/**
 * @module tests/lifecycle/biographyHarness
 * @description The referee for the LIFECYCLE LANE (see `biography.test.ts`):
 * a plain in-memory SHADOW MODEL of a brain's contents, updated by every act
 * the biography performs (add/update/remove/relate/updateRelation/vfs writes),
 * plus `verifyChapter()`, which asserts the live brain agrees with the model
 * after every chapter. No engine code runs inside the model — it is an
 * independent ledger, not a mirror of the implementation under test.
 *
 * COUNT SEMANTICS this harness encodes (verified against the live engine,
 * not assumed — see the module-level comments below for how each was
 * confirmed):
 *
 * - `getNounCount()` / `getVerbCount()` count PUBLIC-tier alive records only
 *   (visibility absent or `'public'`) — `'internal'` and `'system'` are both
 *   excluded. `storage.getCanonicalCounts()` mirrors that same PUBLIC-only
 *   scalar as `counted`, and additionally reports `all` — every tier,
 *   unfiltered — as the coverage-ledger denominator (see
 *   tests/integration/canonical-count-ledger.test.ts).
 * - `brain.vfs.writeFile()` for a brand-new file at a path directly under the
 *   VFS root creates exactly ONE new File noun plus ONE new `Contains` verb
 *   (root -> file), and BOTH are ordinary PUBLIC records (no visibility
 *   field is set) — so they count toward `getNounCount()`/`getVerbCount()`
 *   as well as the canonical `all` scalars. Only the VFS ROOT entity itself
 *   is `'system'`-tier (created once, at `init()`, before any biography
 *   chapter runs) — that lone record is the only hidden-tier footprint the
 *   model does not construct explicitly, so it is captured empirically via
 *   `snapshotVfsBaseline()` immediately after `init()` rather than hardcoded.
 * - `related()` filters edges by the RELATION's own visibility tier, not by
 *   the visibility of the entities the edge connects — flipping an entity to
 *   `'internal'` does not hide its edges from `related()`. This lane never
 *   sets relation visibility, so every relation the model tracks is exactly
 *   as reachable as its presence in `model.relations` implies.
 * - `remove()` cascades: every relation touching the removed entity (as
 *   `from` or `to`) is hard-deleted along with it. The model mirrors this by
 *   deleting the relation entirely from `model.relations` (no relation
 *   "alive" flag — presence in the map IS aliveness).
 */
import { expect } from 'vitest'
import type { Brainy } from '../../src/brainy.js'
import type { NounType, VerbType } from '../../src/types/graphTypes.js'
import type { EntityVisibility, StorageAdapter } from '../../src/coreTypes.js'

/**
 * One entity's complete lifecycle-relevant state, as the biography's acts
 * leave it. `alive: false` means the model believes the id has been removed
 * — the entry is KEPT (never deleted from the map) so `verifyChapter` can
 * assert the negative half of the contract: a dead id must read as `null`.
 */
export interface ShadowEntity {
  type: NounType
  subtype?: string
  metadata: Record<string, unknown>
  visibility?: EntityVisibility
  alive: boolean
}

/**
 * One relation's complete lifecycle-relevant state. There is no `alive`
 * flag here — presence in {@link ShadowModel.relations} IS aliveness,
 * mirroring the engine's hard delete of the canonical verb record on
 * cascade (see the module header).
 */
export interface ShadowRelation {
  from: string
  to: string
  type: VerbType
  subtype?: string
  metadata: Record<string, unknown>
}

/**
 * The independent truth ledger the biography updates on every act it
 * performs. `verifyChapter` checks the live brain against this — never the
 * other way around.
 */
export interface ShadowModel {
  entities: Map<string, ShadowEntity>
  relations: Map<string, ShadowRelation>
  /**
   * `getCanonicalCounts()` nouns.all / verbs.all captured right after
   * `init()`, before chapter 1 — the VFS root's own system-tier footprint.
   * Set once via {@link snapshotVfsBaseline}; never hardcoded.
   */
  vfsBaselineNouns: number
  vfsBaselineVerbs: number
  /**
   * Public nouns/verbs created by `vfs.writeFile()` for a brand-new file at
   * a flat top-level path: exactly one File noun + one Contains verb per
   * call (see the module header). Bumped by {@link recordVfsFileWrite}.
   */
  vfsFileNouns: number
  vfsContainsVerbs: number
}

/** A fresh, empty shadow model — call once before chapter 1. */
export function createModel(): ShadowModel {
  return {
    entities: new Map(),
    relations: new Map(),
    vfsBaselineNouns: 0,
    vfsBaselineVerbs: 0,
    vfsFileNouns: 0,
    vfsContainsVerbs: 0
  }
}

