/**
 * `init()` — the hand-over to the broker, and the one thing that must happen before it.
 *
 * The real `@ng-org/web` `init()` navigates a top-level page to NextGraph's login as its
 * FIRST statement, carrying `window.location.href` AS IT FINDS IT. Everything the
 * application would have done afterwards runs in a document that no longer exists. So an
 * application that signed in on the next line never signed in at all: no barrier, no
 * identifier in the URL that crossed, and a first-time user parked on a login with no
 * wallet and no error anywhere.
 *
 * The library's `init()` therefore settles the identity BEFORE it delegates. That order is
 * carried by composition, not by an instruction to a caller — so what these tests pin is
 * what the injected `init` OBSERVES when it is called, never the sequence of calls: a
 * regression that delegated first would still call things in the right order, and would
 * still hand over a bare URL.
 */
import { test, expect, afterEach } from "bun:test";
import { configure, ensureIdentity } from "../src/index";
import { init } from "../src/surface/lifecycle";
import { resetConfig, resetStoreRegistry, setCurrentUser } from "../src/shared-wallet/bootstrap";
import type { RegistrySession } from "../src/shared-wallet/account-registry";

const KEY = "ng-eventually:identity";
const APP = "https://app.example/";

/** A localStorage double — the real one is absent in `bun test`. */
function fakeStorage(initial: Record<string, string> = {}) {
  const map = new Map(Object.entries(initial));
  return {
    getItem: (k: string) => map.get(k) ?? null,
    setItem: (k: string, v: string) => void map.set(k, v),
    removeItem: (k: string) => void map.delete(k),
  };
}

/**
 * Which side of the broker frontier the page is on. It decides whether the barrier shows
 * at all — top-level it always does, past the round-trip it never does — so no page here
 * may leave it unsaid: `window.self !== window.top` is what the gate reads, and a double
 * without a `window` would silently be top-level.
 */
type Side = "top-level" | "in the broker iframe";

/**
 * A browser page, faithful in the one way these assertions depend on: `location.search`
 * tracks `href`, and `history.replaceState` MOVES `href` — as a real browser does, and as
 * the real `init()` relies on when it reads the address bar. A double whose `replaceState`
 * did nothing would let a broken `init()` pass.
 */
function inBrowser(url: string, storage: ReturnType<typeof fakeStorage>, side: Side) {
  let href = url;
  const location = {
    get href(): string { return href; },
    get search(): string { return new URL(href).search; },
  };
  const self = {};
  Object.assign(globalThis, {
    location,
    history: { replaceState: (_s: unknown, _t: string, next: string): void => void (href = next) },
    localStorage: storage,
    window: { self, top: side === "top-level" ? self : {}, addEventListener: (): void => {} },
  });
  return { location };
}

/** One element of the barrier, holding the listeners the gate attaches to it. */
function fakeElement() {
  const handlers = new Map<string, ((e: unknown) => void)[]>();
  return {
    value: "",
    disabled: false,
    addEventListener(type: string, fn: (e: unknown) => void): void {
      handlers.set(type, [...(handlers.get(type) ?? []), fn]);
    },
    focus(): void {},
    fire(type: string): void {
      for (const fn of handlers.get(type) ?? []) fn({});
    },
  };
}

/**
 * A DOM that COUNTS the barriers mounted on it — the one thing this file needs from a
 * document. It does not parse markup, so `querySelector` hands back the elements it was
 * built with; what the markup contains is `access-gate.test.ts`'s subject and the e2e's.
 */
function fakeDom() {
  const input = fakeElement();
  const go = fakeElement();
  let mounted = 0;
  const root = {
    innerHTML: "",
    querySelector: (sel: string) => (sel === "input" ? input : sel === "button.go" ? go : null),
  };
  const host = {
    setAttribute: (): void => {},
    attachShadow: () => root,
    remove: (): void => void (mounted -= 1),
  };
  return {
    document: { createElement: () => host, body: { appendChild: (): void => void (mounted += 1) } },
    /** How many barriers are on screen right now. */
    get mounted(): number {
      return mounted;
    },
    /** What a user does at the barrier: type an identifier, then press Entrer. */
    submit(id: string): void {
      input.value = id;
      input.fire("input");
      go.fire("click");
    },
    /** What a returning user does: press Entrer on the field as they found it, prefilled. */
    confirm(): void {
      go.fire("click");
    },
  };
}

