/**
 * Docker Compose baseline test — locks in the [E00-S02-T01/T02/T03] `docker
 * compose up -d` DB + app baseline, the PostgreSQL health gate and the app
 * health endpoint for the workspace.
 *
 * Acceptance criteria covered (each test fails without the committed state):
 *   - "docker compose up -d starts the database" → the committed
 *     `compose.yaml` declares a `db` service backed by a PostgreSQL image
 *     with the credentials the app expects and a published default port, so
 *     `docker compose up -d` creates and starts the database container. When
 *     a Docker daemon + Compose plugin are available (CI/dev machines), the
 *     suite additionally runs the real stack (`docker compose up -d` →
 *     `docker compose ps` → `docker compose down`) and asserts the `db`
 *     container is up (and healthy).
 *   - "docker compose up -d starts the application" → the committed
 *     `compose.yaml` declares an `app` service built from the committed
 *     `apps/server/Dockerfile` (multi-stage: Node 24.19.0 bookworm-slim +
 *     frozen pnpm install → `tsc` build of `@personal-blog/server` →
 *     `node apps/server/dist/index.js`), with a published default port. Since
 *     T03 the real-stack probe asserts the `app` container stays **running**
 *     (the server now serves the health endpoint instead of exiting) and the
 *     health endpoint answers HTTP 200 with a healthy body inside the
 *     container.
 *   - "PostgreSQL health check gates application start" → the committed
 *     `compose.yaml` declares a `healthcheck` on the `db` service that probes
 *     readiness with `pg_isready` against the same credentials the database
 *     was created with (`$$`-escaped so the container env applies), with an
 *     interval/retries so a still-booting database is re-probed rather than
 *     failed instantly.
 *   - "app waits for the database before starting" → the `app` service
 *     depends on `db` with `condition: service_healthy`, so Compose only
 *     starts the application once PostgreSQL reports healthy (the real-stack
 *     probe asserts the `db` container is healthy when Docker reports it).
 *
 * Run: `node --test tests/compose-config.test.mjs`
 * (node:test — built into Node >= 18; no dependencies, lockfile untouched.)
 */

import test from 'node:test';
import assert from 'node:assert/strict';
import { readFileSync, existsSync } from 'node:fs';
import { spawnSync } from 'node:child_process';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const REPO_ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');

const read = (relPath) => readFileSync(path.join(REPO_ROOT, relPath), 'utf8');

/** The committed Compose file and app image definition under test. */
const COMPOSE_PATH = 'compose.yaml';
const DOCKERFILE_PATH = 'apps/server/Dockerfile';
const DOCKERIGNORE_PATH = '.dockerignore';

// ---------------------------------------------------------------------------
// Minimal block-YAML parser (no dependencies, lockfile untouched)
// ---------------------------------------------------------------------------
//
// Covers exactly the subset the committed compose.yaml uses: nested block
// mappings, block sequences of scalars, plain / single-quoted / double-quoted
// scalars and `#` comments. Anything else (flow collections, anchors/aliases,
// `|`/`>` block scalars, merge keys) is rejected loudly so the parser can
// never silently misread the structure it locks in.

/** Drops a `#` comment that is not inside a quoted scalar. */
function stripComment(line) {
  let quote = null;
  for (let i = 0; i < line.length; i += 1) {
    const ch = line[i];
    if (quote) {
      if (ch === quote) quote = null;
    } else if (ch === "'" || ch === '"') {
      quote = ch;
    } else if (ch === '#' && (i === 0 || /\s/.test(line[i - 1]))) {
      return line.slice(0, i).trimEnd();
    }
  }
  return line.trimEnd();
}

/** Unquotes a plain / single-quoted / double-quoted scalar. */
function scalarValue(raw) {
  if (raw.length >= 2 && raw.startsWith("'") && raw.endsWith("'")) return raw.slice(1, -1);
  if (raw.length >= 2 && raw.startsWith('"') && raw.endsWith('"')) {
    return raw.slice(1, -1).replace(/\\"/g, '"').replace(/\\\\/g, '\\');
  }
  return raw;
}

