import PaperKit

import PaperKit
import PencilKit
import UIKit

class MarkupViewController: UIViewController, PaperMarkupViewController.Delegate {
    var paperVC: PaperMarkupViewController!
    var toolPicker: PKToolPicker!

    override func viewDidLoad() {
        super.viewDidLoad()

        let markup = PaperMarkup(bounds: view.bounds)
        paperVC = PaperMarkupViewController(
            markup: markup,
            supportedFeatureSet: .latest
        )
        paperVC.delegate = self

        addChild(paperVC)
        paperVC.view.frame = view.bounds
        paperVC.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        view.addSubview(paperVC.view)
        paperVC.didMove(toParent: self)

        toolPicker = PKToolPicker()
        toolPicker.addObserver(paperVC)
        paperVC.pencilKitResponderState.activeToolPicker = toolPicker
        paperVC.pencilKitResponderState.toolPickerVisibility = .visible
    }

    func paperMarkupViewControllerDidChangeMarkup(
        _ controller: PaperMarkupViewController
    ) {
        guard let markup = controller.markup else { return }
        Task { try await save(markup) }
    }
}

paperVC.directTouchMode = .drawing    // Finger draws
paperVC.directTouchMode = .selection  // Finger selects elements
paperVC.directTouchAutomaticallyDraws = true  // System decides based on Pencil state

paperVC.contentView = UIImageView(image: UIImage(named: "template"))

// New empty model
let markup = PaperMarkup(bounds: CGRect(x: 0, y: 0, width: 612, height: 792))

// Load from saved data
let markup = try PaperMarkup(dataRepresentation: savedData)

// Save — dataRepresentation() is async throws
func save(_ markup: PaperMarkup) async throws {
    let data = try await markup.dataRepresentation()
    try data.write(to: fileURL)
}

// Text box
markup.insertNewTextbox(
    attributedText: AttributedString("Annotation"),
    frame: CGRect(x: 50, y: 100, width: 200, height: 40),
    rotation: 0
)

// Image
markup.insertNewImage(cgImage, frame: CGRect(x: 50, y: 200, width: 300, height: 200), rotation: 0)

// Shape
let shapeConfig = ShapeConfiguration(
    type: .rectangle,
    fillColor: UIColor.systemBlue.withAlphaComponent(0.2).cgColor,
    strokeColor: UIColor.systemBlue.cgColor,
    lineWidth: 2
)
markup.insertNewShape(configuration: shapeConfig, frame: CGRect(x: 50, y: 420, width: 200, height: 100), rotation: 0)

// Line with arrow end marker
let lineConfig = ShapeConfiguration(type: .line, fillColor: nil, strokeColor: UIColor.red.cgColor, lineWidth: 3)
markup.insertNewLine(
    configuration: lineConfig,
    from: CGPoint(x: 50, y: 550), to: CGPoint(x: 250, y: 550),
    startMarker: false, endMarker: true
)

markup.append(contentsOf: otherMarkup)       // Merge another PaperMarkup
markup.append(contentsOf: pkDrawing)          // Merge a PKDrawing
markup.transformContent(CGAffineTransform(...)) // Apply affine transform
markup.removeContentUnsupported(by: featureSet) // Strip unsupported elements

func showInsertionMenu(from barButtonItem: UIBarButtonItem) {
    let editVC = MarkupEditViewController(
        supportedFeatureSet: .latest,
        additionalActions: []
    )
    editVC.delegate = paperVC  // PaperMarkupViewController conforms to the delegate
    editVC.modalPresentationStyle = .popover
    editVC.popoverPresentationController?.barButtonItem = barButtonItem
    present(editVC, animated: true)
}

let toolbar = MarkupToolbarViewController(supportedFeatureSet: .latest)
toolbar.delegate = paperVC
addChild(toolbar)
toolbar.view.frame = toolbarContainerView.bounds
toolbarContainerView.addSubview(toolbar.view)
toolbar.didMove(toParent: self)

var features = FeatureSet.latest
features.remove(.stickers)
features.remove(.images)

