/**
 * @module tests/vfs/vfs-search-path-scope.unit
 * @description `vfs.search({ path })` scopes with a SERVED filter.
 *
 * The scope used to be emitted as `path: { $startsWith }` — an operator that is
 * not in the filter vocabulary at all, and whose `$`-less spelling the metadata
 * index refuses by the served-operator law (an equality/range posting index
 * cannot evaluate a substring without reading every row). Every path-scoped VFS
 * search threw; none has ever worked on this engine line.
 *
 * The scope is now a half-open range over `metadata.path`, which is the VFS's
 * truth, is indexed on every VFS entity, and is served by the ordered range
 * operators: `[dir + '/', dir + '0')` — '0' being the code point after '/', so
 * membership in the range is EXACTLY "carries the prefix `dir/`". The
 * non-recursive scope is the directory's own identity, `parent`, an equality.
 *
 * These pins hold the answer (descendants at every depth, siblings never — the
 * `/scope-sibling` trap included), the shape (the operators the search emits
 * are answered by the index's own door, never refused), and the law that the
 * scope narrows the search BEFORE it runs rather than filtering an over-fetch.
 */
import { describe, it, expect, beforeAll, afterAll, vi } from 'vitest'
import { VirtualFileSystem } from '../../src/vfs/VirtualFileSystem.js'
import { Brainy } from '../../src/brainy.js'
import { VFSErrorCode } from '../../src/vfs/types.js'

/** A word every fixture file carries, so the text leg reaches all of them. */
const TOKEN = 'quasar'

describe('vfs.search({ path }) scopes with a served filter', () => {
  let brain: Brainy
  let vfs: VirtualFileSystem

  /** In scope for '/scope', at three depths. */
  const inScope = ['/scope/a.txt', '/scope/sub/b.txt', '/scope/sub/deep/c.txt']
  /** Out of scope — including the two prefix traps a naive test misses. */
  const outOfScope = ['/scope-sibling/d.txt', '/scope0/e.txt', '/elsewhere/f.txt', '/g.txt']

  beforeAll(async () => {
    brain = new Brainy({ requireSubtype: false, storage: { type: 'memory' }, silent: true })
    await brain.init()
    vfs = brain.vfs
    await vfs.init()

    await vfs.mkdir('/scope/sub/deep', { recursive: true })
    await vfs.mkdir('/scope-sibling', { recursive: true })
    await vfs.mkdir('/scope0', { recursive: true })
    await vfs.mkdir('/elsewhere', { recursive: true })

    for (const path of [...inScope, ...outOfScope]) {
      await vfs.writeFile(path, `${TOKEN} content for ${path}`)
    }
  })

  afterAll(async () => {
    await vfs?.close()
    await brain?.close()
  })

  it('includes every descendant depth and excludes every sibling', async () => {
    const results = await vfs.search(TOKEN, { path: '/scope', limit: 50 })
    const paths = results.map((r) => r.path).sort()

    expect(paths).toEqual([...inScope].sort())
    for (const path of outOfScope) expect(paths).not.toContain(path)
  })

  it('a trailing slash and a doubled slash name the same scope', async () => {
    const plain = await vfs.search(TOKEN, { path: '/scope', limit: 50 })
    const trailing = await vfs.search(TOKEN, { path: '/scope/', limit: 50 })
    const doubled = await vfs.search(TOKEN, { path: '//scope//', limit: 50 })

    const ids = (rs: Array<{ entityId: string }>) => rs.map((r) => r.entityId).sort()
    expect(ids(trailing)).toEqual(ids(plain))
    expect(ids(doubled)).toEqual(ids(plain))
  })

  it('the root scope is every VFS file — it adds no clause to narrow with', async () => {
    const rooted = await vfs.search(TOKEN, { path: '/', limit: 50 })
    const unscoped = await vfs.search(TOKEN, { limit: 50 })

    const paths = rooted.map((r) => r.path).sort()
    expect(paths).toEqual([...inScope, ...outOfScope].sort())
    expect(paths).toEqual(unscoped.map((r) => r.path).sort())
  })

  it('recursive: false is the immediate children, not the subtree', async () => {
    const results = await vfs.search(TOKEN, { path: '/scope', recursive: false, limit: 50 })
    expect(results.map((r) => r.path)).toEqual(['/scope/a.txt'])
  })

  it('recursive: false on a path that does not exist refuses by name', async () => {
    await expect(
      vfs.search(TOKEN, { path: '/no-such-dir', recursive: false, limit: 50 })
    ).rejects.toMatchObject({ code: VFSErrorCode.ENOENT })
  })

  it('every operator the search emits is ANSWERED by the index door, never refused', async () => {
    const index = (brain as any).metadataIndex
    const emitted: any[] = []
    const find = vi.spyOn(brain as any, 'find')
    try {
      await vfs.search(TOKEN, { path: '/scope', limit: 50 })
      await vfs.search(TOKEN, { path: '/scope/sub', where: { mimeType: 'text/plain' }, limit: 50 })
      await vfs.search(TOKEN, { path: '/scope', recursive: false, limit: 50 })
      await vfs.search(TOKEN, { path: '/', limit: 50 })
      for (const call of find.mock.calls) emitted.push((call[0] as any).where)
    } finally {
      find.mockRestore()
    }

    expect(emitted).toHaveLength(4)
    for (const where of emitted) {
      // The door itself is the judge: an operator outside the served set is
      // REFUSED here (BrainyError INVALID_QUERY), never answered.
      await expect(index.getIdsForFilter(where)).resolves.toBeInstanceOf(Array)
    }

    // And the scope really is a range on the path — the shape this fix chose.
    expect(emitted[0].path).toEqual({ gte: '/scope/', lt: '/scope0' })
    expect(emitted[3].path).toBeUndefined()
  })

  it('the scope narrows the search before it runs — no over-fetch to filter', async () => {
    const index = (brain as any).metadataIndex
    const filter = vi.spyOn(index, 'getIdsForFilter')
    let universe: string[] = []
    try {
      await vfs.search(TOKEN, { path: '/scope', limit: 50 })
      // The search's own call — the one carrying the scope. (Path resolution
      // asks this same door for the root, before the search is built.)
      const scoped = filter.mock.calls.findIndex(
        (c) => (c[0] as any)?.path?.gte === '/scope/'
      )
      expect(scoped).toBeGreaterThanOrEqual(0)
      universe = (await filter.mock.results[scoped].value) as string[]
    } finally {
      filter.mockRestore()
    }

    // The id universe the index resolved for the search is already the scope:
    // three files, and not one row from outside it.
    const rows = await brain.batchGet(universe)
    const paths = [...rows.values()].map((e: any) => e.metadata.path).sort()
    expect(paths).toEqual([...inScope].sort())
  })

  it('the range answers the same ids as walking the tree', async () => {
    // The path is the truth and the Contains edges are its projection; a scope
    // read from the truth must agree with one walked over the projection.
    const walked: string[] = []
    const walk = async (dir: string): Promise<void> => {
      for (const name of await vfs.readdir(dir)) {
        const child = dir === '/' ? `/${name}` : `${dir}/${name}`
        const stat = await vfs.stat(child)
        if (stat.isDirectory()) await walk(child)
        else walked.push(child)
      }
    }
    await walk('/scope')

    const searched = await vfs.search(TOKEN, { path: '/scope', limit: 50 })
    expect(searched.map((r) => r.path).sort()).toEqual(walked.sort())
  })
})