/**
 * @module tests/unit/graph/graph-adjacency-watermark
 * @description Watermark-stamp pins for the graph-adjacency projection.
 *
 * THE LAW under test: the persisted adjacency artifact (the two verb-id LSM
 * trees' SSTables + manifests) carries a stamp asserting "this state
 * reflects every committed generation ≤ W and nothing above W" — written
 * AFTER both trees' flushes complete — and init() computes the three-way
 * verdict: stamped==committed → 'adopt' · stamped<committed → 'catchup'
 * (gap reported) · stamped>committed OR unstamped → 'rescan', LOUDLY.
 *
 * The verdict is COMPUTED AND EXPOSED only — cold-load recovery and rebuild
 * triggers are unchanged.
 */
import { describe, it, expect, vi, afterEach } from 'vitest'
import { v4 as uuidv4 } from 'uuid'
import {
  GraphAdjacencyIndex,
  GRAPH_ADJACENCY_STAMP_KEY
} from '../../../src/graph/graphAdjacencyIndex.js'
import { EntityIdMapper } from '../../../src/utils/entityIdMapper.js'
import { MemoryStorage } from '../../../src/storage/adapters/memoryStorage.js'
import { VerbType } from '../../../src/types/graphTypes.js'
import type { GraphVerb } from '../../../src/coreTypes.js'
import { prodLog } from '../../../src/utils/logger.js'

function makeVerb(id: string, sourceId: string, targetId: string): GraphVerb {
  return {
    id,
    sourceId,
    targetId,
    vector: [],
    type: VerbType.RelatedTo,
    verb: VerbType.RelatedTo
  }
}

async function makeStorage(committed: number | null): Promise<MemoryStorage> {
  const storage = new MemoryStorage()
  await storage.init()
  if (committed !== null) {
    vi.spyOn(storage, 'committedGeneration').mockReturnValue(committed)
  }
  return storage
}

function setCommitted(storage: MemoryStorage, committed: number): void {
  vi.spyOn(storage, 'committedGeneration').mockReturnValue(committed)
}

/** Session 1: index verbs, optionally stamp, flush + close — the artifact. */
async function writeArtifact(storage: MemoryStorage, stamp: number | null): Promise<void> {
  const idMapper = new EntityIdMapper({ storage, storageKey: 'test:graph:idMapper' })
  await idMapper.init()
  const index = new GraphAdjacencyIndex(storage, {}, idMapper)
  const a = uuidv4()
  const b = uuidv4()
  const aInt = BigInt(idMapper.getOrAssign(a))
  const bInt = BigInt(idMapper.getOrAssign(b))
  await index.addVerb(makeVerb(uuidv4(), a, b), aInt, bInt, 1n)
  if (stamp !== null) index.stampWatermark(stamp)
  await index.flush()
  await index.close()
}

/** Session 2: reopen on the same storage via the cold-load path. */
async function reopen(storage: MemoryStorage): Promise<GraphAdjacencyIndex> {
  const index = new GraphAdjacencyIndex(storage)
  await index.init()
  return index
}

afterEach(() => {
  vi.restoreAllMocks()
})

describe('graph adjacency index — watermark stamp + three-way load verdict', () => {
  it("save-with-stamp then reopen at the same committed generation → 'adopt'", async () => {
    const storage = await makeStorage(5)
    await writeArtifact(storage, 5)

    const index = await reopen(storage)
    expect(index.watermarkVerdict()).toBe('adopt')
    expect(index.watermark()).toBe(5)
    expect(index.watermarkGap()).toBeNull()
    await index.close()
  })

  it("stamp BEHIND the committed generation → 'catchup' with the exact gap reported", async () => {
    const storage = await makeStorage(5)
    await writeArtifact(storage, 5)

    setCommitted(storage, 11)

    const index = await reopen(storage)
    expect(index.watermarkVerdict()).toBe('catchup')
    expect(index.watermark()).toBe(5)
    expect(index.watermarkGap()).toEqual({ from: 5, to: 11 })
    await index.close()
  })

  it("stamp ABOVE the committed generation → 'rescan', said out loud", async () => {
    const storage = await makeStorage(9)
    await writeArtifact(storage, 9)

    setCommitted(storage, 4)

