import { test } from "node:test";
import assert from "node:assert/strict";
import { existsSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";
import {
  INSTANCE_SCHEMA_VERSION,
  clearInstance,
  instanceFileName,
  instancesDir,
  makeInstanceId,
  manifestPath,
  projectsOf,
  pruneInstances,
  readInstances,
  readManifest,
  refreshDiscovery,
  writeInstance,
  writeManifest,
} from "../out/agent/instances.js";
import { endpointPath, readEndpoint } from "../out/agent/endpoint.js";

function instanceHome() {
  return mkdtempSync(join(tmpdir(), "ra3-instances-"));
}

function makeInstance(id, pid = process.pid) {
  return {
    instanceId: id,
    url: `http://127.0.0.1:${10000 + (pid % 1000)}`,
    token: `tok-${id}`,
    projectDir: "D:/Mods/Alpha",
    projects: ["D:/Mods/Alpha"],
    processId: pid,
  };
}

test("instances are written and read back", async () => {
  const home = instanceHome();
  try {
    const file = await writeInstance(makeInstance("a-1"), home);
    assert.ok(existsSync(file));
    assert.ok(file.includes(instancesDir(home)));
    assert.equal(file.endsWith(instanceFileName("a-1")), true);

    const all = await readInstances(home);
    assert.equal(all.length, 1);
    assert.equal(all[0].instanceId, "a-1");
    assert.equal(all[0].token, "tok-a-1");
  } finally {
    rmSync(home, { recursive: true, force: true });
  }
});

test("concurrent windows do not overwrite each other", async () => {
  const home = instanceHome();
  try {
    // Two windows enabling agent access at the same time: separate files, so
    // there is no read-modify-write race to guard.
    await writeInstance(makeInstance("win-a"), home);
    await writeInstance(makeInstance("win-b"), home);
    const ids = (await readInstances(home)).map((i) => i.instanceId).sort();
    assert.deepEqual(ids, ["win-a", "win-b"]);
  } finally {
    rmSync(home, { recursive: true, force: true });
  }
});

test("pruneInstances removes entries whose PID is dead", async () => {
  const home = instanceHome();
  try {
    // 0x7fffffff is not a valid Windows PID, so it cannot be alive.
    await writeInstance(makeInstance("alive", process.pid), home);
    await writeInstance(makeInstance("dead", 0x7fffffff), home);

    const result = await pruneInstances(home);
    assert.deepEqual(result.removed, ["dead"]);
    assert.deepEqual(
      result.kept.map((i) => i.instanceId),
      ["alive"],
    );
    // The dead file must actually be gone from disk.
    assert.equal(existsSync(join(instancesDir(home), instanceFileName("dead"))), false);
    assert.equal((await readInstances(home)).length, 1);
  } finally {
    rmSync(home, { recursive: true, force: true });
  }
});

test("pruneInstances keeps entries with an unknown PID", async () => {
  const home = instanceHome();
  try {
    // An older/simpler instance file without processId must never be pruned.
    await writeInstance(
      { instanceId: "no-pid", url: "http://127.0.0.1:1", token: "t" },
      home,
    );
    const result = await pruneInstances(home);
    assert.deepEqual(result.removed, []);
    assert.equal(result.kept.length, 1);
  } finally {
    rmSync(home, { recursive: true, force: true });
  }
});

test("clearInstance only removes its own file", async () => {
  const home = instanceHome();
  try {
    await writeInstance(makeInstance("mine"), home);
    await writeInstance(makeInstance("theirs"), home);
    await clearInstance("mine", home);
    const ids = (await readInstances(home)).map((i) => i.instanceId);
    assert.deepEqual(ids, ["theirs"]);
  } finally {
    rmSync(home, { recursive: true, force: true });
  }
});