// Or build up from empty
var features = FeatureSet.empty
features.insert(.drawing)
features.insert(.text)
features.insert(.shapeStrokes)

var features = FeatureSet.latest
features.colorMaximumLinearExposure = 4.0
toolPicker.maximumLinearExposure = features.colorMaximumLinearExposure

features.shapes = [.rectangle, .ellipse, .arrowShape, .line]
features.inks = [.pen, .pencil, .marker]
features.lineMarkerPositions = .all  // .single, .double, .plain, or .all

import PencilKit

// Set drawing tool
paperVC.drawingTool = PKInkingTool(.pen, color: .black, width: 3)

// Merge existing PKDrawing into markup
markup.append(contentsOf: existingPKDrawing)

let toolPicker = PKToolPicker()
toolPicker.addObserver(paperVC)
paperVC.pencilKitResponderState.activeToolPicker = toolPicker
paperVC.pencilKitResponderState.toolPickerVisibility = .visible

let pkVersion = features.contentVersion.pencilKitContentVersion

struct MarkupView: UIViewControllerRepresentable {
    @Binding var markup: PaperMarkup

    func makeUIViewController(context: Context) -> PaperMarkupViewController {
        let vc = PaperMarkupViewController(markup: markup, supportedFeatureSet: .latest)
        vc.delegate = context.coordinator
        let toolPicker = PKToolPicker()
        toolPicker.addObserver(vc)
        vc.pencilKitResponderState.activeToolPicker = toolPicker
        vc.pencilKitResponderState.toolPickerVisibility = .visible
        context.coordinator.toolPicker = toolPicker
        return vc
    }

    func updateUIViewController(_ vc: PaperMarkupViewController, context: Context) {
        if vc.markup != markup { vc.markup = markup }
    }

    func makeCoordinator() -> Coordinator { Coordinator(parent: self) }

    class Coordinator: NSObject, PaperMarkupViewController.Delegate {
        let parent: MarkupView
        var toolPicker: PKToolPicker?
        init(parent: MarkupView) { self.parent = parent }

        func paperMarkupViewControllerDidChangeMarkup(
            _ controller: PaperMarkupViewController
        ) {
            if let markup = controller.markup { parent.markup = markup }
        }
    }
}

// DON'T
let paperVC = PaperMarkupViewController(markup: m, supportedFeatureSet: .latest)
let editVC = MarkupEditViewController(supportedFeatureSet: .version1, additionalActions: [])

// DO — use the same FeatureSet for both
let features = FeatureSet.latest
let paperVC = PaperMarkupViewController(markup: m, supportedFeatureSet: features)
let editVC = MarkupEditViewController(supportedFeatureSet: features, additionalActions: [])

// DON'T
let markup = try PaperMarkup(dataRepresentation: data)
paperVC.markup = markup

// DO — check version compatibility
let markup = try PaperMarkup(dataRepresentation: data)
if markup.featureSet.isSubset(of: paperVC.supportedFeatureSet) {
    paperVC.markup = markup
} else {
    showVersionMismatchAlert()
}

// DON'T — dataRepresentation() is async, don't try to work around it

// DO — save from an async context
func paperMarkupViewControllerDidChangeMarkup(_ controller: PaperMarkupViewController) {
    guard let markup = controller.markup else { return }
    Task {
        let data = try await markup.dataRepresentation()
        try data.write(to: fileURL)
    }
}

// DON'T — local variable gets deallocated
func viewDidLoad() {
    let toolPicker = PKToolPicker()
    toolPicker.addObserver(paperVC)
}

// DO — store as instance property
var toolPicker: PKToolPicker!

// DON'T — MarkupEditViewController is iOS/iPadOS/visionOS only

// DO
#if os(macOS)
let toolbar = MarkupToolbarViewController(supportedFeatureSet: features)
#else
let editVC = MarkupEditViewController(supportedFeatureSet: features, additionalActions: [])
#endif