/**
 * @file Tests scripts/systemd-service.js, and specifically the split that
 * exists because of one incident: the plugin self-update killed the dashboard
 * and left it dead.
 *
 * The bootstrap that performs an update is spawned by the running server, so
 * it lives in that server's systemd cgroup. The old code SIGTERM-ed the server
 * from inside that cgroup, which (a) exits 0, and `Restart=on-failure` reads a
 * clean exit as "meant to stop", and (b) trips `KillMode=control-group`, so
 * systemd reaped the bootstrap before it could write state or repoint the unit
 * at the new plugin root. The dashboard then stayed down until some later
 * Claude Code session happened to bootstrap again.
 *
 * Hence: writing the unit must not start anything, restarting must not block,
 * and a clean exit must no longer be read as "leave it stopped".
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const { describe, it, beforeEach, after } = require("node:test");
const assert = require("node:assert/strict");
const fs = require("node:fs");
const os = require("node:os");
const path = require("node:path");

const TMP_HOME = fs.mkdtempSync(path.join(os.tmpdir(), "agenthub-systemd-"));
const prevHome = process.env.HOME;
process.env.HOME = TMP_HOME;

const svc = require("../../scripts/systemd-service");

/** Every systemctl invocation this test saw, as flat argv strings. */
let calls = [];

beforeEach(() => {
  calls = [];
  // Each test starts from "no unit on disk" — otherwise a previous test's
  // write turns the next one's `written` into `unchanged`.
  fs.rmSync(svc.unitPath("agenthub"), { force: true });
  svc.__setExecImpl((args) => {
    // `--version` is the availability probe every entry point runs first, not
    // an action — recording it would bury the calls these tests are about.
    if (args[0] !== "--version") calls.push(args.join(" "));
    return { status: 0 };
  });
});

after(() => {
  svc.__reset();
  if (prevHome === undefined) delete process.env.HOME;
  else process.env.HOME = prevHome;
  fs.rmSync(TMP_HOME, { recursive: true, force: true });
});

const UNIT = {
  name: "agenthub",
  description: "AgentHub dashboard server (Claude Code plugin)",
  workingDir: "/plugin/root/new",
  execStart: "/usr/bin/node /plugin/root/new/server/index.js",
  env: { NODE_ENV: "production" },
};

function unitFile() {
  return fs.readFileSync(svc.unitPath("agenthub"), "utf8");
}

const linuxOnly = { skip: process.platform !== "linux" ? "systemd is Linux-only" : false };

describe("systemd-service — unit content", linuxOnly, () => {
  it("restarts always, because a graceful SIGTERM exits 0", () => {
    svc.writeUserService(UNIT);
    const body = unitFile();

    // `on-failure` is what let one stray kill (or an out-of-band stop during
    // an update) leave the dashboard down indefinitely.
    assert.match(body, /^Restart=always$/m);
    assert.doesNotMatch(body, /^Restart=on-failure$/m);
  });

  it("stops only the server process, so an update never takes the lane panes with it", () => {
    // tmux forks its server from whichever process first asks for a session —
    // the dashboard, after a boot with autostart on — and that server sits in
    // this unit's cgroup. The default KillMode=control-group would kill it,
    // and every running agent, on each update's restart.
    svc.writeUserService(UNIT);
    assert.match(unitFile(), /^KillMode=process$/m);
  });

  it("carries the ownership marker, so a hand-written unit is never clobbered", () => {
    svc.writeUserService(UNIT);
    assert.match(unitFile(), /agenthub-managed-unit/);
  });
});

describe("systemd-service — writeUserService", linuxOnly, () => {
  it("writes and enables the unit but starts NOTHING", () => {
    // The point of the split: the update must be able to repoint the unit at
    // the new plugin root while the old server is still serving requests.
    const result = svc.writeUserService(UNIT);

    assert.equal(result, "written");
    assert.ok(
      calls.some((c) => c.startsWith("daemon-reload")),
      "a rewritten unit must be reloaded"
    );
    assert.ok(
      calls.some((c) => c === "enable agenthub.service"),
      "it must still be enabled for boot"
    );
    assert.ok(
      !calls.some((c) => c.includes("--now") || c.startsWith("restart") || c.startsWith("start")),
      `nothing may be started here, got: ${JSON.stringify(calls)}`
    );
  });

  it("reports an identical unit as unchanged and touches systemd not at all", () => {
    svc.writeUserService(UNIT);
    calls = [];

