//
//  KBKeyboardRowBuilder.m
//  CustomKeyboard
//

#import "KBKeyboardRowBuilder.h"
#import "KBKeyboardLayoutConfig.h"
#import "KBKeyboardLayoutEngine.h"
#import "KBKeyboardKeyFactory.h"
#import "KBKeyButton.h"
#import "KBKey.h"
#import "KBBackspaceLongPressHandler.h"
#import "KBSkinManager.h"
#import <Masonry/Masonry.h>

@interface KBKeyboardRowBuilder ()
@property (nonatomic, strong) KBKeyboardLayoutConfig *layoutConfig;
@property (nonatomic, strong) KBKeyboardLayoutEngine *layoutEngine;
@property (nonatomic, strong) KBKeyboardKeyFactory *keyFactory;
@end

@implementation KBKeyboardRowBuilder

- (instancetype)initWithLayoutConfig:(KBKeyboardLayoutConfig *)layoutConfig
                        layoutEngine:(KBKeyboardLayoutEngine *)layoutEngine
                          keyFactory:(KBKeyboardKeyFactory *)keyFactory {
    self = [super init];
    if (self) {
        _layoutConfig = layoutConfig;
        _layoutEngine = layoutEngine;
        _keyFactory = keyFactory;
    }
    return self;
}

- (void)buildRow:(UIView *)row
   withRowConfig:(KBKeyboardRowConfig *)rowConfig
uniformCharWidth:(CGFloat)uniformCharWidth
         shiftOn:(BOOL)shiftOn
backspaceHandler:(KBBackspaceLongPressHandler *)backspaceHandler
          target:(id)target
          action:(SEL)action {
    if (!row || !rowConfig) { return; }
    CGFloat gap = [self.layoutEngine gapForRow:rowConfig];
    CGFloat insetLeft = [self.layoutEngine insetLeftForRow:rowConfig];
    CGFloat insetRight = [self.layoutEngine insetRightForRow:rowConfig];

    if (rowConfig.segments) {
        KBKeyboardRowSegments *segments = rowConfig.segments;
        NSArray<KBKeyboardRowItem *> *leftItems = [segments leftItems];
        NSArray<KBKeyboardRowItem *> *centerItems = [segments centerItems];
        NSArray<KBKeyboardRowItem *> *rightItems = [segments rightItems];
        UIView *leftContainer = [UIView new];
        UIView *centerContainer = [UIView new];
        UIView *rightContainer = [UIView new];
        [row addSubview:leftContainer];
        [row addSubview:centerContainer];
        [row addSubview:rightContainer];

        [leftContainer mas_makeConstraints:^(MASConstraintMaker *make) {
            make.left.equalTo(row.mas_left).offset(insetLeft);
            make.top.bottom.equalTo(row);
        }];
        [rightContainer mas_makeConstraints:^(MASConstraintMaker *make) {
            make.right.equalTo(row.mas_right).offset(-insetRight);
            make.top.bottom.equalTo(row);
        }];
        [centerContainer mas_makeConstraints:^(MASConstraintMaker *make) {
            make.centerX.equalTo(row);
            make.top.bottom.equalTo(row);
            make.left.greaterThanOrEqualTo(leftContainer.mas_right).offset(gap);
            make.right.lessThanOrEqualTo(rightContainer.mas_left).offset(-gap);
        }];

        if (leftItems.count == 0) {
            [leftContainer mas_makeConstraints:^(MASConstraintMaker *make) {
                make.width.mas_equalTo(0);
            }];
        }
        if (centerItems.count == 0) {
            [centerContainer mas_makeConstraints:^(MASConstraintMaker *make) {
                make.width.mas_equalTo(0);
            }];
        }
        if (rightItems.count == 0) {
            [rightContainer mas_makeConstraints:^(MASConstraintMaker *make) {
                make.width.mas_equalTo(0);
            }];
        }

