/**
 * Regression tests (a) + (d) for scripts/run-unit-parallel.sh:
 *   (a) Exit-code propagation: a failing test in any shard MUST cause the
 *       wrapper to exit non-zero. The hardest contract to silently break
 *       in a fan-out wrapper (`for ... &; wait` returns the LAST child's
 *       status, not any failure's).
 *   (d) Failure-log contract: when any test fails, the wrapper writes
 *       extracted failure block(s) to .context/test-failures.log with
 *       `--- shard $i:` prefixes, and prints a loud stderr banner with
 *       the absolute path. Empty log ⇔ exit 0.
 *
 * The wrapper takes ~1.5 minutes against the real test suite. To keep
 * this regression test fast and hermetic, we point it at a tiny tempdir
 * containing one passing and one failing test, override the discovery
 * roots via env-vars, and run with --shards=2.
 *
 * NOT covered here: the heartbeat (timing-sensitive, not load-bearing
 * for correctness) and timeout / WEDGED markers (require synthesizing a
 * hung test which is fragile across machines). Those rely on the live
 * smoke tests captured in CHANGELOG measurements.
 */

import { describe, it, expect, beforeAll, afterAll } from 'bun:test';
import { execFileSync, spawnSync } from 'child_process';
import { mkdtempSync, mkdirSync, writeFileSync, readFileSync, existsSync, rmSync, copyFileSync, chmodSync, symlinkSync } from 'fs';
import { tmpdir } from 'os';
import { join, resolve } from 'path';

const REPO_ROOT = resolve(import.meta.dir, '..', '..');
const PARALLEL_SH_SRC = resolve(REPO_ROOT, 'scripts/run-unit-parallel.sh');
const SHARD_SH_SRC = resolve(REPO_ROOT, 'scripts/run-unit-shard.sh');
const SERIAL_SH_SRC = resolve(REPO_ROOT, 'scripts/run-serial-tests.sh');

let TMPROOT: string;

beforeAll(() => {
  // Build a tiny repo-shaped tempdir with the wrapper scripts copied in
  // and 4 fixture test files (3 pass, 1 fail). The wrapper's `find test`
  // expression will pick them up via cwd.
  TMPROOT = mkdtempSync(join(tmpdir(), 'gbrain-parallel-test-'));
  mkdirSync(join(TMPROOT, 'scripts'), { recursive: true });
  mkdirSync(join(TMPROOT, 'test'), { recursive: true });

  copyFileSync(PARALLEL_SH_SRC, join(TMPROOT, 'scripts', 'run-unit-parallel.sh'));
  copyFileSync(SHARD_SH_SRC, join(TMPROOT, 'scripts', 'run-unit-shard.sh'));
  copyFileSync(SERIAL_SH_SRC, join(TMPROOT, 'scripts', 'run-serial-tests.sh'));
  chmodSync(join(TMPROOT, 'scripts', 'run-unit-parallel.sh'), 0o755);
  chmodSync(join(TMPROOT, 'scripts', 'run-unit-shard.sh'), 0o755);
  chmodSync(join(TMPROOT, 'scripts', 'run-serial-tests.sh'), 0o755);

  // 3 passing + 1 failing test file. Round-robin sharding will land
  // them across 2 shards so we exercise the multi-shard merge path.
  const passing = `import { describe, it, expect } from 'bun:test';
describe('passing', () => {
  it('arithmetic works', () => { expect(1 + 1).toBe(2); });
});`;
  const failing = `import { describe, it, expect } from 'bun:test';
describe('failing-on-purpose', () => {
  it('expects 1 to equal 2 (this should fail)', () => { expect(1).toBe(2); });
});`;

  writeFileSync(join(TMPROOT, 'test', 'a-pass.test.ts'), passing);
  writeFileSync(join(TMPROOT, 'test', 'b-pass.test.ts'), passing);
  writeFileSync(join(TMPROOT, 'test', 'c-pass.test.ts'), passing);
  writeFileSync(join(TMPROOT, 'test', 'd-fail.test.ts'), failing);
});

afterAll(() => {
  if (TMPROOT) rmSync(TMPROOT, { recursive: true, force: true });
});

