//
//  KBKeyboardView.m
//  CustomKeyboard
//

#import "KBKeyboardView.h"
#import "KBKeyButton.h"
#import "KBKey.h"
#import "KBBackspaceLongPressHandler.h"
#import "KBKeyboardLayoutConfig.h"
#import "KBKeyboardLayoutResolver.h"
#import "KBKeyboardKeyFactory.h"
#import "KBKeyboardLayoutEngine.h"
#import "KBKeyboardRowBuilder.h"
#import "KBKeyboardInputHandler.h"
#import "KBKeyboardLegacyBuilder.h"
#import "KBKeyboardLegacyLayoutProvider.h"
#import "KBKeyboardInteractionHandler.h"
#import "KBKeyboardRowContainerBuilder.h"
#import "KBSkinManager.h"
#import <Masonry/Masonry.h>
#import <objc/runtime.h>

// 第二行字母行的左右占位比例（用于居中）
static const CGFloat kKBLettersRow2EdgeSpacerMultiplier = 0.5;
static const NSTimeInterval kKBKeyVariantLongPressMinDuration = 0.35;
static const CGFloat kKBKeyVariantPopupPaddingX = 8.0;
static const CGFloat kKBKeyVariantPopupPaddingY = 6.0;
static const CGFloat kKBKeyVariantItemWidth = 34.0;
static const CGFloat kKBKeyVariantItemHeight = 40.0;
static const CGFloat kKBKeyVariantPopupAnchorGap = 6.0;
static NSString * const kKBDiacriticsConfigFileName = @"kb_diacritics_map";
static const void *kKBDiacriticsLongPressBoundKey = &kKBDiacriticsLongPressBoundKey;

static inline NSString *kb_normalizeLanguageCode(NSString *languageCode) {
    NSString *lc = (languageCode ?: @"").lowercaseString;
    return lc.length > 0 ? lc : @"en";
}

static inline NSString *kb_baseLanguageCode(NSString *languageCode) {
    NSString *lc = kb_normalizeLanguageCode(languageCode);
    NSRange r = [lc rangeOfString:@"-"];
    if (r.location == NSNotFound) { return lc; }
    if (r.location == 0) { return lc; }
    return [lc substringToIndex:r.location];
}

static NSDictionary<NSString *, NSDictionary<NSString *, NSArray<NSString *> *> *> *kb_diacriticsLanguagesMap(void) {
    static NSDictionary<NSString *, NSDictionary<NSString *, NSArray<NSString *> *> *> *cached = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        NSString *path = [[NSBundle mainBundle] pathForResource:kKBDiacriticsConfigFileName ofType:@"json"];
        NSData *data = path.length ? [NSData dataWithContentsOfFile:path] : nil;
        if (data.length == 0) { return; }

        NSError *error = nil;
        id json = [NSJSONSerialization JSONObjectWithData:data options:0 error:&error];
        if (error || ![json isKindOfClass:[NSDictionary class]]) {
            NSLog(@"[KBKeyboardView] Failed to parse %@.json: %@", kKBDiacriticsConfigFileName, error);
            return;
        }

        NSDictionary *dict = (NSDictionary *)json;
        id languages = dict[@"languages"];
        if (![languages isKindOfClass:[NSDictionary class]]) { return; }
        cached = (NSDictionary *)languages;
    });
    return cached ?: @{};
}

static inline NSUInteger kb_composedCharacterCount(NSString *string) {
    if (string.length == 0) { return 0; }
    __block NSUInteger count = 0;
    [string enumerateSubstringsInRange:NSMakeRange(0, string.length)
                               options:NSStringEnumerationByComposedCharacterSequences
                            usingBlock:^(__unused NSString *substring,
                                         __unused NSRange substringRange,
                                         __unused NSRange enclosingRange,
                                         __unused BOOL *stop) {
        count += 1;
    }];
    return count;
}

@interface KBKeyVariantPopupView : UIView
@property (nonatomic, copy) NSArray<NSString *> *variants;
@property (nonatomic, assign) NSInteger selectedIndex;
- (void)configureWithVariants:(NSArray<NSString *> *)variants selectedIndex:(NSInteger)selectedIndex;
- (void)updateSelectionWithPointInSelf:(CGPoint)point;
- (nullable NSString *)selectedVariant;
- (CGSize)preferredSize;
- (void)applyTheme;
@end

#pragma mark - KBKeyVariantPopupView

@interface KBKeyVariantPopupView ()
@property (nonatomic, strong) UIView *contentView;
@property (nonatomic, strong) NSMutableArray<UILabel *> *itemLabels;
@end

@implementation KBKeyVariantPopupView

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        self.layer.cornerRadius = 10.0;
        self.layer.masksToBounds = NO;
        self.layer.borderWidth = 0.5;
        self.layer.borderColor = [UIColor colorWithWhite:0 alpha:0.15].CGColor;
        self.layer.shadowColor = [UIColor colorWithWhite:0 alpha:0.28].CGColor;
        self.layer.shadowOpacity = 0.7;
        self.layer.shadowOffset = CGSizeMake(0, 2);
        self.layer.shadowRadius = 6.0;

