import UIKit
import FloatingPanel

class ViewController: UIViewController, FloatingPanelControllerDelegate {
    var fpc: FloatingPanelController!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Initialize a `FloatingPanelController` object.
        fpc = FloatingPanelController()

        // Assign self as the delegate of the controller.
        fpc.delegate = self // Optional

        // Set a content view controller.
        let contentVC = ContentViewController()
        fpc.set(contentViewController: contentVC)

        // Track a scroll view(or the siblings) in the content view controller.
        fpc.track(scrollView: contentVC.tableView)

        // Add and show the views managed by the `FloatingPanelController` object to self.view.
        fpc.addPanel(toParent: self)
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)

        // Remove the views managed by the `FloatingPanelController` object from self.view.
        fpc.removePanelFromParent()
    }
}

let fpc = FloatingPanelController()
let contentVC = ...
fpc.set(contentViewController: contentVC)

fpc.isRemovalInteractionEnabled = true // Optional: Let it removable by a swipe-down

self.present(fpc, animated: true, completion: nil)

// Add the floating panel view to the controller's view on top of other views.
self.view.addSubview(fpc.view)

// REQUIRED. It makes the floating panel view have the same size as the controller's view.
fpc.view.frame = self.view.bounds

// In addition, Auto Layout constraints are highly recommended.
// Constraint the fpc.view to all four edges of your controller's view.
// It makes the layout more robust on trait collection change.
fpc.view.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
  fpc.view.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 0.0),
  fpc.view.leftAnchor.constraint(equalTo: self.view.leftAnchor, constant: 0.0),
  fpc.view.rightAnchor.constraint(equalTo: self.view.rightAnchor, constant: 0.0),
  fpc.view.bottomAnchor.constraint(equalTo: self.view.bottomAnchor, constant: 0.0),
])

// Add the floating panel controller to the controller hierarchy.
self.addChild(fpc)

// Show the floating panel at the initial position defined in your `FloatingPanelLayout` object.
fpc.show(animated: true) {
    // Inform the floating panel controller that the transition to the controller hierarchy has completed.
    fpc.didMove(toParent: self)
}

// Inform the panel controller that it will be removed from the hierarchy.
fpc.willMove(toParent: nil)
    
// Hide the floating panel.
fpc.hide(animated: true) {
    // Remove the floating panel view from your controller's view.
    fpc.view.removeFromSuperview()
    // Remove the floating panel controller from the controller hierarchy.
    fpc.removeFromParent()
}

fpc.contentMode = .fitToBounds

class ViewController: UIViewController, FloatingPanelControllerDelegate {
    ...
    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
        return MyFloatingPanelLayout()
    }
}

class MyFloatingPanelLayout: FloatingPanelLayout {
    public var initialPosition: FloatingPanelPosition {
        return .tip
    }

    public func insetFor(position: FloatingPanelPosition) -> CGFloat? {
        switch position {
            case .full: return 16.0 // A top inset from safe area
            case .half: return 216.0 // A bottom inset from the safe area
            case .tip: return 44.0 // A bottom inset from the safe area
            default: return nil // Or `case .hidden: return nil`
        }
    }
}

class ViewController: UIViewController, FloatingPanelControllerDelegate {
    ...
    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
        return (newCollection.verticalSizeClass == .compact) ? FloatingPanelLandscapeLayout() : nil // Returning nil indicates to use the default layout
    }
}

class FloatingPanelLandscapeLayout: FloatingPanelLayout {
    public var initialPosition: FloatingPanelPosition {
        return .tip
    }
    public var supportedPositions: Set<FloatingPanelPosition> {
        return [.full, .tip]
    }

    public func insetFor(position: FloatingPanelPosition) -> CGFloat? {
        switch position {
            case .full: return 16.0
            case .tip: return 69.0
            default: return nil
        }
    }

    public func prepareLayout(surfaceView: UIView, in view: UIView) -> [NSLayoutConstraint] {
        return [
            surfaceView.leftAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leftAnchor, constant: 8.0),
            surfaceView.widthAnchor.constraint(equalToConstant: 291),
        ]
    }
}

class ViewController: UIViewController, FloatingPanelControllerDelegate {
    ...
    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
        return RemovablePanelLayout()
    }
}

class RemovablePanelLayout: FloatingPanelIntrinsicLayout {
    var supportedPositions: Set<FloatingPanelPosition> {
        return [.full, .half]
    }
    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
        switch position {
        case .half: return 130.0
        default: return nil  // Must return nil for .full
        }
    }
    ...
}

class MyFullScreenLayout: FloatingPanelLayout {
    ...
    var positionReference: FloatingPanelLayoutReference {
        return .fromSuperview
    }
}

