import UIKit

extension RDReaderView {

    func tapCenter() {
        refreshToolViewsFromProviderIfNeeded()
        isShowToolView = !isShowToolView
        RDReaderTapDebug.log(
            "ReaderView.tapCenter",
            "toggle toolView visible=\(isShowToolView) top=\(RDReaderTapDebug.describe(topToolView)) bottom=\(RDReaderTapDebug.describe(bottomToolView))"
        )
        if isShowToolView {
            if let topToolView = topToolView {
                installToolViewIfNeeded(topToolView, position: .top)
                layoutIfNeeded()
                topToolView.transform = CGAffineTransform(translationX: 0, y: -topToolView.bounds.height)
                UIView.animate(withDuration: toolViewAnimationDuration) {
                    topToolView.transform = .identity
                }
            }

            if let bottomToolView = bottomToolView {
                installToolViewIfNeeded(bottomToolView, position: .bottom)
                layoutIfNeeded()
                bottomToolView.transform = CGAffineTransform(translationX: 0, y: bottomToolView.bounds.height)
                UIView.animate(withDuration: toolViewAnimationDuration) {
                    bottomToolView.transform = .identity
                }
            }

            collectionView.isUserInteractionEnabled = false
            pageViewController.view.isUserInteractionEnabled = false
            RDReaderTapDebug.log("ReaderView.tapCenter", "disabled collectionView/pageViewController interaction while toolView is visible")
        } else {
            if let topToolView = topToolView {
                UIView.animate(withDuration: toolViewAnimationDuration, animations: {
                    topToolView.transform = CGAffineTransform(translationX: 0, y: -topToolView.bounds.height)
                }) { _ in
                    topToolView.removeFromSuperview()
                }
            }

            if let bottomToolView = bottomToolView {
                UIView.animate(withDuration: toolViewAnimationDuration, animations: {
                    bottomToolView.transform = CGAffineTransform(translationX: 0, y: bottomToolView.bounds.height)
                }) { _ in
                    bottomToolView.removeFromSuperview()
                }
            }

            collectionView.isUserInteractionEnabled = true
            pageViewController.view.isUserInteractionEnabled = true
            RDReaderTapDebug.log("ReaderView.tapCenter", "re-enabled collectionView/pageViewController interaction after hiding toolView")
        }
        onToolViewVisibilityChanged?(isShowToolView)
    }

    func isHitView(_ hitView: UIView?, inside toolView: UIView, point: CGPoint) -> Bool {
        if let hitView, hitView === toolView || hitView.isDescendant(of: toolView) {
            return true
        }

        if toolView.frame.contains(point) {
            // For search bar views, only consider the hit inside the visible
            // panel area. Taps on the dimmed scrim should pass through to
            // the reader content to allow chrome toggling. Touches that
            // resolved to a search bar subview (e.g. the accessibility-only
            // navigation buttons outside the panel) are already claimed by
            // the descendant check above.
            if let searchBarView = toolView as? RDEPUBReaderSearchBarView {
                let panelPoint = convert(point, to: searchBarView.panelView)
                if !searchBarView.panelView.point(inside: panelPoint, with: nil) {
                    return false
                }
            }
            return true
        }

        return false
    }

    enum ToolViewPosition {

        case top

        case bottom
    }

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

        toolView.removeFromSuperview()
        addSubview(toolView)
        toolView.translatesAutoresizingMaskIntoConstraints = false

        let heightConstraint: NSLayoutConstraint
        switch position {
        case .top:
            topToolViewHeightConstraint?.isActive = false
            heightConstraint = toolView.heightAnchor.constraint(equalToConstant: resolvedToolViewHeight(for: .top))
            topToolViewHeightConstraint = heightConstraint
            NSLayoutConstraint.activate([
                toolView.leadingAnchor.constraint(equalTo: leadingAnchor),
                toolView.trailingAnchor.constraint(equalTo: trailingAnchor),
                toolView.topAnchor.constraint(equalTo: topAnchor),
                heightConstraint
            ])
        case .bottom:
            bottomToolViewHeightConstraint?.isActive = false
            heightConstraint = toolView.heightAnchor.constraint(equalToConstant: resolvedToolViewHeight(for: .bottom))
            bottomToolViewHeightConstraint = heightConstraint
            NSLayoutConstraint.activate([
                toolView.leadingAnchor.constraint(equalTo: leadingAnchor),
                toolView.trailingAnchor.constraint(equalTo: trailingAnchor),
                toolView.bottomAnchor.constraint(equalTo: bottomAnchor),
                heightConstraint
            ])
        }
    }

    func updateToolViewHeightConstraintsIfNeeded() {
        topToolViewHeightConstraint?.constant = resolvedToolViewHeight(for: .top)
        bottomToolViewHeightConstraint?.constant = resolvedToolViewHeight(for: .bottom)
    }

    private func resolvedToolViewHeight(for position: ToolViewPosition) -> CGFloat {
        let contentHeight: CGFloat = 52
        switch position {
        case .top:
            return safeAreaInsets.top + contentHeight
        case .bottom:
            return safeAreaInsets.bottom + contentHeight
        }
    }
}