/**
 * storeRegistry — resolves (account, scope) → document NURI.
 *
 * Stopgap / polyfill-era. Emulates the target infrastructure — where each
 * user owns their own public/protected/private stores — on top of one shared
 * wallet. It creates one document per (account × scope) inside that shared
 * wallet (via the `docs.docCreate` primitive), so the `scope`
 * (`public|protected|private`) is a logical attribute tracked here, not a
 * physical NextGraph store. Isolation is enforced by the app layer + the
 * emulated cap registry, not by crypto.
 *
 * The mapping (account → its 3 document NURIs) is the **sharedWalletShim**,
 * persisted as RDF in the shared wallet's private store (the anchor, always
 * known from the session). That makes login cross-device: another device
 * opening the same wallet reads the same shim and finds the same accounts.
 *
 * ── Generic by construction ──────────────────────────────────────────────
 * This module knows only the three native scopes; it knows no application
 * entity kind. The consumer maps its entities to a scope and calls
 * `createEntityDoc(scope)` / `listEntityDocs(scope)` with the resulting native
 * scope. No application domain here.
 *
 * ── What disappears at migration ─────────────────────────────────────────
 * At the real multi-store migration the shim vanishes entirely: `(account,
 * scope)` maps to the user's REAL store NURI instead of a document in the
 * shared wallet, `docCreate` targets the real per-user store, and the
 * per-scope index document (the store-container emulation) is replaced by the
 * store itself. The consumer-facing surface (`createEntityDoc`,
 * `listEntityDocs`, resolvers) is designed to survive that swap unchanged.
 *
 * All NextGraph I/O routes through the T01.a `docs` primitive (real injected
 * `ng`), so this module imports **no** `@ng-org` package.
 */

import { docCreate, sparqlUpdate, sparqlQuery } from "./docs";
import { getStoreRegistryDeps } from "./polyfill";
import { escapeLiteral, escapeIri, assertNuri } from "./sparql";
import type { Nuri, Scope } from "./types";

// --- sharedWalletShim model ----------------------------------------------

/** One account's three scope-document NURIs, as recorded in the shim. */
export interface AccountRecord {
  id: string;
  docPublic: Nuri;
  docProtected: Nuri;
  docPrivate: Nuri;
}

const SHIM = "urn:ng-eventually:shim";
const P = {
  type: `${SHIM}:Account`,
  id: `${SHIM}:id`,
  docPublic: `${SHIM}:docPublic`,
  docProtected: `${SHIM}:docProtected`,
  docPrivate: `${SHIM}:docPrivate`,
  contains: `${SHIM}:contains`, // scope-index → entity document NURI
} as const;
// Fixed subject of the per-(account×scope) index document. The index doc plays
// the role of the future store-container: it lists the NURIs of the entity
// documents (one per entity) that live "in" that scope.
const INDEX_SUBJECT = `${SHIM}:index`;

function accountSubject(id: string): string {
  // The id is UNTRUSTED and lands in an IRI position. Percent-encode it
  // (escapeIri) so no `>` / `"` / whitespace / control char can break out of
  // the `<...>` and inject triples into the shim graph (the account→doc trust
  // root). accountKey() runs first so the subject stays stable per shim key.
  return `${SHIM}:account:${escapeIri(accountKey(id))}`;
}

// --- reserved accounts -----------------------------------------------------
//
// Some accounts are internal to the lib (e.g. the discovery index owner) and
// must NOT collide with any user-chosen id. A reserved account is created
// via {@link reservedAccount}, which marks the name with a sentinel PREFIX that
// `normalizeId` (consumer-injected) can never produce: it strips a leading
// `@`, trims, and lowercases, so a NUL prefix is unreachable. Reserved
// keys therefore live in a disjoint namespace from every normalized id —
// a real user named "index"/"@index" can never resolve to the reserved
// `reservedAccount("index")` account.
const RESERVED_PREFIX = "\u0000reserved:";

/**
 * Wrap an internal account name so it occupies a key that no user input can
 * produce (see {@link RESERVED_PREFIX}). Pass the result to {@link ensureAccount}
 * (and the other registry calls) instead of a bare id.
 */
export function reservedAccount(name: string): string {
  return `${RESERVED_PREFIX}${name}`;
}