/** Narrow, documented private-storage access (the same style already used by
 * `tests/helpers/durabilityKillMatrix.ts`'s `storeOf()`), needed because
 * `getCanonicalCounts()` lives on the storage adapter, not on `Brainy`. */
function storageOf(brain: Brainy): StorageAdapter {
  return (brain as unknown as { storage: StorageAdapter }).storage
}

/** Public wrapper around the private-storage `getCanonicalCounts()` read, so
 * callers never need their own private-access cast — used internally by
 * {@link snapshotVfsBaseline} and {@link verifyChapter}, and by
 * `biography.test.ts` for its final standalone exactness check. */
export async function getCanonicalCountsFor(brain: Brainy): ReturnType<NonNullable<StorageAdapter['getCanonicalCounts']>> {
  const storage = storageOf(brain)
  if (!storage.getCanonicalCounts) {
    throw new Error(
      'lifecycle lane: the storage adapter under test has no getCanonicalCounts() — the canonical-count-exactness leg of this lane is unrepresentable without it.'
    )
  }
  return storage.getCanonicalCounts()
}

/**
 * Snapshot the VFS root's own hidden-tier footprint. Call exactly once,
 * immediately after `init()` and before chapter 1 does anything — this is
 * the ONE baseline offset the model does not construct by hand (see the
 * module header for why: the root is `'system'`-tier plumbing the biography
 * never explicitly creates).
 */
export async function snapshotVfsBaseline(brain: Brainy, model: ShadowModel): Promise<void> {
  const counts = await getCanonicalCountsFor(brain)
  model.vfsBaselineNouns = counts.nouns.all
  model.vfsBaselineVerbs = counts.verbs.all
}

/**
 * Record one `brain.vfs.writeFile()` call for a brand-new file at a flat
 * top-level path (no intermediate directories). Bumps both the noun and verb
 * VFS counters by one, matching the engine's actual write path exactly (see
 * the module header) — never call this for an overwrite of an existing path,
 * a nested path (which would also vivify intermediate directory nouns/edges,
 * a different, unmodeled shape), or the biography loses its exactness.
 */
export function recordVfsFileWrite(model: ShadowModel): void {
  model.vfsFileNouns += 1
  model.vfsContainsVerbs += 1
}

/** Record a fresh `add()` (or a Ch6 resurrection — `Map.set` fully replaces
 * whatever a prior dead entry held, which is exactly the "new metadata only"
 * contract a resurrection must honor). */
export function modelAdd(
  model: ShadowModel,
  id: string,
  entity: { type: NounType; subtype?: string; metadata: Record<string, unknown>; visibility?: EntityVisibility }
): void {
  model.entities.set(id, {
    type: entity.type,
    subtype: entity.subtype,
    metadata: { ...entity.metadata },
    visibility: entity.visibility,
    alive: true
  })
}

/** Record an `update()` — merges metadata by default, matching the engine's
 * `merge: true` default; pass `merge: false` to mirror a full replace. */
export function modelUpdate(
  model: ShadowModel,
  id: string,
  patch: { metadata?: Record<string, unknown>; merge?: boolean; visibility?: EntityVisibility }
): void {
  const existing = model.entities.get(id)
  if (!existing || !existing.alive) {
    throw new Error(`shadow model: update() targeted ${id}, which the model does not have alive — biography sequencing bug`)
  }
  if (patch.metadata) {
    existing.metadata = patch.merge === false ? { ...patch.metadata } : { ...existing.metadata, ...patch.metadata }
  }
  if (patch.visibility !== undefined) {
    existing.visibility = patch.visibility
  }
}

/** Record a `remove()` — marks the entity dead (entry retained, per
 * {@link ShadowEntity}) and cascades: every relation touching it, in either
 * direction, is hard-deleted from the model too (matching the engine). */
export function modelDelete(model: ShadowModel, id: string): void {
  const existing = model.entities.get(id)
  if (!existing || !existing.alive) {
    throw new Error(`shadow model: remove() targeted ${id}, which the model does not have alive — biography sequencing bug`)
  }
  existing.alive = false
  for (const [relId, rel] of model.relations) {
    if (rel.from === id || rel.to === id) model.relations.delete(relId)
  }
}

/** Record a `relate()` — `id` is the relation id the real call returned. */
export function modelRelate(
  model: ShadowModel,
  id: string,
  relation: { from: string; to: string; type: VerbType; subtype?: string; metadata?: Record<string, unknown> }
): void {
  model.relations.set(id, {
    from: relation.from,
    to: relation.to,
    type: relation.type,
    subtype: relation.subtype,
    metadata: { ...(relation.metadata ?? {}) }
  })
}

