import type { Task } from "graphile-worker";
import { PrismaClient } from "../../generated/prisma";
import { createHash } from 'crypto';
import { access } from "node:fs/promises";
import { pipeline } from 'stream/promises';
import path from 'path';
import { createReadStream } from "node:fs";
import { getOrDownloadAsset } from "../utils/cache";
import { env } from "../config/env";
import { getS3Client } from "../utils/s3";

const prisma = new PrismaClient();

interface Payload {
  vodId: string;
}

const client = getS3Client()

const generateVideoChecksum: Task = async (payload: unknown, helpers) => {
  const { vodId } = payload as Payload;
  helpers.logger.info(`Generating checksum for VOD ${vodId}`);

  // 1. Get VOD record with source video path
  const vod = await prisma.vod.findUnique({
    where: { id: vodId },
    select: { sourceVideo: true }
  });

  if (!vod?.sourceVideo) {
    throw new Error(`VOD ${vodId} has no source video`)
  }

  // 2. Verify file exists
  const videoPath = await getOrDownloadAsset(client, env.S3_BUCKET, vod.sourceVideo)
  helpers.logger.info(`videoPath=${videoPath}`)

  try {
    await access(videoPath);
  } catch (err) {
    throw new Error(`Source video not found at ${videoPath}`);
  }

  // 3. Generate SHA-256 hash
  try {
    const hash = createHash('sha256');
    const fileStream = createReadStream(videoPath);

    await pipeline(
      fileStream,
      hash
    );

    const checksum = hash.digest('hex');
    helpers.logger.info(`Generated checksum for ${path.basename(vod.sourceVideo)}: ${checksum}`);

    // 4. Update VOD record
    await prisma.vod.update({
      where: { id: vodId },
      data: { sha256sum: checksum }
    });

  } catch (err) {
    helpers.logger.error(`Failed to generate checksum: ${err.message}`);
    throw err; // Will trigger retry if configured
  }
};

export default generateVideoChecksum;