import UIKit
import UniformTypeIdentifiers

final class ShareViewController: UIViewController {
    private let statusLabel = UILabel()

    override func viewDidLoad() {
        super.viewDidLoad()
        setupUI()
        Task { await handleIncomingShare() }
    }

    private func setupUI() {
        view.backgroundColor = .systemBackground
        statusLabel.translatesAutoresizingMaskIntoConstraints = false
        statusLabel.textAlignment = .center
        statusLabel.numberOfLines = 0
        statusLabel.text = "Paylaşılan bağlantı alınıyor..."

        view.addSubview(statusLabel)
        NSLayoutConstraint.activate([
            statusLabel.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20),
            statusLabel.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20),
            statusLabel.centerYAnchor.constraint(equalTo: view.centerYAnchor)
        ])
    }

    @MainActor
    private func updateStatus(_ text: String) {
        statusLabel.text = text
    }

    private func handleIncomingShare() async {
        guard let item = extensionContext?.inputItems.first as? NSExtensionItem,
              let providers = item.attachments else {
            updateStatus("Paylaşılan içerik okunamadı.")
            return
        }

        for provider in providers {
            if let extracted = await extractURL(from: provider), isSupportedStreamingURL(extracted) {
                SharedPayloadStore.saveIncomingURL(extracted.absoluteString)
                updateStatus("Bağlantı alındı, uygulama açılıyor...")
                openHostApp()
                return
            }
        }

        updateStatus("Geçerli bir Netflix/Prime Video linki bulunamadı.")
    }

    private func extractURL(from provider: NSItemProvider) async -> URL? {
        if provider.hasItemConformingToTypeIdentifier(UTType.url.identifier) {
            return await withCheckedContinuation { continuation in
                provider.loadItem(forTypeIdentifier: UTType.url.identifier, options: nil) { item, _ in
                    continuation.resume(returning: item as? URL)
                }
            }
        }

        if provider.hasItemConformingToTypeIdentifier(UTType.text.identifier) {
            return await withCheckedContinuation { continuation in
                provider.loadItem(forTypeIdentifier: UTType.text.identifier, options: nil) { item, _ in
                    if let raw = item as? String, let url = URL(string: raw.trimmingCharacters(in: .whitespacesAndNewlines)) {
                        continuation.resume(returning: url)
                        return
                    }
                    continuation.resume(returning: nil)
                }
            }
        }

        return nil
    }

    private func isSupportedStreamingURL(_ url: URL) -> Bool {
        let host = url.host?.lowercased() ?? ""
        let netflixHosts = ["www.netflix.com", "netflix.com", "www.netflix.com.tr", "netflix.com.tr"]
        let primeHosts = ["www.primevideo.com", "primevideo.com", "www.amazon.com", "amazon.com"]

        let isNetflix = netflixHosts.contains(host)
        let isPrime = primeHosts.contains(host)
        guard isNetflix || isPrime else { return false }

        let path = url.path.lowercased()
        if path.contains("/title/") || path.contains("/watch/") || path.contains("/detail/") {
            return true
        }

        // Some share links can be shortened/redirect style without a canonical path.
        return !path.isEmpty && path != "/"
    }

    private func openHostApp() {
        guard let url = URL(string: "\(SharedConfig.appURLScheme)://ingest") else {
            extensionContext?.completeRequest(returningItems: nil)
            return
        }

        extensionContext?.open(url) { success in
            // If opening succeeded, the system should transition to the host app.
            // Completing the extension request immediately can bounce back to the source app.
            guard !success else { return }
            self.extensionContext?.completeRequest(returningItems: nil)
        }
    }
}