/** Record an `updateRelation()` metadata patch — merges by default. */
export function modelUpdateRelation(
  model: ShadowModel,
  id: string,
  patch: { metadata?: Record<string, unknown>; merge?: boolean }
): void {
  const existing = model.relations.get(id)
  if (!existing) {
    throw new Error(`shadow model: updateRelation() targeted ${id}, which the model does not have — biography sequencing bug`)
  }
  if (patch.metadata) {
    existing.metadata = patch.merge === false ? { ...patch.metadata } : { ...existing.metadata, ...patch.metadata }
  }
}

/** Order-independent structural equality for plain JSON-shaped metadata. */
function deepEqual(a: unknown, b: unknown): boolean {
  if (a === b) return true
  if (typeof a !== typeof b) return false
  if (a === null || b === null) return a === b
  if (typeof a !== 'object') return false
  const aKeys = Object.keys(a as Record<string, unknown>)
  const bKeys = Object.keys(b as Record<string, unknown>)
  if (aKeys.length !== bKeys.length) return false
  for (const k of aKeys) {
    if (!deepEqual((a as Record<string, unknown>)[k], (b as Record<string, unknown>)[k])) return false
  }
  return true
}

/** One hub entity to sample for the `related()` adjacency check, plus the
 * verb type(s) it is known (by biography construction) to have OUT-edges
 * of, so the type-filtered variant is exercised too. */
export interface HubCheck {
  id: string
  typeFilters: VerbType[]
}

/** Options steering one `verifyChapter()` call. */
export interface VerifyOptions {
  /** Hub entities to sample for the `related()` adjacency check. */
  hubs: HubCheck[]
  /** The metadata field `find()` bucket-checks against (a bare string field
   * every alive entity may or may not carry — distinct values present among
   * ALIVE model entities are discovered automatically each call, so a
   * chapter that moves entities across buckets is re-checked exactly). */
  bucketField: string
}

/**
 * Assert the live brain agrees with the model, in full, after one chapter.
 * Every failure message names the chapter `label`, the id (where
 * applicable), and expected-vs-actual — a red here must be diagnosable from
 * the assertion message alone, with no need to re-read this file.
 */
export async function verifyChapter(brain: Brainy, model: ShadowModel, label: string, opts: VerifyOptions): Promise<void> {
  // (a) + (b): every alive entity reads back exactly as modeled; every dead
  // entity reads as null.
  for (const [id, entity] of model.entities) {
    const live = await brain.get(id)
    if (entity.alive) {
      expect(live, `[${label}] alive entity ${id} (type=${entity.type}) must be readable via get(), got null`).not.toBeNull()
      const e = live!
      expect(e.type, `[${label}] entity ${id} .type mismatch: expected ${entity.type}, got ${e.type}`).toBe(entity.type)
      expect(e.subtype, `[${label}] entity ${id} .subtype mismatch: expected ${JSON.stringify(entity.subtype)}, got ${JSON.stringify(e.subtype)}`).toBe(entity.subtype)
      expect(
        e.visibility,
        `[${label}] entity ${id} .visibility mismatch: expected ${JSON.stringify(entity.visibility)}, got ${JSON.stringify(e.visibility)}`
      ).toBe(entity.visibility)
      const metaMatches = deepEqual(e.metadata ?? {}, entity.metadata)
      expect(
        metaMatches,
        `[${label}] entity ${id} .metadata mismatch: expected ${JSON.stringify(entity.metadata)}, got ${JSON.stringify(e.metadata)}`
      ).toBe(true)
    } else {
      expect(live, `[${label}] dead entity ${id} (type=${entity.type}) must read as null, got ${JSON.stringify(live)}`).toBeNull()
    }
  }

  // (c) find({ where: { <bucketField>: value } }) returns exactly the
  // model's matching alive set, per distinct value currently present.
  const bucketValues = new Set<string>()
  for (const entity of model.entities.values()) {
    if (!entity.alive) continue
    const v = entity.metadata[opts.bucketField]
    if (typeof v === 'string') bucketValues.add(v)
  }
  for (const value of bucketValues) {
    const expectedIds = [...model.entities.entries()]
      .filter(([, e]) => e.alive && e.metadata[opts.bucketField] === value)
      .map(([id]) => id)
      .sort()
    const results = await brain.find({
      where: { [opts.bucketField]: value } as Record<string, unknown>,
      includeInternal: true,
      limit: 100000
    })
    const actualIds = results.map((r) => r.id).sort()
    expect(
      actualIds,
      `[${label}] find({ where: { ${opts.bucketField}: ${JSON.stringify(value)} } }) mismatch: expected ${expectedIds.length} ids ${JSON.stringify(expectedIds)}, got ${actualIds.length} ids ${JSON.stringify(actualIds)}`
    ).toEqual(expectedIds)
  }