function runWrapper(extraArgs: string[] = []): { code: number; stdout: string; stderr: string } {
  const result = spawnSync(
    'bash',
    [join(TMPROOT, 'scripts', 'run-unit-parallel.sh'), '--shards', '2', ...extraArgs],
    { cwd: TMPROOT, encoding: 'utf-8', env: { ...process.env } },
  );
  return {
    code: result.status ?? -1,
    stdout: result.stdout || '',
    stderr: result.stderr || '',
  };
}

describe('run-unit-parallel.sh exit-code propagation (a)', () => {
  it('exits non-zero when any shard contains a failing test', () => {
    const r = runWrapper();
    expect(r.code).not.toBe(0);
  });

  it('exits zero when all shards pass (after removing the failing fixture)', () => {
    rmSync(join(TMPROOT, 'test', 'd-fail.test.ts'));
    try {
      const r = runWrapper();
      expect(r.code).toBe(0);
    } finally {
      // Restore the failing fixture for any downstream tests in the same
      // describe block (afterAll cleans the whole tempdir; this is belt-
      // and-suspenders).
      const failing = `import { describe, it, expect } from 'bun:test';
describe('failing-on-purpose', () => {
  it('expects 1 to equal 2', () => { expect(1).toBe(2); });
});`;
      writeFileSync(join(TMPROOT, 'test', 'd-fail.test.ts'), failing);
    }
  });
});

describe('run-unit-parallel.sh failure-log contract (d)', () => {
  it('writes failures to .context/test-failures.log with --- shard prefix on failure', () => {
    const r = runWrapper();
    expect(r.code).not.toBe(0);

    const failureLog = join(TMPROOT, '.context/test-failures.log');
    expect(existsSync(failureLog)).toBe(true);
    const contents = readFileSync(failureLog, 'utf-8');
    expect(contents.length).toBeGreaterThan(0);
    expect(contents).toMatch(/--- shard \d+:/);
    expect(contents).toContain('failing-on-purpose');
  });

  it('prints loud stderr banner with absolute failure-log path on failure', () => {
    const r = runWrapper();
    expect(r.code).not.toBe(0);
    expect(r.stderr).toContain('TEST FAILURES');
    // Banner includes the absolute path so users can `cat` it directly.
    expect(r.stderr).toContain(join(TMPROOT, '.context', 'test-failures.log'));
  });

  it('clears .context/test-failures.log to empty when all shards pass', () => {
    // Pre-seed a stale failure log to prove it gets cleared.
    mkdirSync(join(TMPROOT, '.context'), { recursive: true });
    writeFileSync(join(TMPROOT, '.context', 'test-failures.log'), 'STALE\n');
    rmSync(join(TMPROOT, 'test', 'd-fail.test.ts'));
    try {
      const r = runWrapper();
      expect(r.code).toBe(0);
      const contents = readFileSync(join(TMPROOT, '.context', 'test-failures.log'), 'utf-8');
      expect(contents).toBe('');
    } finally {
      const failing = `import { describe, it, expect } from 'bun:test';
describe('failing-on-purpose', () => {
  it('expects 1 to equal 2', () => { expect(1).toBe(2); });
});`;
      writeFileSync(join(TMPROOT, 'test', 'd-fail.test.ts'), failing);
    }
  });

  it('writes per-shard summary lines to .context/test-summary.txt', () => {
    runWrapper();
    const summary = readFileSync(join(TMPROOT, '.context', 'test-summary.txt'), 'utf-8');
    // Format: `shard 1/2: pass=N fail=N skip=N rc=N`
    expect(summary).toMatch(/shard 1\/2: pass=\d+ fail=\d+ skip=\d+ rc=\d+/);
    expect(summary).toMatch(/shard 2\/2: pass=\d+ fail=\d+ skip=\d+ rc=\d+/);
  });
});

describe('run-unit-parallel.sh no-timeout-binary fallback (rc from shard wait, not watchdog teardown)', () => {
  // Forces the no-gtimeout/no-timeout branch by running the wrapper under a
  // curated PATH that has every tool the scripts call EXCEPT timeout
  // binaries (real `bun` symlinked in), so the fallback executes even on
  // hosts with coreutils installed.
  //
  // Regression pinned here: the shard's sentinel .exit file must record the
  // exit code read right after `wait $pid` (the shard's own rc). The
  // watchdog subshell is killed with SIGTERM and reports 143; reading `$?`
  // after that teardown stamped rc=143 into every shard's sentinel — the
  // wrapper exited non-zero with rc=143 summaries even when every test
  // passed.
  let FROOT: string;
  let FENV: Record<string, string>;

