// modules/declared.js — resolving the module set an environment declares.
//
// Phase 4, slice 3 of MODULE_SYSTEM.md §2.7.2, decision 4. Two claims are worth
// more than the rest and both are about what does NOT happen:
//
//   - a module already unpacked at the declared version does not touch the
//     network, because that is what makes a restart with the internet down come
//     up unchanged;
//   - a module that cannot be resolved does not fail the boot, and does not stop
//     the next declaration from resolving.
//
// The last test in the file runs the whole path through the real install.js
// against a fake transport — a real gzipped tar, really hashed, really unpacked
// — because everything above it stubs `installImpl` and would keep passing if
// the two files stopped agreeing about what an install returns.
process.env.DB_HOST = '127.0.0.1'
process.env.DB_PORT = '59999'

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

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

const db = require('../src/utils/db')

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

const HOSTS = ['releases.example.com']
const URL_030 = 'https://releases.example.com/mod/uo-0.3.0.json'

let tmpRoot
let declared

/**
 * A fresh declared.js bound to a fresh modules directory.
 *
 * loader.js resolves MODULES_DIR once at require time and install.js reads
 * `loader.dir()`, so all three have to come back together — the same dance
 * moduleInstall.test.js and moduleLifecycle.test.js do.
 */
function fresh(dir) {
  process.env.MODULES_DIR = dir
  for (const m of ['loader', 'install', 'declared']) {
    delete require.cache[require.resolve(`../src/modules/${m}`)]
  }
  // eslint-disable-next-line global-require
  return require('../src/modules/declared')
}

/** Put a module directory on the volume, as an unpack would leave it. */
function place(id, version) {
  const dir = path.join(tmpRoot, id)
  fs.mkdirSync(dir, { recursive: true })
  fs.writeFileSync(
    path.join(dir, 'module.json'),
    JSON.stringify({ id, name: 'Ultima Online', version, coreApi: '^1.0.0' }),
  )
  return dir
}

/**
 * A stub install service.
 *
 * Records every call, so "did this reach the network at all" is a question the
 * tests can ask directly rather than inferring from an outcome.
 */
function fakeInstall({ version = '0.3.0', throws = null } = {}) {
  const calls = []
  return {
    calls,
    InstallError: Error,
    async install(args) {
      calls.push(args)
      if (throws) throw new Error(throws)
      return {
        id: 'uo',
        name: 'Ultima Online',
        version,
        sha256: 'a'.repeat(64),
        source: args.url,
        bytes: 1024,
        replaced: false,
      }
    },
  }
}

/** A modules.model stand-in that remembers what provenance it was given. */
function fakeModel() {
  const recorded = []
  return { recorded, async recordInstalled(row) { recorded.push(row); return row } }
}

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

// ── Parsing ────────────────────────────────────────────────────────────────

test('parses id@version=url entries separated by whitespace or commas', () => {
  const { entries, errors } = declared.parse(
    ` uo@0.3.0=https://a.example/uo.json,\n  market@1.2.3=https://a.example/market.json `,
  )
  assert.deepEqual(errors, [])
  assert.deepEqual(entries, [
    { id: 'uo', version: '0.3.0', url: 'https://a.example/uo.json' },
    { id: 'market', version: '1.2.3', url: 'https://a.example/market.json' },
  ])
})

test('an empty or unset declaration parses to nothing, without complaint', () => {
  for (const value of [undefined, '', '   ']) {
    const { entries, errors } = declared.parse(value)
    assert.deepEqual(entries, [])
    assert.deepEqual(errors, [])
  }
})

test('a malformed entry is refused on its own, leaving the others', () => {
  // A bare URL, a missing version, and an id that is not one — each of which an
  // operator can plausibly type, and none of which should cost the module that
  // was written correctly.
  const { entries, errors } = declared.parse(
    'https://a.example/uo.json uo@=https://a.example/uo.json Uo@1=https://a.example/uo.json'
      + ' good@1.0.0=https://a.example/good.json',
  )
  assert.equal(entries.length, 1)
  assert.equal(entries[0].id, 'good')
  assert.equal(errors.length, 3)
})

test('a duplicate id keeps the first and says so', () => {
  const { entries, errors } = declared.parse(
    'uo@1.0.0=https://a.example/one.json uo@2.0.0=https://a.example/two.json',
  )
  assert.equal(entries.length, 1)
  assert.equal(entries[0].version, '1.0.0')
  assert.match(errors[0], /declared more than once/)
})

