// `recover`: the supervised pre-start behind the service unit. It may clear
// a lock whose owner is gone and remove only the STOP it wrote for that;
// every operator brake, and every held binding, refuses with exit 3.
import { test } from "node:test";
import assert from "node:assert/strict";
import { writeFileSync, existsSync, mkdirSync, readFileSync, unlinkSync } from "node:fs";
import { join } from "node:path";
import { spawn, spawnSync } from "node:child_process";
import { fileURLToPath } from "node:url";
import {
  ensureJournal, recover, requestStop, readStop, stopRequested, stopPath, lockPath, ownerPath, writePid, BRAKE_EXIT,
  RECOVER_REASON,
} from "../src/journal.mjs";
import { DiscordError } from "../src/errors.mjs";
import { makeRoot, makeRepo, makeDeployment } from "./helpers.mjs";

const cli = fileURLToPath(new URL("../src/cli.mjs", import.meta.url));
const worker = fileURLToPath(new URL("../fixtures/legacy-owner-worker.mjs", import.meta.url));
const BOOT = "01234567-89ab-cdef-0123-456789abcdef";

function journal() {
  const dir = join(makeRoot(), "journal");
  ensureJournal(dir);
  return dir;
}

function deadPid() {
  const r = spawnSync(process.execPath, ["-e", "process.stdout.write(String(process.pid))"], { encoding: "utf8" });
  return Number(r.stdout);
}

function publish(dir, rec) {
  mkdirSync(lockPath(dir), { recursive: true });
  writeFileSync(ownerPath(dir), JSON.stringify(rec) + "\n", { mode: 0o600 });
}

const brake = (re) => (err) => err instanceof DiscordError && err.exitCode === BRAKE_EXIT && re.test(err.message);

// A live owner with the given identity arguments, held until `release`.
function holdLock(dir, startArg, bootArg) {
  const done = join(dir, `done-${startArg}-${bootArg}`);
  const child = spawn(process.execPath, [worker, dir, done, startArg, bootArg], { stdio: ["ignore", "pipe", "inherit"] });
  const published = new Promise((resolve) => {
    let out = "";
    child.stdout.on("data", (d) => { out += d; if (out.includes("legacy-published")) resolve(); });
  });
  const closed = new Promise((resolve) => child.on("close", resolve));
  return { published, release: () => { writeFileSync(done, ""); return closed; } };
}

test("recover: nothing to do is clean; a lock whose owner is gone or that has no record is cleared and STOP ends up absent", () => {
  const dir = journal();
  assert.equal(recover(dir), "clean");
  assert.equal(stopRequested(dir), false);

  publish(dir, { pid: deadPid(), start: "1", boot: BOOT, at: "x" });
  assert.equal(recover(dir), "cleared");
  assert.equal(existsSync(lockPath(dir)), false, "dead owner's lock removed");
  assert.equal(stopRequested(dir), false, "the STOP written for the unlock is gone again");

  mkdirSync(lockPath(dir));
  assert.equal(recover(dir), "cleared", "a lock without a record (interrupted start) is cleared too");
  assert.equal(existsSync(lockPath(dir)), false);
  assert.equal(stopRequested(dir), false);
  assert.equal(recover(dir), "clean");
});

test("recover: an operator STOP refuses with exit 3 and is never removed, whatever the lock says", () => {
  const dir = journal();
  requestStop(dir, "cli stop");
  assert.throws(() => recover(dir), brake(/STOP is present/));
  assert.equal(stopRequested(dir), true);
  publish(dir, { pid: deadPid(), start: "1", boot: BOOT, at: "x" });
  assert.throws(() => recover(dir), brake(/STOP is present/));
  assert.equal(existsSync(lockPath(dir)), true, "the lock is not touched behind a brake");
  assert.equal(readStop(dir).length, 1, "nothing appended to STOP");

  // A STOP that recover itself wrote and then failed to remove is ours, but
  // only when it is the whole file.
  const own = journal();
  requestStop(own, RECOVER_REASON);
  assert.equal(recover(own), "clean");
  assert.equal(stopRequested(own), false);
  requestStop(own, RECOVER_REASON);
  requestStop(own, "unlock");
  assert.throws(() => recover(own), brake(/STOP is present/));
  assert.equal(readStop(own).length, 2);

