// ── GET /api/v1/public/modules ─────────────────────────────────────────────
//
// Phase 2, PR 6. The endpoint is small; what is worth testing is the boundary it
// draws. `installed_modules` records five states and the loader records a
// failure stage and reason beside them, and exactly none of that may reach an
// anonymous caller — the public answer is "what is serving", and a module that
// is not serving is ABSENT (MODULE_API.md §4.4, MODULE_SYSTEM.md §2.4).
//
// A leak here would not fail anything else: the routes still 503, the nav is
// still absent, the site still boots. It would just quietly publish that a
// module broke and how far it got. So the tests below assert the negative — no
// `state`, no `stage`, no `reason`, no extra key — as well as the positive.
//
// Like the other module tests, each case builds a throwaway modules directory,
// points MODULES_DIR at it and re-requires the loader AND the controller with a
// clean cache: the controller holds the loader in a file-scope const, so a stale
// cache would leave it reading the previous test's module list.
//
// Point the pool at a closed port before requiring anything — buildCtx pulls in
// the models, which build a mariadb pool at require time. That no test here has
// to stub a query is itself the point: this endpoint never touches a database.
process.env.DB_HOST = '127.0.0.1'
process.env.DB_PORT = '59999'

const fs = require('fs')
const os = require('os')
const path = require('path')

const { test, beforeEach, after } = require('node:test')
const assert = require('node:assert/strict')

const express = require('express')

const db = require('../src/utils/db')
const registries = require('../src/modules/registries')
const { startApp } = require('./_helper')

after(() => db.close())

let tmpRoot

const emptyTiers = () => ({
  public: express.Router(),
  admin: express.Router(),
  player: express.Router(),
})

/**
 * Load a throwaway modules directory and hand back the loader plus a live app
 * serving the real router at the real path.
 */
function freshApp(dir) {
  process.env.MODULES_DIR = dir
  registries._reset()
  delete require.cache[require.resolve('../src/modules/loader')]
  delete require.cache[require.resolve('../src/router/v1/public/modules.controller')]
  delete require.cache[require.resolve('../src/router/v1/public/modules.router')]
  /* eslint-disable global-require */
  const loader = require('../src/modules/loader')
  loader.load(emptyTiers())
  const modulesRouter = require('../src/router/v1/public/modules.router')
  /* eslint-enable global-require */
  return { loader, mount: (app) => app.use('/api/v1/public/modules', modulesRouter) }
}

function writeModule(id, manifest = {}) {
  const dir = path.join(tmpRoot, id)
  fs.mkdirSync(dir, { recursive: true })
  fs.writeFileSync(path.join(dir, 'module.json'), JSON.stringify({
    id, name: id, version: '1.0.0', coreApi: '^1.0.0', ...manifest,
  }))
  return dir
}

async function get(mount) {
  const app = await startApp(mount)
  try {
    const res = await fetch(`${app.url}/api/v1/public/modules`)
    return { status: res.status, body: await res.json() }
  } finally {
    await app.close()
  }
}

beforeEach(() => {
  tmpRoot = fs.mkdtempSync(path.join(os.tmpdir(), 'rg-pubmod-'))
})

// ── The answer ─────────────────────────────────────────────────────────────

test('a core with no modules answers an empty list, not a 404', async () => {
  // The shipping state of Phase 2: the endpoint exists and is truthful before
  // any module does. A client that has to distinguish "no modules" from "old
  // backend" would otherwise have to read a status code to find out.
  const { mount } = freshApp(path.join(tmpRoot, 'does-not-exist'))
  const res = await get(mount)
  assert.equal(res.status, 200)
  assert.deepEqual(res.body, { modules: [] })
})

test('a started module is published with exactly id, name, version and capabilities', async () => {
  writeModule('uo', { name: 'Ultima Online', version: '2.1.0', capabilities: ['shard', 'atlas'] })
  const { loader, mount } = freshApp(tmpRoot)
  loader.setState('uo', 'started')