        [self addSubview:self.contentView];
        [self.contentView mas_makeConstraints:^(MASConstraintMaker *make) {
            make.edges.equalTo(self).insets(UIEdgeInsetsMake(kKBKeyVariantPopupPaddingY,
                                                            kKBKeyVariantPopupPaddingX,
                                                            kKBKeyVariantPopupPaddingY,
                                                            kKBKeyVariantPopupPaddingX));
        }];

        [self applyTheme];
    }
    return self;
}

- (void)applyTheme {
    KBSkinTheme *t = [KBSkinManager shared].current;
    UIColor *bg = t.keyBackground ?: [UIColor whiteColor];
    self.backgroundColor = bg;
}

- (UIView *)contentView {
    if (!_contentView) {
        _contentView = [UIView new];
        _contentView.backgroundColor = [UIColor clearColor];
    }
    return _contentView;
}

- (NSMutableArray<UILabel *> *)itemLabels {
    if (!_itemLabels) {
        _itemLabels = [NSMutableArray array];
    }
    return _itemLabels;
}

- (CGSize)preferredSize {
    NSUInteger count = self.variants.count;
    if (count == 0) { return CGSizeMake(0, 0); }
    CGFloat width = kKBKeyVariantPopupPaddingX * 2 + kKBKeyVariantItemWidth * (CGFloat)count;
    CGFloat height = kKBKeyVariantPopupPaddingY * 2 + kKBKeyVariantItemHeight;
    return CGSizeMake(width, height);
}

- (void)configureWithVariants:(NSArray<NSString *> *)variants selectedIndex:(NSInteger)selectedIndex {
    self.variants = variants ?: @[];
    self.selectedIndex = MAX(0, MIN(selectedIndex, (NSInteger)self.variants.count - 1));

    [self.itemLabels makeObjectsPerformSelector:@selector(removeFromSuperview)];
    [self.itemLabels removeAllObjects];

    UILabel *previous = nil;
    for (NSInteger i = 0; i < (NSInteger)self.variants.count; i++) {
        UILabel *label = [UILabel new];
        label.textAlignment = NSTextAlignmentCenter;
        label.text = self.variants[i];
        label.font = [UIFont systemFontOfSize:20 weight:UIFontWeightSemibold];
        label.layer.cornerRadius = 8.0;
        label.layer.masksToBounds = YES;

        [self.contentView addSubview:label];
        [self.itemLabels addObject:label];

        [label mas_makeConstraints:^(MASConstraintMaker *make) {
            make.top.bottom.equalTo(self.contentView);
            make.width.mas_equalTo(kKBKeyVariantItemWidth);
            if (previous) {
                make.left.equalTo(previous.mas_right);
            } else {
                make.left.equalTo(self.contentView.mas_left);
            }
        }];
        previous = label;
    }

    if (previous) {
        [previous mas_makeConstraints:^(MASConstraintMaker *make) {
            make.right.equalTo(self.contentView.mas_right);
        }];
    }

    [self kb_refreshSelectionAppearance];
}

- (void)updateSelectionWithPointInSelf:(CGPoint)point {
    if (self.variants.count == 0) { return; }
    CGPoint p = [self convertPoint:point toView:self.contentView];
    CGFloat contentWidth = CGRectGetWidth(self.contentView.bounds);
    if (contentWidth <= 0) { return; }

    NSInteger count = (NSInteger)self.variants.count;
    CGFloat unit = contentWidth / (CGFloat)count;
    NSInteger index = (NSInteger)floor(p.x / MAX(unit, 1.0));
    index = MAX(0, MIN(index, count - 1));
    if (index == self.selectedIndex) { return; }
    self.selectedIndex = index;
    [self kb_refreshSelectionAppearance];
}

- (nullable NSString *)selectedVariant {
    if (self.selectedIndex < 0 || self.selectedIndex >= (NSInteger)self.variants.count) { return nil; }
    return self.variants[self.selectedIndex];
}

- (void)kb_refreshSelectionAppearance {
    KBSkinTheme *t = [KBSkinManager shared].current;
    UIColor *textColor = t.keyTextColor ?: [UIColor blackColor];
    UIColor *selectedBg = t.keyHighlightBackground ?: (t.accentColor ?: [UIColor colorWithWhite:0 alpha:0.12]);
    for (NSInteger i = 0; i < (NSInteger)self.itemLabels.count; i++) {
        UILabel *label = self.itemLabels[i];
        label.textColor = textColor;
        label.backgroundColor = (i == self.selectedIndex) ? selectedBg : [UIColor clearColor];
    }
}