// ── Resolution ─────────────────────────────────────────────────────────────

test('a module already at the declared version is a no-op that never fetches', async () => {
  place('uo', '0.3.0')
  const installer = fakeInstall()
  const model = fakeModel()

  const results = await declared.resolve({
    value: `uo@0.3.0=${URL_030}`,
    hosts: HOSTS,
    model,
    installImpl: installer,
  })

  assert.deepEqual(results.map((r) => r.action), ['noop'])
  // The offline guarantee, stated as an assertion: nothing was fetched and
  // nothing was written. A restart with no route to the internet is this case.
  assert.equal(installer.calls.length, 0)
  assert.equal(model.recorded.length, 0)
})

test('a missing module is installed, with its provenance recorded', async () => {
  const installer = fakeInstall()
  const model = fakeModel()

  const results = await declared.resolve({
    value: `uo@0.3.0=${URL_030}`,
    hosts: HOSTS,
    model,
    installImpl: installer,
  })

  assert.deepEqual(results.map((r) => r.action), ['installed'])
  assert.equal(installer.calls[0].url, URL_030)
  assert.deepEqual(installer.calls[0].hosts, HOSTS)
  // The declaration is handed down so install.js can refuse a URL that turns out
  // to be another module or another version BEFORE it downloads it.
  assert.deepEqual(installer.calls[0].expect, { id: 'uo', version: '0.3.0' })
  // Written exactly as the admin route writes it — the reason this runs in the
  // server process rather than in a script that cannot reach the database.
  assert.deepEqual(model.recorded, [
    { id: 'uo', name: 'Ultima Online', version: '0.3.0', source: URL_030, sha256: 'a'.repeat(64) },
  ])
})

test('a module at a different version is re-resolved', async () => {
  place('uo', '0.2.0')
  const installer = fakeInstall()

  const results = await declared.resolve({
    value: `uo@0.3.0=${URL_030}`,
    hosts: HOSTS,
    model: fakeModel(),
    installImpl: installer,
  })

  assert.deepEqual(results.map((r) => r.action), ['installed'])
  assert.equal(installer.calls.length, 1)
})

test('a directory with no readable module.json counts as absent', async () => {
  fs.mkdirSync(path.join(tmpRoot, 'uo'), { recursive: true })
  fs.writeFileSync(path.join(tmpRoot, 'uo', 'module.json'), '{ this is not json')
  const installer = fakeInstall()

  await declared.resolve({
    value: `uo@0.3.0=${URL_030}`,
    hosts: HOSTS,
    model: fakeModel(),
    installImpl: installer,
  })

  // Whatever is in that directory, it is not the declared module — so the
  // declared module is fetched rather than assumed to be there.
  assert.equal(installer.calls.length, 1)
})

test('a failure is carried, not thrown, and does not stop the next module', async () => {
  const model = fakeModel()
  const installer = {
    calls: [],
    async install(args) {
      installer.calls.push(args)
      if (args.expect.id === 'uo') throw new Error('could not reach releases.example.com')
      return {
        id: args.expect.id,
        name: 'Market',
        version: args.expect.version,
        sha256: 'b'.repeat(64),
        source: args.url,
        bytes: 10,
        replaced: false,
      }
    },
  }

  const results = await declared.resolve({
    value: `uo@0.3.0=${URL_030} market@1.0.0=https://releases.example.com/market.json`,
    hosts: HOSTS,
    model,
    installImpl: installer,
  })

  assert.deepEqual(results.map((r) => r.action), ['failed', 'installed'])
  assert.match(results[0].message, /could not reach/)
  // The second module still installed: one unreachable release host costs that
  // module, not the deployment.
  assert.equal(model.recorded.length, 1)
  assert.equal(model.recorded[0].id, 'market')
})

test('a failed resolution leaves whatever was already on the volume', async () => {
  place('uo', '0.2.0')
  const installer = fakeInstall({ throws: 'the host is down' })

  const results = await declared.resolve({
    value: `uo@0.3.0=${URL_030}`,
    hosts: HOSTS,
    model: fakeModel(),
    installImpl: installer,
  })

  assert.equal(results[0].action, 'failed')
  // The site comes up serving the version it already had rather than not at all.
  assert.equal(declared.installedVersion('uo'), '0.2.0')
})

test('resolution without a model records nothing and still installs', async () => {
  // `npm run seed` and the test harness both reach code paths with no model to
  // hand; the volume half must not depend on the database half.
  const installer = fakeInstall()
  const results = await declared.resolve({ value: `uo@0.3.0=${URL_030}`, hosts: HOSTS, installImpl: installer })
  assert.deepEqual(results.map((r) => r.action), ['installed'])
})

test('state() reports the last resolution and is replaced by the next', async () => {
  const installer = fakeInstall()
  await declared.resolve({ value: `uo@0.3.0=${URL_030}`, hosts: HOSTS, installImpl: installer })
  assert.equal(declared.state().length, 1)
  assert.equal(declared.state()[0].id, 'uo')

  await declared.resolve({ value: '', hosts: HOSTS, installImpl: installer })
  assert.deepEqual(declared.state(), [])
})

