import { readdirSync, readFileSync } from 'node:fs';
import { join, relative, sep } from 'node:path';

// HoneyBatch.amount is the running rest of the movement book (spec 7.7): only
// HoneyBatchLedgerService writes it. A second writer would break the
// invariant amount = initialAmount + sum(quantity) / 1000.
//
// The regexes see an `amount` inside the call itself. A spread such as
// `data: { ...dto }` is invisible to them; honey-batches.service.spec.ts
// covers that case.
const SRC = join(__dirname, '..');
const LEDGER = 'src/honey-batches/honey-batch-ledger.service.ts';

function productionSources(dir: string): string[] {
  return readdirSync(dir, { withFileTypes: true }).flatMap((entry) => {
    const path = join(dir, entry.name);
    if (entry.isDirectory()) {
      return productionSources(path);
    }
    return entry.name.endsWith('.ts') && !entry.name.endsWith('.spec.ts')
      ? [path]
      : [];
  });
}

function writersOf(...patterns: RegExp[]): string[] {
  return productionSources(SRC)
    .filter((file) => {
      const source = readFileSync(file, 'utf8');
      return patterns.some((pattern) => pattern.test(source));
    })
    .map((file) => `src/${relative(SRC, file).split(sep).join('/')}`)
    .sort();
}

describe('honey batch amount writes', () => {
  it('honey batch amount is written only by the ledger', () =>
    expect(
      writersOf(
        /honeyBatch\.(update|updateMany|upsert)\([^)]*amount/s,
        /UPDATE "HoneyBatch"[^;]*"amount"/,
      ),
    ).toEqual([LEDGER]));

  it('the guard sees a write: the ledger itself is found', () =>
    expect(writersOf(/honeyBatch\.update\(\{[^)]*data: \{ amount/s)).toContain(
      LEDGER,
    ));
});