/**
 * @module tests/integration/find-planner-door
 * @description The optional `MetadataIndexProvider.planFindPage` door.
 *
 * The stage doors each serve one stage, so a `find()` that consults three of
 * them crosses into the index three times and marshals a result set at every
 * crossing — a filter matching a hundred thousand rows builds a hundred
 * thousand id strings to return a page of twenty-five. An index that can decide
 * the stage order itself answers the page in one call.
 *
 * These pins hold the three properties that make such a door safe to add:
 *
 * 1. **Absent, nothing changes.** The reference index has no planner, and every
 *    find is served by the stage doors exactly as before. That is also what
 *    makes this engine the ordering oracle for any index that implements one.
 * 2. **Present, it is asked first and its answer is used** — above the branch
 *    selection, with the params already normalized, the hidden ids passed, and
 *    the graph provider handed over.
 * 3. **`null` is routing, not an answer.** A door that declines a shape leaves
 *    it to the path that always served it, and the result is unchanged.
 *
 * Plus the serving law: an empty page stamped `emptyAt: 'graph'` is re-verified
 * against the adjacency before it is believed, so a not-serving graph refuses
 * loudly instead of answering `[]` as truth.
 */
import { describe, it, expect, beforeAll, vi } from 'vitest'
import { Brainy } from '../../src/brainy'
import { NounType, VerbType } from '../../src/types/graphTypes'
import { generateTestVector } from '../helpers/test-factory'

describe('find(): the optional planner door', () => {
  let brain: Brainy<any>
  const anchor = 'planner-anchor'
  let neighbourId = ''

  beforeAll(async () => {
    brain = new Brainy({ requireSubtype: false, storage: { type: 'memory' } })
    await brain.init()
    await brain.add({
      id: anchor,
      data: 'anchor',
      type: NounType.Person,
      metadata: { kind: 'anchor' },
      vector: generateTestVector()
    })
    for (let i = 0; i < 12; i++) {
      const id = await brain.add({
        id: `row-${i}`,
        data: `row ${i}`,
        type: NounType.Person,
        metadata: { kind: 'note', rank: i },
        vector: generateTestVector()
      })
      if (i === 0) neighbourId = id
      await brain.relate({ from: anchor, to: id, type: VerbType.Knows })
    }
  })

  /** Install a planner door for one call, then remove it. */
  const withDoor = async <T>(
    door: (...a: any[]) => Promise<any>,
    body: () => Promise<T>
  ): Promise<T> => {
    const index = (brain as any).metadataIndex
    index.planFindPage = door
    try {
      return await body()
    } finally {
      delete index.planFindPage
    }
  }

  it('is absent on the reference index — every find is served by the stage doors', async () => {
    expect((brain as any).metadataIndex.planFindPage).toBeUndefined()
    const results = await brain.find({ where: { kind: 'note' }, limit: 5 })
    expect(results).toHaveLength(5)
  })

  it('is asked before the branches, with normalized params and the graph provider', async () => {
    const door = vi.fn(async () => null)
    await withDoor(door, async () => {
      await brain.find({ where: { kind: 'note' }, limit: 5 })
    })
    expect(door).toHaveBeenCalledTimes(1)
    const [params, hidden, graph] = door.mock.calls[0] as any[]
    expect(params.where).toEqual({ kind: 'note' })
    expect(Array.isArray(hidden)).toBe(true)
    expect(graph).toBe((brain as any).graphIndex)
  })

  it('uses the page it answers, hydrated and in the door\'s order', async () => {
    const results = await withDoor(
      async () => ({ ids: [neighbourId], emptyAt: 'none' as const }),
      async () => brain.find({ where: { kind: 'note' }, limit: 5 })
    )
    expect(results).toHaveLength(1)
    expect(results[0].entity.id).toBe(neighbourId)
  })

  it('a declining door changes nothing — the shape is served as it always was', async () => {
    const withoutDoor = await brain.find({ where: { kind: 'note' }, orderBy: 'rank', limit: 4 })
    const declined = await withDoor(
      async () => null,
      async () => brain.find({ where: { kind: 'note' }, orderBy: 'rank', limit: 4 })
    )
    expect(declined.map((r) => r.entity.id)).toEqual(withoutDoor.map((r) => r.entity.id))
  })

  it('re-verifies the adjacency before believing an empty graph answer', async () => {
    const verify = vi.spyOn(brain as any, 'verifyGraphAdjacencyLive')
    try {
      const results = await withDoor(
        async () => ({ ids: [], emptyAt: 'graph' as const }),
        async () => brain.find({ connected: { from: anchor }, where: { kind: 'note' }, limit: 5 })
      )
      expect(results).toEqual([])
      expect(verify).toHaveBeenCalled()
    } finally {
      verify.mockRestore()
    }
  })

  it('does not re-verify the adjacency for an empty the FILTER produced', async () => {
    const verify = vi.spyOn(brain as any, 'verifyGraphAdjacencyLive')
    verify.mockClear()
    try {
      const results = await withDoor(
        async () => ({ ids: [], emptyAt: 'filter' as const }),
        async () => brain.find({ where: { kind: 'note' }, limit: 5 })
      )
      expect(results).toEqual([])
      expect(verify).not.toHaveBeenCalled()
    } finally {
      verify.mockRestore()
    }
  })
})