@end

@interface KBKeyboardView ()
@property (nonatomic, strong) NSMutableArray<UIView *> *rowViews;
@property (nonatomic, strong) NSArray<NSArray<KBKey *> *> *keysForRows;
@property (nonatomic, strong) KBBackspaceLongPressHandler *backspaceHandler;
@property (nonatomic, strong) KBKeyboardLayoutConfig *layoutConfig;
@property (nonatomic, strong) KBKeyboardKeyFactory *keyFactory;
@property (nonatomic, strong) KBKeyboardLayoutEngine *layoutEngine;
@property (nonatomic, strong) KBKeyboardRowBuilder *rowBuilder;
@property (nonatomic, strong) KBKeyboardInputHandler *inputHandler;
@property (nonatomic, strong) KBKeyboardLegacyBuilder *legacyBuilder;
@property (nonatomic, strong) KBKeyboardLegacyLayoutProvider *legacyLayoutProvider;
@property (nonatomic, strong) KBKeyboardInteractionHandler *interactionHandler;
@property (nonatomic, strong) KBKeyboardRowContainerBuilder *rowContainerBuilder;
/// 跨行统一字符键宽度（按最多字符键的行计算），0 表示不启用
@property (nonatomic, assign) CGFloat kb_uniformCharKeyWidth;
/// 记录当前行间距，便于切换布局时判断是否需要重建容器
@property (nonatomic, assign) CGFloat kb_currentRowSpacing;
/// 记录当前顶/底间距，便于切换布局时判断是否需要重建容器
@property (nonatomic, assign) CGFloat kb_currentTopInset;
@property (nonatomic, assign) CGFloat kb_currentBottomInset;

/// 长按字符变体（如葡语重音字符）
@property (nonatomic, strong) KBKeyVariantPopupView *kb_variantPopupView;
@property (nonatomic, weak) KBKeyButton *kb_variantAnchorButton;
@property (nonatomic, copy) NSString *kb_variantBaseOutput;
@property (nonatomic, assign) BOOL kb_variantBaseDeleted;
@property (nonatomic, assign) NSUInteger kb_variantBaseDeleteCount;
@property (nonatomic, copy) NSString *kb_currentLanguageCode;
@end

@implementation KBKeyboardView

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        self.backgroundColor = [UIColor clearColor];
        _layoutStyle = KBKeyboardLayoutStyleLetters;
        // 默认小写：与需求一致，初始不开启 Shift
        _shiftOn = NO;
        _symbolsMoreOn = NO; // 数字面板默认第一页（123）

        // 从 App Group 读取当前 profileId 并设置布局
        NSString *profileId = [[KBKeyboardLayoutResolver sharedResolver] currentProfileId];
        if (profileId.length > 0) {
            _currentLayoutJsonId = [[KBKeyboardLayoutResolver sharedResolver] layoutJsonIdForProfileId:profileId];
            NSLog(@"[KBKeyboardView] Loaded profileId: %@, layoutJsonId: %@", profileId, _currentLayoutJsonId);
        } else {
            _currentLayoutJsonId = @"letters";
            NSLog(@"[KBKeyboardView] No profileId found, using default 'letters'");
        }

        self.layoutConfig = [KBKeyboardLayoutConfig sharedConfig];
        self.backspaceHandler = [[KBBackspaceLongPressHandler alloc] initWithContainerView:self];
        [self buildBase];
    }
    return self;
}

// 当切换大布局（字母/数字）时，重置数字二级页状态
- (void)setLayoutStyle:(KBKeyboardLayoutStyle)layoutStyle {
    _layoutStyle = layoutStyle;
    if (_layoutStyle != KBKeyboardLayoutStyleNumbers) {
        _symbolsMoreOn = NO;
    }
}

#pragma mark - Base Layout

- (void)buildBase {
    KBKeyboardLayout *layout = [self kb_currentLayout];
    NSArray<KBKeyboardRowConfig *> *rows = layout.rows ?: @[];
    if (rows.count == 0) {
        // Fallback: 至少创建 4 行容器
        rows = @[[KBKeyboardRowConfig new], [KBKeyboardRowConfig new],
                 [KBKeyboardRowConfig new], [KBKeyboardRowConfig new]];
    }
    CGFloat rowSpacing = [self.layoutEngine rowSpacingForLayout:layout];
    CGFloat topInset = [self.layoutEngine topInsetForLayout:layout];
    CGFloat bottomInset = [self.layoutEngine bottomInsetForLayout:layout];
    self.kb_currentRowSpacing = rowSpacing;
    self.kb_currentTopInset = topInset;
    self.kb_currentBottomInset = bottomInset;
    [self.rowContainerBuilder rebuildRowContainersForRows:rows
                                              inContainer:self
                                                 rowViews:self.rowViews
                                               rowSpacing:rowSpacing
                                                 topInset:topInset
                                              bottomInset:bottomInset];
    [self.interactionHandler bringPreviewToFrontIfNeededInContainer:self];
}

