import {
  buildCarFile,
  CID,
  cborEncode,
  cborEncodeDagCbor,
  cidToBytes,
  cidToString,
  createCid,
} from '@pdsjs/core/repo';
import { describe, expect, it } from 'vitest';
import { commitWrites, decodeFrame } from '../src/firehose.js';

const COLLECTION = 'dev.pdsjs.git.repo';
const DID = 'did:plc:abc123';

/**
 * A #commit frame carrying one record write, built the way the server builds
 * it so the decoder is tested against the real encoding.
 * @param {{path: string, value: Record<string, unknown>}[]} writes
 */
async function commitFrame(writes) {
  const blocks = [];
  const ops = [];
  for (const write of writes) {
    const data = cborEncodeDagCbor(write.value);
    const cid = cidToString(await createCid(data));
    blocks.push({ cid, data });
    ops.push({
      action: 'create',
      path: write.path,
      cid: new CID(cidToBytes(cid)),
    });
  }
  const header = cborEncode({ op: 1, t: '#commit' });
  const body = cborEncodeDagCbor({
    seq: 42,
    repo: DID,
    rev: '3ktest',
    blocks: blocks.length
      ? buildCarFile(blocks[0].cid, blocks)
      : new Uint8Array(0),
    ops,
    time: '2026-08-18T00:00:00.000Z',
  });
  const frame = new Uint8Array(header.length + body.length);
  frame.set(header, 0);
  frame.set(body, header.length);
  return frame;
}

describe('decodeFrame', () => {
  it('splits the header from the body', async () => {
    const frame = await commitFrame([
      { path: `${COLLECTION}/proj`, value: { name: 'proj' } },
    ]);
    const { header, body } = decodeFrame(frame);
    expect(header).toEqual({ op: 1, t: '#commit' });
    expect(body.seq).toBe(42);
    expect(body.repo).toBe(DID);
  });

  it('decodes an error frame', () => {
    const header = cborEncode({ op: -1 });
    const body = cborEncode({ error: 'FutureCursor' });
    const frame = new Uint8Array(header.length + body.length);
    frame.set(header, 0);
    frame.set(body, header.length);
    expect(decodeFrame(frame).header.op).toBe(-1);
    expect(decodeFrame(frame).body.error).toBe('FutureCursor');
  });
});

describe('commitWrites', () => {
  it('returns the record whole, with its uri and cid', async () => {
    const value = {
      name: 'proj',
      refs: [{ name: 'refs/heads/main', sha: 'aa' }],
    };
    const frame = await commitFrame([{ path: `${COLLECTION}/proj`, value }]);
    const { body } = decodeFrame(frame);

    const writes = commitWrites(body, [COLLECTION]);
    expect(writes).toHaveLength(1);
    expect(writes[0].did).toBe(DID);
    expect(writes[0].collection).toBe(COLLECTION);
    expect(writes[0].rkey).toBe('proj');
    expect(writes[0].uri).toBe(`at://${DID}/${COLLECTION}/proj`);
    expect(writes[0].seq).toBe(42);
    expect(writes[0].value.refs).toEqual(value.refs);
    expect(writes[0].cid).toMatch(/^b[a-z2-7]+$/);
  });

  it('tags each write with the collection it landed in', async () => {
    const other = 'dev.pdsjs.git.checkRequest';
    const frame = await commitFrame([
      { path: `${COLLECTION}/proj`, value: { name: 'proj' } },
      { path: `${other}/proj_refs_heads_main`, value: { repo: 'proj' } },
      { path: 'app.bsky.feed.post/xyz', value: { text: 'hello' } },
    ]);
    const writes = commitWrites(decodeFrame(frame).body, [COLLECTION, other]);
    expect(writes.map((write) => write.collection)).toEqual([
      COLLECTION,
      other,
    ]);
    expect(writes[1].rkey).toBe('proj_refs_heads_main');
  });

  it('ignores writes to other collections', async () => {
    const frame = await commitFrame([
      { path: 'app.bsky.feed.post/xyz', value: { text: 'hello' } },
    ]);
    expect(commitWrites(decodeFrame(frame).body, [COLLECTION])).toEqual([]);
  });

  it('ignores a delete, which carries no record', () => {
    const body = {
      repo: DID,
      seq: 1,
      ops: [{ action: 'delete', path: `${COLLECTION}/proj`, cid: null }],
      blocks: new Uint8Array(0),
    };
    expect(commitWrites(body, [COLLECTION])).toEqual([]);
  });

  it('skips an op whose block is absent, as in a tooBig commit', () => {
    const body = {
      repo: DID,
      seq: 1,
      ops: [
        {
          action: 'create',
          path: `${COLLECTION}/proj`,
          cid: cidToBytes(
            'bafyreib2rxk3rh6kzwq6rhcbo6ykvzvyq5zqjnvpsxbrnfvqvjqqbqrqvi',
          ),
        },
      ],
      blocks: new Uint8Array(0),
    };
    expect(commitWrites(body, [COLLECTION])).toEqual([]);
  });
});