const { BlobServiceClient } = require("@azure/storage-blob");
const unzipper = require("unzipper");

const ONE_MEGABYTE = 1024 * 1024;
const uploadOptions = { bufferSize: 4 * ONE_MEGABYTE, maxBuffers: 20 };

const AZURE_STORAGE_CONNECTION_STRING = process.env.IMPORT_AZURE_STORAGE_CONNECTION;
// Create the BlobServiceClient object which will be used to create a container client
const blobService = BlobServiceClient.fromConnectionString(AZURE_STORAGE_CONNECTION_STRING);

module.exports = async function (context, zipName) {
    context.log("Unzip: " + zipName);

    const importContainer = blobService.getContainerClient("zip-import");
    const processContainer = blobService.getContainerClient("zip-process");

    // Stream zip 
    const blobClient = importContainer.getBlobClient(zipName);
    const downloadBlockBlobResponse = await blobClient.download();
    const zipStream = downloadBlockBlobResponse.readableStreamBody.pipe(unzipper.Parse({ forceStream: true }));

    for await (const entry of zipStream) {
        const blockBlobClient = processContainer.getBlockBlobClient(entry.path);
        try {
            await blockBlobClient.uploadStream(entry, uploadOptions.bufferSize, uploadOptions.maxBuffers);
            context.log(`Uploaded ${entry.path} from unzipped ${zipName}`);
        } catch (error) {
            throw new Error(`Error while uploading unzipped file ${entry.path}: ${error}`);
        }
    }
};