#!/usr/bin/env node
//
// Static checks on RunicNPC, run on every pull request and again on the commit
// being released.
//
// 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. It is the bridge's
// checker (Rust-Plugins' scripts/checkPlugin.js) adapted to what RunicNPC can get
// silently wrong.
//
// Both frameworks bind hooks, chat commands and `Call` targets **by name and
// arity, through reflection**, with no compile-time check and no warning when a
// name matches nothing. So:
//
//   1. A hook the plugin implements but does not list in `ExpectedHooks` is
//      invisible to `rnpc.status`, the instrument that answers "does this hook
//      fire on this framework". A name listed and never implemented reports
//      silent for ever, which reads exactly like a hook the framework dropped.
//
//   2. A hook that ANSWERS changes what the game does: it can cancel a death,
//      stop a turret targeting, or replace a corpse's loot. RunicNPC WILL answer
//      some hooks — that is how an NPC plugin works (PLAN.md §3) — but each one
//      must be a decision written down, so the rule is inverted: EVERY hook is
//      `void` unless it is listed in `ANSWERS_DELIBERATELY` below, with a reason.
//      A list of "dangerous" hook names would have to be maintained against a
//      catalogue in another repository, and the first one somebody forgot would
//      be the one that passed. There is nothing to forget this way.
//
//   3. A chat command with the wrong signature is never called, and nobody says
//      so: the admin types `/rnpc` and nothing happens.
//
//   4. An API method (`RunicNpc_*`) that is `public` without `[HookMethod]` is
//      unreachable: Oxide's `Call` finds a non-public method by name, and a public
//      one only when it carries that attribute. The spike found HumanNPC's
//      `RefreshNPC` and `RemoveNPC` in exactly this state (PLAN.md §1.2).
//
//   5. The facts declared twice must agree:
//        • `ApiVersion` in the plugin and `api` in plugin.toml. The release copies
//          plugin.toml into the manifest the installer and the bridge read, so a
//          disagreement ships a RunicNPC that answers one version and claims
//          another.
//        • the plugin's `// Requires:` lines and plugin.toml's `requires_plugins`.
//          The first stops the framework loading RunicNPC without Kits; the
//          second is what `doctor` reports. Kits must be in both (D217).
//        • exactly one `[Info("RunicNPC", "Runic Gateway", "…")]`, because the
//          release stamps its version into that one line.
//
// 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, 'plugin', 'RunicNPC.cs')
const PLUGIN_TOML = path.join(ROOT, 'plugin.toml')

/**
 * Hooks this plugin answers on purpose, and why.
 *
 * Empty in stage 0, which spawns nothing. From stage 2 an entry here is a
 * deliberate decision to let RunicNPC change what the game does — and, because
 * the plugin shares the server with everyone else's entities, every one of them
 * must answer for RunicNPC's OWN NPCs only and return null for anything else.
 * That half cannot be read statically; it is the reviewer's to check, which is
 * why the reason goes here where the reviewer will see it.
 */
const ANSWERS_DELIBERATELY = Object.create(null)

/** Plugins RunicNPC must require, whatever else it requires (D217). */
const REQUIRED_PLUGINS = ['Kits']

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

/** Every call of the public API carries this prefix (PLAN.md §4). */
const API_NAME = /^RunicNpc_\w+$/

/**
 * The parameter list both frameworks bind a chat command on: the caller, the command word, and
 * whatever followed it. Names are the author's; the types are not.
 */
const CHAT_SIGNATURE = /^BasePlayer\s+\w+,\s*string\s+\w+,\s*string\[\]\s+\w+$/

/**
 * Method declarations, as this file cares about them: any attributes directly above, the access
 * modifier, 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 against the real plugin rather than assumed. `\r?` because a Windows checkout has
 * CRLF endings, and an attribute line that failed to match there would hide a [HookMethod].
 */
const METHOD =
  /((?:^[ \t]*\[[^\]\r\n]*\][ \t]*\r?\n)*)^[ \t]*(private|public|protected|internal)\s+(?:static\s+)?([\w.<>[\],\s]+?)\s+(\w+)\s*\(/gm

/** The attribute the release stamps a version into. */
const INFO = /^[ \t]*\[Info\("RunicNPC", "Runic Gateway", "[^"]*"\)\]/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({ attributes: m[1], access: m[2], returns: m[3].trim(), name: m[4] })
  }
  return found
}

/**
 * Every `[ChatCommand("x")]` and the signature of the method under it.
 *
 * **A chat command binds by reflection, exactly like a hook**, and fails the same silent way: a
 * method with the wrong parameter list is never called and neither framework says a word.
 */
function readChatCommands(source) {
  const found = []
  const attribute =
    /\[ChatCommand\("([^"]+)"\)\]\s*(?:\/\/[^\n]*\n\s*)*(?:private|public|protected|internal)\s+(?:static\s+)?([\w.<>[\],\s]+?)\s+(\w+)\s*\(([^)]*)\)/g

  let match
  while ((match = attribute.exec(source)) !== null) {
    found.push({
      command: match[1],
      returns: match[2].trim(),
      name: match[3],
      params: match[4].replace(/\s+/g, ' ').trim(),
    })
  }

  return found
}

/** The plugin names in `// Requires: A, B` lines at the top of the file, in order. */
function readRequires(source) {
  const names = []
  const line = /^\s*\/\/\s*Requires:\s*(.+)$/gm
  let m
  while ((m = line.exec(source)) !== null) {
    for (const name of m[1].split(',')) {
      if (name.trim()) names.push(name.trim())
    }
  }
  return names
}