#pragma mark - Public

- (void)reloadKeys {
    [self.backspaceHandler bindDeleteButton:nil showClearLabel:NO];
    [self kb_hideVariantPopupIfNeeded];
    self.kb_currentLanguageCode = [[KBKeyboardLayoutResolver sharedResolver] currentLanguageCode] ?: @"en";

    KBKeyboardLayout *layout = [self kb_currentLayout];
    CGFloat rowSpacing = [self.layoutEngine rowSpacingForLayout:layout];
    CGFloat topInset = [self.layoutEngine topInsetForLayout:layout];
    CGFloat bottomInset = [self.layoutEngine bottomInsetForLayout:layout];
    NSLog(@"[KBKeyboardView] reloadKeys: layoutName=%@ rows=%lu shiftRows=%lu shiftOn=%d",
          self.currentLayoutJsonId, (unsigned long)layout.rows.count, (unsigned long)layout.shiftRows.count, self.shiftOn);

    NSArray<KBKeyboardRowConfig *> *rows = nil;

    if (self.shiftOn && layout.shiftRows.count > 0) {
        rows = layout.shiftRows;
    } else {
        rows = layout.rows ?: @[];
    }

    NSLog(@"[KBKeyboardView] reloadKeys: usingRows=%lu currentContainers=%lu",
          (unsigned long)rows.count, (unsigned long)self.rowViews.count);

    // 行数变化时（如从 4 行布局切到 5 行注音布局），重建行容器
    if (rows.count >= 4 &&
        (rows.count != self.rowViews.count ||
         fabs(self.kb_currentRowSpacing - rowSpacing) > 0.1 ||
         fabs(self.kb_currentTopInset - topInset) > 0.1 ||
         fabs(self.kb_currentBottomInset - bottomInset) > 0.1)) {
        self.kb_currentRowSpacing = rowSpacing;
        self.kb_currentTopInset = topInset;
        self.kb_currentBottomInset = bottomInset;
        [self.rowContainerBuilder rebuildRowContainersForRows:rows
                                                  inContainer:self
                                                     rowViews:self.rowViews
                                                   rowSpacing:rowSpacing
                                                     topInset:topInset
                                                  bottomInset:bottomInset];
        [self.interactionHandler bringPreviewToFrontIfNeededInContainer:self];
    }

    // 移除旧按钮
    for (UIView *row in self.rowViews) {
        [row.subviews makeObjectsPerformSelector:@selector(removeFromSuperview)];
    }

    if (rows.count < 4) {
        NSLog(@"[KBKeyboardView] reloadKeys: rows.count < 4, fallback to legacy");
        self.kb_uniformCharKeyWidth = 0.0;
        [self kb_buildLegacyLayout];
        [self kb_bindVariantLongPressIfNeeded];
        return;
    }

    // 计算跨行统一字符键宽度（若各行字符键数量不同，则按最多键的行为基准）
    self.kb_uniformCharKeyWidth = [self.layoutEngine calculateUniformCharKeyWidthForRows:rows
                                                                             keyFactory:self.keyFactory
                                                                                shiftOn:self.shiftOn];

    for (NSUInteger i = 0; i < rows.count && i < self.rowViews.count; i++) {
        [self.rowBuilder buildRow:self.rowViews[i]
                    withRowConfig:rows[i]
                 uniformCharWidth:self.kb_uniformCharKeyWidth
                          shiftOn:self.shiftOn
                 backspaceHandler:self.backspaceHandler
                           target:self
                           action:@selector(onKeyTapped:)];
    }

    NSUInteger totalButtons = [self kb_totalKeyButtonCount];
    NSLog(@"[KBKeyboardView] reloadKeys: totalButtons=%lu", (unsigned long)totalButtons);
    if (totalButtons == 0) {
        NSLog(@"[KBKeyboardView] config layout produced no keys, fallback to legacy.");
        for (UIView *row in self.rowViews) {
            [row.subviews makeObjectsPerformSelector:@selector(removeFromSuperview)];
        }
        [self kb_buildLegacyLayout];
        [self kb_bindVariantLongPressIfNeeded];
        return;
    }

    [self kb_bindVariantLongPressIfNeeded];
}

- (void)didMoveToWindow {
    [super didMoveToWindow];
    if (!self.window) { return; }
    if ([self kb_totalKeyButtonCount] > 0) { return; }
    // 兜底：系统编辑菜单切出切回等场景下，若按键丢失则自动重建。
    [self reloadKeys];
    // 自动重建后再触发一次上层主题应用，避免“按键恢复了但皮肤背景没恢复”。
    UIView *container = self.superview;
    if ([container respondsToSelector:@selector(kb_applyTheme)]) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
        [container performSelector:@selector(kb_applyTheme)];
#pragma clang diagnostic pop
    }
}