class MyFullScreenLayout: FloatingPanelFullScreenLayout {
    ...
}

class ViewController: UIViewController, FloatingPanelControllerDelegate {
    ...
    func floatingPanel(_ vc: FloatingPanelController, behaviorFor newCollection: UITraitCollection) -> FloatingPanelBehavior? {
        return FloatingPanelStocksBehavior()
    }
}

class FloatingPanelStocksBehavior: FloatingPanelBehavior {
    ...
    func interactionAnimator(_ fpc: FloatingPanelController, to targetPosition: FloatingPanelPosition, with velocity: CGVector) -> UIViewPropertyAnimator {
        let damping = self.damping(with: velocity)
        let springTiming = UISpringTimingParameters(dampingRatio: damping, initialVelocity: velocity)
        return UIViewPropertyAnimator(duration: 0.5, timingParameters: springTiming)
    }
}

class FloatingPanelBehavior: FloatingPanelBehavior {
    ...
    func allowsRubberBanding(for edge: UIRectEdge) -> Bool {
        return true
    }
}

class FloatingPanelBehavior: FloatingPanelBehavior {
    ...
    func shouldProjectMomentum(_ fpc: FloatingPanelController, for proposedTargetPosition: FloatingPanelPosition) -> Bool {
        return true
    }
}

let myGrabberHandleView = MyGrabberHandleView()
fpc.surfaceView.grabberHandle.isHidden = true
fpc.surfaceView.addSubview(myGrabberHandleView)

fpc.surfaceView.grabberTopPadding = 10.0
fpc.surfaceView.grabberHandleWidth = 44.0
fpc.surfaceView.grabberHandleHeight = 12.0

fpc.surfaceView.contentInsets = .init(top: 20, left: 20, bottom: 20, right: 20)

fpc.surfaceView.containerMargins = .init(top: 20.0, left: 16.0, bottom: 16.0, right: 16.0)

fpc.panGestureRecognizer.isEnable = false

func floatingPanelShouldBeginDragging(_ vc: FloatingPanelController) -> Bool {
    return aCondition ?  false : true
}

override func viewDidLoad() {
    ...
    surfaceTapGesture = UITapGestureRecognizer(target: self, action: #selector(handleSurface(tapGesture:)))
    fpc.surfaceView.addGestureRecognizer(surfaceTapGesture)

    backdropTapGesture = UITapGestureRecognizer(target: self, action: #selector(handleBackdrop(tapGesture:)))
    fpc.backdropView.addGestureRecognizer(backdropTapGesture)

    surfaceTapGesture.isEnabled = (fpc.position == .tip)
}

// Enable `surfaceTapGesture` only at `tip` position
func floatingPanelDidChangePosition(_ vc: FloatingPanelController) {
    surfaceTapGesture.isEnabled = (vc.position == .tip)
}

override func viewDidLoad() {
    // Setup Search panel
    self.searchPanelVC = FloatingPanelController()

    let searchVC = SearchViewController()
    self.searchPanelVC.set(contentViewController: searchVC)
    self.searchPanelVC.track(scrollView: contentVC.tableView)

    self.searchPanelVC.addPanel(toParent: self)

    // Setup Detail panel
    self.detailPanelVC = FloatingPanelController()

    let contentVC = ContentViewController()
    self.detailPanelVC.set(contentViewController: contentVC)
    self.detailPanelVC.track(scrollView: contentVC.scrollView)

    self.detailPanelVC.addPanel(toParent: self)
}

func searchBarCancelButtonClicked(_ searchBar: UISearchBar) {
    ...
    fpc.move(to: .half, animated: true)
}

func searchBarTextDidBeginEditing(_ searchBar: UISearchBar) {
    ...
    fpc.move(to: .full, animated: true)
}

class ViewController: UIViewController, FloatingPanelControllerDelegate {
    ...
    func floatingPanelWillBeginDragging(_ vc: FloatingPanelController) {
        if vc.position == .full {
            searchVC.searchBar.showsCancelButton = false
            searchVC.searchBar.resignFirstResponder()
        }
    }

    func floatingPanelDidEndDragging(_ vc: FloatingPanelController, withVelocity velocity: CGPoint, targetPosition: FloatingPanelPosition) {
        if targetPosition != .full {
            searchVC.hideHeader()
        }
    }
}

class ViewController: UIViewController {
    var fpc: FloatingPanelController!
    var secondFpc: FloatingPanelController!

    ...
    override func show(_ vc: UIViewController, sender: Any?) {
        secondFpc = FloatingPanelController()

        secondFpc.set(contentViewController: vc)

        secondFpc.addPanel(toParent: self)
    }
}

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    if #available(iOS 10, *) {
        visualEffectView.layer.cornerRadius = 9.0
        visualEffectView.clipsToBounds = true
    }
}