import UIKit

final class RDEPUBAttachmentTooltipView: UIView {

    enum ArrowPlacement {

        case top

        case bottom
    }

    private let contentInsets = UIEdgeInsets(top: 18, left: 20, bottom: 24, right: 20)

    private let arrowSize = CGSize(width: 20, height: 10)

    private let cornerRadius: CGFloat = 18

    private(set) var minimumArrowX: CGFloat = 28

    private var arrowTipX: CGFloat?

    private var arrowPlacement: ArrowPlacement = .bottom

    private let textLabel: UILabel = {
        let label = UILabel()
        label.numberOfLines = 0
        label.textColor = .white
        label.font = .systemFont(ofSize: 16, weight: .regular)
        label.lineBreakMode = .byWordWrapping
        return label
    }()

    private let shapeLayer = CAShapeLayer()

    override init(frame: CGRect) {
        super.init(frame: frame)
        backgroundColor = .clear
        isOpaque = false
        layer.addSublayer(shapeLayer)
        addSubview(textLabel)
        accessibilityIdentifier = "epub.reader.attachment.tooltip"
    }

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

    override func layoutSubviews() {
        super.layoutSubviews()
        shapeLayer.frame = bounds
        shapeLayer.path = bubblePath(in: bounds).cgPath
        shapeLayer.fillColor = UIColor(white: 0.26, alpha: 0.96).cgColor

        let topInset = contentInsets.top + (arrowPlacement == .top ? arrowSize.height : 0)
        let bottomInset = contentInsets.bottom + (arrowPlacement == .bottom ? arrowSize.height : 0)
        let labelFrame = bounds.inset(by: UIEdgeInsets(
            top: topInset,
            left: contentInsets.left,
            bottom: bottomInset,
            right: contentInsets.right
        ))
        textLabel.frame = labelFrame
    }

    func setArrowTipX(_ value: CGFloat, placement: ArrowPlacement) {
        arrowTipX = value
        arrowPlacement = placement
        setNeedsLayout()
    }

    func configure(text: String, maxWidth: CGFloat) {
        textLabel.text = text
        let labelMaxWidth = max(maxWidth - contentInsets.left - contentInsets.right, 120)
        let labelSize = textLabel.sizeThatFits(CGSize(width: labelMaxWidth, height: .greatestFiniteMagnitude))
        frame.size = CGSize(
            width: min(maxWidth, labelSize.width + contentInsets.left + contentInsets.right),
            height: labelSize.height + contentInsets.top + contentInsets.bottom + arrowSize.height
        )
        setNeedsLayout()
        layoutIfNeeded()
    }

    private func bubblePath(in rect: CGRect) -> UIBezierPath {
        let bubbleRect: CGRect
        switch arrowPlacement {
        case .bottom:
            bubbleRect = CGRect(
                x: rect.minX,
                y: rect.minY,
                width: rect.width,
                height: rect.height - arrowSize.height
            )
        case .top:
            bubbleRect = CGRect(
                x: rect.minX,
                y: rect.minY + arrowSize.height,
                width: rect.width,
                height: rect.height - arrowSize.height
            )
        }
        let arrowMidX = min(
            max(arrowTipX ?? bubbleRect.midX, minimumArrowX),
            bubbleRect.width - minimumArrowX
        )
        let arrowHalfWidth = arrowSize.width / 2

        let path = UIBezierPath()
        switch arrowPlacement {
        case .bottom:
            path.move(to: CGPoint(x: bubbleRect.minX + cornerRadius, y: bubbleRect.minY))
            path.addLine(to: CGPoint(x: bubbleRect.maxX - cornerRadius, y: bubbleRect.minY))
            path.addArc(
                withCenter: CGPoint(x: bubbleRect.maxX - cornerRadius, y: bubbleRect.minY + cornerRadius),
                radius: cornerRadius,
                startAngle: -.pi / 2,
                endAngle: 0,
                clockwise: true
            )
            path.addLine(to: CGPoint(x: bubbleRect.maxX, y: bubbleRect.maxY - cornerRadius))
            path.addArc(
                withCenter: CGPoint(x: bubbleRect.maxX - cornerRadius, y: bubbleRect.maxY - cornerRadius),
                radius: cornerRadius,
                startAngle: 0,
                endAngle: .pi / 2,
                clockwise: true
            )
            path.addLine(to: CGPoint(x: arrowMidX + arrowHalfWidth, y: bubbleRect.maxY))
            path.addLine(to: CGPoint(x: arrowMidX, y: bubbleRect.maxY + arrowSize.height))
            path.addLine(to: CGPoint(x: arrowMidX - arrowHalfWidth, y: bubbleRect.maxY))
            path.addLine(to: CGPoint(x: bubbleRect.minX + cornerRadius, y: bubbleRect.maxY))
            path.addArc(
                withCenter: CGPoint(x: bubbleRect.minX + cornerRadius, y: bubbleRect.maxY - cornerRadius),
                radius: cornerRadius,
                startAngle: .pi / 2,
                endAngle: .pi,
                clockwise: true
            )
            path.addLine(to: CGPoint(x: bubbleRect.minX, y: bubbleRect.minY + cornerRadius))
            path.addArc(
                withCenter: CGPoint(x: bubbleRect.minX + cornerRadius, y: bubbleRect.minY + cornerRadius),
                radius: cornerRadius,
                startAngle: .pi,
                endAngle: -.pi / 2,
                clockwise: true
            )
        case .top:
            path.move(to: CGPoint(x: bubbleRect.minX + cornerRadius, y: bubbleRect.minY))
            path.addLine(to: CGPoint(x: arrowMidX - arrowHalfWidth, y: bubbleRect.minY))
            path.addLine(to: CGPoint(x: arrowMidX, y: bubbleRect.minY - arrowSize.height))
            path.addLine(to: CGPoint(x: arrowMidX + arrowHalfWidth, y: bubbleRect.minY))
            path.addLine(to: CGPoint(x: bubbleRect.maxX - cornerRadius, y: bubbleRect.minY))
            path.addArc(
                withCenter: CGPoint(x: bubbleRect.maxX - cornerRadius, y: bubbleRect.minY + cornerRadius),
                radius: cornerRadius,
                startAngle: -.pi / 2,
                endAngle: 0,
                clockwise: true
            )
            path.addLine(to: CGPoint(x: bubbleRect.maxX, y: bubbleRect.maxY - cornerRadius))
            path.addArc(
                withCenter: CGPoint(x: bubbleRect.maxX - cornerRadius, y: bubbleRect.maxY - cornerRadius),
                radius: cornerRadius,
                startAngle: 0,
                endAngle: .pi / 2,
                clockwise: true
            )
            path.addLine(to: CGPoint(x: bubbleRect.minX + cornerRadius, y: bubbleRect.maxY))
            path.addArc(
                withCenter: CGPoint(x: bubbleRect.minX + cornerRadius, y: bubbleRect.maxY - cornerRadius),
                radius: cornerRadius,
                startAngle: .pi / 2,
                endAngle: .pi,
                clockwise: true
            )
            path.addLine(to: CGPoint(x: bubbleRect.minX, y: bubbleRect.minY + cornerRadius))
            path.addArc(
                withCenter: CGPoint(x: bubbleRect.minX + cornerRadius, y: bubbleRect.minY + cornerRadius),
                radius: cornerRadius,
                startAngle: .pi,
                endAngle: -.pi / 2,
                clockwise: true
            )
        }
        path.close()
        return path
    }
}