/**
 * @module tests/integration/find-connected-order
 * @description The graph-first law for `find({ connected })` (10.4.8).
 *
 * With `connected` present the neighbour set is the candidate universe: it is
 * resolved from the adjacency first, the metadata filter is evaluated over
 * those ids only, and the page is cut last. The earlier order materialized the
 * whole-store filtered id list, paged it, hydrated the page, and only then
 * intersected with the neighbours — so a neighbour outside the first page of
 * the filtered STORE was silently dropped, and every call paid O(store).
 *
 * These pins hold both halves. The answer: every matching neighbour is
 * reachable by paging, a non-neighbour never appears, a negation (`missing`)
 * is evaluated over the neighbours, `orderBy` sorts the whole neighbour set
 * before the page is cut, and the vector leg walks the neighbours only. The
 * cost shape: the metadata index is asked about the neighbour ids only, and
 * hydration is one page — never the store.
 */
import { describe, it, expect, beforeAll, afterAll, vi } from 'vitest'
import { Brainy } from '../../src/brainy'
import { NounType, VerbType } from '../../src/types/graphTypes'
import { v5 } from '../../src/universal/uuid'
import { generateTestVector } from '../helpers/test-factory'

/** Matching rows that are NOT neighbours — added FIRST, so the whole-store filtered list leads with them. */
const NOISE = 120
/** Matching rows that ARE neighbours of the anchor. */
const NEIGHBOURS = 30
/** Neighbours carrying `retracted: true` — excluded by the `missing` negation. */
const RETRACTED = 4

describe('find({ connected }) is graph-first: neighbours → filter → page', () => {
  let brain: Brainy<any>
  const anchor = 'anchor'
  const sharedVector = generateTestVector()
  const neighbourIds = new Set(Array.from({ length: NEIGHBOURS }, (_, i) => v5(`nb-${i}`)))

  beforeAll(async () => {
    brain = new Brainy({ requireSubtype: false, storage: { type: 'memory' } })
    await brain.init()
    await brain.add({
      id: anchor,
      data: 'the anchor',
      type: NounType.Person,
      metadata: { kind: 'anchor' },
      vector: generateTestVector()
    })
    for (let i = 0; i < NOISE; i++) {
      await brain.add({
        id: `noise-${i}`,
        data: `noise ${i}`,
        type: NounType.Person,
        metadata: { kind: 'note', rank: 1000 + i },
        vector: sharedVector
      })
    }
    for (let i = 0; i < NEIGHBOURS; i++) {
      await brain.add({
        id: `nb-${i}`,
        data: `neighbour ${i}`,
        type: NounType.Person,
        metadata: { kind: 'note', rank: i + 1, ...(i < RETRACTED ? { retracted: true } : {}) },
        vector: sharedVector
      })
      await brain.relate({ from: anchor, to: `nb-${i}`, type: VerbType.Knows })
    }
  })

  afterAll(async () => {
    brain = null as any
  })

  it('returns the matching neighbours page by page — none dropped, never a non-neighbour', async () => {
    const seen = new Set<string>()
    for (let offset = 0; offset <= NEIGHBOURS; offset += 10) {
      const page = await brain.find({
        connected: { from: anchor, direction: 'out' },
        where: { kind: 'note' },
        limit: 10,
        offset
      })
      expect(page).toHaveLength(offset < NEIGHBOURS ? 10 : 0)
      for (const r of page) {
        expect(neighbourIds.has(r.entity.id)).toBe(true)
        expect(seen.has(r.entity.id)).toBe(false)
        seen.add(r.entity.id)
      }
    }
    expect(seen.size).toBe(NEIGHBOURS)
  })

  it('evaluates a negation (`missing`) over the neighbour set, not the store', async () => {
    const results = await brain.find({
      connected: { from: anchor, direction: 'out' },
      where: { kind: 'note', retracted: { missing: true } },
      limit: 100
    })
    expect(results).toHaveLength(NEIGHBOURS - RETRACTED)
    for (const r of results) {
      expect(neighbourIds.has(r.entity.id)).toBe(true)
      expect(r.entity.metadata.retracted).toBeUndefined()
    }
  })

  it('asks the metadata index about the neighbour ids only, and hydrates one page', async () => {
    const index = (brain as any).metadataIndex
    const within = vi.spyOn(index, 'filterIdsWithin')
    const hydrate = vi.spyOn(brain as any, 'batchGet')
    try {
      const results = await brain.find({
        connected: { from: anchor, direction: 'out' },
        where: { kind: 'note' },
        limit: 10
      })
      expect(results).toHaveLength(10)
      expect(within).toHaveBeenCalledTimes(1)
      const askedIds = within.mock.calls[0][1] as string[]
      expect(askedIds).toHaveLength(NEIGHBOURS)
      for (const id of askedIds) expect(neighbourIds.has(id)).toBe(true)
      expect(hydrate).toHaveBeenCalledTimes(1)
      expect(hydrate.mock.calls[0][0]).toHaveLength(10)
    } finally {
      within.mockRestore()
      hydrate.mockRestore()
    }
  })

  it('orders the WHOLE neighbour set before cutting the page', async () => {
    const results = await brain.find({
      connected: { from: anchor, direction: 'out' },
      where: { kind: 'note' },
      orderBy: 'rank',
      order: 'desc',
      limit: 5
    })
    expect(results.map((r) => r.entity.metadata.rank)).toEqual([30, 29, 28, 27, 26])
  })

  it('walks the vector leg over the neighbours only', async () => {
    const results = await brain.find({
      vector: sharedVector,
      connected: { from: anchor, direction: 'out' },
      where: { kind: 'note' },
      limit: 5
    })
    expect(results).toHaveLength(5)
    for (const r of results) expect(neighbourIds.has(r.entity.id)).toBe(true)
  })

  it('an anchor without neighbours answers [] before the filter is asked', async () => {
    const index = (brain as any).metadataIndex
    const within = vi.spyOn(index, 'filterIdsWithin')
    try {
      const results = await brain.find({
        connected: { from: 'noise-0', direction: 'out' },
        where: { kind: 'note' },
        limit: 10
      })
      expect(results).toEqual([])
      expect(within).not.toHaveBeenCalled()
    } finally {
      within.mockRestore()
    }
  })
})