import { test } from "node:test";
import assert from "node:assert/strict";
import { spawnSync } from "node:child_process";
import { mkdtempSync, writeFileSync, readFileSync, existsSync, chmodSync } from "node:fs";
import { tmpdir } from "node:os";
import { join, dirname } from "node:path";
import { fileURLToPath } from "node:url";

const CLI = fileURLToPath(new URL("../src/cli.js", import.meta.url));

function run(file, ...args) {
  return spawnSync(process.execPath, [CLI, ...args], {
    env: { ...process.env, TODO_FILE: file },
    encoding: "utf8",
  });
}

const tempFile = () => join(mkdtempSync(join(tmpdir(), "todo-")), "todos.json");

test("ls with no file prints the empty message and writes nothing", () => {
  const file = tempFile();
  const res = run(file, "ls");
  assert.equal(res.status, 0);
  assert.equal(res.stdout.trim(), "Nothing to do.");
  assert.equal(existsSync(file), false);
});

test("add with no text fails without saving", () => {
  const file = tempFile();
  const res = run(file, "add", "  ");
  assert.equal(res.status, 1);
  assert.match(res.stderr, /Missing todo text/);
  assert.equal(existsSync(file), false);
});

for (const [label, args, message] of [
  ["missing id", [], /Invalid id: \(missing\)/],
  ["non-numeric id", ["abc"], /Invalid id: abc/],
  ["hex id", ["0x1"], /Invalid id: 0x1/],
  ["exponent id", ["1e0"], /Invalid id: 1e0/],
  ["decimal id", ["1.0"], /Invalid id: 1\.0/],
  ["padded id", [" 1 "], /Invalid id:  1 /],
  ["empty id", [""], /Invalid id: \n/],
  ["unknown id", ["99"], /No todo with id 99/],
]) {
  for (const cmd of ["done", "rm"]) {
    test(`${cmd} with ${label} fails and leaves the file unchanged`, () => {
      const file = tempFile();
      run(file, "add", "a");
      const before = readFileSync(file, "utf8");
      const res = run(file, cmd, ...args);
      assert.equal(res.status, 1);
      assert.match(res.stderr, message);
      assert.equal(readFileSync(file, "utf8"), before);
    });
  }
}

test("unknown command prints usage even when the file is corrupt", () => {
  const file = tempFile();
  writeFileSync(file, "{ not json");
  const res = run(file, "--help");
  assert.equal(res.status, 1);
  assert.match(res.stderr, /Unknown command: --help\nUsage:/);
});

test("a failed save gives a readable error instead of a stack trace", () => {
  const file = tempFile();
  chmodSync(dirname(file), 0o500);
  try {
    const res = run(file, "add", "a");
    assert.equal(res.status, 1);
    assert.match(res.stderr, /^Could not save /);
    assert.doesNotMatch(res.stderr, /at .*\.js:\d+/);
  } finally {
    chmodSync(dirname(file), 0o700);
  }
});

test("a corrupt file gives a readable error instead of a stack trace", () => {
  const file = tempFile();
  writeFileSync(file, "{ not json");
  const res = run(file, "ls");
  assert.equal(res.status, 1);
  assert.match(res.stderr, /^Could not read /);
  assert.doesNotMatch(res.stderr, /at .*\.js:\d+/);
});