/**
 * @module tests/unit/brainy/graph-subgraph
 * @description Graph engine #25: `brain.graph.subgraph()` — bounded multi-hop
 * neighborhood extraction. These exercise the pure-TS fallback (no native
 * GraphAccelerationProvider is registered in CI); the native path returns the
 * same `GraphView` shape, cross-layer-tested against the provider.
 *
 * Graph under test (RelatedTo unless noted):
 *   e → a → b → c ,  a →(ReportsTo) d ,  a →(internal) f
 */

import { describe, it, expect, beforeEach, afterEach } from 'vitest'
import { Brainy } from '../../../src/index.js'
import { NounType, VerbType } from '../../../src/types/graphTypes.js'
import { createTestConfig } from '../../helpers/test-factory.js'

describe('brain.graph.subgraph() (graph engine #25)', () => {
  let brain: Brainy
  let a: string, b: string, c: string, d: string, e: string, f: string

  beforeEach(async () => {
    brain = new Brainy(createTestConfig())
    await brain.init()
    a = await brain.add({ type: NounType.Person, subtype: 'employee', data: 'A' })
    b = await brain.add({ type: NounType.Person, subtype: 'employee', data: 'B' })
    c = await brain.add({ type: NounType.Person, subtype: 'employee', data: 'C' })
    d = await brain.add({ type: NounType.Project, subtype: 'milestone', data: 'D' })
    e = await brain.add({ type: NounType.Person, subtype: 'employee', data: 'E' })
    f = await brain.add({ type: NounType.Person, subtype: 'employee', data: 'F' })
    await brain.relate({ from: a, to: b, type: VerbType.RelatedTo, subtype: 'colleague' })
    await brain.relate({ from: b, to: c, type: VerbType.RelatedTo, subtype: 'colleague' })
    await brain.relate({ from: a, to: d, type: VerbType.ReportsTo, subtype: 'direct' })
    await brain.relate({ from: e, to: a, type: VerbType.RelatedTo, subtype: 'colleague' })
    await brain.relate({ from: a, to: f, type: VerbType.RelatedTo, subtype: 'colleague', visibility: 'internal' })
  })

  afterEach(async () => {
    await brain.close()
  })

  it('depth-1 returns the seed + immediate neighbors (both directions) with depths', async () => {
    const view = await brain.graph.subgraph(a, { depth: 1 })
    const byId = new Map(view.nodes.map((n) => [n.id, n]))
    // a is the seed (depth 0); b, d (out) and e (in) are 1 hop. f is internal → hidden.
    expect(new Set(byId.keys())).toEqual(new Set([a, b, d, e]))
    expect(byId.get(a)?.depth).toBe(0)
    expect(byId.get(b)?.depth).toBe(1)
    expect(byId.get(e)?.depth).toBe(1)
    // Edges among them.
    const pairs = view.edges.map((r) => `${r.from}->${r.to}`).sort()
    expect(pairs).toEqual([`${a}->${b}`, `${a}->${d}`, `${e}->${a}`].sort())
  })

  it('depth-2 expands one more hop (c via b), tracking depth', async () => {
    const view = await brain.graph.subgraph(a, { depth: 2 })
    const byId = new Map(view.nodes.map((n) => [n.id, n]))
    expect(byId.has(c)).toBe(true)
    expect(byId.get(c)?.depth).toBe(2)
    expect(view.edges.some((r) => r.from === b && r.to === c)).toBe(true)
  })

  it("direction:'out' follows only outgoing edges", async () => {
    const view = await brain.graph.subgraph(a, { depth: 1, direction: 'out' })
    const ids = new Set(view.nodes.map((n) => n.id))
    expect(ids).toEqual(new Set([a, b, d])) // e (e→a, incoming) excluded
  })

  it('composes with a verb-type filter', async () => {
    const view = await brain.graph.subgraph(a, { depth: 1, type: VerbType.ReportsTo })
    expect(view.edges.map((r) => `${r.from}->${r.to}`)).toEqual([`${a}->${d}`])
    expect(new Set(view.nodes.map((n) => n.id))).toEqual(new Set([a, d]))
  })

  it('includeInternal surfaces the hidden edge/node', async () => {
    const view = await brain.graph.subgraph(a, { depth: 1, includeInternal: true })
    expect(view.nodes.some((n) => n.id === f)).toBe(true)
    expect(view.edges.some((r) => r.to === f)).toBe(true)
  })

  it('hydrates node type/subtype by default; skips it with hydrateNodes:false', async () => {
    const hydrated = await brain.graph.subgraph(a, { depth: 1 })
    const dNode = hydrated.nodes.find((n) => n.id === d)
    expect(dNode?.type).toBe(NounType.Project)
    expect(dNode?.subtype).toBe('milestone')

    const bare = await brain.graph.subgraph(a, { depth: 1, hydrateNodes: false })
    expect(bare.nodes.every((n) => n.type === undefined)).toBe(true)
  })

  it('caps the result and flags truncated when maxNodes is hit', async () => {
    const view = await brain.graph.subgraph(a, { depth: 2, maxNodes: 2 })
    expect(view.truncated).toBe(true)
    expect(view.nodes.length).toBeLessThanOrEqual(2)
  })

  it('accepts multiple seeds', async () => {
    const view = await brain.graph.subgraph([a, c], { depth: 0 })
    // depth 0 = just the seeds, no expansion.
    expect(new Set(view.nodes.map((n) => n.id))).toEqual(new Set([a, c]))
  })

  // ---- Query→expand fusion (graph #61): seed from a query / find() result ----

  it('query→expand: subgraph(query) seeds from the matches and expands their neighborhood', async () => {
    // The only Project is d; 1-hop expansion brings in a (a → d ReportsTo).
    const view = await brain.graph.subgraph({ type: NounType.Project }, { depth: 1 })
    const ids = new Set(view.nodes.map((n) => n.id))
    expect(ids.has(d)).toBe(true) // the query match (seed)
    expect(ids.has(a)).toBe(true) // expanded neighbor
    expect(view.edges.some((r) => r.from === a && r.to === d)).toBe(true)
  })

  it('query→expand: depth 0 returns just the matches, no expansion', async () => {
    const view = await brain.graph.subgraph({ type: NounType.Project }, { depth: 0 })
    expect(new Set(view.nodes.map((n) => n.id))).toEqual(new Set([d]))
  })

  it('accepts a find() result array as the seed set', async () => {
    const matches = await brain.find({ type: NounType.Project }) // → [d]
    expect(matches.length).toBeGreaterThan(0)
    const view = await brain.graph.subgraph(matches, { depth: 1 })
    const ids = new Set(view.nodes.map((n) => n.id))
    expect(ids.has(d)).toBe(true)
    expect(ids.has(a)).toBe(true)
  })

  it('query→expand returns empty when the query matches nothing', async () => {
    const view = await brain.graph.subgraph({ type: NounType.Event }, { depth: 1 })
    expect(view.nodes).toEqual([])
    expect(view.edges).toEqual([])
  })
})