  // A line this code did not write is never ours.
  const foreign = journal();
  writeFileSync(stopPath(foreign), "stop\n", { mode: 0o600 });
  assert.throws(() => recover(foreign), brake(/STOP is present/));
  assert.deepEqual(readStop(foreign), [{ reason: null }]);
});

test("recover: a brake written during the unlock wins; STOP stays with both lines and the start is refused", () => {
  const dir = journal();
  publish(dir, { pid: deadPid(), start: "1", boot: BOOT, at: "x" });
  assert.throws(
    () => recover(dir, { beforeRemove: () => requestStop(dir, "cli stop") }),
    brake(/written by an operator while recovering/),
  );
  assert.equal(existsSync(lockPath(dir)), false, "the dead lock was removed before the brake was seen");
  assert.deepEqual(readStop(dir).map((l) => l.reason), [RECOVER_REASON, "cli stop"]);
  assert.throws(() => recover(dir), brake(/STOP is present/), "and it stays refused afterwards");
});

test("recover: a held binding refuses with exit 3 and writes no STOP: live owner, alive pid without verifiable identity, unreadable record", async () => {
  const live = journal();
  const held = holdLock(live, "real", "real");
  await held.published;
  try {
    assert.throws(() => recover(live), brake(/another connector is running/));
    assert.equal(stopRequested(live), false, "recover never brakes a running connector");
    assert.equal(existsSync(ownerPath(live)), true);
  } finally {
    await held.release();
  }

  const unknown = journal();
  const legacy = holdLock(unknown, "real", "-");
  await legacy.published;
  try {
    assert.throws(() => recover(unknown), brake(/cannot be verified/));
    assert.equal(stopRequested(unknown), false);
    assert.equal(existsSync(ownerPath(unknown)), true);
  } finally {
    await legacy.release();
  }

  const invalid = journal();
  mkdirSync(lockPath(invalid));
  writeFileSync(ownerPath(invalid), "{not json", { mode: 0o600 });
  assert.throws(() => recover(invalid), brake(/cannot be read/));
  assert.equal(stopRequested(invalid), false);
  assert.equal(readFileSync(ownerPath(invalid), "utf8"), "{not json");

  // Our own live claim is a held binding too.
  const mine = journal();
  writePid(mine, process.pid);
  assert.throws(() => recover(mine), brake(/another connector is running/));
  assert.equal(stopRequested(mine), false);
});

test("cli: recover exits 0 when ready, 3 behind a brake or a held binding, and run's own STOP refusal is 3", () => {
  const root = makeRoot();
  const repo = makeRepo(root);
  const dep = makeDeployment(root);
  const run = (args) => spawnSync(process.execPath, [cli, ...args, "--config", dep.config, "--repo", repo], { encoding: "utf8" });
  let r = run(["recover", "test-seat"]);
  assert.equal(r.status, 0, r.stderr);
  assert.match(r.stdout, /ready to run/);

  r = run(["stop", "test-seat"]);
  assert.equal(r.status, 0, r.stderr);
  r = run(["recover", "test-seat"]);
  assert.equal(r.status, 3, r.stderr);
  assert.match(r.stderr, /the brake is on/);
  r = run(["run", "test-seat"]);
  assert.equal(r.status, 3, r.stderr);

  const journalDir = join(dep.dataRoot, "discord", "test-seat");
  unlinkSync(stopPath(journalDir));
  publish(journalDir, { pid: deadPid(), start: "1", boot: BOOT, at: "x" });
  r = run(["recover", "test-seat"]);
  assert.equal(r.status, 0, r.stderr);
  assert.match(r.stdout, /was removed; STOP is absent/);
  assert.equal(existsSync(lockPath(journalDir)), false);
  assert.equal(stopRequested(journalDir), false);

  r = run(["recover"]);
  assert.equal(r.status, 4);

  // The service unit's form: the same policy inside the main process, so
  // the exit status is the one systemd never retries.
  r = run(["stop", "test-seat"]);
  assert.equal(r.status, 0, r.stderr);
  r = run(["run", "test-seat", "--supervised"]);
  assert.equal(r.status, 3, r.stderr);
  assert.match(r.stderr, /the brake is on/);
  assert.equal(stopRequested(journalDir), true, "the operator's STOP stays");
  unlinkSync(stopPath(journalDir));
  publish(journalDir, { pid: process.pid, at: "x" });
  r = run(["run", "test-seat", "--supervised"]);
  assert.equal(r.status, 3, r.stderr);
  assert.match(r.stderr, /cannot be verified/);
  assert.equal(existsSync(ownerPath(journalDir)), true, "a held binding is left alone");
  assert.equal(stopRequested(journalDir), false);
  r = run(["stop", "test-seat", "--supervised"]);
  assert.equal(r.status, 4);
});