const {

Client,

PrivateKey,

AccountId,

TopicMessageQuery,

TopicCreateTransaction,

TopicMessageSubmitTransaction,

} = require("@hashgraph/sdk");

async function main() {

let client;

if (process.env.HEDERA_NETWORK != null) {

switch (process.env.HEDERA_NETWORK) {

case "previewnet":

client = Client.forPreviewnet();

break;

default:

client = Client.forTestnet();

}

} else {

try {

client = await Client.fromConfigFile(process.env.CONFIG_FILE);

} catch (err) {

client = Client.forTestnet();

}

}

if (process.env.OPERATOR_KEY != null && process.env.OPERATOR_ID != null) {

const operatorKey = PrivateKey.fromString(process.env.OPERATOR_KEY);

const operatorId = AccountId.fromString(process.env.OPERATOR_ID);

client.setOperator(operatorId, operatorKey);

}

const response = await new TopicCreateTransaction()

.setTopicMemo("sdk example create_pub_sub.js")

.execute(client);

const receipt = await response.getReceipt(client);

const topicId = receipt.topicId;

console.log(`topicId = ${topicId}`);

new TopicMessageQuery()

.setTopicId(topicId)

.setStartTime(0)

.subscribe(

client,

(message) => console.log(Buffer.from(message.contents, "utf8").toString())

);

for (let i = 0; ; i += 1) {

// eslint-disable-next-line no-await-in-loop

await (await new TopicMessageSubmitTransaction()

.setTopicId(topicId)

.setMessage(`Hello, HCS! Message ${i}`)

.execute(client))

.getReceipt(client);

console.log(`Sent message ${i}`);

// eslint-disable-next-line no-await-in-loop

await sleep(2500);

}

}

function sleep(ms) {

return new Promise((resolve) => setTimeout(resolve, ms));

}

main();