import Foundation

struct AniConverterError: LocalizedError {
    let message: String
    var errorDescription: String? { message }
}

/// 将源视频/图片转换为设备可用的 ANI 文件。
final class AniConverter {
    private let config: DuooomiBleConfig

    private var endpoint: URL {
        URL(string: "\(config.apiHost)/api/auth/loomart/file/convert-to-ani")!
    }

    private let session: URLSession = {
        let cfg = URLSessionConfiguration.default
        cfg.timeoutIntervalForRequest = 120
        cfg.timeoutIntervalForResource = 180
        cfg.waitsForConnectivity = true
        return URLSession(configuration: cfg)
    }()

    init(config: DuooomiBleConfig) {
        self.config = config
    }

    /// 调用 ANI 转换接口，返回 ani 文件的 CDN URL。
    func convert(fileUrl: String, completion: @escaping (Result<String, Error>) -> Void) {
        performConvert(fileUrl: fileUrl) { result in
            switch result {
            case .success:
                completion(result)
            case .failure(let error):
                // Retry once on connection lost
                if (error as NSError).code == NSURLErrorNetworkConnectionLost {
                    self.performConvert(fileUrl: fileUrl, completion: completion)
                } else {
                    completion(.failure(error))
                }
            }
        }
    }

    private func performConvert(fileUrl: String, completion: @escaping (Result<String, Error>) -> Void) {
        var request = URLRequest(url: endpoint)
        request.httpMethod = "POST"
        request.setValue("application/json", forHTTPHeaderField: "content-type")
        request.setValue(config.apiKey, forHTTPHeaderField: "x-api-key")
        request.timeoutInterval = 120

        let body: [String: Any] = [
            "videoUrl": fileUrl,
            "width": config.aniWidth,
            "height": config.aniHeight,
            "fps": config.aniFps,
        ]

        do {
            request.httpBody = try JSONSerialization.data(withJSONObject: body)
        } catch {
            completion(.failure(error))
            return
        }

        session.dataTask(with: request) { data, response, error in
            if let error = error {
                completion(.failure(error))
                return
            }

            if let http = response as? HTTPURLResponse, !(200..<300).contains(http.statusCode) {
                completion(.failure(AniConverterError(message: "HTTP \(http.statusCode)")))
                return
            }

            guard let data = data,
                  let json = (try? JSONSerialization.jsonObject(with: data)) as? [String: Any] else {
                completion(.failure(AniConverterError(message: "Invalid JSON response")))
                return
            }

            guard (json["success"] as? Bool) == true,
                  let outer = json["data"] as? [String: Any] else {
                completion(.failure(AniConverterError(message: "ANI API reported failure")))
                return
            }

            if (outer["status"] as? Bool) != true {
                let msg = (outer["msg"] as? String) ?? "ANI conversion failed"
                completion(.failure(AniConverterError(message: msg)))
                return
            }

            guard let aniUrl = outer["data"] as? String, !aniUrl.isEmpty else {
                completion(.failure(AniConverterError(message: "Missing ani url in response")))
                return
            }

            completion(.success(aniUrl))
        }.resume()
    }
}