async function handler()

in source/lambda/calculateTreehash/index.js [33:79]
32 lines of code
9 McCabe index (conditional complexity)

async function handler(event) {
    let {aid, key, partNo, startByte, endByte} = JSON.parse(event.Records[0].body);

    console.log(`${key} - ${partNo} hash : ${startByte}-${endByte}`);

    // the only way vdt is present at this section of the code is if the treehash is successfully validated already, but 
    // triggerCopyToDestinationBucket fails, hence retry triggerCopyToDestinationBucket.
    let resultRecord = await db.getStatusRecord(aid);
    
    if (resultRecord.Item.vdt && resultRecord.Item.vdt.S) {
        resultRecord.Attributes = resultRecord.Item;
        console.log(`${key} : treehash has already been processed. Skipping`);
        await trigger.triggerCopyToDestinationBucket(resultRecord);
        return;
    }

    let cc = parseInt(resultRecord.Item.cc.N);

    let chunkHash = await treehash.getChunkHash(key, partNo, startByte, endByte);

    // Single Chunk
    if (cc === 1) {
        resultRecord.Attributes = resultRecord.Item;
        await validateTreehash(chunkHash, resultRecord);
        return;
    }

    // Multi Chunk
    let statusRecord = await db.updateChunkStatusGetLatest(aid, partNo, chunkHash);

    let count = 0;
    for (const entry in statusRecord.Attributes) {
        if (
            entry.includes("chunk") &&
            statusRecord.Attributes[entry].S &&
            statusRecord.Attributes[entry].S.length > 40 // to validate that the field contains hash as opposed to etag
        ) {
            count++;
        }
    }

    if (count < cc) return; // not all chunks have yet been completed

    let multiPartHash = treehash.calculateMultiPartHash(statusRecord);

    await validateTreehash(multiPartHash, statusRecord);
}