/** `requires_plugins = ["A", "B"]`, one line, quoted strings only — or null if it is not that. */
function readTomlRequires(toml) {
  const m = /^\s*requires_plugins\s*=\s*(\[.*\])\s*$/m.exec(toml)
  if (!m) return null
  try {
    const list = JSON.parse(m[1])
    return Array.isArray(list) && list.every((x) => typeof x === 'string') ? list : null
  } catch {
    return null
  }
}

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 `rnpc.status` can report on.
  for (const hook of hooks) {
    if (!expected.includes(hook.name)) {
      problems.push(
        `${hook.name} is implemented but missing from ExpectedHooks, so rnpc.status cannot report it`
      )
    }
  }

  // ... and no phantom entries.
  for (const name of expected) {
    if (!hookNames.has(name)) {
      problems.push(`ExpectedHooks lists ${name}, but no method of that name is implemented`)
    }
  }

  // 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 hook that answers changes what the game ` +
        'does. If RunicNPC must answer it, add it to ANSWERS_DELIBERATELY in scripts/checkPlugin.js ' +
        'with the reason, and answer for RunicNPC\'s own NPCs only.'
    )
  }

  // 3. Every chat command has the signature the frameworks bind, and one name binds once.
  const chat = readChatCommands(source)
  const seen = new Set()

  for (const cmd of chat) {
    if (cmd.returns !== 'void') {
      problems.push(
        `/${cmd.command} (${cmd.name}) returns ${cmd.returns}, not void — a chat command's return ` +
          'value is not read, and a non-void signature is the shape that silently binds nothing.'
      )
    }

    if (!CHAT_SIGNATURE.test(cmd.params)) {
      problems.push(
        `/${cmd.command} (${cmd.name}) takes (${cmd.params}), not (BasePlayer, string, string[]). ` +
          'Both frameworks bind a chat command by reflection on that exact signature, so this one ' +
          'would never be called and neither would log it.'
      )
    }

    if (seen.has(cmd.command)) {
      problems.push(`/${cmd.command} is declared twice; only one of them can ever be bound`)
    }
    seen.add(cmd.command)
  }

  // 4. Every API method is one `Call` can reach.
  for (const method of methods.filter((x) => API_NAME.test(x.name))) {
    if (method.access === 'public' && !/\[HookMethod\(/.test(method.attributes)) {
      problems.push(
        `${method.name} is public without [HookMethod], so Oxide's Call cannot reach it — make it ` +
          'private, as every RunicNpc_ call is (PLAN.md §4).'
      )
    }
  }

  // 5a. The API version, declared twice.
  const inCode = /ApiVersion\s*=\s*(\d+)\s*;/.exec(source)
  const inToml = /^\s*api\s*=\s*(\d+)\s*$/m.exec(toml)

  if (!inCode) problems.push('could not read ApiVersion from the plugin source')
  if (!inToml) problems.push('could not read `api` from plugin.toml')

  if (inCode && inToml && inCode[1] !== inToml[1]) {
    problems.push(
      `the plugin answers API ${inCode[1]} and plugin.toml declares ${inToml[1]}. The release ` +
        'copies plugin.toml into the manifest the installer and the bridge read, so this would ship ' +
        'a RunicNPC that claims one version and answers another.'
    )
  }

  // 5b. The required plugins, declared twice.
  const requires = readRequires(source)
  const tomlRequires = readTomlRequires(toml)

  if (!tomlRequires) {
    problems.push('could not read `requires_plugins` from plugin.toml as a one-line array of strings')
  } else {
    const a = [...new Set(requires)].sort().join(', ')
    const b = [...new Set(tomlRequires)].sort().join(', ')
    if (a !== b) {
      problems.push(
        `the plugin's // Requires: lines name [${a}] and plugin.toml's requires_plugins names [${b}]. ` +
          'The first is what stops the framework loading RunicNPC; the second is what doctor reports.'
      )
    }
  }

  for (const name of REQUIRED_PLUGINS) {
    if (!requires.includes(name)) {
      problems.push(
        `the plugin does not declare // Requires: ${name}. ${name} is required (D217), and without ` +
          'the line the framework loads RunicNPC on a server that cannot equip a single NPC.'
      )
    }
  }

  // 5c. The one line the release stamps.
  const infoCount = (source.match(INFO) || []).length
  if (infoCount !== 1) {
    problems.push(
      `expected exactly one [Info("RunicNPC", "Runic Gateway", "…")] attribute, found ${infoCount}. ` +
        'The release stamps its version into that line; zero or two would ship a plugin whose ' +
        'reported version is a lie.'
    )
  }

  return problems
}

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

  const problems = check(source, toml)

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

  const expected = readExpectedHooks(source)
  const api = /ApiVersion\s*=\s*(\d+)\s*;/.exec(source)[1]
  const calls = readMethods(source).filter((x) => API_NAME.test(x.name)).length
  console.log(
    `plugin ok — API ${api}, ${calls} API call(s), ${expected.length} hook(s) declared, ` +
      `requires ${readRequires(source).join(', ')}`
  )
}

module.exports = {
  check,
  readExpectedHooks,
  readMethods,
  readChatCommands,
  readRequires,
  readTomlRequires,
  HOOK_NAME,
  API_NAME,
}

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