        [self kb_buildButtonsInContainer:leftContainer
                                   items:leftItems
                                     gap:gap
                               insetLeft:0
                              insetRight:0
                             alignCenter:NO
                           isTopLevelRow:NO
                        uniformCharWidth:uniformCharWidth
                                 shiftOn:shiftOn
                        backspaceHandler:backspaceHandler
                                  target:target
                                  action:action];
        [self kb_buildButtonsInContainer:centerContainer
                                   items:centerItems
                                     gap:gap
                               insetLeft:0
                              insetRight:0
                             alignCenter:NO
                           isTopLevelRow:NO
                        uniformCharWidth:uniformCharWidth
                                 shiftOn:shiftOn
                        backspaceHandler:backspaceHandler
                                  target:target
                                  action:action];
        [self kb_buildButtonsInContainer:rightContainer
                                   items:rightItems
                                     gap:gap
                               insetLeft:0
                              insetRight:0
                             alignCenter:NO
                           isTopLevelRow:NO
                        uniformCharWidth:uniformCharWidth
                                 shiftOn:shiftOn
                        backspaceHandler:backspaceHandler
                                  target:target
                                  action:action];
        return;
    }

    BOOL alignCenter = [rowConfig.align.lowercaseString isEqualToString:@"center"];
    [self kb_buildButtonsInContainer:row
                               items:[rowConfig resolvedItems]
                                 gap:gap
                           insetLeft:insetLeft
                          insetRight:insetRight
                         alignCenter:alignCenter
                       isTopLevelRow:YES
                    uniformCharWidth:uniformCharWidth
                             shiftOn:shiftOn
                    backspaceHandler:backspaceHandler
                              target:target
                              action:action];
}

#pragma mark - Private

- (void)kb_buildButtonsInContainer:(UIView *)container
                             items:(NSArray<KBKeyboardRowItem *> *)items
                               gap:(CGFloat)gap
                         insetLeft:(CGFloat)insetLeft
                        insetRight:(CGFloat)insetRight
                       alignCenter:(BOOL)alignCenter
                     isTopLevelRow:(BOOL)isTopLevelRow
                  uniformCharWidth:(CGFloat)uniformCharWidth
                           shiftOn:(BOOL)shiftOn
                  backspaceHandler:(KBBackspaceLongPressHandler *)backspaceHandler
                            target:(id)target
                            action:(SEL)action {
    if (items.count == 0) { return; }

    UIView *leftSpacer = nil;
    UIView *rightSpacer = nil;
    if (alignCenter) {
        leftSpacer = [UIView new];
        rightSpacer = [UIView new];
        [container addSubview:leftSpacer];
        [container addSubview:rightSpacer];
        [leftSpacer mas_makeConstraints:^(MASConstraintMaker *make) {
            make.left.equalTo(container.mas_left).offset(insetLeft);
            make.top.bottom.equalTo(container);
        }];
        [rightSpacer mas_makeConstraints:^(MASConstraintMaker *make) {
            make.right.equalTo(container.mas_right).offset(-insetRight);
            make.top.bottom.equalTo(container);
        }];
        [leftSpacer mas_makeConstraints:^(MASConstraintMaker *make) {
            make.width.equalTo(rightSpacer);
        }];
    }

    BOOL usingUniformWidth = (uniformCharWidth > 0.0);
    BOOL allCharacterKeys = YES; // 跟踪该容器内是否全部为字符键

    KBKeyButton *previous = nil;
    KBKeyButton *firstCharBtn = nil; // 用于非统一模式下的行内等宽约束
    for (KBKeyboardRowItem *item in items) {
        KBKeyButton *btn = [self kb_buttonForItem:item
                                          shiftOn:shiftOn
                                 backspaceHandler:backspaceHandler
                                           target:target
                                           action:action];
        if (!btn) { continue; }
        [container addSubview:btn];

        [btn mas_makeConstraints:^(MASConstraintMaker *make) {
            make.top.bottom.equalTo(container);
            if (previous) {
                make.left.equalTo(previous.mas_right).offset(gap);
            } else {
                if (leftSpacer) {
                    make.left.equalTo(leftSpacer.mas_right).offset(gap);
                } else {
                    make.left.equalTo(container.mas_left).offset(insetLeft);
                }
            }
        }];

        // 字符键（letter/digit/sym）使用等宽约束，自动分配可用空间；
        // 功能键（shift/backspace/mode 等）使用固定宽度。
        BOOL isCharacterKey = [item.itemId hasPrefix:@"letter:"] ||
                              [item.itemId hasPrefix:@"digit:"] ||
                              [item.itemId hasPrefix:@"sym:"];

