#!/usr/bin/env node
//
// Static checks on the bridge plugin, run on every pull request.
//
// This plugin has no unit tests and cannot have any in the ordinary sense: it is
// deployed as SOURCE and compiled by Oxide or Carbon against game assemblies that
// exist only on a Rust server. There is no way to build it here, and the nearest
// thing to a compiler this repository owns is a reader.
//
// So these checks ask the questions a compiler would not answer anyway. Both
// frameworks bind hooks **by name and arity, through reflection**, with no
// compile-time check and no warning when a name matches nothing — which makes
// three mistakes silent, and each has a cost bigger than it looks:
//
//   1. A hook method the plugin declares but never lists in `ExpectedHooks`.
//      `rg.hooks` is how we answer "does this hook fire on this framework" —
//      the standing answer to Facepunch renaming one and to Carbon's catalogue
//      omitting thirteen names (CARBON.md §6). A hook missing from that list is
//      invisible to the one instrument built to see it.
//
//   2. A hook that ANSWERS. Four of the hooks in the read path are documented as
//      "returning a non-null value overrides default behavior" — a bridge that
//      returned something would cancel a death, swallow a player's gathered
//      wood, or refuse a login, on somebody's production server at 3am
//      (PROTOCOL.md §8.7).
//
//      The rule is inverted on purpose: EVERY hook must be `void`, rather than
//      every *vetoable* hook. A list of vetoable hook names would have to be
//      maintained here, against a catalogue in another repository, and the first
//      hook somebody forgot to add to it would be the one that passed. There is
//      nothing to forget this way — a hook that must genuinely answer is added
//      to `ANSWERS_DELIBERATELY` below, with a reason, as a visible exception.
//
//   3. A protocol version that disagrees with `overlay.toml`. The game link has
//      no version handshake (PROTOCOL.md §2), so a half-bumped pair does not
//      refuse — it mis-parses. `overlay.toml` exists precisely so the installer
//      can refuse the pairing BEFORE an operator deploys it, and it is worth
//      exactly as much as its agreement with the code.
//
// Dependency-free by design, like every check script in this project: it runs on
// a bare Node with no install step, which is also how a contributor runs it.
//
//   node scripts/checkPlugin.js

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

const ROOT = path.resolve(__dirname, '..')
const PLUGIN = path.join(ROOT, 'overlay', 'oxide', 'plugins', 'RunicGateway.cs')
const OVERLAY_TOML = path.join(ROOT, 'overlay.toml')

/**
 * Hooks this plugin answers on purpose, and why.
 *
 * Empty, and it should stay empty for as long as the plugin is a read path. A
 * name here is a deliberate decision to let the bridge change what the game
 * does — reviewable because it is written down in one place rather than implied
 * by a return type somewhere in 1,500 lines.
 */
const ANSWERS_DELIBERATELY = Object.create(null)

/** Anything shaped like this is a game hook, by both frameworks' own convention. */
const HOOK_NAME = /^(?:On|Can)[A-Z]\w*$/

/**
 * Method declarations, as this file cares about them: the return type and the
 * name. Deliberately narrow — it matches the plugin's own single style
 * (`private [static] <type> <Name>(`) rather than trying to parse C#. A method
 * written some other way is not matched, which would let a hook through, so the
 * shape is asserted by the self-test rather than assumed.
 */
const METHOD = /^\s*(?:private|public|protected|internal)\s+(?:static\s+)?([\w.<>[\],\s]+?)\s+(\w+)\s*\(/gm

function readExpectedHooks(source) {
  const block = /ExpectedHooks\s*=\s*\{([\s\S]*?)\}\s*;/.exec(source)
  if (!block) return null

  return block[1]
    .split(',')
    .map((entry) => /"([^"]+)"/.exec(entry))
    .filter(Boolean)
    .map((m) => m[1])
}

function readMethods(source) {
  const found = []
  let m
  METHOD.lastIndex = 0
  while ((m = METHOD.exec(source)) !== null) {
    found.push({ returns: m[1].trim(), name: m[2] })
  }
  return found
}

function check(source, toml) {
  const problems = []

  const expected = readExpectedHooks(source)
  if (!expected) {
    return ['could not find the ExpectedHooks array in the plugin source']
  }

  const methods = readMethods(source)
  const hooks = methods.filter((x) => HOOK_NAME.test(x.name))
  const hookNames = new Set(hooks.map((x) => x.name))

  // 1. Every hook the plugin implements is one `rg.hooks` can report on.
  for (const hook of hooks) {
    if (!expected.includes(hook.name)) {
      problems.push(
        `${hook.name} is implemented but missing from ExpectedHooks, so rg.hooks cannot report it`
      )
    }
  }

  // 2. Every hook is void, unless answering is a decision somebody wrote down.
  for (const hook of hooks) {
    if (hook.returns === 'void') continue
    if (hook.name in ANSWERS_DELIBERATELY) continue

    problems.push(
      `${hook.name} returns ${hook.returns}, not void — a read-path hook must not be able to ` +
        'veto what the game was going to do (PROTOCOL.md §8.7). If it must answer, add it to ' +
        'ANSWERS_DELIBERATELY with a reason.'
    )
  }

  // 3. No phantom entries: a name listed but never implemented reports "silent"
  //    for ever, which reads exactly like a hook the framework does not fire.
  for (const name of expected) {
    if (!hookNames.has(name)) {
      problems.push(`ExpectedHooks lists ${name}, but no method of that name is implemented`)
    }
  }

  // 4. The two declaration sites this repository owns must agree.
  const inCode = /ProtocolVersion\s*=\s*(\d+)\s*;/.exec(source)
  const inToml = /^\s*protocol\s*=\s*(\d+)\s*$/m.exec(toml)

  if (!inCode) problems.push('could not read ProtocolVersion from the plugin source')
  if (!inToml) problems.push('could not read `protocol` from overlay.toml')

  if (inCode && inToml && inCode[1] !== inToml[1]) {
    problems.push(
      `the plugin speaks protocol ${inCode[1]} and overlay.toml declares ${inToml[1]}. ` +
        'The installer refuses to pair a sidecar and an overlay that disagree, so a bundle built ' +
        'from this would not compose — and the game link itself has no version check to catch it.'
    )
  }

  return problems
}

function main() {
  const source = fs.readFileSync(PLUGIN, 'utf8')
  const toml = fs.readFileSync(OVERLAY_TOML, 'utf8')

  const problems = check(source, toml)

  if (problems.length > 0) {
    console.error('The bridge plugin failed its static checks:\n')
    for (const p of problems) console.error(`  • ${p}`)
    console.error('')
    process.exit(1)
  }

  const expected = readExpectedHooks(source)
  const version = /ProtocolVersion\s*=\s*(\d+)\s*;/.exec(source)[1]
  console.log(
    `plugin ok — protocol ${version}, ${expected.length} hooks declared, every one void and listed`
  )
}

module.exports = { check, readExpectedHooks, readMethods, HOOK_NAME }

if (require.main === module) main()