/**
 * @module tests/unit/vector-cold-read-guard
 * @description Pattern-A / Finding 1: a pure semantic find({ query }) has no
 * filter, so verifyMetadataLive never fires — nothing guarded the vector index.
 * A cold native vector index that loaded its COUNT but not its serving structure
 * returned a silent []. verifyVectorLive() closes that: honest isReady() first,
 * else a known-vector self-match probe; self-heal (rebuild) or throw
 * VectorIndexNotReadyError — never a silent empty result.
 */
import { describe, it, expect, beforeEach } from 'vitest'
import { Brainy, NounType, VectorIndexNotReadyError } from '../../src/index.js'

const V = (): number[] => Array.from({ length: 384 }, (_, i) => Math.sin(i * 0.1) + 0.001)

describe('Vector cold-read guard (verifyVectorLive) — silent-[] on cold semantic find', () => {
  let brain: any
  beforeEach(async () => {
    process.env.BRAINY_DETERMINISTIC_EMBEDDINGS = 'true'
    brain = new Brainy({ requireSubtype: false, storage: { type: 'memory' }, dimensions: 384 })
    await brain.init()
    await brain.add({ vector: V(), type: NounType.Concept, metadata: { status: 'active' } })
    await brain.add({ vector: V(), type: NounType.Concept, metadata: { status: 'archived' } })
    await brain.flush()
  })

  it('warm brain: semantic find is correct and the guard does not rebuild', async () => {
    const vi = brain.index
    let rebuilds = 0
    const origRebuild = vi.rebuild.bind(vi)
    vi.rebuild = async (...a: any[]) => { rebuilds++; return origRebuild(...a) }
    await brain.find({ query: 'anything', searchMode: 'semantic', limit: 100 })
    expect(rebuilds).toBe(0)
    expect(brain._vectorVerified).toBe(true)
    vi.rebuild = origRebuild
  })

  it('cold index: verifyVectorLive self-heals via rebuild — semantic find is correct, NOT silent []', async () => {
    const vi = brain.index
    const origSearch = vi.search.bind(vi)
    const origRebuild = vi.rebuild.bind(vi)
    let cold = true
    brain._vectorVerified = false
    // size()>0 (count present) but search returns nothing until a rebuild warms it.
    vi.search = async (...a: any[]) => (cold ? [] : origSearch(...a))
    vi.rebuild = async (...a: any[]) => { await origRebuild(...a); cold = false }
    try {
      const res = await brain.find({ query: 'x', searchMode: 'semantic', limit: 100 })
      expect(res.length).toBeGreaterThan(0) // self-healed
    } finally {
      vi.search = origSearch; vi.rebuild = origRebuild
    }
  })

  it('unrecoverably cold index: semantic find throws VectorIndexNotReadyError', async () => {
    const vi = brain.index
    const origSearch = vi.search.bind(vi)
    const origRebuild = vi.rebuild.bind(vi)
    brain._vectorVerified = false
    vi.search = async () => []      // always cold; rebuild can't fix it
    vi.rebuild = async () => {}
    try {
      await expect(
        brain.find({ query: 'x', searchMode: 'semantic', limit: 100 })
      ).rejects.toBeInstanceOf(VectorIndexNotReadyError)
    } finally {
      vi.search = origSearch; vi.rebuild = origRebuild
    }
  })

  it('native provider reporting isReady()===false rebuilds, then serves', async () => {
    const vi = brain.index
    const origRebuild = vi.rebuild.bind(vi)
    let ready = false
    brain._vectorVerified = false
    vi.isReady = () => ready
    vi.rebuild = async (...a: any[]) => { await origRebuild(...a); ready = true }
    try {
      const res = await brain.find({ query: 'x', searchMode: 'semantic', limit: 100 })
      expect(ready).toBe(true) // rebuild ran because isReady() was false
      expect(res).toBeDefined()
    } finally {
      delete vi.isReady; vi.rebuild = origRebuild
    }
  })

  it('a text-only query does not trigger the vector guard', async () => {
    brain._vectorVerified = false
    await brain.find({ query: 'active', searchMode: 'text', limit: 5 })
    expect(brain._vectorVerified).toBe(false) // executeVectorSearch never called
  })

  // Regression: the probe must check "returns ANY hit", not an exact self-match —
  // HNSW is approximate and get() may re-hydrate the vector, so a healthy
  // many-entity index would false-positive under an exact-self check, wrongly
  // rebuild, and throw VectorIndexNotReadyError on working data.
  it('a healthy many-entity brain with distinct vectors serves semantic find, never throws/rebuilds', async () => {
    const many = new Brainy({ requireSubtype: false, storage: { type: 'memory' }, dimensions: 384 })
    await many.init()
    for (let i = 0; i < 25; i++) {
      const v = Array.from({ length: 384 }, (_, j) => Math.sin((i * 7 + j) * 0.13) + 0.001)
      await many.add({ vector: v, type: NounType.Concept, metadata: { n: i } })
    }
    await many.flush()
    let rebuilds = 0
    const vi = (many as any).index
    const origRebuild = vi.rebuild.bind(vi)
    vi.rebuild = async (...a: any[]) => { rebuilds++; return origRebuild(...a) }
    const res = await many.find({ query: 'x', searchMode: 'semantic', limit: 10 })
    expect(res.length).toBeGreaterThan(0)
    expect(rebuilds).toBe(0)
    expect((many as any)._vectorVerified).toBe(true)
    vi.rebuild = origRebuild
    await many.close()
  })
})