/** Whether a name is a reserved-account sentinel (from {@link reservedAccount}). */
function isReserved(id: string): boolean {
  return id.startsWith(RESERVED_PREFIX);
}

/**
 * The shim/cache key for an account. Reserved accounts bypass `normalizeId`
 * entirely and key on their sentinel-prefixed name, so they cannot collide with
 * a normalized id; everyone else normalizes as usual.
 */
function accountKey(id: string): string {
  return isReserved(id) ? id : normalize(id);
}

// --- session / normalization access (injected by the consumer) ------------

/** Minimal session shape the registry needs — provided by the consumer. */
export interface RegistrySession {
  sessionId: string;
  /** The shared wallet's private store id — the shim anchor. */
  privateStoreId: string;
  /** The shared wallet's protected store id (native store). Optional: only the
   *  scope resolvers need it; the shim only needs the private anchor. */
  protectedStoreId?: string;
  /** The shared wallet's public store id (native store). Optional. */
  publicStoreId?: string;
}

function normalize(id: string): string {
  return getStoreRegistryDeps().normalizeId(id);
}

async function session(): Promise<RegistrySession> {
  return getStoreRegistryDeps().getSession();
}

/** The shim lives in the shared wallet's private store (always-known anchor). */
async function anchorNuri(): Promise<Nuri> {
  const s = await session();
  return `did:ng:${s.privateStoreId}`;
}

// --- cache ----------------------------------------------------------------

// In-memory cache of the FULL shim (all accounts), keyed by account key. Set
// only once loadShim() has read every account — used by the all-accounts paths.
let cache: Map<string, AccountRecord> | null = null;

// Per-account cache, keyed by account key. Populated by the TARGETED resolver
// (resolveAccount) and by loadShim(). Independent of `cache` so a single
// targeted resolve never forces a full shim scan. Both are cleared together.
const accountCache = new Map<string, AccountRecord>();

/** Reset cache (e.g. after switching the shared wallet). Mostly for tests. */
export function resetRegistryCache(): void {
  cache = null;
  accountCache.clear();
}

// --- SPARQL result helpers ------------------------------------------------

/** Tolerant extraction of SPARQL SELECT bindings across possible shapes. */
function readBindings(result: unknown): Array<Record<string, { value: string }>> {
  if (!result) return [];
  const anyRes = result as {
    results?: { bindings?: Array<Record<string, { value: string }>> };
  };
  if (Array.isArray(result)) return result as Array<Record<string, { value: string }>>;
  if (anyRes.results?.bindings) return anyRes.results.bindings;
  return [];
}

function bindingValue(row: Record<string, { value: string }>, key: string): string {
  return row[key]?.value ?? "";
}

// --- shim load / account bootstrap ----------------------------------------

/** Load all accounts from the shim into the cache. */
export async function loadShim(): Promise<Map<string, AccountRecord>> {
  if (cache) return cache;
  const s = await session();
  const anchor = await anchorNuri();
  const query = `
    SELECT ?id ?docPublic ?docProtected ?docPrivate WHERE {
      GRAPH <${assertNuri(anchor)}> {
        ?acc a <${P.type}> ;
             <${P.id}> ?id ;
             <${P.docPublic}> ?docPublic ;
             <${P.docProtected}> ?docProtected ;
             <${P.docPrivate}> ?docPrivate .
      }
    }`;
  const map = new Map<string, AccountRecord>();
  try {
    const result = await sparqlQuery(s.sessionId, query, undefined, anchor);
    for (const row of readBindings(result)) {
      const id = bindingValue(row, "id");
      if (!id) continue;
      const key = accountKey(id);
      const record: AccountRecord = {
        id,
        docPublic: bindingValue(row, "docPublic"),
        docProtected: bindingValue(row, "docProtected"),
        docPrivate: bindingValue(row, "docPrivate"),
      };
      map.set(key, record);
      // Feed the per-account cache too, so a subsequent targeted resolve is free.
      accountCache.set(key, record);
    }
  } catch (error) {
    console.error("[storeRegistry] loadShim failed:", error);
  }
  cache = map;
  return map;
}