    const warnSpy = vi.spyOn(prodLog, 'warn')
    const index = await reopen(storage)
    expect(index.watermarkVerdict()).toBe('rescan')
    expect(index.watermarkGap()).toBeNull()
    const said = warnSpy.mock.calls.map(c => String(c[0])).join('\n')
    expect(said).toContain('RESCAN')
    expect(said).toContain('ABOVE')
    await index.close()
  })

  it("legacy unstamped artifact on a stamped store → 'rescan', LOUD — never a silent adopt", async () => {
    const storage = await makeStorage(3)
    await writeArtifact(storage, null) // pre-stamp adjacency: SSTables, no stamp

    expect(await storage.getMetadata(GRAPH_ADJACENCY_STAMP_KEY)).toBeNull()

    const warnSpy = vi.spyOn(prodLog, 'warn')
    const index = await reopen(storage)
    expect(index.watermarkVerdict()).toBe('rescan')
    expect(index.watermark()).toBeNull()
    const said = warnSpy.mock.calls.map(c => String(c[0])).join('\n')
    expect(said).toContain('RESCAN')
    expect(said).toContain('unstamped')
    await index.close()
  })

  it("a store with no committed-generation capability keeps pre-stamp behavior → 'adopt'", async () => {
    const storage = await makeStorage(null)
    await writeArtifact(storage, null)

    const index = await reopen(storage)
    expect(index.watermarkVerdict()).toBe('adopt')
    expect(index.watermark()).toBeNull()
    await index.close()
  })

  it('STAMP-AFTER-DATA: the stamp is the last saveMetadata of the flush, after both trees’ SSTable + manifest writes', async () => {
    const storage = await makeStorage(2)
    const idMapper = new EntityIdMapper({ storage, storageKey: 'test:graph:idMapper' })
    await idMapper.init()
    const index = new GraphAdjacencyIndex(storage, {}, idMapper)
    const a = uuidv4()
    const b = uuidv4()
    await index.addVerb(
      makeVerb(uuidv4(), a, b),
      BigInt(idMapper.getOrAssign(a)),
      BigInt(idMapper.getOrAssign(b)),
      1n
    )

    const keys: string[] = []
    const originalSave = storage.saveMetadata.bind(storage)
    vi.spyOn(storage, 'saveMetadata').mockImplementation(async (id, metadata) => {
      keys.push(id)
      return originalSave(id, metadata)
    })

    index.stampWatermark(2)
    await index.flush()

    const stampAt = keys.indexOf(GRAPH_ADJACENCY_STAMP_KEY)
    expect(stampAt, 'stamp record was written').toBeGreaterThanOrEqual(0)
    expect(stampAt, 'stamp is the FINAL metadata write of the flush').toBe(keys.length - 1)
    // Both trees flushed durable bytes before the stamp landed.
    expect(
      keys.slice(0, stampAt).some(k => k.startsWith('graph-lsm-verbs-source')),
      'verbs-by-source tree wrote before the stamp'
    ).toBe(true)
    expect(
      keys.slice(0, stampAt).some(k => k.startsWith('graph-lsm-verbs-target')),
      'verbs-by-target tree wrote before the stamp'
    ).toBe(true)

    const record = (await storage.getMetadata(GRAPH_ADJACENCY_STAMP_KEY)) as {
      watermark: number
      formatVersion: number
      stampedAt: number
    }
    expect(record.watermark).toBe(2)
    expect(record.formatVersion).toBe(1)
    expect(typeof record.stampedAt).toBe('number')

    await index.close()
  })

  it('a pending stamp also lands on the close() shutdown path, after the final tree flushes', async () => {
    const storage = await makeStorage(6)
    const idMapper = new EntityIdMapper({ storage, storageKey: 'test:graph:idMapper' })
    await idMapper.init()
    const index = new GraphAdjacencyIndex(storage, {}, idMapper)
    const a = uuidv4()
    const b = uuidv4()
    await index.addVerb(
      makeVerb(uuidv4(), a, b),
      BigInt(idMapper.getOrAssign(a)),
      BigInt(idMapper.getOrAssign(b)),
      1n
    )

    index.stampWatermark(6)
    await index.close() // no explicit flush — close() flushes, then stamps

    const record = (await storage.getMetadata(GRAPH_ADJACENCY_STAMP_KEY)) as { watermark: number }
    expect(record?.watermark).toBe(6)
  })
})