- (NSUInteger)kb_totalKeyButtonCount {
    NSUInteger total = 0;
    for (UIView *row in self.rowViews) {
        total += [self.interactionHandler collectKeyButtonsInView:row].count;
    }
    return total;
}

#pragma mark - Hit Test

- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
    UIView *hit = [super hitTest:point withEvent:event];
    return [self.interactionHandler resolveHitView:hit
                                             point:point
                                         container:self
                                          rowViews:self.rowViews];
}

#pragma mark - Config Helpers

- (KBKeyboardLayoutConfig *)kb_layoutConfig {
    if (!self.layoutConfig) {
        self.layoutConfig = [KBKeyboardLayoutConfig sharedConfig];
    }
    return self.layoutConfig;
}

- (KBKeyboardKeyFactory *)keyFactory {
    if (!_keyFactory) {
        _keyFactory = [[KBKeyboardKeyFactory alloc] initWithLayoutConfig:[self kb_layoutConfig]];
    }
    return _keyFactory;
}

- (KBKeyboardLayoutEngine *)layoutEngine {
    if (!_layoutEngine) {
        _layoutEngine = [[KBKeyboardLayoutEngine alloc] initWithLayoutConfig:[self kb_layoutConfig]];
    }
    return _layoutEngine;
}

- (KBKeyboardRowBuilder *)rowBuilder {
    if (!_rowBuilder) {
        _rowBuilder = [[KBKeyboardRowBuilder alloc] initWithLayoutConfig:[self kb_layoutConfig]
                                                           layoutEngine:self.layoutEngine
                                                             keyFactory:self.keyFactory];
    }
    return _rowBuilder;
}

- (KBKeyboardInputHandler *)inputHandler {
    if (!_inputHandler) {
        _inputHandler = [[KBKeyboardInputHandler alloc] init];
        __weak typeof(self) weakSelf = self;
        _inputHandler.onToggleShift = ^{
            __strong typeof(weakSelf) self = weakSelf;
            if (!self) { return; }
            self.shiftOn = !self.shiftOn;
            [self reloadKeys];
        };
        _inputHandler.onToggleSymbols = ^{
            __strong typeof(weakSelf) self = weakSelf;
            if (!self) { return; }
            self.symbolsMoreOn = !self.symbolsMoreOn;
            [self reloadKeys];
        };
        _inputHandler.onKeyTapped = ^(KBKey *key) {
            __strong typeof(weakSelf) self = weakSelf;
            if (!self) { return; }
            if ([self.delegate respondsToSelector:@selector(keyboardView:didTapKey:)]) {
                [self.delegate keyboardView:self didTapKey:key];
            }
        };
    }
    return _inputHandler;
}

- (KBKeyboardLegacyBuilder *)legacyBuilder {
    if (!_legacyBuilder) {
        _legacyBuilder = [[KBKeyboardLegacyBuilder alloc] init];
    }
    return _legacyBuilder;
}

- (KBKeyboardLegacyLayoutProvider *)legacyLayoutProvider {
    if (!_legacyLayoutProvider) {
        _legacyLayoutProvider = [[KBKeyboardLegacyLayoutProvider alloc] init];
    }
    return _legacyLayoutProvider;
}

- (KBKeyboardInteractionHandler *)interactionHandler {
    if (!_interactionHandler) {
        _interactionHandler = [[KBKeyboardInteractionHandler alloc] init];
    }
    return _interactionHandler;
}

- (KBKeyboardRowContainerBuilder *)rowContainerBuilder {
    if (!_rowContainerBuilder) {
        _rowContainerBuilder = [[KBKeyboardRowContainerBuilder alloc] init];
    }
    return _rowContainerBuilder;
}

- (KBKeyboardLayout *)kb_layoutForName:(NSString *)name {
    return [[self kb_layoutConfig] layoutForName:name];
}

- (KBKeyboardLayout *)kb_currentLayout {
    NSString *baseLayoutName = self.currentLayoutJsonId.length > 0 ? self.currentLayoutJsonId : @"letters";
    
    if (self.layoutStyle == KBKeyboardLayoutStyleNumbers) {
        // 优先查找当前语言的数字/符号布局，如 letters_es_numbers / letters_es_symbols
        // 如果不存在，回退到通用布局 numbers / symbolsMore
        NSString *numbersName = [NSString stringWithFormat:@"%@_numbers", baseLayoutName];
        NSString *symbolsName = [NSString stringWithFormat:@"%@_symbols", baseLayoutName];
        NSString *targetName = self.symbolsMoreOn ? symbolsName : numbersName;
        
        KBKeyboardLayout *layout = [self kb_layoutForName:targetName];
        if (layout && layout.rows.count >= 4) {
            return layout;
        }
        // 回退到通用布局
        return [self kb_layoutForName:(self.symbolsMoreOn ? @"symbolsMore" : @"numbers")];
    }
    
    return [self kb_layoutForName:baseLayoutName];
}

- (void)reloadLayoutWithProfileId:(NSString *)profileId {
    if (profileId.length == 0) {
        NSLog(@"[KBKeyboardView] reloadLayoutWithProfileId: empty profileId, ignoring");
        return;
    }

