import Foundation

/// 文件传输服务：下载文件并通过协议发送二进制数据
final class FileTransferService {
    private let protocolService: BleProtocolService

    init(protocolService: BleProtocolService) {
        self.protocolService = protocolService
    }

    /// 传输文件到设备
    func transferFile(
        fileUri: String,
        commandType: CommandType,
        onProgress: ((Double) -> Void)? = nil,
        completion: @escaping (Result<Void, Error>) -> Void
    ) {
        BleLog.i("Load file: \(fileUri)", "Transfer")
        loadFileData(from: fileUri) { [weak self] result in
            switch result {
            case .failure(let error):
                completion(.failure(error))
            case .success(let data):
                BleLog.d("File loaded: size=\(data.count) bytes", "Transfer")
                self?.protocolService.send(
                    type: commandType.rawValue,
                    data: data,
                    onProgress: onProgress,
                    completion: completion
                )
            }
        }
    }

    private func loadFileData(from uri: String, completion: @escaping (Result<Data, Error>) -> Void) {
        guard let url = URL(string: uri) else {
            completion(.failure(DuooomiBleError.transferFailed("Invalid URL: \(uri)")))
            return
        }

        if url.isFileURL {
            do {
                let data = try Data(contentsOf: url)
                completion(.success(data))
            } catch {
                completion(.failure(DuooomiBleError.transferFailed("Failed to read local file: \(error.localizedDescription)")))
            }
            return
        }

        URLSession.shared.dataTask(with: url) { data, response, error in
            if let error = error {
                completion(.failure(DuooomiBleError.transferFailed("Download failed: \(error.localizedDescription)")))
                return
            }
            guard let httpResponse = response as? HTTPURLResponse,
                  (200...299).contains(httpResponse.statusCode) else {
                completion(.failure(DuooomiBleError.transferFailed("Failed to download file: \(uri)")))
                return
            }
            guard let data = data, !data.isEmpty else {
                completion(.failure(DuooomiBleError.transferFailed("Empty download response")))
                return
            }
            completion(.success(data))
        }.resume()
    }
}