/**
 * @module tests/unit/brainy/migration-gate-family-scoped
 * @description The coordinated migration LOCK is FAMILY-SCOPED: a read waits only
 * on the index families it actually consults. A one-time native migration of ONE
 * family (its `isMigrating()` held) must NOT block a read served entirely from
 * canonical storage (get / VFS content + dir) or from a HEALTHY family — only a
 * read that needs the migrating family blocks. Regression for the whole-brain
 * gate that hung getStats / readdir / readFile behind an unrelated family's
 * migration until the wait timed out.
 */
import { describe, it, expect, beforeEach } from 'vitest'
import { Brainy } from '../../../src/brainy.js'
import { MigrationInProgressError } from '../../../src/errors/brainyError.js'

const seed = async () => {
  const brain = new Brainy({
    storage: { type: 'memory' },
    dimensions: 384,
    requireSubtype: false,
    silent: true,
    // Short so a genuine block resolves fast; a real block would otherwise wait
    // the 30 s default — this test asserts the wait does NOT happen for scoped
    // reads, and DOES (bounded) for the one that needs the migrating family.
    migrationWaitTimeoutMs: 300
  })
  await brain.init()
  for (let i = 0; i < 5; i++) {
    await brain.add({ data: `doc ${i}`, type: 'document', metadata: { i } })
  }
  await brain.vfs.writeFile('/notes/hello.txt', 'canonical bytes — no index needed')
  await brain.flush()
  return brain
}

/** Force a provider to report an in-flight (stuck) migration. */
const jam = (provider: unknown) => {
  ;(provider as { isMigrating: () => boolean }).isMigrating = () => true
}

describe('migration LOCK is family-scoped', () => {
  beforeEach(() => {
    process.env.BRAINY_DETERMINISTIC_EMBEDDINGS = 'true'
  })

  it('a stuck VECTOR migration does not block canonical or graph/metadata reads', async () => {
    const brain = await seed()
    const childId = (
      (await brain.vfs.readdir('/notes', { withFileTypes: true })) as Array<{ entityId: string }>
    )[0].entityId

    jam((brain as any).index) // vector provider migrating; graph + metadata healthy

    // None of these consult the vector family → they serve immediately.
    await expect(brain.getStats()).resolves.toBeDefined()
    await expect(brain.vfs.readdir('/notes')).resolves.toHaveLength(1) // graph traversal
    await expect(brain.vfs.readFile('/notes/hello.txt')).resolves.toBeDefined() // canonical blob
    await expect(brain.get(childId)).resolves.not.toBeNull() // canonical by id
    await expect(brain.find({ where: { i: 1 } })).resolves.toBeDefined() // metadata filter
  })

  it('a stuck VECTOR migration STILL blocks a read that needs the vector family', async () => {
    const brain = await seed()
    jam((brain as any).index)

    // A semantic query consults the vector index — it must wait, and (bounded by
    // migrationWaitTimeoutMs) surface the retryable MigrationInProgressError
    // rather than serve a half-built result.
    await expect(brain.find({ query: 'doc' })).rejects.toBeInstanceOf(MigrationInProgressError)
  })

  it('a stuck GRAPH migration blocks traversal but not vector/canonical reads', async () => {
    const brain = await seed()
    const childId = (
      (await brain.vfs.readdir('/notes', { withFileTypes: true })) as Array<{ entityId: string }>
    )[0].entityId

    jam((brain as any).graphIndex) // graph provider migrating; vector + metadata healthy

    // Canonical + vector + metadata are unaffected.
    await expect(brain.get(childId)).resolves.not.toBeNull()
    await expect(brain.find({ query: 'doc' })).resolves.toBeDefined()
    await expect(brain.find({ where: { i: 1 } })).resolves.toBeDefined()

    // A graph traversal needs the migrating family → it blocks (bounded).
    await expect(brain.related({ from: childId })).rejects.toBeInstanceOf(MigrationInProgressError)
  })

  it('with no migration in flight, every read serves (the fast path is a no-op)', async () => {
    const brain = await seed()
    await expect(brain.getStats()).resolves.toBeDefined()
    await expect(brain.find({ query: 'doc' })).resolves.toBeDefined()
    await expect(brain.vfs.readdir('/notes')).resolves.toHaveLength(1)
  })
})