/**
 * Parses the supported block-YAML subset into plain JS objects/arrays.
 * Throws on any construct the committed file does not use.
 */
function parseYaml(text) {
  const lines = [];
  for (const raw of text.split(/\r?\n/)) {
    const expanded = raw.replace(/\t/g, '  ');
    if (!expanded.trim() || expanded.trim().startsWith('#')) continue;
    const indent = expanded.length - expanded.trimStart().length;
    const content = stripComment(expanded.trimStart()).trim();
    if (!content) continue;
    lines.push({ indent, content });
  }

  let pos = 0;

  const parseBlock = (indent) => {
    const node = {};
    while (pos < lines.length && lines[pos].indent >= indent) {
      if (lines[pos].indent > indent) {
        throw new Error(`unexpected indentation at "${lines[pos].content}"`);
      }
      const { content } = lines[pos];
      const match = /^([^:#][^:]*):(?:\s+(.*))?$/.exec(content);
      if (!match) {
        throw new Error(`expected "key: value", got "${content}"`);
      }
      const key = scalarValue(match[1].trim());
      const rest = match[2] === undefined ? undefined : match[2].trim();
      pos += 1;
      if (rest === undefined || rest === '') {
        if (pos < lines.length && lines[pos].indent > indent) {
          if (lines[pos].content.startsWith('-')) {
            node[key] = parseSequence(lines[pos].indent);
          } else {
            node[key] = parseBlock(lines[pos].indent);
          }
        } else {
          node[key] = null;
        }
      } else {
        node[key] = scalarValue(rest);
      }
    }
    return node;
  };

  const parseSequence = (indent) => {
    const items = [];
    while (pos < lines.length && lines[pos].indent >= indent) {
      if (lines[pos].indent > indent) {
        throw new Error(`unexpected indentation in sequence at "${lines[pos].content}"`);
      }
      const { content } = lines[pos];
      if (!content.startsWith('-')) break;
      const rest = content.slice(1).trim();
      if (!rest) throw new Error(`empty sequence item at "-"`);
      items.push(scalarValue(rest));
      pos += 1;
    }
    return items;
  };

  if (lines.length === 0) return {};
  return parseBlock(0);
}

// ---------------------------------------------------------------------------
// Compose structure assertions (shared by the tests and the mutation probes)
// ---------------------------------------------------------------------------

/**
 * Asserts the committed compose.yaml declares a `db` service that
 * `docker compose up -d` can start: a PostgreSQL image, the credentials the
 * app expects, and a published default port.
 */
function assertDbService(compose) {
  assert.ok(compose.services, 'compose.yaml must declare a top-level "services" map');
  const db = compose.services.db;
  assert.ok(db, 'compose.yaml must declare a "db" service (docker compose up -d starts the database)');
  assert.equal(
    db.image,
    'postgres:18-bookworm',
    'the "db" service must use the committed PostgreSQL 18 image (postgres:18-bookworm)',
  );
  const env = db.environment ?? {};
  assert.equal(env.POSTGRES_DB, '${POSTGRES_DB:-eppp}', 'db must set POSTGRES_DB (with a default)');
  assert.equal(env.POSTGRES_USER, '${POSTGRES_USER:-eppp}', 'db must set POSTGRES_USER (with a default)');
  assert.ok(
    typeof env.POSTGRES_PASSWORD === 'string' && env.POSTGRES_PASSWORD.length > 0,
    'db must set POSTGRES_PASSWORD (with a default)',
  );
  assert.ok(
    Array.isArray(db.ports) && db.ports.some((p) => p.endsWith(':5432')),
    'db must publish the PostgreSQL port (a mapping ending in ":5432")',
  );
}