test("readInstances tolerates corrupt and unrelated files", async () => {
  const home = instanceHome();
  try {
    await writeInstance(makeInstance("good"), home);
    writeFileSync(join(instancesDir(home), "broken.json"), "{ not json");
    writeFileSync(join(instancesDir(home), "notes.txt"), "ignore me");
    const all = await readInstances(home);
    assert.deepEqual(all.map((i) => i.instanceId), ["good"]);
  } finally {
    rmSync(home, { recursive: true, force: true });
  }
});

test("projectsOf unions projects across instances without duplicates", () => {
  const projects = projectsOf([
    { instanceId: "a", url: "u", token: "t", projectDir: "D:/Mods/Alpha", projects: ["D:/Mods/Alpha"] },
    { instanceId: "b", url: "u", token: "t", projectDir: "D:/Mods/Beta", projects: ["D:/Mods/beta", "D:/Mods/Gamma"] },
  ]);
  // "beta" appears twice with different casing and must collapse to one entry,
  // keeping the first spelling seen.
  assert.deepEqual(projects, ["D:/Mods/Alpha", "D:/Mods/beta", "D:/Mods/Gamma"]);
});

test("writeManifest produces a discovery manifest without tokens", async () => {
  const home = instanceHome();
  try {
    const manifest = await writeManifest(
      [makeInstance("a-1"), makeInstance("b-2")],
      home,
    );
    assert.equal(manifest.schemaVersion, INSTANCE_SCHEMA_VERSION);
    assert.deepEqual(manifest.projects, ["D:/Mods/Alpha"]);
    assert.equal(manifest.instances.length, 2);

    const raw = readFileSync(manifestPath(home), "utf8");
    // The manifest is for discovery; secrets must not leak into it.
    assert.equal(raw.includes("tok-a-1"), false);
    assert.equal(raw.includes('"token"'), false);

    const reread = await readManifest(home);
    assert.equal(reread?.instances.length, 2);
  } finally {
    rmSync(home, { recursive: true, force: true });
  }
});

test("makeInstanceId is unique across rapid calls", () => {
  const ids = new Set();
  for (let i = 0; i < 200; i++) ids.add(makeInstanceId(1234));
  assert.equal(ids.size, 200);
  for (const id of ids) assert.ok(id.startsWith("1234-"), id);
});

test("refreshDiscovery keeps surviving windows discoverable", async () => {
  const home = instanceHome();
  try {
    const mine = makeInstance("mine");
    const other = {
      ...makeInstance("other"),
      url: "http://127.0.0.1:19999",
      token: "tok-other",
      projectDir: "D:/Mods/Beta",
      projects: ["D:/Mods/Beta"],
    };
    await writeInstance(mine, home);
    await writeInstance(other, home);
    // This window closes: only its own instance file goes away.
    await clearInstance(mine.instanceId, home);

    const manifest = await refreshDiscovery(home);
    assert.deepEqual(manifest.projects, ["D:/Mods/Beta"]);
    assert.deepEqual(manifest.instances.map((i) => i.instanceId), ["other"]);

    // The legacy global pointer must follow the survivor, not be deleted.
    const endpoint = await readEndpoint(home);
    assert.equal(endpoint?.url, other.url);
    assert.equal(endpoint?.token, other.token);
    assert.equal(existsSync(endpointPath(home)), true);

    // The merged manifest on disk must agree with the returned value.
    const reread = await readManifest(home);
    assert.deepEqual(reread?.instances.map((i) => i.instanceId), ["other"]);
  } finally {
    rmSync(home, { recursive: true, force: true });
  }
});

test("refreshDiscovery clears the global pointer when the last window closes", async () => {
  const home = instanceHome();
  try {
    await writeInstance(makeInstance("only"), home);
    await clearInstance("only", home);

    const manifest = await refreshDiscovery(home);
    assert.deepEqual(manifest.instances, []);
    assert.deepEqual(manifest.projects, []);
    assert.equal(existsSync(endpointPath(home)), false);
  } finally {
    rmSync(home, { recursive: true, force: true });
  }
});