  const res = await get(mount)
  assert.deepEqual(res.body, {
    modules: [{ id: 'uo', name: 'Ultima Online', version: '2.1.0', capabilities: ['shard', 'atlas'] }],
  })
  // Asserted by key set as well as by value: a field added to loader.list()
  // later must not reach the public surface just because it was added.
  assert.deepEqual(Object.keys(res.body.modules[0]).sort(), ['capabilities', 'id', 'name', 'version'])
})

test('a module that declares no capabilities publishes an empty array, never undefined', async () => {
  // `capabilities` is optional in module.json (§2.1). A client iterating the
  // array must not have to null-check it.
  writeModule('bare')
  const { loader, mount } = freshApp(tmpRoot)
  loader.setState('bare', 'started')

  const res = await get(mount)
  assert.deepEqual(res.body.modules[0].capabilities, [])
})

test('modules are published in scan order', async () => {
  for (const id of ['zeta', 'alpha', 'mid']) writeModule(id)
  const { loader, mount } = freshApp(tmpRoot)
  for (const id of ['zeta', 'alpha', 'mid']) loader.setState(id, 'started')

  const res = await get(mount)
  // Alphabetical, because that is the loader's scan order and there is no
  // dependency resolution — any other order would imply a precedence nothing
  // computes (§4.2).
  assert.deepEqual(res.body.modules.map((m) => m.id), ['alpha', 'mid', 'zeta'])
})

// ── The boundary ───────────────────────────────────────────────────────────

test('a registered-but-not-yet-started module is absent', async () => {
  // The state between a clean load and onBoot. It is not serving yet, so it is
  // not published — the endpoint answers what IS serving, not what will be.
  writeModule('uo')
  const { mount } = freshApp(tmpRoot)
  const res = await get(mount)
  assert.deepEqual(res.body.modules, [])
})

test('a disabled module is absent — the operator switched it off', async () => {
  writeModule('uo')
  const { loader, mount } = freshApp(tmpRoot)
  loader.setState('uo', 'disabled')

  const res = await get(mount)
  assert.deepEqual(res.body.modules, [])
})

test('a failed module is absent, and its stage and reason never leave the server', async () => {
  // The leak this whole file exists to prevent. `startup_failed` carries the
  // step that broke and the error message; both belong to the admin Modules
  // screen and neither is anonymous-visitor business.
  writeModule('uo', { capabilities: ['shard'] })
  const { loader, mount } = freshApp(tmpRoot)
  loader.setState('uo', 'startup_failed', { stage: 'require', reason: 'Cannot find module ./nope' })

  const res = await get(mount)
  assert.deepEqual(res.body.modules, [])
  const raw = JSON.stringify(res.body)
  for (const leak of ['require', 'nope', 'startup_failed', 'stage', 'reason']) {
    assert.ok(!raw.includes(leak), `published "${leak}"`)
  }
})

test('one failed module does not hide the ones that started', async () => {
  writeModule('broken')
  writeModule('working', { capabilities: ['shard'] })
  const { loader, mount } = freshApp(tmpRoot)
  loader.setState('broken', 'startup_failed', { stage: 'schema', reason: 'boom' })
  loader.setState('working', 'started')

  const res = await get(mount)
  assert.deepEqual(res.body.modules.map((m) => m.id), ['working'])
})

// ── Failure ────────────────────────────────────────────────────────────────

test('the module list read before load() is a 500, not a lie', async () => {
  // §7.6: `{ modules: [] }` is a true answer for a core with no modules and a
  // caller cannot tell it from a mis-ordered boot. So the guard's throw becomes
  // a 500 rather than an empty list — the one case where an error is the honest
  // answer.
  process.env.MODULES_DIR = tmpRoot
  registries._reset()
  delete require.cache[require.resolve('../src/modules/loader')]
  delete require.cache[require.resolve('../src/router/v1/public/modules.controller')]
  delete require.cache[require.resolve('../src/router/v1/public/modules.router')]
  // eslint-disable-next-line global-require
  const modulesRouter = require('../src/router/v1/public/modules.router')

  const res = await get((app) => app.use('/api/v1/public/modules', modulesRouter))
  assert.equal(res.status, 500)
})