  // (d) related(id) / related(id, { type }) for the hub sample matches the
  // model's adjacency exactly (out-edges — related(id) is shorthand for
  // { from: id }).
  for (const hub of opts.hubs) {
    const expectedAll = [...model.relations.entries()]
      .filter(([, r]) => r.from === hub.id)
      .map(([id]) => id)
      .sort()
    const liveAll = await brain.related({ from: hub.id, limit: 100000 })
    const actualAllIds = liveAll.map((r) => r.id).sort()
    expect(
      actualAllIds,
      `[${label}] related(${hub.id}) mismatch: expected ${expectedAll.length} ids ${JSON.stringify(expectedAll)}, got ${actualAllIds.length} ids ${JSON.stringify(actualAllIds)}`
    ).toEqual(expectedAll)

    for (const typeFilter of hub.typeFilters) {
      const expectedTyped = [...model.relations.entries()]
        .filter(([, r]) => r.from === hub.id && r.type === typeFilter)
        .map(([id]) => id)
        .sort()
      const liveTyped = await brain.related({ from: hub.id, type: typeFilter, limit: 100000 })
      const actualTypedIds = liveTyped.map((r) => r.id).sort()
      expect(
        actualTypedIds,
        `[${label}] related(${hub.id}, { type: '${typeFilter}' }) mismatch: expected ${expectedTyped.length} ids ${JSON.stringify(expectedTyped)}, got ${actualTypedIds.length} ids ${JSON.stringify(actualTypedIds)}`
      ).toEqual(expectedTyped)
    }
  }

  // (e) getNounCount() / getVerbCount(): PUBLIC-tier alive records
  // (visibility absent/'public'; 'internal' and 'system' both excluded — see
  // the module header) plus the VFS's own public contributions.
  const alivePublicNouns = [...model.entities.values()].filter((e) => e.alive && (e.visibility ?? 'public') === 'public').length
  const aliveVerbs = model.relations.size
  const expectedNounCount = alivePublicNouns + model.vfsFileNouns
  const expectedVerbCount = aliveVerbs + model.vfsContainsVerbs
  expect(
    await brain.getNounCount(),
    `[${label}] getNounCount() mismatch: expected ${expectedNounCount} (alive public entities ${alivePublicNouns} + vfs file nouns ${model.vfsFileNouns})`
  ).toBe(expectedNounCount)
  expect(
    await brain.getVerbCount(),
    `[${label}] getVerbCount() mismatch: expected ${expectedVerbCount} (alive relations ${aliveVerbs} + vfs contains verbs ${model.vfsContainsVerbs})`
  ).toBe(expectedVerbCount)

  // (f) getCanonicalCounts(): ALL-visibility scalars (every tier) equal the
  // model's alive totals including hidden tiers, plus the VFS's own
  // contributions (both file nouns/verbs AND the once-measured root
  // baseline). suspect must be false — every delete in this biography goes
  // through brain.remove(), which always proves the record it decrements.
  const ledger = await getCanonicalCountsFor(brain)
  const aliveAllNouns = [...model.entities.values()].filter((e) => e.alive).length
  const expectedNounsAll = aliveAllNouns + model.vfsFileNouns + model.vfsBaselineNouns
  const expectedVerbsAll = aliveVerbs + model.vfsContainsVerbs + model.vfsBaselineVerbs
  expect(
    ledger.nouns.all,
    `[${label}] getCanonicalCounts().nouns.all mismatch: expected ${expectedNounsAll} (alive incl. internal ${aliveAllNouns} + vfs file nouns ${model.vfsFileNouns} + vfs root baseline ${model.vfsBaselineNouns})`
  ).toBe(expectedNounsAll)
  expect(
    ledger.verbs.all,
    `[${label}] getCanonicalCounts().verbs.all mismatch: expected ${expectedVerbsAll} (alive relations ${aliveVerbs} + vfs contains verbs ${model.vfsContainsVerbs} + vfs root baseline ${model.vfsBaselineVerbs})`
  ).toBe(expectedVerbsAll)
  expect(ledger.nouns.counted, `[${label}] getCanonicalCounts().nouns.counted mismatch (should mirror getNounCount())`).toBe(expectedNounCount)
  expect(ledger.verbs.counted, `[${label}] getCanonicalCounts().verbs.counted mismatch (should mirror getVerbCount())`).toBe(expectedVerbCount)
  expect(ledger.suspect, `[${label}] getCanonicalCounts().suspect must be false — every delete in this biography proves its record`).toBe(false)
}