tencent cloud

import 'dart:convert';
import 'dart:io';

import 'package:flutter/foundation.dart';
import 'package:tencentcloud_cos_sdk_plugin/fetch_credentials.dart';
import 'package:tencentcloud_cos_sdk_plugin/pigeon.dart';

// Implement a IFetchCredentials class to handle the process of requesting temporary keys and returning the results.
class FetchCredentials implements IFetchCredentials{
  @override
  Future<SessionQCloudCredentials> fetchSessionCredentials() async {
    // First, obtain the response containing key information from your temporary key server, for example:
    var httpClient = HttpClient();
    try {
      // url for the temporary key server. For the temporary key generation service, see https://www.tencentcloud.com/document/product/436/14048
      var stsUrl = "http://stsservice.com/sts";
      var request = await httpClient.getUrl(Uri.parse(stsUrl));
      var response = await request.close();
      if (response.statusCode == HttpStatus.OK) {
        var json = await response.transform(utf8.decoder).join();
        print(json);

        // Then parse the response to obtain temporary key information
        var data = jsonDecode(json);
        // Finally, return the temporary key information object
        return SessionQCloudCredentials(
            secretId: data['credentials']['tmpSecretId'], // Temporary key SecretId
            secretKey: data['credentials']['tmpSecretKey'], // Temporary key SecretKey
            token: data['credentials']['sessionToken'], // Temporary key Token
            startTime: data['startTime'], // Temporary key validity start time, in seconds
            expiredTime: data['expiredTime']//Expiration timestamp of the temporary key, in seconds
        );
      } else {
        throw ArgumentError();
      }
    } catch (exception) {
      throw ArgumentError();
    }
  }
}

await Cos().initWithSessionCredential(FetchCredentials());

String SECRET_ID = "SECRETID"; // User's SecretId. It is recommended to use a sub-account key; authorization follows the principle of least privilege to reduce usage risks. For obtaining sub-account keys, see https://www.tencentcloud.com/document/product/598/37140?from_cn_redirect=1
String SECRET_KEY = "SECRETKEY"; // User's SecretKey. It is recommended to use a sub-account key; authorization follows the principle of least privilege to reduce usage risks. For obtaining sub-account keys, see https://www.tencentcloud.com/document/product/598/37140?from_cn_redirect=1

await Cos().initWithPlainSecret(SECRET_ID, SECRET_KEY);

    // The advanced download API supports resuming from breakpoints, so it initiates a HEAD request to obtain file information before downloading.
    // If you are using a temporary key or accessing with a sub-account, ensure that the permission list includes the HeadObject permission.

    // TransferManager supports resuming downloads from breakpoints; you only need to ensure the bucket, cosPath, and savePath
    // If the parameters are consistent, the SDK will resume downloading from the last position.

    // Obtain the TransferManager
    CosTransferManger transferManager = Cos().getDefaultTransferManger();
    //CosTransferManger transferManager = Cos().getTransferManger("newRegion");
    // Bucket name in the format of bucketname-appid, where appid must be included. You can view the bucket name in the COS console: https://console.tencentcloud.com/cos5/bucket
    String bucket = "examplebucket-1250000000";
    String cosPath = "exampleobject"; // The location identifier of the object in the bucket, also known as the object key
    String downloadPath = "absolute path of the local file"; // absolute path to save the local file

    // Download success callback
    successCallBack(Map<String?, String?>? header, CosXmlResult? result) {
      // todo Download success follow-up logic
    }
    // Download failure callback
    failCallBack(clientException, serviceException) {
      // todo Download failure follow-up logic
      if (clientException != null) {
        print(clientException);
      }
      if (serviceException != null) {
        print(serviceException);
      }
    }
    // Download status callback, which allows you to view the task progress
    stateCallback(state) {
      // todo notify transfer state
    }
    // Download progress callback
    progressCallBack(complete, target) {
      // todo Do something to download progress...
    }
    // Start download
    TransferTask transferTask = await transferManager.download(bucket, cosPath, downloadPath, 
        resultListener: ResultListener(successCallBack, failCallBack),
        stateCallback: stateCallback,
        progressCallBack: progressCallBack,
        // Configure a single-use temporary key here; if not using the single-use temporary key method, do not pass this parameter
        sessionCredentials: sessionQCloudCredentials
    );
    // Pause task
    //transferTask.pause();
    // Resume task
    //transferTask.resume();
    // Cancel task
    //transferTask.cancel();