/**
 * Asserts the committed compose.yaml declares an `app` service that
 * `docker compose up -d` can start: built from the committed Dockerfile,
 * pointed at the db service, and started only after the database is healthy
 * (depends_on with condition: service_healthy).
 */
function assertAppService(compose) {
  const app = compose.services?.app;
  assert.ok(app, 'compose.yaml must declare an "app" service (docker compose up -d starts the application)');
  assert.equal(
    app.build?.context,
    '.',
    'the "app" service must build from the repository root context (build.context: ".")',
  );
  assert.equal(
    app.build?.dockerfile,
    DOCKERFILE_PATH,
    `the "app" service must build the committed ${DOCKERFILE_PATH} image`,
  );
  const env = app.environment ?? {};
  assert.ok(
    typeof env.DATABASE_URL === 'string' && /@db:5432\//.test(env.DATABASE_URL),
    'app must set DATABASE_URL pointing at the db service host (postgres://…@db:5432/…)',
  );
  assert.ok(
    Array.isArray(app.ports) && app.ports.some((p) => p.endsWith(':3000')),
    'app must publish the application port (a mapping ending in ":3000")',
  );
  assert.equal(
    app.depends_on?.db?.condition,
    'service_healthy',
    'app must depend on db with condition: service_healthy so it waits for the database before starting',
  );
}

/**
 * Asserts the committed compose.yaml gates the app on PostgreSQL health: the
 * `db` service declares a `pg_isready` healthcheck against the credentials it
 * was created with, with an interval and retries so a booting database is
 * re-probed instead of failed instantly.
 */
function assertDbHealthcheck(compose) {
  const db = compose.services?.db;
  assert.ok(db, 'compose.yaml must declare a "db" service');
  const hc = db.healthcheck;
  assert.ok(hc, 'the "db" service must declare a healthcheck (PostgreSQL health check gates application start)');
  assert.match(
    hc.test ?? '',
    /pg_isready/,
    'the db healthcheck must probe readiness with pg_isready',
  );
  assert.ok(
    (hc.test ?? '').includes('$${POSTGRES_USER}') && (hc.test ?? '').includes('$${POSTGRES_DB}'),
    'the db healthcheck must probe the same credentials the database was created with ' +
      '($${POSTGRES_USER}/$${POSTGRES_DB}, $$-escaped so the container env applies)',
  );
  assert.ok(hc.interval, 'the db healthcheck must declare an interval so readiness is re-probed');
  assert.ok(
    Number(hc.retries) >= 1,
    'the db healthcheck must declare retries so a booting database is not failed instantly',
  );
}

// ---------------------------------------------------------------------------
// Docker probe helpers (integration tests skip cleanly without Docker)
// ---------------------------------------------------------------------------

function run(cmd, args, opts = {}) {
  return spawnSync(cmd, args, {
    encoding: 'utf8',
    timeout: 600_000,
    ...opts,
  });
}

/** True when the `docker` CLI with the Compose plugin is on PATH. */
function dockerComposeAvailable() {
  try {
    return run('docker', ['compose', 'version'], { timeout: 15_000 }).status === 0;
  } catch {
    return false;
  }
}

/** True when a reachable Docker daemon exists. */
function dockerDaemonAvailable() {
  try {
    return run('docker', ['info'], { timeout: 15_000 }).status === 0;
  } catch {
    return false;
  }
}

/** Parses `docker compose ps --format json` (JSON array or one object per line). */
function parsePsJson(stdout) {
  const text = String(stdout).trim();
  if (!text) return [];
  try {
    const parsed = JSON.parse(text);
    return Array.isArray(parsed) ? parsed : [parsed];
  } catch {
    return text
      .split('\n')
      .map((line) => line.trim())
      .filter(Boolean)
      .map((line) => JSON.parse(line));
  }
}