  beforeAll(() => {
    FROOT = mkdtempSync(join(tmpdir(), 'gbrain-parallel-fallback-'));
    mkdirSync(join(FROOT, 'scripts'), { recursive: true });
    mkdirSync(join(FROOT, 'test'), { recursive: true });
    for (const s of ['run-unit-parallel.sh', 'run-unit-shard.sh', 'run-serial-tests.sh']) {
      copyFileSync(resolve(REPO_ROOT, 'scripts', s), join(FROOT, 'scripts', s));
      chmodSync(join(FROOT, 'scripts', s), 0o755);
    }
    const passing = `import { describe, it, expect } from 'bun:test';
describe('passing', () => {
  it('arithmetic works', () => { expect(1 + 1).toBe(2); });
});`;
    writeFileSync(join(FROOT, 'test', 'a-pass.test.ts'), passing);
    writeFileSync(join(FROOT, 'test', 'b-pass.test.ts'), passing);

    const bin = join(FROOT, 'bin');
    mkdirSync(bin);
    for (const tool of ['bash', 'sh', 'env', 'dirname', 'basename', 'mktemp', 'date', 'sleep', 'cat', 'tail', 'head', 'rm', 'mkdir', 'pkill', 'grep', 'sed', 'awk', 'wc', 'tr', 'seq', 'find', 'sort', 'bun']) {
      const p = Bun.which(tool);
      if (p) symlinkSync(p, join(bin, tool));
    }
    FENV = {
      PATH: bin,
      HOME: process.env.HOME ?? FROOT,
      TMPDIR: process.env.TMPDIR ?? '/tmp',
      GBRAIN_TEST_SHARD_TIMEOUT: '300',
    };
  });

  afterAll(() => {
    if (FROOT) rmSync(FROOT, { recursive: true, force: true });
  });

  function runFallbackWrapper(): { code: number; stdout: string; stderr: string } {
    const result = spawnSync(
      'bash',
      [join(FROOT, 'scripts', 'run-unit-parallel.sh'), '--shards', '2'],
      { cwd: FROOT, encoding: 'utf-8', env: FENV },
    );
    return {
      code: result.status ?? -1,
      stdout: result.stdout || '',
      stderr: result.stderr || '',
    };
  }

  it('exits zero with rc=0 shard sentinels when all shards pass', () => {
    const r = runFallbackWrapper();
    const summary = readFileSync(join(FROOT, '.context', 'test-summary.txt'), 'utf-8');
    expect(summary).toMatch(/shard 1\/2: pass=\d+ fail=0 skip=0 rc=0/);
    expect(summary).toMatch(/shard 2\/2: pass=\d+ fail=0 skip=0 rc=0/);
    expect(summary).not.toContain('rc=143');
    expect(r.code).toBe(0);
  });

  it('propagates a failing shard rc as the test runner rc (1), not the watchdog 143', () => {
    const failing = `import { describe, it, expect } from 'bun:test';
describe('failing-on-purpose', () => {
  it('expects 1 to equal 2', () => { expect(1).toBe(2); });
});`;
    writeFileSync(join(FROOT, 'test', 'z-fail.test.ts'), failing);
    try {
      const r = runFallbackWrapper();
      expect(r.code).not.toBe(0);
      const summary = readFileSync(join(FROOT, '.context', 'test-summary.txt'), 'utf-8');
      expect(summary).toMatch(/shard \d\/2: pass=\d+ fail=1 skip=0 rc=1/);
      expect(summary).not.toContain('rc=143');
      const failureLog = readFileSync(join(FROOT, '.context', 'test-failures.log'), 'utf-8');
      expect(failureLog).toContain('failing-on-purpose');
    } finally {
      rmSync(join(FROOT, 'test', 'z-fail.test.ts'), { force: true });
    }
  });
});