import Cocoa

/// Delegate to notify the plugin of PiP lifecycle events
protocol MpvPipDelegate: AnyObject {
  func pipWillStart()
  func pipDidStart()
  /// Called when PiP stops. `restored` is true if the user pressed the close button (restore UI).
  func pipDidStop(restored: Bool)
  /// Forward play/pause commands from PiP overlay to mpv
  func pipSetPlaying(_ playing: Bool)
  /// Query whether mpv is currently playing
  var isPipPlaying: Bool { get }
}

/// Encapsulates macOS Picture-in-Picture using the private PIP.framework (PIPViewController).
/// This approach wraps the existing Metal rendering view in PiP — no VO switching needed.
/// mpv continues rendering to its CAMetalLayer throughout PiP.
class MpvPipController: NSObject, PIPViewControllerDelegate {

  // MARK: - Properties

  private lazy var pip: PIPViewController = {
    let vc = PIPViewController()
    vc.delegate = self
    return vc
  }()

  private var pipVideoVC: NSViewController?
  private var pipVideoView: NSView?

  weak var delegate: MpvPipDelegate?
  private(set) var isActive = false
  var autoPipEnabled = false

  // Keep reference to the window for restore animation
  private weak var sourceWindow: NSWindow?

  // MARK: - Public API

  static var isSupported: Bool { true }

  /// Enter PiP by wrapping the given Metal layer in a view and presenting it.
  /// The layer continues receiving mpv frames — no VO switch needed.
  func startPip(metalLayer: CAMetalLayer, window: NSWindow, aspectRatio: NSSize) {
    guard !isActive else { return }

    sourceWindow = window

    // Create a layer-hosting wrapper view for the Metal layer.
    // PIPViewController resizes the view (and its root layer) as the PiP window resizes.
    let videoView = NSView(frame: NSRect(origin: .zero, size: aspectRatio))
    videoView.wantsLayer = true
    videoView.layer = metalLayer

    // Reset drawableSize to zero so it auto-derives from the layer's bounds.
    // Without this, the explicit drawableSize set by updateFrame() (main window size)
    // persists and causes mpv/MoltenVK to render at the wrong resolution in PiP.
    metalLayer.drawableSize = .zero

    // Create a view controller for PIPViewController
    let vc = NSViewController()
    vc.view = videoView

    pipVideoVC = vc
    pipVideoView = videoView

    // Configure PiP
    pip.playing = delegate?.isPipPlaying ?? false
    pip.aspectRatio = aspectRatio
    pip.replacementWindow = window
    pip.replacementRect = window.contentView?.frame ?? .zero

    delegate?.pipWillStart()

    // Present PiP
    pip.presentAsPicture(inPicture: vc)
    isActive = true
    delegate?.pipDidStart()
  }

  func stopPip() {
    guard isActive else { return }
    pip.dismiss(pipVideoVC!)
  }

  /// Update the play/pause button state in the PiP overlay
  func setPlaying(_ playing: Bool) {
    pip.playing = playing
  }

  /// Update the aspect ratio (e.g., when video track changes)
  func setAspectRatio(_ size: NSSize) {
    pip.aspectRatio = size
  }

  func setAutoStart(_ enabled: Bool) {
    autoPipEnabled = enabled
  }

  /// Clean up after PiP closes — detaches the Metal layer from the wrapper view
  /// so MpvPlayerCore can re-add it to the main window.
  /// Returns the Metal layer that was hosted in PiP.
  @discardableResult
  func detachLayer() -> CAMetalLayer? {
    let metalLayer = pipVideoView?.layer as? CAMetalLayer
    pipVideoView?.layer = CALayer()  // detach before removing
    pipVideoView = nil
    pipVideoVC = nil
    return metalLayer
  }

  // MARK: - PIPViewControllerDelegate

  func pipShouldClose(_ pip: PIPViewController) -> Bool {
    prepareForClose()
    return true
  }

  func pipWillClose(_ pip: PIPViewController) {
    prepareForClose()
  }

  func pipDidClose(_ pip: PIPViewController) {
    isActive = false
    delegate?.pipDidStop(restored: true)
  }

  func pipActionPlay(_ pip: PIPViewController) {
    delegate?.pipSetPlaying(true)
  }

  func pipActionPause(_ pip: PIPViewController) {
    delegate?.pipSetPlaying(false)
  }

  func pipActionStop(_ pip: PIPViewController) {
    delegate?.pipSetPlaying(false)
  }

  // MARK: - Private

  private func prepareForClose() {
    guard let window = sourceWindow else { return }
    pip.replacementWindow = window
    pip.replacementRect = window.contentView?.frame ?? .zero
    // Bring the main window forward for the restore animation
    NSApp.activate(ignoringOtherApps: true)
    window.deminiaturize(nil)
  }
}