// Run inside the existing worker, piping the two Spaces credentials as JSON on stdin.
// Copies without deleting or overwriting objects; verifies every destination byte.
import { createHash } from "node:crypto";
import { S3Client, ListObjectsV2Command, GetObjectCommand, PutObjectCommand } from "@aws-sdk/client-s3";

const credentials = JSON.parse(await Bun.stdin.text());
const source = new S3Client({ endpoint: process.env.S3_ENDPOINT, region: process.env.S3_REGION, forcePathStyle: true,
  credentials: { accessKeyId: process.env.S3_ACCESS_KEY!, secretAccessKey: process.env.S3_SECRET_KEY! } });
const destination = new S3Client({ endpoint: "https://nyc3.digitaloceanspaces.com", region: "nyc3",
  credentials: { accessKeyId: credentials.SPACES_ACCESS_KEY, secretAccessKey: credentials.SPACES_SECRET_KEY },
  requestChecksumCalculation: "WHEN_REQUIRED" });
const digest = (bytes: Uint8Array) => createHash("sha256").update(bytes).digest("hex");
let token: string | undefined;
let verified = 0;
let copied = 0;
let bytes = 0;
try {
  do {
    const page = await source.send(new ListObjectsV2Command({ Bucket: process.env.S3_BUCKET!, ContinuationToken: token }));
    for (const object of page.Contents ?? []) {
      if (!object.Key) continue;
      const original = await source.send(new GetObjectCommand({ Bucket: process.env.S3_BUCKET!, Key: object.Key }));
      const body = await original.Body!.transformToByteArray();
      let existing: Uint8Array | undefined;
      try {
        const response = await destination.send(new GetObjectCommand({ Bucket: "hltma", Key: object.Key }));
        existing = await response.Body!.transformToByteArray();
      } catch (error) {
        if ((error as { $metadata?: { httpStatusCode?: number } }).$metadata?.httpStatusCode !== 404) throw error;
      }
      if (!existing) {
        await destination.send(new PutObjectCommand({ Bucket: "hltma", Key: object.Key, Body: body,
          ContentType: original.ContentType, CacheControl: original.CacheControl, ContentDisposition: original.ContentDisposition,
          Metadata: original.Metadata }));
        copied++;
        const response = await destination.send(new GetObjectCommand({ Bucket: "hltma", Key: object.Key }));
        existing = await response.Body!.transformToByteArray();
      }
      if (digest(body) !== digest(existing)) throw new Error("Content mismatch; no objects overwritten or deleted");
      verified++;
      bytes += body.length;
      if (verified % 20 === 0) console.log(JSON.stringify({ verified, copied, bytes }));
    }
    token = page.NextContinuationToken;
  } while (token);
  console.log(JSON.stringify({ complete: true, verified, copied, bytes }));
} catch (error) {
  // Do not print SDK request details, object keys, or credentials.
  console.error(JSON.stringify({ complete: false, verified, copied, error: error instanceof Error ? error.name : "MigrationError" }));
  process.exitCode = 1;
}