/** Tolerant field lookup across compose ps JSON shapes. */
function field(container, ...names) {
  for (const name of names) {
    if (container[name] !== undefined) return container[name];
  }
  return undefined;
}

const DOCKER_COMPOSE = dockerComposeAvailable();
const DOCKER_DAEMON = dockerDaemonAvailable();

// ---------------------------------------------------------------------------
// Tests — the committed state that makes `docker compose up -d` work
// ---------------------------------------------------------------------------

test('compose.yaml exists, parses, and declares exactly the db and app services', () => {
  assert.ok(existsSync(path.join(REPO_ROOT, COMPOSE_PATH)), `committed ${COMPOSE_PATH} must exist`);
  const compose = parseYaml(read(COMPOSE_PATH));
  assert.deepEqual(
    Object.keys(compose.services ?? {}).sort(),
    ['app', 'db'],
    'compose.yaml must declare exactly the "db" and "app" services at T01/T02/T03',
  );
});

test('the database service is defined so "docker compose up -d" starts the database', () => {
  assertDbService(parseYaml(read(COMPOSE_PATH)));
});

test('the application service is defined so "docker compose up -d" starts the application', () => {
  assertAppService(parseYaml(read(COMPOSE_PATH)));
});

test('PostgreSQL health check gates application start (db declares a pg_isready healthcheck)', () => {
  assertDbHealthcheck(parseYaml(read(COMPOSE_PATH)));
});

test('the app waits for the database before starting (depends_on db with condition service_healthy)', () => {
  const app = parseYaml(read(COMPOSE_PATH)).services?.app;
  assert.ok(app, 'compose.yaml must declare an "app" service');
  assert.equal(
    app.depends_on?.db?.condition,
    'service_healthy',
    'app must depend on db with condition: service_healthy so it starts only after PostgreSQL is healthy',
  );
});

test('the application image is defined by a committed multi-stage Dockerfile', () => {
  assert.ok(existsSync(path.join(REPO_ROOT, DOCKERFILE_PATH)), `committed ${DOCKERFILE_PATH} must exist`);
  const dockerfile = read(DOCKERFILE_PATH);
  assert.match(
    dockerfile,
    /FROM node:24\.19\.0-bookworm-slim AS build/,
    'the Dockerfile must build on the committed Node 24.19.0 bookworm-slim base (FROM node:24.19.0-bookworm-slim AS build)',
  );
  assert.match(
    dockerfile,
    /FROM node:24\.19\.0-bookworm-slim AS runtime/,
    'the Dockerfile must ship a Node 24.19.0 bookworm-slim runtime stage (FROM node:24.19.0-bookworm-slim AS runtime)',
  );
  assert.match(
    dockerfile,
    /pnpm install --frozen-lockfile/,
    'the Dockerfile must install with the frozen lockfile (reproducible builds)',
  );
  assert.match(
    dockerfile,
    /pnpm --filter @personal-blog\/server build/,
    'the Dockerfile must compile the server package (pnpm --filter @personal-blog/server build)',
  );
  assert.match(
    dockerfile,
    /node\b[^\n]*apps\/server\/dist\/index\.js/,
    'the Dockerfile runtime stage must run the compiled server entrypoint (node apps/server/dist/index.js)',
  );
});

test('the build context excludes local artifacts and environment files', () => {
  assert.ok(
    existsSync(path.join(REPO_ROOT, DOCKERIGNORE_PATH)),
    `committed ${DOCKERIGNORE_PATH} must exist so local artifacts stay out of the build context`,
  );
  const patterns = read(DOCKERIGNORE_PATH)
    .split(/\r?\n/)
    .map((line) => line.trim())
    .filter((line) => line && !line.startsWith('#'));
  for (const required of ['node_modules', 'dist', '.env', '.git']) {
    assert.ok(
      patterns.includes(required),
      `.dockerignore must exclude "${required}" (got: ${patterns.join(', ')})`,
    );
  }
});