    NSString *newLayoutJsonId = [[KBKeyboardLayoutResolver sharedResolver] layoutJsonIdForProfileId:profileId];
    if ([newLayoutJsonId isEqualToString:self.currentLayoutJsonId]) {
        NSLog(@"[KBKeyboardView] Layout already loaded: %@", newLayoutJsonId);
        return;
    }

    NSLog(@"[KBKeyboardView] Switching layout from %@ to %@", self.currentLayoutJsonId, newLayoutJsonId);
    self.currentLayoutJsonId = newLayoutJsonId;

    // 重新加载键盘布局
    [self reloadKeys];
}

- (void)kb_buildLegacyLayout {
    self.keysForRows = [self.legacyLayoutProvider keysForLayoutStyleIsNumbers:(self.layoutStyle == KBKeyboardLayoutStyleNumbers)
                                                                     shiftOn:self.shiftOn
                                                                symbolsMoreOn:self.symbolsMoreOn
                                                                   keyFactory:self.keyFactory];
    if (self.keysForRows.count < 4) { return; }
    if (self.rowViews.count < 4) { return; }

    [self.legacyBuilder buildRow:self.rowViews[0]
                        withKeys:self.keysForRows[0]
            edgeSpacerMultiplier:0.0
                         shiftOn:self.shiftOn
                 backspaceHandler:self.backspaceHandler
                           target:self
                           action:@selector(onKeyTapped:)];

    CGFloat row2Spacer = (self.layoutStyle == KBKeyboardLayoutStyleLetters)
                         ? kKBLettersRow2EdgeSpacerMultiplier : 0.0;
    [self.legacyBuilder buildRow:self.rowViews[1]
                        withKeys:self.keysForRows[1]
            edgeSpacerMultiplier:row2Spacer
                         shiftOn:self.shiftOn
                 backspaceHandler:self.backspaceHandler
                           target:self
                           action:@selector(onKeyTapped:)];

    [self.legacyBuilder buildRow:self.rowViews[2]
                        withKeys:self.keysForRows[2]
            edgeSpacerMultiplier:0.0
                         shiftOn:self.shiftOn
                 backspaceHandler:self.backspaceHandler
                           target:self
                           action:@selector(onKeyTapped:)];
    [self.legacyBuilder buildRow:self.rowViews[3]
                        withKeys:self.keysForRows[3]
            edgeSpacerMultiplier:0.0
                         shiftOn:self.shiftOn
                 backspaceHandler:self.backspaceHandler
                           target:self
                           action:@selector(onKeyTapped:)];
}

#pragma mark - Actions

- (void)onKeyTapped:(KBKeyButton *)sender {
    [self.inputHandler handleKeyTap:sender.key];
}

// 在字符键按下时，显示一个上方气泡预览（类似系统键盘）。
- (void)showPreviewForButton:(KBKeyButton *)button {
    [self.interactionHandler showPreviewForButton:button inContainer:self];
}

- (void)hidePreview {
    [self.interactionHandler hidePreview];
}

#pragma mark - Key Variant (Diacritics)

- (void)kb_hideVariantPopupIfNeeded {
    if (!self.kb_variantPopupView || self.kb_variantPopupView.hidden) { return; }
    self.kb_variantPopupView.hidden = YES;
    self.kb_variantPopupView.alpha = 1.0;
    self.kb_variantAnchorButton = nil;
    self.kb_variantBaseOutput = nil;
    self.kb_variantBaseDeleted = NO;
    self.kb_variantBaseDeleteCount = 0;
}

- (void)kb_bindVariantLongPressIfNeeded {
    NSString *lc = kb_normalizeLanguageCode(self.kb_currentLanguageCode);
    NSString *baseLc = kb_baseLanguageCode(self.kb_currentLanguageCode);
    NSDictionary<NSString *, NSDictionary<NSString *, NSArray<NSString *> *> *> *languages = kb_diacriticsLanguagesMap();
    if (languages.count == 0) { return; }
    NSDictionary *commonMap = [languages[@"common"] isKindOfClass:[NSDictionary class]] ? languages[@"common"] : nil;
    if (!commonMap && ![languages[lc] isKindOfClass:[NSDictionary class]] && ![languages[baseLc] isKindOfClass:[NSDictionary class]]) { return; }

    for (UIView *row in self.rowViews) {
        NSArray<KBKeyButton *> *buttons = [self.interactionHandler collectKeyButtonsInView:row];
        for (KBKeyButton *btn in buttons) {
            if (![btn isKindOfClass:[KBKeyButton class]]) { continue; }
            if (btn.key.type != KBKeyTypeCharacter) { continue; }
            NSArray<NSString *> *variants = [self kb_variantsForKey:btn.key languageCode:lc];
            if (variants.count <= 1) { continue; }