        if (!isCharacterKey) { allCharacterKeys = NO; }

        if (isCharacterKey && usingUniformWidth) {
            // 使用跨行统一的固定宽度
            CGFloat w = uniformCharWidth;
            [btn mas_makeConstraints:^(MASConstraintMaker *make) {
                make.width.mas_equalTo(w);
            }];
        } else if (isCharacterKey) {
            // 行内等宽：所有字符键与第一个字符键等宽
            if (firstCharBtn) {
                [btn mas_makeConstraints:^(MASConstraintMaker *make) {
                    make.width.equalTo(firstCharBtn);
                }];
            } else {
                firstCharBtn = btn;
            }
        } else {
            CGFloat width = [self.layoutEngine widthForItem:item key:btn.key];
            if (width > 0.0) {
                [btn mas_makeConstraints:^(MASConstraintMaker *make) {
                    make.width.mas_equalTo(width);
                }];
            }
        }

        previous = btn;
    }

    if (!previous) { return; }

    // 当使用统一宽度且顶层行全部为字符键时，跳过右锚约束以实现左对齐（列对齐）
    BOOL skipRightAnchor = isTopLevelRow && usingUniformWidth && allCharacterKeys;

    if (!skipRightAnchor) {
        [previous mas_makeConstraints:^(MASConstraintMaker *make) {
            if (rightSpacer) {
                make.right.equalTo(rightSpacer.mas_left).offset(-gap);
            } else {
                make.right.equalTo(container.mas_right).offset(-insetRight);
            }
        }];
    }
}

- (KBKeyButton *)kb_buttonForItem:(KBKeyboardRowItem *)item
                          shiftOn:(BOOL)shiftOn
                 backspaceHandler:(KBBackspaceLongPressHandler *)backspaceHandler
                           target:(id)target
                           action:(SEL)action {
    if (item.itemId.length == 0) { return nil; }
    KBKeyboardKeyDef *def = [self.layoutConfig keyDefForIdentifier:item.itemId];
    KBKey *key = [self.keyFactory keyForItemId:item.itemId shiftOn:shiftOn];
    if (!key) { return nil; }

    KBKeyButton *btn = [[KBKeyButton alloc] init];
    btn.key = key;
    [btn setTitle:key.title forState:UIControlStateNormal];

    UIColor *bgColor = [self kb_backgroundColorForItem:item keyDef:def];
    if (bgColor) {
        btn.customBackgroundColor = bgColor;
    }

    CGFloat fontSize = [self.layoutEngine fontSizeForItem:item key:key];
    if (fontSize > 0.0) {
        btn.titleLabel.font = [UIFont systemFontOfSize:fontSize weight:UIFontWeightSemibold];
    }

    [btn applyThemeForCurrentKey];
    if (target && action) {
        [btn addTarget:target action:action forControlEvents:UIControlEventTouchDown];
    }

    if (key.type == KBKeyTypeBackspace) {
        [backspaceHandler bindDeleteButton:btn showClearLabel:YES];
    }
    if (key.type == KBKeyTypeShift) {
        btn.selected = shiftOn;
    }
    [self kb_applySymbolIfNeededForButton:btn keyDef:def fontSize:fontSize];
    return btn;
}

- (UIColor *)kb_backgroundColorForItem:(KBKeyboardRowItem *)item keyDef:(KBKeyboardKeyDef *)def {
    NSString *hex = def.backgroundColor;
    if (hex.length == 0) {
        hex = self.layoutConfig.defaultKeyBackground;
    }
    if (hex.length == 0) { return nil; }
    return [KBSkinManager colorFromHexString:hex defaultColor:nil];
}

- (void)kb_applySymbolIfNeededForButton:(KBKeyButton *)button
                                 keyDef:(KBKeyboardKeyDef *)def
                               fontSize:(CGFloat)fontSize {
    if (!button || !def) { return; }
    if (button.iconView.image != nil) { return; }
    NSString *symbolName = button.isSelected ? def.selectedSymbolName : def.symbolName;
    if (symbolName.length == 0) { return; }

    UIImage *image = [UIImage systemImageNamed:symbolName];
    if (!image) { return; }

    UIImageSymbolConfiguration *config = [UIImageSymbolConfiguration configurationWithPointSize:fontSize weight:UIFontWeightSemibold];
    image = [image imageWithConfiguration:config];

    button.iconView.image = image;
    button.iconView.hidden = NO;
    button.iconView.contentMode = UIViewContentModeCenter;
    button.titleLabel.hidden = YES;

    UIColor *textColor = [KBSkinManager shared].current.keyTextColor ?: [UIColor blackColor];
    button.iconView.tintColor = button.isSelected ? [UIColor blackColor] : textColor;
}

@end