import UIKit

/// EPUB WebView 路径的原生装饰覆盖层。
/// 用于在 WebView 上方叠加高亮、下划线等视觉装饰。
/// 对标 WXRead 的页面级装饰绘制思路：JS 只负责提供 rect，实际视觉绘制由原生 CGContext 完成。
final class RDEPUBWebDecorationOverlayView: UIView {
    private var decorations: [RDEPUBTextOverlayDecoration] = []
    private let verticalAdjustment: CGFloat = -1

    override init(frame: CGRect) {
        super.init(frame: frame)
        backgroundColor = .clear
        isOpaque = false
        isUserInteractionEnabled = false
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    /// 应用装饰数据并触发重绘
    /// - Parameter decorations: 装饰项数组（高亮、下划线等）
    func applyDecorations(_ decorations: [RDEPUBTextOverlayDecoration]) {
        self.decorations = decorations.filter { !$0.rects.isEmpty }
        setNeedsDisplay()
    }

    override func draw(_ rect: CGRect) {
        guard let context = UIGraphicsGetCurrentContext() else { return }

        for decoration in decorations {
            switch decoration.kind {
            case .underline:
                context.setStrokeColor(decoration.color.cgColor)
                context.setLineWidth(2)
                for underlineRect in decoration.rects {
                    let y = underlineRect.maxY - 1
                    context.move(to: CGPoint(x: underlineRect.minX, y: y))
                    context.addLine(to: CGPoint(x: underlineRect.maxX, y: y))
                    context.strokePath()
                }
            default:
                context.setFillColor(decoration.color.cgColor)
                for selectionRect in decoration.rects {
                    let adjustedRect = selectionRect.offsetBy(dx: 0, dy: verticalAdjustment)
                    let path = UIBezierPath(roundedRect: adjustedRect.insetBy(dx: -1, dy: -1), cornerRadius: 4)
                    context.addPath(path.cgPath)
                    context.fillPath()
                }
            }
        }
    }
}