            NSNumber *bound = objc_getAssociatedObject(btn, kKBDiacriticsLongPressBoundKey);
            if (bound.boolValue) { continue; }
            objc_setAssociatedObject(btn, kKBDiacriticsLongPressBoundKey, @(YES), OBJC_ASSOCIATION_RETAIN_NONATOMIC);

            UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self
                                                                                                   action:@selector(onKeyVariantLongPress:)];
            longPress.minimumPressDuration = kKBKeyVariantLongPressMinDuration;
            longPress.allowableMovement = CGFLOAT_MAX;
            longPress.cancelsTouchesInView = NO;
            [btn addGestureRecognizer:longPress];
        }
    }
}

- (void)onKeyVariantLongPress:(UILongPressGestureRecognizer *)gr {
    KBKeyButton *button = (KBKeyButton *)gr.view;
    if (![button isKindOfClass:[KBKeyButton class]]) { return; }
    if (button.key.type != KBKeyTypeCharacter) { return; }

    NSString *lc = kb_normalizeLanguageCode(self.kb_currentLanguageCode);
    NSArray<NSString *> *variants = [self kb_variantsForKey:button.key languageCode:lc];
    if (variants.count <= 1) { return; }

    switch (gr.state) {
        case UIGestureRecognizerStateBegan: {
            [self hidePreview];
            self.kb_variantAnchorButton = button;
            self.kb_variantBaseOutput = (button.key.output.length > 0 ? button.key.output : button.key.title) ?: @"";
            self.kb_variantBaseDeleted = NO;
            self.kb_variantBaseDeleteCount = kb_composedCharacterCount(self.kb_variantBaseOutput);

            if (!self.kb_variantPopupView) {
                self.kb_variantPopupView = [[KBKeyVariantPopupView alloc] initWithFrame:CGRectZero];
                self.kb_variantPopupView.hidden = YES;
                [self addSubview:self.kb_variantPopupView];
            } else if (self.kb_variantPopupView.superview != self) {
                [self addSubview:self.kb_variantPopupView];
            }
            [self.kb_variantPopupView applyTheme];
            [self.kb_variantPopupView configureWithVariants:variants selectedIndex:0];

            CGSize preferred = [self.kb_variantPopupView preferredSize];
            CGRect anchorFrame = [button convertRect:button.bounds toView:self];
            CGFloat x = CGRectGetMidX(anchorFrame) - preferred.width * 0.5;
            CGFloat maxX = CGRectGetWidth(self.bounds) - 6.0 - preferred.width;
            x = MIN(MAX(6.0, x), MAX(6.0, maxX));
            CGFloat y = CGRectGetMinY(anchorFrame) - preferred.height - kKBKeyVariantPopupAnchorGap;
            y = MAX(2.0, y);
            self.kb_variantPopupView.frame = CGRectMake(x, y, preferred.width, preferred.height);

            self.kb_variantPopupView.alpha = 0.0;
            self.kb_variantPopupView.hidden = NO;
            [self bringSubviewToFront:self.kb_variantPopupView];
            [UIView animateWithDuration:0.12
                                  delay:0
                                options:UIViewAnimationOptionBeginFromCurrentState | UIViewAnimationOptionCurveEaseOut
                             animations:^{
                                 self.kb_variantPopupView.alpha = 1.0;
                             }
                             completion:nil];
        } break;
        case UIGestureRecognizerStateChanged: {
            if (self.kb_variantPopupView.hidden) { return; }
            CGPoint p = [gr locationInView:self.kb_variantPopupView];
            [self.kb_variantPopupView updateSelectionWithPointInSelf:p];
            if (!self.kb_variantBaseDeleted && self.kb_variantPopupView.selectedIndex != 0) {
                [self kb_emitBackspaceCountForVariantReplacement:self.kb_variantBaseDeleteCount];
                self.kb_variantBaseDeleted = YES;
            }
        } break;
        case UIGestureRecognizerStateEnded: {
            if (self.kb_variantPopupView.hidden) { return; }
            CGPoint p = [gr locationInView:self.kb_variantPopupView];
            [self.kb_variantPopupView updateSelectionWithPointInSelf:p];
            [self kb_commitSelectedVariantAndCleanupWithIdentifier:button.key.identifier];
        } break;
        case UIGestureRecognizerStateCancelled:
        case UIGestureRecognizerStateFailed: {
            if (self.kb_variantPopupView.hidden) { return; }
            // 取消时尽量保持“原本已经插入的 base 字符”不变：若已删除则补回
            if (self.kb_variantBaseDeleted && self.kb_variantBaseOutput.length > 0) {
                [self kb_emitCharacterText:self.kb_variantBaseOutput identifier:button.key.identifier];
            }
            [self kb_hideVariantPopupIfNeeded];
        } break;
        default:
            break;
    }
}