const PAGE_GLOBALS = ["location", "localStorage", "history", "document", "window"] as const;

afterEach(() => {
  setCurrentUser(null);
  resetConfig();
  resetStoreRegistry();
  for (const name of PAGE_GLOBALS) Reflect.deleteProperty(globalThis, name);
});

/**
 * The consumer's real wiring, reduced to the cycle it creates.
 *
 * An application resolves its session FROM `init()`'s callback and hands the library a
 * thunk that waits for it (`examples/notebook/app.ts`). So before `init()` runs the session
 * does not exist and cannot: nothing else resolves it. That is why the injected `init`
 * here resolves it — a `getSession` that answered straight away would be a state the real
 * system never reaches, and it is precisely the state under which the deadlock below is
 * invisible.
 *
 * The spy records what the real `init()` reads at the moment it is called — the address
 * bar — and returns a promise, as the real one does.
 */
function consumerWiring() {
  let arrived!: (s: RegistrySession) => void;
  const sessionReady = new Promise<RegistrySession>((resolve) => { arrived = resolve; });
  const calls: { href: string; args: unknown[] }[] = [];
  const returned = { itsOwnReturnValue: true };
  const injectedInit = (...args: unknown[]): Promise<unknown> => {
    calls.push({ href: String((globalThis as { location?: { href: string } }).location?.href), args });
    arrived({ sessionId: "s", privateStoreId: "did:ng:o:p" });
    return Promise.resolve(returned);
  };
  return { sessionReady, calls, injectedInit, returned, getSession: () => sessionReady };
}

function configured(wiring: ReturnType<typeof consumerWiring>, opts: { sharedWallet?: boolean } = {}) {
  configure({
    ng: {} as never,
    useShape: (() => {}) as never,
    init: wiring.injectedInit,
    getSession: wiring.getSession,
    normalizeId: (id: string) => id.trim().replace(/^@/, "").toLowerCase(),
    ...(opts.sharedWallet === false ? {} : { sharedWallet: { fileUrl: "/w.ngw", password: "pw" } }),
  });
}

/**
 * Turn a hang into a readable failure. NOT part of the mechanism — nothing in the library
 * races or times out; this only says WHY a test stopped, instead of leaving the runner to
 * report a bare timeout on a test whose whole subject is a deadlock.
 */
function within<T>(p: Promise<T>): Promise<T> {
  let timer: ReturnType<typeof setTimeout> | undefined;
  const deadline = new Promise<never>((_, reject) => {
    timer = setTimeout(
      () => reject(new Error("init() never resolved — it is waiting on the session it is itself supposed to open")),
      1000,
    );
  });
  return Promise.race([p, deadline]).finally(() => clearTimeout(timer));
}

test("the injected `init` finds the identifier ALREADY in the address bar", async () => {
  // The assertion is on what the delegate OBSERVES, not on call order: the real `init()`
  // reads `window.location.href` at its first statement and carries it to the broker, so a
  // wrapper that delegated first and settled after would satisfy any ordering check and
  // still send the round-trip off bare. Identity from storage is the case that bites —
  // storage does not cross the broker's partition, the URL does.
  //
  // Top-level, which is the only side that hands over at all, so Hana meets the barrier
  // with her identifier already in the field and confirms it. What must be true when the
  // delegate is finally called is unchanged: the address bar already carries her.
  const wiring = consumerWiring();
  configured(wiring);
  inBrowser(APP, fakeStorage({ [KEY]: "hana" }), "top-level");
  const dom = fakeDom();
  Object.assign(globalThis, { document: dom.document });

