import {
  app,
  BASE_URL,
  createUser,
  db,
  del,
  type FakeInstance,
  fakeInstance,
  federationOff,
  formWithFile,
  get,
  patch,
  PNG,
  post,
  put,
  stubNetwork,
  test,
} from "../helpers.ts";
import { assert, assertEquals } from "@std/assert";
import { createHash } from "node:crypto";
import { decodeJwt, type JSONWebKeySet } from "@panva/jose";
import {
  createPasswordResetToken,
  verifyInstanceToken,
} from "../../lib/jwt.ts";
import {
  deliverOutbox,
  identityClaims,
  withdrawAllGrants,
} from "../../services/identity-provider-service.ts";
import { getUserById } from "../../services/user-service.ts";
import type {
  AuthorizeResponse,
  FederationGrant,
  InstanceMetadata,
  OAuthClient,
} from "../../../shared/federation.ts";

const CLIENT = "https://client.test";
const CALLBACK = `${CLIENT}/federation/callback`;

function network(fake: FakeInstance, events?: () => Response) {
  return stubNetwork((url, init) => {
    if (events && url.pathname === "/api/federation/events") return events();
    return fake.handle(url, init) ?? new Response("", { status: 404 });
  });
}

/** A PKCE pair: the verifier, and the challenge the request carries. */
function pkce() {
  const verifier = crypto.randomUUID() + crypto.randomUUID();
  return {
    verifier,
    challenge: createHash("sha256").update(verifier).digest("base64url"),
  };
}

function authorize(
  auth: { Authorization: string },
  challenge: string,
  overrides: Record<string, string> = {},
) {
  return post<AuthorizeResponse>("/api/oauth/codes", {
    auth,
    json: {
      clientId: CLIENT,
      redirectUri: CALLBACK,
      state: "the-state",
      codeChallenge: challenge,
      codeChallengeMethod: "S256",
      nonce: "the-nonce",
      ...overrides,
    },
  });
}

/** Trades `code` at the token endpoint, as the client's server would. */
async function trade(code: string, verifier: string, client = CLIENT) {
  const res = await app.handle(
    new Request(`${BASE_URL}/api/oauth/tokens`, {
      method: "POST",
      headers: { "Content-Type": "application/x-www-form-urlencoded" },
      body: new URLSearchParams({
        grant_type: "authorization_code",
        code,
        client_id: client,
        redirect_uri: CALLBACK,
        code_verifier: verifier,
      }),
    }),
  );
  return { status: res!.status, body: await res!.json() };
}

async function until(check: () => boolean) {
  for (let i = 0; i < 50 && !check(); i++) {
    await new Promise((r) => setTimeout(r, 10));
  }
}

test("identity provider: metadata and keys are served at the well-known paths", async () => {
  const meta = await get("/.well-known/openid-configuration");
  const body = JSON.parse(
    new TextDecoder().decode(meta.bytes),
  ) as InstanceMetadata;
  assertEquals(body.issuer, BASE_URL);
  assertEquals(body.authorization_endpoint, `${BASE_URL}/authorize`);
  assertEquals(body.gerbeur_redirect_uri, `${BASE_URL}/federation/callback`);
  assertEquals(body.gerbeur_federation, 1);
  assertEquals(body.gerbeur_outgoing, true);
  const jwks = await get("/.well-known/jwks.json");
  const keys = JSON.parse(new TextDecoder().decode(jwks.bytes)).keys;
  assertEquals(keys[0].crv, "Ed25519");
  assertEquals(keys[0].d, undefined);
});

test("identity provider: a consenting user's code trades once for their identity", async () => {
  const fake = await fakeInstance(CLIENT);
  using _net = network(fake);
  const user = await createUser({ username: "carol" });

  const client = await get<OAuthClient>(
    `/api/oauth/clients?client_id=${encodeURIComponent(CLIENT)}`,
    { auth: user.auth },
  );
  assertEquals(client.data, {
    clientId: CLIENT,
    host: "client.test",
    name: "Fake client.test",
    granted: false,
  });

  const { verifier, challenge } = pkce();
  const redirect = new URL(
    (await authorize(user.auth, challenge)).data
      .redirectTo,
  );
  assertEquals(redirect.origin + redirect.pathname, CALLBACK);
  assertEquals(redirect.searchParams.get("state"), "the-state");
  assertEquals(redirect.searchParams.get("iss"), BASE_URL);
  const code = redirect.searchParams.get("code")!;