/**
 * Resolve ONE account by its shim key with a BOUNDED query — O(1), independent
 * of the number of accounts in the shim. This is the HOT-PATH lookup: it hits
 * the account record at its known subject (`accountSubject(id)`) directly,
 * instead of scanning EVERY account like {@link loadShim}. Returns the account's
 * record or `null` if it does not exist yet.
 *
 * Cached per account (in `accountCache`); a hit skips the query entirely, so
 * repeated resolves of the same account are free. `resetRegistryCache` clears it.
 */
export async function resolveAccount(id: string): Promise<AccountRecord | null> {
  const key = accountKey(id);
  const cached = accountCache.get(key);
  if (cached) return cached;

  const s = await session();
  const anchor = await anchorNuri();
  // `subj` is already IRI-safe (accountSubject → escapeIri); `anchor` is a
  // trusted-shaped NURI → assertNuri. The query is bounded to this one subject.
  const subj = accountSubject(id);
  const query = `
    SELECT ?id ?docPublic ?docProtected ?docPrivate WHERE {
      GRAPH <${assertNuri(anchor)}> {
        <${subj}> a <${P.type}> ;
             <${P.id}> ?id ;
             <${P.docPublic}> ?docPublic ;
             <${P.docProtected}> ?docProtected ;
             <${P.docPrivate}> ?docPrivate .
      }
    }`;
  try {
    const result = await sparqlQuery(s.sessionId, query, undefined, anchor);
    const rows = readBindings(result);
    if (rows.length === 0) return null;
    const row = rows[0]!;
    const record: AccountRecord = {
      id: bindingValue(row, "id") || id,
      docPublic: bindingValue(row, "docPublic"),
      docProtected: bindingValue(row, "docProtected"),
      docPrivate: bindingValue(row, "docPrivate"),
    };
    accountCache.set(key, record);
    return record;
  } catch (error) {
    console.error("[storeRegistry] resolveAccount failed:", error);
    return null;
  }
}

/** All known accounts (from the shim). */
export async function allAccounts(): Promise<AccountRecord[]> {
  return [...(await loadShim()).values()];
}

/** Create one graph document in the shared wallet's private store (→ a NURI). */
async function createDoc(): Promise<Nuri> {
  const s = await session();
  // crdt="Graph" (RDF/SPARQL/ORM), class="data:graph", destination="store",
  // store_repo=undefined → shared wallet's private store.
  return docCreate(s.sessionId, "Graph", "data:graph", "store", undefined);
}

/**
 * Ensure an account exists in the shim, creating its 3 scope documents on
 * first sight. Idempotent — returns the existing record if already present.
 */
export async function ensureAccount(id: string): Promise<AccountRecord> {
  const key = accountKey(id);
  // HOT PATH: targeted O(1) lookup — does THIS account already exist? — instead
  // of a full-shim scan (loadShim). Off the read/write hot path entirely.
  const existing = await resolveAccount(id);
  if (existing) return existing;

  const [docPublic, docProtected, docPrivate] = await Promise.all([
    createDoc(),
    createDoc(),
    createDoc(),
  ]);
  const record: AccountRecord = { id, docPublic, docProtected, docPrivate };

  const s = await session();
  const anchor = await anchorNuri();
  const subj = accountSubject(id);
  // `subj` is already IRI-safe (accountSubject → escapeIri). `anchor` is a
  // trusted-shaped NURI → assertNuri. `id` is UNTRUSTED text in a LITERAL
  // position → escapeLiteral. The doc NURIs come from `ng` but are stored as
  // literals here, so they are escaped as literals too (defence in depth).
  const update = `
    INSERT DATA {
      GRAPH <${assertNuri(anchor)}> {
        <${subj}> a <${P.type}> ;
          <${P.id}> "${escapeLiteral(id)}" ;
          <${P.docPublic}> "${escapeLiteral(docPublic)}" ;
          <${P.docProtected}> "${escapeLiteral(docProtected)}" ;
          <${P.docPrivate}> "${escapeLiteral(docPrivate)}" .
      }
    }`;
  try {
    await sparqlUpdate(s.sessionId, update, anchor);
  } catch (error) {
    console.error("[storeRegistry] ensureAccount persist failed:", error);
  }
  // Feed the per-account cache, and the full-shim cache if it is already loaded
  // (so allAccounts / the fan-out see the freshly-created account too).
  accountCache.set(key, record);
  cache?.set(key, record);
  return record;
}

