import { createHash } from 'node:crypto';

import { INestApplication, InternalServerErrorException } from '@nestjs/common';
import { PrismaClient, User } from '@prisma/client';
import request from 'supertest';
import { afterAll, beforeAll, describe, expect, it } from 'vitest';

import { AuthTokensService } from '../auth/auth-tokens.service';
import { createTestApp } from '../testing/test-app';
import { createTestPrisma, hasTestDb, uniqueSuffix } from '../testing/test-db';
import { UsersService } from '../users/users.service';

import { FileStorageService } from './file-storage.service';
import { FilesService } from './files.service';

const PNG_SIGNATURE = Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]);
const pngBuffer = (payload: string): Buffer => Buffer.concat([PNG_SIGNATURE, Buffer.from(payload)]);
const sha256 = (buffer: Buffer): string => createHash('sha256').update(buffer).digest('hex');

/**
 * Attachment integrity (issue #199): uploads store the SHA-256 of the
 * written bytes, downloads verify it and fail closed (audited) on mismatch,
 * and the nightly backfill hashes pre-#199 rows idempotently, reporting
 * unreadable files instead of skipping them.
 */
describe.skipIf(!hasTestDb)('attachment integrity (e2e, issue #199)', () => {
  let app: INestApplication;
  let prisma: PrismaClient;
  let files: FilesService;
  let storage: FileStorageService;
  let user: User;
  let pondId: string;
  const suffix = uniqueSuffix();

  async function uploadPng(payload: string): Promise<{ id: string; bytes: Buffer }> {
    const bytes = pngBuffer(payload);
    const view = await files.upload(user, pondId, {
      buffer: bytes,
      size: bytes.length,
      originalname: `${payload}.png`,
    });
    return { id: view.id, bytes };
  }

  beforeAll(async () => {
    prisma = createTestPrisma();
    app = await createTestApp();
    files = app.get(FilesService);
    storage = app.get(FileStorageService);

    const users = app.get(UsersService);
    user = await users.createUser({
      username: `ines-integrity-${suffix}`,
      email: `ines-integrity-${suffix}@example.org`,
      displayName: `Ines Integrity ${suffix}`,
      password: 'jedes byte bleibt wie es war 1',
      locale: 'en',
    });
    // Verification via the endpoint (not markEmailVerified) because only the
    // endpoint creates the personal pond the uploads go into.
    const token = await app.get(AuthTokensService).issue(user.id, 'EMAIL_VERIFICATION', 600);
    await request(app.getHttpServer())
      .post('/api/v1/auth/verify-email')
      .send({ token })
      .expect(204);
    const pond = await prisma.pond.findFirstOrThrow({ where: { ownerId: user.id } });
    pondId = pond.id;
  });

  afterAll(async () => {
    await prisma.auditEntry.deleteMany({
      where: { action: 'file.integrity_failed', details: { path: ['pondId'], equals: pondId } },
    });
    await prisma.attachment.deleteMany({ where: { pondId } });
    const where = { pond: { owner: { username: { contains: suffix } } } };
    await prisma.roleGrant.deleteMany({ where });
    await prisma.pond.deleteMany({ where: { owner: { username: { contains: suffix } } } });
    await prisma.user.deleteMany({ where: { username: { contains: suffix } } });
    await prisma.$disconnect();
    await app.close();
  });

  it('stores the hash of the written bytes at upload', async () => {
    const { id, bytes } = await uploadPng('honest-upload');
    const row = await prisma.attachment.findUniqueOrThrow({ where: { id } });
    expect(row.sha256).toBe(sha256(bytes));
  });

  it('serves an intact file and fails closed, audited, on a tampered one', async () => {
    const { id, bytes } = await uploadPng('will-be-tampered');

    // Intact: the download succeeds and streams the exact bytes.
    const intact = await files.download(null, id, { actorId: null, sessionKey: 'anon' });
    const chunks: Buffer[] = [];
    for await (const chunk of intact.stream) chunks.push(chunk as Buffer);
    expect(Buffer.concat(chunks).equals(bytes)).toBe(true);

    // Tampered on disk (row untouched): fail closed with the dedicated code.
    await storage.save(pondId, id, pngBuffer('evil-replacement'));
    const failure = await files
      .download(null, id, { actorId: null, sessionKey: 'anon' })
      .catch((error: unknown) => error);
    expect(failure).toBeInstanceOf(InternalServerErrorException);
    expect((failure as InternalServerErrorException).getResponse()).toMatchObject({
      code: 'attachment_integrity_failure',
    });

    // The mismatch is on the audit trail with both hashes.
    const audit = await prisma.auditEntry.findFirst({
      where: { action: 'file.integrity_failed', targetId: id },
    });
    expect(audit).not.toBeNull();
    expect(audit!.details).toMatchObject({
      expected: sha256(bytes),
      actual: sha256(pngBuffer('evil-replacement')),
    });
  });

  it('backfills missing hashes idempotently and reports unreadable files', async () => {
    const readable = await uploadPng('backfill-me');
    const unreadable = await uploadPng('bytes-will-vanish');
    await prisma.attachment.updateMany({
      where: { id: { in: [readable.id, unreadable.id] } },
      data: { sha256: null },
    });
    await storage.delete(pondId, unreadable.id);

    // A null-hash row is served unverified (pre-#199 status quo).
    const unverified = await files.download(null, readable.id, {
      actorId: null,
      sessionKey: 'anon',
    });
    expect(unverified.attachment.sha256).toBeNull();

    const first = await files.backfillHashes();
    expect(first.hashed).toBeGreaterThanOrEqual(1);
    expect(first.unreadable).toBeGreaterThanOrEqual(1);
    const rehashed = await prisma.attachment.findUniqueOrThrow({ where: { id: readable.id } });
    expect(rehashed.sha256).toBe(sha256(readable.bytes));

    // The unreadable row keeps its null hash — reported, retried next run,
    // never silently marked done.
    const vanished = await prisma.attachment.findUniqueOrThrow({ where: { id: unreadable.id } });
    expect(vanished.sha256).toBeNull();

    // Idempotent: a second run finds nothing new to hash here.
    const second = await files.backfillHashes();
    const third = await prisma.attachment.findUniqueOrThrow({ where: { id: readable.id } });
    expect(third.sha256).toBe(sha256(readable.bytes));
    expect(second.unreadable).toBeGreaterThanOrEqual(1);
  });
});