    assert.equal(svc.writeUserService(UNIT), "unchanged");
    assert.deepEqual(calls, [], "an unchanged unit needs no systemctl call");
  });

  it("refuses a unit it did not write", () => {
    fs.mkdirSync(path.dirname(svc.unitPath("agenthub")), { recursive: true });
    fs.writeFileSync(svc.unitPath("agenthub"), "[Service]\nExecStart=/opt/mine\n", "utf8");

    assert.equal(svc.writeUserService(UNIT), "foreign");
    assert.equal(svc.unitIsOurs("agenthub"), false);
  });
});

describe("systemd-service — restartUserService", linuxOnly, () => {
  it("never blocks, because the caller is inside the cgroup being restarted", () => {
    assert.equal(svc.restartUserService("agenthub"), "restarted");
    assert.deepEqual(calls, ["restart --no-block agenthub.service"]);
  });

  it("reports failure rather than throwing when systemctl refuses", () => {
    // Available, but the restart itself is rejected — distinct from "no
    // systemd here", which must not be reported as a failure.
    svc.__setExecImpl((args) => ({ status: args[0] === "--version" ? 0 : 1 }));
    assert.equal(svc.restartUserService("agenthub"), "failed");
  });
});

describe("systemd-service — unitIsStale", linuxOnly, () => {
  it("is true when the unit names a plugin root that is no longer the current one", () => {
    // Invisible while the server runs, fatal at the next reboot: the unit
    // starts a path Claude Code garbage-collected after the update.
    svc.writeUserService({ ...UNIT, workingDir: "/plugin/root/old" });
    assert.equal(svc.unitIsStale("agenthub", "/plugin/root/new"), true);
  });

  it("is false for a unit already naming the current root", () => {
    svc.writeUserService(UNIT);
    assert.equal(svc.unitIsStale("agenthub", "/plugin/root/new"), false);
  });

  it("is false when there is no unit, and for one we do not own", () => {
    assert.equal(svc.unitIsStale("agenthub", "/plugin/root/new"), false);

    fs.mkdirSync(path.dirname(svc.unitPath("agenthub")), { recursive: true });
    fs.writeFileSync(svc.unitPath("agenthub"), "[Service]\nWorkingDirectory=/opt/mine\n", "utf8");
    assert.equal(
      svc.unitIsStale("agenthub", "/plugin/root/new"),
      false,
      "a foreign unit is not ours to call stale, or to rewrite"
    );
  });

  it("spawns nothing — the bootstrap fast path runs it on every SessionStart", () => {
    svc.writeUserService(UNIT);
    calls = [];

    svc.unitIsStale("agenthub", "/plugin/root/new");
    assert.deepEqual(calls, []);
  });
});

describe("systemd-service — unitRoot", linuxOnly, () => {
  it("reports the directory the unit runs from", () => {
    svc.writeUserService({ ...UNIT, workingDir: "/plugin/root/old" });
    assert.equal(svc.unitRoot("agenthub"), "/plugin/root/old");
  });

  it("reports a FOREIGN unit's directory too", () => {
    // Not ours to rewrite, but still a directory the cache pruner may not
    // delete out from under a running service.
    fs.mkdirSync(path.dirname(svc.unitPath("agenthub")), { recursive: true });
    fs.writeFileSync(svc.unitPath("agenthub"), "[Service]\nWorkingDirectory=/opt/mine\n", "utf8");
    assert.equal(svc.unitRoot("agenthub"), "/opt/mine");
  });

  it("is null when there is no unit", () => {
    assert.equal(svc.unitRoot("agenthub"), null);
  });
});

describe("systemd-service — unitIsActive", linuxOnly, () => {
  it("is true only for `active`", () => {
    svc.__setExecImpl((args) => ({ status: 0, stdout: args[0] === "is-active" ? "active\n" : "" }));
    assert.equal(svc.unitIsActive("agenthub"), true);

    svc.__setExecImpl((args) => ({
      status: 3,
      stdout: args[0] === "is-active" ? "inactive\n" : "",
    }));
    assert.equal(svc.unitIsActive("agenthub"), false);
  });
});

describe("systemd-service — unitIsOurs", linuxOnly, () => {
  it("is false when no unit exists at all", () => {
    fs.rmSync(svc.unitPath("agenthub"), { force: true });
    assert.equal(svc.unitIsOurs("agenthub"), false);
  });

  it("is true for a unit this code wrote", () => {
    svc.writeUserService(UNIT);
    assert.equal(svc.unitIsOurs("agenthub"), true);
  });
});