  assertEquals((await trade(code, pkce().verifier)).status, 400);
  // A failed trade used the code up too.
  assertEquals((await trade(code, verifier)).status, 400);

  const { challenge: c2, verifier: v2 } = pkce();
  const code2 = new URL((await authorize(user.auth, c2)).data.redirectTo)
    .searchParams.get("code")!;
  assertEquals((await trade(code2, v2, "https://elsewhere.test")).status, 400);
  const { challenge: c3, verifier: v3 } = pkce();
  const code3 = new URL((await authorize(user.auth, c3)).data.redirectTo)
    .searchParams.get("code")!;
  const traded = await trade(code3, v3);
  assertEquals(traded.status, 200);

  const keys = JSON.parse(
    new TextDecoder().decode((await get("/.well-known/jwks.json")).bytes),
  ) as JSONWebKeySet;
  const claims = await verifyInstanceToken(traded.body.id_token, keys, {
    issuer: BASE_URL,
    audience: CLIENT,
  });
  assertEquals(claims.sub, user.id);
  assertEquals(claims.preferred_username, "carol");
  assertEquals(claims.email, user.email);
  assertEquals(claims.nonce, "the-nonce");

  const again = await get<OAuthClient>(
    `/api/oauth/clients?client_id=${encodeURIComponent(CLIENT)}`,
    { auth: user.auth },
  );
  assertEquals(again.data.granted, true);
  const grants = await get<FederationGrant[]>("/api/me/grants", {
    auth: user.auth,
  });
  assertEquals(grants.data.map((g) => g.host), ["client.test"]);
});

test("identity provider: codes are only for a known client's own callback", async () => {
  const fake = await fakeInstance(CLIENT);
  using _net = network(fake);
  const user = await createUser();
  const admin = await createUser({ role: "admin" });
  const { challenge } = pkce();
  assertEquals(
    (await authorize(user.auth, challenge, {
      redirectUri: "https://evil.test/cb",
    })).status,
    400,
  );
  assertEquals(
    (await authorize(user.auth, challenge, { clientId: BASE_URL })).status,
    400,
  );
  assertEquals(
    (await authorize(user.auth, challenge, { codeChallengeMethod: "plain" }))
      .status,
    400,
  );
  assertEquals(
    (await authorize(user.auth, challenge, {
      clientId: "https://nowhere.test",
    })).status,
    502,
  );
  await put("/api/federation/peers", {
    auth: admin.auth,
    json: { instance: CLIENT, status: "blocked" },
  });
  assertEquals((await authorize(user.auth, challenge)).status, 403);
});

test("identity provider: an account from another instance doesn't sign in elsewhere from here", async () => {
  const fake = await fakeInstance(CLIENT);
  using _net = network(fake);
  const user = await createUser();
  db.prepare(`UPDATE users SET password_hash = '' WHERE id = ?;`).run(user.id);
  assertEquals((await authorize(user.auth, pkce().challenge)).status, 400);
});

test("identity provider: the instances a user signed in to hear of their changes", async () => {
  const fake = await fakeInstance(CLIENT);
  using _net = network(fake);
  const user = await createUser({ username: "dave" });
  const admin = await createUser({ role: "admin" });
  await authorize(user.auth, pkce().challenge);

  await patch(`/api/users/${user.id}/username`, {
    auth: admin.auth,
    json: { username: "david" },
  });
  await until(() => fake.received.length === 1);
  const update = decodeJwt(fake.received[0]);
  assertEquals(update.type, "update");
  assertEquals(update.sub, user.id);
  assertEquals(update.aud, CLIENT);
  assertEquals(
    (update.claims as { preferred_username: string }).preferred_username,
    "david",
  );

  await put("/api/me/password", {
    auth: user.auth,
    json: { currentPassword: "correct-horse", newPassword: "new-password" },
  });
  await until(() => fake.received.length === 2);
  assertEquals(decodeJwt(fake.received[1]).type, "revoke");

  const token = (await post<{ token: string }>("/api/sessions", {
    json: { username: "david", password: "new-password" },
  })).data.token;
  const auth = { Authorization: `Bearer ${token}` };
  assertEquals(
    (await del("/api/me/grants/client.test", { auth })).status,
    200,
  );
  await until(() => fake.received.length === 3);
  assertEquals(decodeJwt(fake.received[2]).type, "revoke");
  assertEquals(
    (await get<FederationGrant[]>("/api/me/grants", { auth })).data,
    [],
  );
});

