdField) {
        self.tempConfig.streamId = _streamIdField.text.length > 0 ? _streamIdField.text : @"";
    }
    if (_nicknameField) {
        self.tempConfig.nickname = _nicknameField.text.length > 0 ? _nicknameField.text : @"test";
    }
    if (_resolutionSegment) {
        [self.tempConfig setResolution:_resolutionSegment.selectedSegmentIndex];
    }
    if (_fpsField) {
        NSInteger fps = [_fpsField.text integerValue];
        // Validate FPS
        if (fps <= 0) {
            fps = 30;
        }
        self.tempConfig.videoFrameRate = fps;
        self.tempConfig.videoMaxKeyframeInterval = fps * 2;
    }
    if (_maxBitrateField) {
        NSInteger maxBitrate = [_maxBitrateField.text integerValue];
        // Validate max bitrate
        if (maxBitrate <= 0) {
            maxBitrate = 2000;
        }
        self.tempConfig.videoBitRate = maxBitrate * 1000; // Convert kbps to bps
    }
    if (_minBitrateField) {
        NSInteger minBitrate = [_minBitrateField.text integerValue];
        // Validate min bitrate
        if (minBitrate <= 0) {
            minBitrate = 500;
        }
        self.tempConfig.videoMinBitRate = minBitrate * 1000; // Convert kbps to bps
    }

    if (self.callback) {
        self.callback(self.tempConfig);
    }

    [self dismiss];
}

- (void)backgroundTapped:(UITapGestureRecognizer *)recognizer {
    CGPoint location = [recognizer locationInView:self];
    if (!CGRectContainsPoint(_containerView.frame, location)) {
        // 点击背景关闭弹窗
        [self dismiss];
    } else {
        // 点击容器内部，收起键盘
        [self endEditing:YES];
    }
}

#pragma mark - Keyboard Handling

- (void)keyboardWillShow:(NSNotification *)notification {
    NSDictionary *userInfo = notification.userInfo;
    CGRect keyboardFrame = [userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
    CGFloat keyboardHeight = keyboardFrame.size.height;
    NSTimeInterval duration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    UIViewAnimationCurve curve = [userInfo[UIKeyboardAnimationCurveUserInfoKey] integerValue];
    
    // 方案：调整 ScrollView 的 contentInset，而不是移动整个容器
    // 计算键盘遮挡的高度
    CGRect containerFrameInWindow = [_containerView convertRect:_containerView.bounds toView:self];
    CGFloat containerBottom = CGRectGetMaxY(containerFrameInWindow);
    CGFloat keyboardTop = CGRectGetHeight(self.bounds) - keyboardHeight;
    CGFloat overlap = containerBottom - keyboardTop;
    
    if (overlap > 0) {
        // 键盘会遮挡容器，调整 scrollView 的 contentInset
        UIEdgeInsets contentInset = _scrollView.contentInset;
        contentInset.bottom = overlap + 20; // 额外留20px边距
        
        [UIView animateWithDuration:duration delay:0 options:(curve << 16) animations:^{
            self.scrollView.contentInset = contentInset;
            self.scrollView.scrollIndicatorInsets = contentInset;
            
            // 如果有激活的输入框，滚动到可见位置
            if (self.activeTextField) {
                [self scrollToTextField:self.activeTextField];
            }
        } completion:nil];
    }
}

- (void)keyboardWillHide:(NSNotification *)notification {
    NSDictionary *userInfo = notification.userInfo;
    NSTimeInterval duration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    UIViewAnimationCurve curve = [userInfo[UIKeyboardAnimationCurveUserInfoKey] integerValue];
    
    // 恢复 scrollView 的 contentInset
    [UIView animateWithDuration:duration delay:0 options:(curve << 16) animations:^{
        self.scrollView.contentInset = UIEdgeInsetsZero;
        self.scrollView.scrollIndicatorInsets = UIEdgeInsetsZero;
    } completion:nil];
}

- (void)scrollToTextField:(UITextField *)textField {
    // 计算 textField 在 scrollView 中的位置
    CGRect textFieldFrame = [textField convertRect:textField.bounds toView:_contentView];
    
    // 添加一些边距，确保输入框上下都有空间
    CGFloat padding = 20;
    CGRect targetRect = CGRectMake(textFieldFrame.origin.x,
                                   textFieldFrame.origin.y - padding,
                                   textFieldFrame.size.width,
                                   textFieldFrame.size.height + padding * 2);
    
    // 滚动到目标位置
    [_scrollView scrollRectToVisible:targetRect animated:YES];
}

#pragma mark - Helper Methods

- (void)addDoneToolbarToTextField:(UITextField *)textField {
    UIToolbar *toolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, CGRectGetWidth(self.bounds), 44)];
    toolbar.barStyle = UIBarStyleDefault;
    
    UIBarButtonItem *flexSpace = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
    UIBarButtonItem *doneButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(doneButtonTapped)];
    
    toolbar.items = @[flexSpace, doneButton];
    textField.inputAccessoryView = toolbar;
}

- (void)doneButtonTapped {
    [self endEditing:YES];
}

#pragma mark - UITextFieldDelegate

- (void)textFieldDidBeginEditing:(UITextField *)textField {
    self.activeTextField = textField;
    
    // 延迟一点点，等键盘动画开始
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        [self scrollToTextField:textField];
    });
}

- (void)textFieldDidEndEditing:(UITextField *)textField {
    if (self.activeTextField == textField) {
        self.activeTextField = nil;
    }
}

- (BOOL)textFieldShouldReturn:(UITextField *)textField {
    [textField resignFirstResponder];
    return YES;
}

@end