  const delegated = init(() => {}, true, []);
  await Promise.resolve();
  dom.confirm();
  await within(delegated);

  expect(wiring.calls.length).toBe(1);
  expect(wiring.calls[0]!.href).toBe(APP + "?ng-id=hana");
});

test("it resolves though the session exists only AFTER it delegates — the cycle, pinned", async () => {
  // The deadlock this split exists to prevent, reproduced exactly. Signing in fully
  // (`ensureIdentity`) awaits the connection work → `resolveAccount` → `lookupAccount` →
  // `session()` → the consumer's thunk → a promise only `init()`'s callback resolves. Await
  // that here and nothing ever runs: `init` is never called, so the session never arrives,
  // so the wait never ends. `init()` therefore awaits the SESSION-FREE half only.
  //
  // Inside the iframe, which is where the cycle actually closes: the identifier arrived in
  // the URL, the barrier stands aside, and delegating is what opens the session.
  const wiring = consumerWiring();
  configured(wiring);
  inBrowser(APP + "?ng-id=iris", fakeStorage(), "in the broker iframe");

  await within(init(() => {}, true, []));

  expect(wiring.calls.length).toBe(1);
  // And the direction the cycle was broken in: delegating is what made the session exist.
  await expect(within(wiring.sessionReady)).resolves.toMatchObject({ sessionId: "s" });
});

test("a settling failure rejects — the page is not handed to the broker without an identity", async () => {
  // Nothing known, and no shared wallet to hand the user one. Delegating anyway IS the
  // defect: the page navigates to a login the user cannot complete and cannot come back
  // from, silently. Failing at the call the application made is the only place the cause
  // is still visible.
  const wiring = consumerWiring();
  configured(wiring, { sharedWallet: false });
  inBrowser(APP, fakeStorage(), "top-level");

  await expect(init(() => {}, true, [])).rejects.toThrow(/no shared wallet configured/i);
  expect(wiring.calls.length).toBe(0);
});

test("`init` and `ensureIdentity` in the same tick raise ONE barrier, not two", async () => {
  // Exactly the reference application's bootstrap: `init()` at module load, then `signIn()`
  // awaiting `ensureIdentity()` (`examples/notebook/app.ts`). Both settle the identity now,
  // so both reach the barrier in the same tick. Two barriers is not a cosmetic fault: the
  // user answers whichever is on top, the other never resolves, and the `init()` waiting on
  // it never hands the page to the broker — the application hangs before it ever loads.
  const wiring = consumerWiring();
  configured(wiring);
  inBrowser(APP, fakeStorage(), "top-level");
  const dom = fakeDom();
  Object.assign(globalThis, { document: dom.document });

  const delegated = init(() => {}, true, []);
  const signedIn = ensureIdentity();
  await Promise.resolve();

  expect(dom.mounted).toBe(1);
  dom.submit("kira");
  await within(delegated);
  expect(await within(signedIn)).toBe("kira");
  expect(wiring.calls[0]!.href).toBe(APP + "?ng-id=kira");
});

test("arguments and return value pass through untouched — it is still a forwarder", async () => {
  // Settling is added BEFORE the delegate, never around it: `init` takes a callback and
  // upstream returns a promise, so anything this wrapper altered on the way in or out
  // would be a difference the application has to unlearn at migration.
  const wiring = consumerWiring();
  configured(wiring);
  inBrowser(APP, fakeStorage(), "top-level");
  setCurrentUser("juno");
  const callback = (): void => {};

  const result = await within(init(callback, true, ["a-broker"]));

  expect(wiring.calls[0]!.args).toEqual([callback, true, ["a-broker"]]);
  expect(result).toBe(wiring.returned);
});