test("identity provider: with sign-ins elsewhere off, no instance signs the users in, and their grants are withdrawn", async () => {
  const fake = await fakeInstance(CLIENT);
  using _net = network(fake);
  const user = await createUser();
  const { verifier, challenge } = pkce();
  const pending = new URL(
    (await authorize(user.auth, challenge)).data.redirectTo,
  ).searchParams.get("code")!;

  using _off = federationOff("outgoing");
  const meta = await get("/.well-known/openid-configuration");
  assertEquals(
    (JSON.parse(new TextDecoder().decode(meta.bytes)) as InstanceMetadata)
      .gerbeur_outgoing,
    false,
  );
  assertEquals(
    (await get(`/api/oauth/clients?client_id=${encodeURIComponent(CLIENT)}`, {
      auth: user.auth,
    })).status,
    403,
  );
  assertEquals((await authorize(user.auth, challenge)).status, 403);

  assertEquals(await withdrawAllGrants(), 1);
  await until(() => fake.received.length === 1);
  assertEquals(decodeJwt(fake.received[0]).type, "revoke");
  assertEquals((await trade(pending, verifier)).status, 400);
  assertEquals(
    (await get<FederationGrant[]>("/api/me/grants", { auth: user.auth })).data,
    [],
  );
});

test("identity provider: an event an instance fails to take waits in the outbox", async () => {
  const fake = await fakeInstance(CLIENT);
  using _net = network(fake, () => new Response("", { status: 503 }));
  const user = await createUser();
  await authorize(user.auth, pkce().challenge);
  await patch("/api/me", { auth: user.auth, json: { email: "e@new.test" } });
  let row: { attempts: number } | undefined;
  await until(() => {
    row = db.prepare(`SELECT attempts FROM federation_outbox;`).get() as
      | { attempts: number }
      | undefined;
    return (row?.attempts ?? 0) > 0;
  });
  assert(row);
  assertEquals(row.attempts, 1);
});

test("identity provider: a password reset ends the user's sessions where they signed in", async () => {
  const fake = await fakeInstance(CLIENT);
  using _net = network(fake);
  const user = await createUser();
  await authorize(user.auth, pkce().challenge);
  const token = await createPasswordResetToken(user.id);
  db.prepare(
    `INSERT INTO password_reset_tokens (token, user_id, expires_at) VALUES (?, ?, ?);`,
  ).run(token, user.id, new Date(Date.now() + 3600_000).toISOString());
  assertEquals(
    (await put(`/api/password-resets/${token}`, {
      json: { newPassword: "reset-password-1" },
    })).status,
    200,
  );
  await until(() => fake.received.length === 1);
  assertEquals(decodeJwt(fake.received[0]).type, "revoke");
});

test("identity provider: an instance gets its events in order, a failed one holding back the next", async () => {
  const fake = await fakeInstance(CLIENT);
  let down = true;
  using _net = stubNetwork((url, init) =>
    down && url.pathname === "/api/federation/events"
      ? new Response("", { status: 503 })
      : fake.handle(url, init) ?? new Response("", { status: 404 })
  );
  const user = await createUser();
  await authorize(user.auth, pkce().challenge);
  await patch("/api/me", { auth: user.auth, json: { email: "a@new.test" } });
  await until(() =>
    !!db.prepare(`SELECT 1 FROM federation_outbox WHERE attempts > 0;`).get()
  );

  // Up again, but the first event still waits: the second must wait behind.
  down = false;
  await patch("/api/me", { auth: user.auth, json: { email: "b@new.test" } });
  await new Promise((r) => setTimeout(r, 50));
  assertEquals(fake.received.length, 0);

  db.prepare(`UPDATE federation_outbox SET next_attempt_at = ?;`).run(
    new Date().toISOString(),
  );
  await deliverOutbox();
  assertEquals(
    fake.received.map((e) => (decodeJwt(e).claims as { email: string }).email),
    ["a@new.test", "b@new.test"],
  );
});

test("identity provider: the avatar's URL changes with the avatar only", async () => {
  const user = await createUser();
  await put("/api/me/avatar", { auth: user.auth, form: formWithFile(PNG) });
  const before = identityClaims(getUserById(user.id)).picture;
  assert(before);
  await new Promise((r) => setTimeout(r, 5));
  await patch("/api/me", { auth: user.auth, json: { description: "hi" } });
  assertEquals(identityClaims(getUserById(user.id)).picture, before);
  await put("/api/me/avatar", { auth: user.auth, form: formWithFile(PNG) });
  assert(identityClaims(getUserById(user.id)).picture !== before);
});