// ---------------------------------------------------------------------------
// Real-stack probes — run the actual acceptance command when Docker is present
// ---------------------------------------------------------------------------

test('the committed compose.yaml validates against the Compose spec (docker compose config)', { skip: !DOCKER_COMPOSE }, () => {
  const result = run('docker', ['compose', 'config', '--quiet'], { cwd: REPO_ROOT });
  assert.equal(
    result.status,
    0,
    `"docker compose config" must exit 0 for the committed ${COMPOSE_PATH}:\n` +
      `${(result.stdout || '')}\n${(result.stderr || '')}`.trim(),
  );
});

test('docker compose up -d starts the database and application containers', { skip: !DOCKER_COMPOSE || !DOCKER_DAEMON }, (t) => {
  const up = run('docker', ['compose', 'up', '-d'], { cwd: REPO_ROOT });
  assert.equal(
    up.status,
    0,
    `"docker compose up -d" must exit 0:\n${(up.stdout || '')}\n${(up.stderr || '')}`.trim(),
  );
  try {
    const ps = run('docker', ['compose', 'ps', '-a', '--format', 'json'], { cwd: REPO_ROOT });
    assert.equal(ps.status, 0, `"docker compose ps" must exit 0:\n${(ps.stderr || ps.stdout || '').trim()}`);
    const containers = parsePsJson(ps.stdout);

    const db = containers.find((c) => field(c, 'Service', 'service') === 'db');
    assert.ok(db, 'docker compose up -d must create the "db" container');
    const dbState = String(field(db, 'State', 'state') ?? '');
    assert.match(
      dbState,
      /running|up/i,
      `the "db" container must be running after "docker compose up -d" (state: "${dbState}")`,
    );
    const dbHealth = String(field(db, 'Health', 'health') ?? '');
    if (dbHealth) {
      assert.match(
        dbHealth,
        /healthy/i,
        `the "db" container must be healthy before the app starts (health: "${dbHealth}")`,
      );
    }

    const app = containers.find((c) => field(c, 'Service', 'service') === 'app');
    assert.ok(app, 'docker compose up -d must create the "app" container');
    const appState = String(field(app, 'State', 'state') ?? '');
    assert.match(
      appState,
      /running|up/i,
      `the "app" container must stay running after "docker compose up -d" (state: "${appState}") — since T03 the server serves the health endpoint and must not exit`,
    );

    // T03: the app serves the health endpoint — HTTP smoke test against the
    // endpoint inside the app container (no host-port dependency), polling
    // until it answers or times out.
    let healthOutput = '';
    let healthOk = false;
    for (let attempt = 0; attempt < 30 && !healthOk; attempt += 1) {
      const probe = run('docker', ['compose', 'exec', '-T', 'app', 'node', '-e', `
        fetch('http://127.0.0.1:3000/health')
          .then(async (res) => { console.log(res.status, await res.text()); process.exit(res.ok ? 0 : 1); })
          .catch(() => process.exit(2));
      `], { cwd: REPO_ROOT, timeout: 15_000 });
      const output = String(probe.stdout ?? '') + String(probe.stderr ?? '');
      if (probe.status === 0) {
        healthOk = true;
        healthOutput = output;
      } else if (probe.status === 1) {
        healthOutput = output; // answered but not 2xx — fail fast
        break;
      } else {
        run(process.execPath, ['-e', 'setTimeout(() => {}, 1000)']); // app still starting — retry
      }
    }
    assert.ok(
      healthOk,
      `GET /health must answer 2xx inside the app container once the stack is up (last probe: "${healthOutput.trim()}")`,
    );
    assert.match(healthOutput, /200/, `GET /health must return HTTP 200 (got: "${healthOutput.trim()}")`);
    assert.match(
      healthOutput,
      /"status":"ok"/,
      `GET /health must report a healthy application (got: "${healthOutput.trim()}")`,
    );
  } finally {
    run('docker', ['compose', 'down'], { cwd: REPO_ROOT });
  }
});

