import {
  DeleteObjectCommand,
  GetObjectCommand,
  ListObjectsV2Command,
  S3Client,
} from "@aws-sdk/client-s3";
import { WidgetRequestRetriever } from ".";
import { WidgetRequest } from "@/shared/schema";
import { TracingLogger } from "@/consumer/log";

export class S3WidgetRequestRetriever implements WidgetRequestRetriever {
  static LIST_KEY_MAX = 1;
  private bucket: string;
  private s3Client: S3Client;
  private logger: TracingLogger;

  constructor(bucket: string, s3Client: S3Client, logger: TracingLogger) {
    this.bucket = bucket;
    this.s3Client = s3Client;
    this.logger = logger;
  }

  private async getWidgetRequest(key: string) {
    const getCommand = new GetObjectCommand({
      Bucket: this.bucket,
      Key: key,
    });

    const response = await this.s3Client.send(getCommand);
    const body = await response.Body?.transformToString();

    if (body && body.length) return WidgetRequest.parse(JSON.parse(body));
  }

  public async refreshRequests() {
    // ListObjectsV2 returns keys in ascending lexicographical order
    const listCommand = new ListObjectsV2Command({
      MaxKeys: S3WidgetRequestRetriever.LIST_KEY_MAX,
      Bucket: this.bucket,
    });
    const response = await this.s3Client.send(listCommand);

    const key = response.Contents && response.Contents[0]?.Key;

    if (!key) {
      this.logger.info(`No more keys in Bucket=(${this.bucket}).`);
      return [];
    }

    const widgetRequest = await this.getWidgetRequest(key);

    const deleteWidgetRequest = new DeleteObjectCommand({
      Key: key,
      Bucket: this.bucket,
    });
    await this.s3Client.send(deleteWidgetRequest);

    if (!widgetRequest) {
      this.logger.warn(`No valid widget at Key=(${key}).`);
      return [];
    }
    return [widgetRequest];
  }
}