import { S3Client, PutObjectCommand, GetObjectCommand, HeadObjectCommand } from "@aws-sdk/client-s3";
import { getSignedUrl } from "@aws-sdk/s3-request-presigner";

const accountId = process.env.R2_ACCOUNT_ID ?? "";
const bucket = process.env.R2_BUCKET ?? "continuum";

export const s3 = new S3Client({
  region: "auto",
  endpoint: process.env.R2_ENDPOINT ?? `https://${accountId}.r2.cloudflarestorage.com`,
  credentials: {
    accessKeyId: process.env.R2_ACCESS_KEY_ID ?? "",
    secretAccessKey: process.env.R2_SECRET_ACCESS_KEY ?? "",
  },
});

/** Presigned PUT for clients uploading a G-code/3MF file directly to R2. */
export async function getUploadUrl(key: string, contentType = "application/octet-stream", expiresInSeconds = 900) {
  const command = new PutObjectCommand({ Bucket: bucket, Key: key, ContentType: contentType });
  return getSignedUrl(s3, command, { expiresIn: expiresInSeconds });
}

/** Presigned GET for the edge proxy to download a job file over LAN via FTPS relay or direct fetch. */
export async function getDownloadUrl(key: string, expiresInSeconds = 900) {
  const command = new GetObjectCommand({ Bucket: bucket, Key: key });
  return getSignedUrl(s3, command, { expiresIn: expiresInSeconds });
}

/**
 * Whether the object is actually in the bucket, and how big it is.
 *
 * The scheduler needs this because `POST /jobs` returns a presigned PUT and
 * the client has not used it yet: the row exists before the file does. Rather
 * than trust a client to tell us it finished - a client that crashes
 * mid-upload would never say so, and one that lies would have a gateway
 * download an error document - this asks the bucket.
 *
 * Returns `undefined` for a missing object rather than throwing, because for
 * this caller "not uploaded yet" is the ordinary case on every tick between
 * queueing a job and the upload finishing.
 */
export async function headObject(key: string): Promise<{ size: number } | undefined> {
  try {
    const head = await s3.send(new HeadObjectCommand({ Bucket: bucket, Key: key }));
    return { size: head.ContentLength ?? 0 };
  } catch (err) {
    // 404/NotFound is the expected answer for a job whose file has not
    // arrived. Anything else - credentials, networking, a bucket that does
    // not exist - is a real problem and must not be reported as "no file",
    // or every job on a misconfigured deployment would sit queued forever
    // with nothing saying why.
    const name = (err as { name?: string }).name;
    const status = (err as { $metadata?: { httpStatusCode?: number } }).$metadata?.httpStatusCode;
    if (name === "NotFound" || name === "NoSuchKey" || status === 404) return undefined;
    throw err;
  }
}

export function jobFileKey(farmId: string, jobId: string, fileName: string) {
  return `farms/${farmId}/jobs/${jobId}/${fileName}`;
}

export function frameKey(farmId: string, printerId: string, frameId: string) {
  return `farms/${farmId}/printers/${printerId}/frames/${frameId}.jpg`;
}