// --- resolvers ------------------------------------------------------------

/** The index document NURI of an account for a scope (the store-container). */
function indexDocOf(record: AccountRecord, scope: Scope): Nuri {
  return scope === "public"
    ? record.docPublic
    : scope === "protected"
    ? record.docProtected
    : record.docPrivate;
}

/**
 * NURI of the document where `id` writes GROUPED entities of `scope` (a single
 * per-scope index document, for entities that need no per-entity document / no
 * inbox). For per-entity scopes use {@link createEntityDoc} instead.
 */
export async function resolveWriteGraph(id: string, scope: Scope): Promise<Nuri> {
  const record = await ensureAccount(id);
  return indexDocOf(record, scope);
}

/** NURIs of every account's document for `scope` (read fan-out). */
export async function resolveReadGraphs(scope: Scope): Promise<Nuri[]> {
  const accounts = await allAccounts();
  return accounts.map((a) => indexDocOf(a, scope));
}

// --- SDK-shaped scope resolvers (no store-id ever leaves the lib) ----------
//
// The consumer asks by SCOPE ("give me the graph to write/read entities of
// scope X", "give me the inbox anchor") and NEVER constructs a `did:ng:${…}`
// store NURI itself. The lib owns the physical placement — which is the whole
// point of the SDK boundary. In THIS polyfill the placement is the shared
// wallet's native stores (Axis A, per the two-axes doctrine in
// docs/simulation.md): a scope maps to a native store NURI resolved from the
// injected session. `public` currently co-locates with `protected` because
// `doc_create`/ORM cannot target a non-private/protected native store today
// (the SDK blocker recorded in migration-guide.md); at migration each scope
// resolves to the user's REAL per-scope store and this mapping changes here,
// in the lib, with no consumer change.

/** The native store NURI backing `scope`, resolved from the injected session.
 *  Requires `protectedStoreId` on the session for the non-private scopes. */
async function scopeStoreNuri(scope: Scope): Promise<Nuri> {
  const s = await session();
  if (scope === "private") return `did:ng:${s.privateStoreId}`;
  // public + protected → the protected native store (see note above). Falls
  // back to the private store if the session didn't carry a protected id.
  const store = s.protectedStoreId ?? s.privateStoreId;
  return `did:ng:${store}`;
}

/**
 * The graph NURI where the current session WRITES entities of `scope`, and
 * whose repo `useShape` must subscribe to read them back. SDK-shaped: the
 * consumer passes a logical scope and gets an opaque graph NURI — it holds no
 * store-id and builds no NURI. Use the returned value as both the read scope
 * (`useShape(shape, nuri)`) and the `@graph` write target.
 */
export async function resolveScopeGraph(scope: Scope): Promise<Nuri> {
  return scopeStoreNuri(scope);
}

/**
 * The reserved account that OWNS the shared registration-inbox document. Like the
 * discovery index's special account, it lives in the reserved namespace (no user
 * can produce this key) and only HOSTS a document — its `public` scope document is
 * the inbox anchor. Disappears at migration (native per-document inboxes).
 */
const INBOX_ANCHOR_ACCOUNT = reservedAccount("inbox");

/**
 * The inbox anchor NURI for the current session (where emulated inbox deposits
 * physically land). SDK-shaped: the consumer never resolves a store itself.
 *
 * This is a DEDICATED inbox DOCUMENT (a reserved account's public scope document —
 * a real repo NURI from `docCreate`, stable across clients via the shim), NOT the
 * shared wallet's private-store root. Reason (perf + hygiene): the shim (the
 * account→document trust root) lives in the private-store graph and is scanned on
 * every `loadShim`; routing every inbox deposit into that SAME graph bloats it
 * without bound (thousands of deposit triples across sessions), turning `loadShim`
 * into a multi-second full-graph scan. A separate inbox document keeps the shim
 * graph small and the deposits isolated. At migration this becomes the host's
 * native per-document inbox and the resolution moves here.
 */
export async function resolveInboxAnchor(): Promise<Nuri> {
  const record = await ensureAccount(INBOX_ANCHOR_ACCOUNT);
  return record.docPublic;
}

