import UIKit
import SnapKit

/// 阅读器 Chrome 的安装、尺寸更新与显示动画。
extension RDPDFReaderView {
    enum ToolViewPosition { case top, bottom }

    func toggleToolbars() {
        isToolViewVisible.toggle()
        if isToolViewVisible {
            if let topToolView { showToolView(topToolView, position: .top) }
            if let bottomToolView { showToolView(bottomToolView, position: .bottom) }
        } else {
            if let topToolView { hideToolView(topToolView, position: .top) }
            if let bottomToolView { hideToolView(bottomToolView, position: .bottom) }
        }
        delegate?.toolViewVisibilityChanged?(readerView: self, isVisible: isToolViewVisible)
    }

    func showToolView(_ toolView: UIView, position: ToolViewPosition) {
        installToolViewIfNeeded(toolView, position: position)
        layoutIfNeeded()
        toolView.transform = CGAffineTransform(translationX: 0, y: position == .top ? -toolView.bounds.height : toolView.bounds.height)
        UIView.animate(withDuration: 0.25) { toolView.transform = .identity }
    }

    func hideToolView(_ toolView: UIView, position: ToolViewPosition) {
        UIView.animate(withDuration: 0.25, animations: {
            toolView.transform = CGAffineTransform(translationX: 0, y: position == .top ? -toolView.bounds.height : toolView.bounds.height)
        }) { _ in
            toolView.removeFromSuperview()
            toolView.transform = .identity
        }
    }

    func installToolViewIfNeeded(_ toolView: UIView, position: ToolViewPosition) {
        guard toolView.superview !== self else { return }
        toolView.removeFromSuperview()
        addSubview(toolView)

        let heightConstraint: Constraint
        switch position {
        case .top:
            topToolViewHeightConstraint?.deactivate()
            var height: Constraint!
            toolView.snp.makeConstraints { make in
                make.leading.trailing.top.equalToSuperview()
                height = make.height.equalTo(safeAreaInsets.top + 52).constraint
            }
            heightConstraint = height
            topToolViewHeightConstraint = heightConstraint
        case .bottom:
            bottomToolViewHeightConstraint?.deactivate()
            var height: Constraint!
            toolView.snp.makeConstraints { make in
                make.leading.trailing.bottom.equalToSuperview()
                height = make.height.equalTo(safeAreaInsets.bottom + 52).constraint
            }
            heightConstraint = height
            bottomToolViewHeightConstraint = heightConstraint
        }
    }

    func updateToolViewHeightConstraintsIfNeeded() {
        topToolViewHeightConstraint?.update(offset: safeAreaInsets.top + 52)
        bottomToolViewHeightConstraint?.update(offset: safeAreaInsets.bottom + 52)
    }
}