- (void)kb_emitBackspaceCountForVariantReplacement:(NSUInteger)count {
    if (count == 0) { count = 1; }
    if (![self.delegate respondsToSelector:@selector(keyboardView:didTapKey:)]) { return; }
    KBKey *backspace = [KBKey keyWithTitle:@"" type:KBKeyTypeBackspace];
    for (NSUInteger i = 0; i < count; i++) {
        [self.delegate keyboardView:self didTapKey:backspace];
    }
}

- (void)kb_emitCharacterText:(NSString *)text identifier:(NSString *)identifier {
    if (text.length == 0) { return; }
    if (![self.delegate respondsToSelector:@selector(keyboardView:didTapKey:)]) { return; }
    KBKey *key = [KBKey keyWithIdentifier:identifier title:text output:text type:KBKeyTypeCharacter];
    [self.delegate keyboardView:self didTapKey:key];
}

- (void)kb_commitSelectedVariantAndCleanupWithIdentifier:(NSString *)identifier {
    NSInteger index = self.kb_variantPopupView.selectedIndex;
    NSString *selected = [self.kb_variantPopupView selectedVariant] ?: @"";
    NSString *base = self.kb_variantBaseOutput ?: @"";

    if (index <= 0 || selected.length == 0) {
        if (self.kb_variantBaseDeleted && base.length > 0) {
            [self kb_emitCharacterText:base identifier:identifier];
        }
        [self kb_hideVariantPopupIfNeeded];
        return;
    }

    if (!self.kb_variantBaseDeleted) {
        [self kb_emitBackspaceCountForVariantReplacement:self.kb_variantBaseDeleteCount];
        self.kb_variantBaseDeleted = YES;
    }
    [self kb_emitCharacterText:selected identifier:identifier];
    [self kb_hideVariantPopupIfNeeded];
}

- (NSArray<NSString *> *)kb_variantsForKey:(KBKey *)key languageCode:(NSString *)languageCode {
    if (!key || key.type != KBKeyTypeCharacter) { return @[]; }
    NSString *base = (key.output.length > 0 ? key.output : key.title) ?: @"";
    if (base.length == 0) { return @[]; }

    NSDictionary<NSString *, NSDictionary<NSString *, NSArray<NSString *> *> *> *languages = kb_diacriticsLanguagesMap();
    NSString *lc = kb_normalizeLanguageCode(languageCode);
    NSDictionary<NSString *, NSArray<NSString *> *> *langMap = [languages[lc] isKindOfClass:[NSDictionary class]] ? languages[lc] : nil;
    if (langMap.count == 0) {
        NSString *baseLc = kb_baseLanguageCode(languageCode);
        langMap = [languages[baseLc] isKindOfClass:[NSDictionary class]] ? languages[baseLc] : nil;
    }
    NSDictionary<NSString *, NSArray<NSString *> *> *commonMap = [languages[@"common"] isKindOfClass:[NSDictionary class]] ? languages[@"common"] : nil;
    if (langMap.count == 0 && commonMap.count == 0) { return @[]; }

    BOOL hasLetter = NO;
    NSCharacterSet *letters = [NSCharacterSet letterCharacterSet];
    for (NSUInteger i = 0; i < base.length; i++) {
        unichar c = [base characterAtIndex:i];
        if ([letters characterIsMember:c]) {
            hasLetter = YES;
            break;
        }
    }
    BOOL upper = hasLetter && [base isEqualToString:base.uppercaseString] && ![base isEqualToString:base.lowercaseString];
    NSString *queryKey = upper ? base.lowercaseString : base;

    id raw = langMap[queryKey];
    if (!(raw && [raw isKindOfClass:[NSArray class]] && ((NSArray *)raw).count > 0)) {
        raw = commonMap[queryKey];
    }
    if (![raw isKindOfClass:[NSArray class]]) { return @[]; }

    NSMutableArray<NSString *> *variants = [NSMutableArray array];
    for (id obj in (NSArray *)raw) {
        if (![obj isKindOfClass:[NSString class]]) { continue; }
        NSString *s = (NSString *)obj;
        if (s.length == 0) { continue; }
        [variants addObject:s];
    }

    if (variants.count == 0) { return @[]; }
    if (![[variants firstObject] isEqualToString:queryKey]) {
        [variants insertObject:queryKey atIndex:0];
    }
    if (variants.count <= 1) { return @[]; }

    if (!upper) {
        return variants.copy;
    }

    NSMutableArray<NSString *> *upperVariants = [NSMutableArray arrayWithCapacity:variants.count];
    for (NSString *s in variants) {
        [upperVariants addObject:s.uppercaseString];
    }
    return upperVariants.copy;
}

#pragma mark - Lazy

- (NSMutableArray<UIView *> *)rowViews {
    if (!_rowViews) _rowViews = [NSMutableArray array];
    return _rowViews;
}

@end