// --- per-entity documents + per-scope index -------------------------------

/**
 * Create a dedicated document for ONE entity — mirrors the target, where each
 * such entity is its own document/repo (addressable, future inbox). The new
 * document's NURI is appended to the account's scope index document (the
 * store-container). Returns the entity document NURI (use it as `@graph`).
 */
export async function createEntityDoc(id: string, scope: Scope): Promise<Nuri> {
  const record = await ensureAccount(id);
  const indexDoc = indexDocOf(record, scope);
  const entityNuri = await createDoc();
  const s = await session();
  try {
    await sparqlUpdate(
      s.sessionId,
      // NO explicit `GRAPH <…>` wrapper: write the anchored DEFAULT graph (the
      // `indexDoc` anchor scopes it) — the CANONICAL, always-safe shape the
      // anchored default-graph read queries (readScopeIndex below, same as
      // read-model.ts). Not a round-trip necessity on the current broker: the e2e
      // harness (`packages/client/e2e/`) verified an anchored `GRAPH <plainNuri>`
      // write ALSO round-trips here (same repo graph, no phantom graph); no-GRAPH
      // is kept as a simplicity/safety convention. entityNuri is a NURI stored as
      // a literal → escapeLiteral.
      `INSERT DATA { <${INDEX_SUBJECT}> <${P.contains}> "${escapeLiteral(entityNuri)}" }`,
      indexDoc,
    );
  } catch (error) {
    console.error("[storeRegistry] createEntityDoc index append failed:", error);
  }
  return entityNuri;
}

/** Read the entity-document NURIs contained in ONE scope index document. */
async function readScopeIndex(indexDoc: Nuri): Promise<Nuri[]> {
  const s = await session();
  const out: Nuri[] = [];
  try {
    const res = await sparqlQuery(
      s.sessionId,
      // NO explicit `GRAPH <…>` clause — read the anchored DEFAULT graph (see
      // the note in createEntityDoc). The `indexDoc` anchor scopes the query.
      `SELECT ?e WHERE { <${INDEX_SUBJECT}> <${P.contains}> ?e }`,
      undefined,
      indexDoc,
    );
    for (const row of readBindings(res)) {
      const v = bindingValue(row, "e");
      if (v) out.push(v);
    }
  } catch (error) {
    console.error("[storeRegistry] readScopeIndex read failed:", error);
  }
  return out;
}

/**
 * Every entity document NURI of `scope`, across all accounts — the read
 * fan-out for per-entity scopes. Reads each account's scope index document and
 * unions the contained NURIs. Use as `useShape(shape, { graphs })`.
 *
 * NOTE (read-by-need): this ALL-ACCOUNTS fan-out contradicts the read-by-need
 * model (docs/read-model.md) — it opens/syncs other accounts' possibly-unsynced
 * docs, which HANGS. Prefer {@link listMyEntityDocs} (my own account's scope
 * docs) for "my entities", and the discovery index for "all public events".
 * Retained for callers that legitimately need every account (tests).
 */
export async function listEntityDocs(scope: Scope): Promise<Nuri[]> {
  const accounts = await allAccounts();
  const out: Nuri[] = [];
  for (const a of accounts) {
    out.push(...(await readScopeIndex(indexDocOf(a, scope))));
  }
  return out;
}

/**
 * The entity-document NURIs of `scope` belonging to ONE account (`id`) —
 * the read-by-need path for one account's own entities. Bounded to a SINGLE
 * account: it resolves only that account's scope index doc (via `ensureAccount`)
 * and reads the contained NURIs — NO cross-account fan-out, so it never touches
 * another account's unsynced docs. This is the helper a consumer application uses
 * for its own my-entities path, instead of the all-accounts `listEntityDocs`.
 */
export async function listMyEntityDocs(id: string, scope: Scope): Promise<Nuri[]> {
  const record = await ensureAccount(id);
  return readScopeIndex(indexDocOf(record, scope));
}