/// <reference types="npm:@types/node" />

import {
  GetObjectCommand,
  ListObjectsV2Command,
  S3Client,
} from "@aws-sdk/client-s3";

import { generateTimeStringForFileName } from "../util.ts";
import { getLogger } from "../logger.ts";
import { AwsContext, s3MoveObject } from "./context.ts";
import { getConfig } from "../config.ts";

export class AwsMailRetriever {
  readonly liveMailPrefix = "mail/live/";
  readonly archiveMailPrefix = "mail/archive/";
  readonly mailBucket = getConfig().getValue("awsMailBucket");

  private readonly s3Client;
  private readonly liveMailRecyclerAborter = new AbortController();

  constructor(
    aws: AwsContext,
    private readonly callback: (rawMail: string) => Promise<void>,
  ) {
    const { region, credentials } = aws;
    this.s3Client = new S3Client({ region, credentials });
  }

  setupLiveMailRecycler() {
    Deno.cron("live-mail-recycler", "0 */6 * * *", {
      signal: this.liveMailRecyclerAborter.signal,
    }, () => {
    });
  }

  generateArchivePrefix(instant: Date | Temporal.Instant): string {
    return `${this.archiveMailPrefix}${
      generateTimeStringForFileName(instant, true)
    }/`;
  }

  async listLiveMails(): Promise<string[]> {
    const listCommand = new ListObjectsV2Command({
      Bucket: this.mailBucket,
      Prefix: this.liveMailPrefix,
    });
    const res = await this.s3Client.send(listCommand);

    if (res.Contents == null) {
      getLogger().warn("Listing live mails in S3 returns null Content.");
      return [];
    }

    const result: string[] = [];
    for (const object of res.Contents) {
      if (object.Key != null) {
        result.push(object.Key);
      } else {
        getLogger().warn(
          "Listing live mails in S3 returns an object with no Key.",
        );
      }
    }
    return result;
  }

  async deliverS3MailObject(messageId: string) {
    const mailPath = `${this.liveMailPrefix}${messageId}`;
    const command = new GetObjectCommand({
      Bucket: this.mailBucket,
      Key: mailPath,
    });
    const res = await this.s3Client.send(command);

    if (res.Body == null) {
      // TODO: Better error.
      throw new Error();
    }

    const rawMail = await res.Body.transformToString();
    await this.callback(rawMail);

    // TODO: Continue here.
    await s3MoveObject(this.s3Client, this.mailBucket, mailPath, );
  }

  async recycleLiveMails() {
    const mails = await this.listLiveMails();
  }
}