/**
 * One runtime per node serves every assigned module's tools (novox/hq ADR 0175, to-be 38 WP1). The
 * node's runtime is handed a list of modules and their bundles on the node's credential; it reads
 * one membership per module, serves each module's tools on that module's subjects and each held
 * seat's verbs on the seat's, names a bundle that fails to load without dropping the others, and
 * re-serves a module whose membership is re-issued mid-run. Against a real bus with JetStream.
 *
 *   docker run -d --rm --name t -p 14232:4222 nats:2.10-alpine -js
 *   MESH_TEST_NATS=nats://127.0.0.1:14232 node --test --experimental-strip-types test/node-runtime.test.ts
 */
import assert from "node:assert/strict";
import { test } from "node:test";
import { fileURLToPath } from "node:url";
import { connect, StringCodec } from "nats";

import { resetTools } from "@novox/mesh-sdk/tools";

import { connectNats, membershipSubject } from "../dist/broker-nats.js";
import { callTool, toolsOn } from "../dist/client.js";
import { servedModulesFrom } from "../dist/main.js";
import { runTools } from "../dist/runtime.js";

const url = process.env.MESH_TEST_NATS;
const fixture = (name: string) => fileURLToPath(new URL(`./fixtures/${name}`, import.meta.url));
const sc = StringCodec();

/** The controller's job, done by hand: the ASSIGNMENTS stream (last-per-subject, direct get) and an
 *  EVENTS stream for what a tool emits. */
async function aMesh() {
  const nc = await connect({ servers: url! });
  const jsm = await nc.jetstreamManager();
  for (const name of ["ASSIGNMENTS", "EVENTS"]) {
    try {
      await jsm.streams.delete(name);
    } catch {
      // none yet
    }
  }
  await jsm.streams.add({ name: "ASSIGNMENTS", subjects: ["mesh.assignment.>"], max_msgs_per_subject: 1, allow_direct: true } as never);
  await jsm.streams.add({ name: "EVENTS", subjects: ["mesh.mod.*.event.>"] });
  return {
    async issue(m: object & { node: string; module: string }) {
      await nc.jetstream().publish(membershipSubject(m.node, m.module), sc.encode(JSON.stringify(m)));
    },
    /** The next subject an event lands on, under a pattern. */
    nextEvent(pattern: string): Promise<string> {
      const sub = nc.subscribe(pattern, { max: 1 });
      return (async () => {
        for await (const m of sub) return m.subject;
        throw new Error("no event");
      })();
    },
    async close() {
      await nc.close();
    },
  };
}

/** A membership as the controller issues one on a machine, with the module's own subject when it
 *  answers for the module anywhere, and the verbs of the node seats it holds. */
function membershipOf(module: string, node: string, opts: { plain?: boolean; seats?: Record<string, string[]> } = {}) {
  const own = `mesh.mod.${module}`;
  const serves: { subject: string; queue?: string }[] = [{ subject: `${own}.tool.{tool}.${node}` }];
  if (opts.plain) serves.push({ subject: `${own}.tool.{tool}`, queue: `serve.${module}` });
  const seats = Object.entries(opts.seats ?? {}).flatMap(([seat, verbs]) =>
    verbs.map((verb) => ({ seat, verb, subject: `mesh.seat.${seat}.tool.${verb}.${node}` })));
  return { node, module, serves, seats, emits: `${own}.event.{event}`, tools: `${own}.tool.tools` };
}

/** Wait for something to be served: the bus answers "no responders" at once until it is. */
async function until<T>(attempt: () => Promise<T>, tries = 50): Promise<T> {
  for (let i = 0; ; i++) {
    try {
      return await attempt();
    } catch (e) {
      if (i >= tries) throw e;
      await new Promise((r) => setTimeout(r, 100));
    }
  }
}

test("MESH_TOOL_MODULES names modules and their entrypoints; a bare path is the credential's own module's", () => {
  const have = servedModulesFrom(" alpha=/a/tools/index.js, beta=/b/one.js ,beta=/b/two.js, /mine/index.js ,node-tools=/own/x.js", "node-tools");
  assert.deepEqual(have.serves, [
    { module: "alpha", entrypoints: ["/a/tools/index.js"] },
    { module: "beta", entrypoints: ["/b/one.js", "/b/two.js"] },
  ]);
  // The credential's own module, named or bare, is the one-module form either way.
  assert.deepEqual(have.moduleEntrypoints, ["/mine/index.js", "/own/x.js"]);
  assert.throws(() => servedModulesFrom("=/nothing.js", undefined), /neither <module>=<entrypoint>/);
  assert.deepEqual(servedModulesFrom("", "x"), { serves: [], moduleEntrypoints: [] });
});