// ---------------------------------------------------------------------------
// Non-vacuous probes — the assertions above really do fail on violations
// ---------------------------------------------------------------------------

test('the YAML parser reads the committed structure (non-vacuous parser probe)', () => {
  const parsed = parseYaml(`
services:
  db:
    image: postgres:18-bookworm
    environment:
      POSTGRES_DB: eppp
    ports:
      - "5432:5432"
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U \$\${POSTGRES_USER} -d \$\${POSTGRES_DB}"]
      interval: 5s
      retries: 5
  app:
    build:
      context: .
      dockerfile: apps/server/Dockerfile
    depends_on:
      db:
        condition: service_healthy
`);
  assert.equal(parsed.services.db.image, 'postgres:18-bookworm');
  assert.equal(parsed.services.db.environment.POSTGRES_DB, 'eppp');
  assert.deepEqual(parsed.services.db.ports, ['5432:5432']);
  assert.match(parsed.services.db.healthcheck.test, /pg_isready/);
  assert.equal(parsed.services.db.healthcheck.retries, '5');
  assert.equal(parsed.services.app.build.dockerfile, 'apps/server/Dockerfile');
  assert.equal(parsed.services.app.depends_on.db.condition, 'service_healthy');
});

test('removing the db service makes the database criterion fail (mutation probe)', () => {
  const text = read(COMPOSE_PATH);
  const withoutDb = text.replace(/^  db:\n(?:    .*\n?)*/m, '');
  assert.notEqual(withoutDb, text, 'the mutation must actually remove the db service block');
  const compose = parseYaml(withoutDb);
  assert.throws(() => assertDbService(compose), /"db" service/);
});

test('removing the app service makes the application criterion fail (mutation probe)', () => {
  const text = read(COMPOSE_PATH);
  const withoutApp = text.replace(/^  app:\n(?:    .*\n?)*/m, '');
  assert.notEqual(withoutApp, text, 'the mutation must actually remove the app service block');
  const compose = parseYaml(withoutApp);
  assert.throws(() => assertAppService(compose), /"app" service/);
});

test('removing the db healthcheck makes the health-gate criterion fail (mutation probe)', () => {
  const text = read(COMPOSE_PATH);
  const withoutHealthcheck = text.replace(/^    healthcheck:\n(?:      .*\n?)*/m, '');
  assert.notEqual(withoutHealthcheck, text, 'the mutation must actually remove the db healthcheck block');
  const compose = parseYaml(withoutHealthcheck);
  assert.throws(() => assertDbHealthcheck(compose), /healthcheck/);
});

test('reverting depends_on to a plain list breaks the healthy-gate criterion (mutation probe)', () => {
  const text = read(COMPOSE_PATH);
  const withoutGate = text.replace(
    /^    depends_on:\n      db:\n        condition: service_healthy\n/m,
    '    depends_on:\n      - db\n',
  );
  assert.notEqual(withoutGate, text, 'the mutation must actually replace the healthy-conditioned depends_on');
  const compose = parseYaml(withoutGate);
  assert.throws(() => {
    const app = compose.services?.app;
    assert.equal(
      app?.depends_on?.db?.condition,
      'service_healthy',
      'app must depend on db with condition: service_healthy',
    );
  }, /service_healthy/);
});

test('a Dockerfile without the runtime entrypoint fails the image criterion (mutation probe)', () => {
  const dockerfile = read(DOCKERFILE_PATH);
  const withoutCmd = dockerfile.replace(/CMD \[[^\]]*\]/g, '');
  assert.notEqual(withoutCmd, dockerfile, 'the mutation must actually remove the CMD');
  const asserts = () => {
    assert.match(withoutCmd, /node\s+apps\/server\/dist\/index\.js/, 'must run the compiled entrypoint');
  };
  assert.throws(asserts, /compiled entrypoint/);
});