// ── The whole path, once, for real ─────────────────────────────────────────

const BLOCK = 512

function octal(value, width) {
  return Number(value).toString(8).padStart(width - 1, '0') + '\0'
}

function member({ name, type = '0', body = '' }) {
  const header = Buffer.alloc(BLOCK, 0)
  const data = Buffer.from(body, 'utf8')
  header.write(name, 0, 100, 'utf8')
  header.write(octal(0o644, 8), 100, 8, 'ascii')
  header.write(octal(0, 8), 108, 8, 'ascii')
  header.write(octal(0, 8), 116, 8, 'ascii')
  header.write(octal(data.length, 12), 124, 12, 'ascii')
  header.write(octal(0, 12), 136, 12, 'ascii')
  header.write('        ', 148, 8, 'ascii')
  header.write(type, 156, 1, 'ascii')
  header.write('ustar\0', 257, 6, 'ascii')
  header.write('00', 263, 2, 'ascii')
  let sum = 0
  for (const byte of header) sum += byte
  header.write(`${sum.toString(8).padStart(6, '0')}\0 `, 148, 8, 'ascii')
  const padding = Buffer.alloc((BLOCK - (data.length % BLOCK)) % BLOCK, 0)
  return Buffer.concat([header, data, padding])
}

/** A bundle tarball, named the way module-uo's release workflow names one. */
function bundle(version) {
  const root = `module-uo-${version}`
  return zlib.gzipSync(Buffer.concat([
    member({ name: `${root}/`, type: '5' }),
    member({
      name: `${root}/module.json`,
      body: JSON.stringify({ id: 'uo', name: 'Ultima Online', version, coreApi: '^1.0.0', server: 'server/index.js' }),
    }),
    member({ name: `${root}/server/`, type: '5' }),
    member({ name: `${root}/server/index.js`, body: 'module.exports = () => {}\n' }),
    Buffer.alloc(BLOCK * 2, 0),
  ]))
}

test('end to end: a declaration installs a real bundle through the real install path', async (t) => {
  const tarball = bundle('0.3.0')
  const artifactUrl = 'https://releases.example.com/mod/uo-0.3.0.tar.gz'
  const manifest = JSON.stringify({
    schema: 1,
    id: 'uo',
    name: 'Ultima Online',
    version: '0.3.0',
    coreApi: '^1.0.0',
    artifact: 'uo-0.3.0.tar.gz',
    url: artifactUrl,
    sha256: crypto.createHash('sha256').update(tarball).digest('hex'),
    size: tarball.length,
  })
  const routes = { [URL_030]: manifest, [artifactUrl]: tarball }
  const fetched = []
  const fetchImpl = async (url) => {
    fetched.push(String(url))
    const body = routes[String(url)]
    return body === undefined ? new Response('nope', { status: 404 }) : new Response(body, { status: 200 })
  }

  // The real install.js, with only the transport replaced — same seam the
  // install tests use, and the same reason: what is under test is the decisions,
  // not Node's TLS.
  // eslint-disable-next-line global-require
  const install = require('../src/modules/install')
  const installImpl = { install: (args) => install.install({ ...args, fetchImpl }) }
  const model = fakeModel()

  const first = await declared.resolve({
    value: `uo@0.3.0=${URL_030}`,
    hosts: HOSTS,
    model,
    installImpl,
  })
  assert.deepEqual(first.map((r) => r.action), ['installed'])
  // Unpacked, with the release's top-level directory stripped, under the id.
  assert.equal(
    JSON.parse(fs.readFileSync(path.join(tmpRoot, 'uo', 'module.json'), 'utf8')).version,
    '0.3.0',
  )
  assert.equal(model.recorded[0].sha256, JSON.parse(manifest).sha256)

  // And again, which is what every restart after the first one is.
  const before = fetched.length
  const second = await declared.resolve({ value: `uo@0.3.0=${URL_030}`, hosts: HOSTS, model, installImpl })
  assert.deepEqual(second.map((r) => r.action), ['noop'])
  assert.equal(fetched.length, before, 'the second resolution must not fetch anything')

  // A declaration whose URL resolves to a different version is refused BEFORE
  // the artifact is downloaded — the module on the volume is left alone.
  const wrong = await declared.resolve({ value: `uo@0.4.0=${URL_030}`, hosts: HOSTS, model, installImpl })
  assert.equal(wrong[0].action, 'failed')
  assert.match(wrong[0].message, /v0\.4\.0 was asked for/)
  assert.equal(declared.installedVersion('uo'), '0.3.0')
  t.diagnostic(`fetched ${fetched.length} URL(s) across three resolutions`)
})
