import Foundation
import SwiftUI
import UIKit
import CoreImage.CIFilterBuiltins

class GoalShareService {
    static let shared = GoalShareService()

    /// App Store URL - auto-redirects to user's country
    static let appStoreURL = URL(string: "https://apps.apple.com/app/portfolio-journal/id6744983373")!

    /// Website URL - has Open Graph tags for social media previews
    static let websiteURL = URL(string: "https://portfoliojournal.app")!

    /// Share page base URL - parameters will be appended
    static let sharePageBaseURL = "https://portfoliojournal.app/share"

    private init() {}

    /// Build share URL with goal parameters for dynamic OG tags
    static func buildShareURL(goalName: String, progressPercent: Int) -> URL {
        var components = URLComponents(string: sharePageBaseURL)!
        components.queryItems = [
            URLQueryItem(name: "goal", value: goalName),
            URLQueryItem(name: "progress", value: String(progressPercent))
        ]
        return components.url ?? URL(string: sharePageBaseURL)!
    }

    /// Generate a QR code image for the App Store URL
    static func generateQRCode(for url: URL, size: CGFloat = 60) -> UIImage? {
        let context = CIContext()
        let filter = CIFilter.qrCodeGenerator()

        filter.message = Data(url.absoluteString.utf8)
        filter.correctionLevel = "M"

        guard let outputImage = filter.outputImage else { return nil }

        // Scale up the QR code
        let scale = size / outputImage.extent.size.width
        let scaledImage = outputImage.transformed(by: CGAffineTransform(scaleX: scale, y: scale))

        guard let cgImage = context.createCGImage(scaledImage, from: scaledImage.extent) else {
            return nil
        }

        return UIImage(cgImage: cgImage)
    }

    @MainActor
    func shareGoal(
        name: String,
        progress: Double,
        currentValue: Decimal,
        targetValue: Decimal,
        targetDate: Date? = nil,
        estimatedCompletionDate: Date? = nil,
        privacyMode: Bool = false
    ) {
        guard let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
              let viewController = windowScene.windows.first?.rootViewController else {
            return
        }

        // Generate QR code for the card
        let qrCodeImage = Self.generateQRCode(for: Self.appStoreURL, size: 200)

        let card = GoalShareCardView(
            name: name,
            progress: progress,
            currentValue: currentValue,
            targetValue: targetValue,
            targetDate: targetDate,
            estimatedCompletionDate: estimatedCompletionDate,
            privacyMode: privacyMode,
            qrCodeImage: qrCodeImage
        )

        let progressPercent = Int(progress * 100)
        let shareURL = Self.buildShareURL(goalName: name, progressPercent: progressPercent)

        if #available(iOS 16.0, *) {
            let renderer = ImageRenderer(content: card)
            let scale = viewController.view.window?.windowScene?.screen.scale
                ?? viewController.traitCollection.displayScale
            renderer.scale = scale

            if let image = renderer.uiImage {
                // Use combined item provider for text + image together
                let shareItem = GoalShareItem(
                    image: image,
                    goalName: name,
                    progressPercent: progressPercent,
                    shareURL: shareURL
                )
                presentShareSheet(items: [shareItem], from: viewController)
            } else {
                // Fallback to text only
                let text = buildShareText(goalName: name, progressPercent: progressPercent, shareURL: shareURL)
                presentShareSheet(items: [text], from: viewController)
            }
        } else {
            // iOS 15 fallback - text only
            let text = buildShareText(goalName: name, progressPercent: progressPercent, shareURL: shareURL)
            presentShareSheet(items: [text], from: viewController)
        }
    }

    private func buildShareText(goalName: String, progressPercent: Int, shareURL: URL) -> String {
        return """
        I'm \(progressPercent)% towards my "\(goalName)" goal! 🎯

        Track your investment goals with Portfolio Journal.
        \(shareURL.absoluteString)
        """
    }

    private func presentShareSheet(items: [Any], from viewController: UIViewController) {
        let activityVC = UIActivityViewController(activityItems: items, applicationActivities: nil)

        // Exclude some activities that don't make sense for goal sharing
        activityVC.excludedActivityTypes = [
            .addToReadingList,
            .assignToContact,
            .openInIBooks
        ]

        // iPad support - prevent crash by setting popover source
        if let popover = activityVC.popoverPresentationController {
            popover.sourceView = viewController.view
            popover.sourceRect = CGRect(
                x: viewController.view.bounds.midX,
                y: viewController.view.bounds.midY,
                width: 0,
                height: 0
            )
            popover.permittedArrowDirections = []
        }

        viewController.present(activityVC, animated: true)
    }
}

/// Combined share item that provides both image and text together
private class GoalShareItem: NSObject, UIActivityItemSource {
    let image: UIImage
    let goalName: String
    let progressPercent: Int
    let shareURL: URL

    init(image: UIImage, goalName: String, progressPercent: Int, shareURL: URL) {
        self.image = image
        self.goalName = goalName
        self.progressPercent = progressPercent
        self.shareURL = shareURL
        super.init()
    }

    func activityViewControllerPlaceholderItem(_ activityViewController: UIActivityViewController) -> Any {
        return image
    }

    func activityViewController(_ activityViewController: UIActivityViewController, itemForActivityType activityType: UIActivity.ActivityType?) -> Any? {
        // For most activities, return the image
        // The text will be provided via LPLinkMetadata or as a separate item
        return image
    }

    func activityViewController(_ activityViewController: UIActivityViewController, subjectForActivityType activityType: UIActivity.ActivityType?) -> String {
        return "My Investment Goal Progress - Portfolio Journal"
    }

    func activityViewControllerLinkMetadata(_ activityViewController: UIActivityViewController) -> LPLinkMetadata? {
        let metadata = LPLinkMetadata()
        metadata.title = "I'm \(progressPercent)% towards my \"\(goalName)\" goal! 🎯"
        metadata.originalURL = shareURL
        metadata.url = shareURL
        metadata.imageProvider = NSItemProvider(object: image)

        // Set icon
        if let appIcon = UIImage(named: "BrandMark") {
            metadata.iconProvider = NSItemProvider(object: appIcon)
        }

        return metadata
    }
}

import LinkPresentation