import Foundation
import UIKit
import DypaySDK

public class TbDouyinPayNative {
    private static var pending: ((String) -> Void)?
    private static var generation = UUID()

    public static func initialize(_ appId: String, _ scheme: String, _ link: String) {
        if link.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
            // Use the SDK's Scheme-only API instead of registering an empty
            // Universal Link with the higher-priority Universal Link API.
            DypayAPI.register(withAppID: appId, callbackScheme: scheme)
        } else {
            DypayAPI.register(withAppID: appId, universalLink: link, callbackScheme: scheme)
        }
    }

    public static func available() -> Bool { DypayAPI.canOpenDypay() }

    public static func resetPending() {
        DispatchQueue.main.async {
            generation = UUID()
            pending = nil
        }
    }

    public static func pay(_ payload: String, _ done: @escaping (String) -> Void) {
        DispatchQueue.main.async {
            guard pending == nil else {
                done("{\"resultCode\":\"103\",\"errorMsg\":\"已有支付正在处理，请先查单\"}")
                return
            }
            guard DypayAPI.canOpenDypay() else {
                done("{\"resultCode\":\"100\",\"errorMsg\":\"请安装或升级抖音客户端\"}")
                return
            }
            guard let bytes = payload.data(using: .utf8),
                  let info = try? JSONSerialization.jsonObject(with: bytes) as? [String: String],
                  let controller = foregroundController() else {
                done("{\"resultCode\":\"2\",\"errorMsg\":\"支付参数或当前页面不可用\"}")
                return
            }
            generation = UUID()
            let ticket = generation
            pending = done
            DypayAPI.openDypay(withInfo: info, from: controller) { result in
                finish(result as? [AnyHashable: Any], ticket)
            }
            // Only authenticated server reconciliation can release a missing callback's lock.
            // URL callbacks are hints, never payment success; the host always queries its saved order.
        }
    }

    public static func processURL(_ url: URL) -> Bool {
        let ticket = generation
        return DypayAPI.processDypayResult(with: url) { result in
            finish(result as? [AnyHashable: Any], ticket)
        }
    }

    public static func processActivity(_ activity: NSUserActivity) -> Bool {
        let ticket = generation
        return DypayAPI.processDypayResult(with: activity) { result in
            finish(result as? [AnyHashable: Any], ticket)
        }
    }

    private static func finish(_ result: [AnyHashable: Any]?, _ ticket: UUID) {
        DispatchQueue.main.async {
            guard ticket == generation, let callback = pending else { return }
            pending = nil
            let code = result?["resultCode"].map { String(describing: $0) } ?? "3"
            let message = result?["errorMsg"] as? String ?? ""
            let normalized = ["resultCode": code, "errorMsg": message]
            guard let data = try? JSONSerialization.data(withJSONObject: normalized),
                  let json = String(data: data, encoding: .utf8) else {
                callback("{\"resultCode\":\"3\",\"errorMsg\":\"请查询订单状态\"}")
                return
            }
            callback(json)
        }
    }

    private static func foregroundController() -> UIViewController? {
        var windows: [UIWindow] = []
        if #available(iOS 13.0, *) {
            windows = UIApplication.shared.connectedScenes
                .compactMap { $0 as? UIWindowScene }
                .filter { $0.activationState == .foregroundActive }
                .flatMap { $0.windows }
        } else {
            windows = UIApplication.shared.windows
        }
        var controller = windows.first(where: { $0.isKeyWindow })?.rootViewController
        while let current = controller {
            if let presented = current.presentedViewController { controller = presented }
            else if let nav = current as? UINavigationController { controller = nav.visibleViewController }
            else if let tabs = current as? UITabBarController { controller = tabs.selectedViewController }
            else { break }
        }
        return controller
    }
}