test("the node's runtime serves three modules' bundles on one credential, names the one that fails, and follows a re-issued membership", async (t) => {
  if (!url) return t.skip("MESH_TEST_NATS unset");
  resetTools();
  const mesh = await aMesh();
  // Three modules assigned to the machine: alpha answers for itself anywhere, beta only here and
  // holds the node-shelf seat, gamma's bundle is broken.
  await mesh.issue(membershipOf("alpha", "anchor", { plain: true }));
  await mesh.issue(membershipOf("beta", "anchor", { seats: { "node-shelf": ["list", "clear"] } }));
  await mesh.issue(membershipOf("gamma", "anchor"));
  // The node's credential: the runtime module's name, no claims (seats come from the memberships).
  const credential = { url, node: "anchor", module: "node-tools" };
  const nodeTools = await connectNats(credential);
  const asker = await connectNats({ url, module: "console", node: "workstation" });
  const said: string[] = [];
  const log = console.log;
  console.log = (...a: unknown[]) => said.push(a.join(" "));
  let stop = () => {};
  try {
    process.env.MESH_OPERATOR_ACCOUNT = "somebody";
    process.env.MESH_OPERATOR_HOME = "/home/somebody";
    stop = await runTools({
      broker: nodeTools,
      credential,
      serves: [
        { module: "alpha", entrypoints: [fixture("many-alpha.mjs")] },
        { module: "beta", entrypoints: [fixture("many-beta.mjs")] },
        { module: "gamma", entrypoints: [fixture("many-broken.mjs")] },
      ],
    });
    console.log = log;
    assert.deepEqual(nodeTools.serving().sort(), ["alpha", "beta", "gamma", "node-tools"]);
    assert.ok(said.some((s) => /the operator's account here is somebody \(home \/home\/somebody\)/.test(s)), said.join("\n"));
    assert.ok(said.some((s) => /gamma's bundle .*many-broken\.mjs failed to load: gamma's bundle cannot find its client; its tools are not served here/.test(s)), said.join("\n"));
    assert.ok(said.some((s) => /serving 5 tool\(s\) for 3 module\(s\): alpha\.one, alpha\.two, beta\.three, beta\.four, beta\.five; not serving gamma/.test(s)), said.join("\n"));

    // Five tools answer, each where its module's membership says: alpha anywhere and here, beta here only.
    assert.deepEqual((await callTool(asker, "alpha.one", {})).result, { alpha: 1 });
    assert.deepEqual((await callTool(asker, "alpha.one@anchor", {})).result, { alpha: 1 });
    assert.deepEqual((await callTool(asker, "beta.three@anchor", {})).result, { beta: 3 });
    assert.deepEqual((await callTool(asker, "beta.four@anchor", {})).result, { beta: 4 });
    assert.deepEqual((await callTool(asker, "beta.five@anchor", {})).result, { beta: 5 });
    await assert.rejects(callTool(asker, "beta.three", {}), /no responders|503/i, "beta was not issued the module's plain subject");

    // Two seat verbs answer on the seat's subjects, held by beta.
    assert.deepEqual((await callTool(asker, "seat:node-shelf.list@anchor", {})).result, { shelf: ["a", "b"] });
    assert.deepEqual((await callTool(asker, "seat:node-shelf.clear@anchor", {})).result, { cleared: true });

    // A tool that emits does so as its module, not as the runtime.
    const landed = mesh.nextEvent("mesh.mod.*.event.>");
    assert.deepEqual((await callTool(asker, "alpha.two", {})).result, { alpha: 2 });
    assert.equal(await landed, "mesh.mod.alpha.event.happened");

    // `tools` answers for each: what alpha and beta serve, and why gamma serves nothing.
    const gamma = await asker.request<Record<string, never>, { module: string; tools: unknown[]; failed?: string }>("gamma.tools@anchor", {});
    assert.deepEqual(gamma, { module: "gamma", tools: [], failed: "gamma's bundle cannot find its client" });
    const beta = await asker.request<Record<string, never>, { tools: { name: string; subjects?: string[] }[] }>("beta.tools@anchor", {});
    assert.deepEqual(beta.tools.map((x) => x.name), ["three", "four", "five"]);
    assert.deepEqual(beta.tools[0]!.subjects, ["mesh.mod.beta.tool.three.anchor"]);

    // And discovery says so, with the reason, beside the modules that answered.
    const catalogue = await connectNats({ url, module: "mesh-catalog" });
    await catalogue.handle("catalog_modules", async () => ({ modules: [{ module: "alpha" }, { module: "beta" }, { module: "gamma" }] }));
    try {
      const have = await toolsOn(asker);
      assert.deepEqual(have.tools.map((x) => `${x.module}.${x.name}`), ["alpha.one", "alpha.two", "beta.five", "beta.four", "beta.three"]);
      assert.deepEqual(have.notAnswering, ["gamma (its tools bundle failed to load: gamma's bundle cannot find its client)", "mesh-controller (seat)"]);
    } finally {
      await catalogue.close();
    }

    // The mesh re-issues beta's membership mid-run — now answering for the module anywhere — and
    // the runtime serves the new subject without a restart.
    await mesh.issue(membershipOf("beta", "anchor", { plain: true, seats: { "node-shelf": ["list", "clear"] } }));
    assert.deepEqual((await until(() => callTool(asker, "beta.three", {}))).result, { beta: 3 });
    assert.deepEqual((await callTool(asker, "seat:node-shelf.list@anchor", {})).result, { shelf: ["a", "b"] });
  } finally {
    console.log = log;
    delete process.env.MESH_OPERATOR_ACCOUNT;
    delete process.env.MESH_OPERATOR_HOME;
    stop();
    await asker.close();
    await nodeTools.close();
    await mesh.close();
    resetTools();
  }
});