import { createHash } from 'node:crypto'
import { existsSync, readFileSync, readdirSync } from 'node:fs'
import path from 'node:path'

const NATIVE_EXTENSIONS = new Set([
  '.c',
  '.cc',
  '.cmake',
  '.cpp',
  '.gradle',
  '.h',
  '.java',
  '.kts',
  '.kt',
  '.properties',
  '.toml',
  '.xml',
])
const IGNORED_DIRECTORIES = new Set(['.cxx', '.gradle', 'build', 'generated'])
const IGNORED_FILES = new Set(['local.properties'])

function walkNativeFiles(directory, root = directory) {
  if (!existsSync(directory)) return []
  const files = []
  for (const entry of readdirSync(directory, { withFileTypes: true })) {
    if (entry.isDirectory() && IGNORED_DIRECTORIES.has(entry.name)) continue
    const absolute = path.join(directory, entry.name)
    if (entry.isDirectory()) files.push(...walkNativeFiles(absolute, root))
    else if (
      !IGNORED_FILES.has(entry.name) &&
      (NATIVE_EXTENSIONS.has(path.extname(entry.name)) || entry.name === 'gradlew')
    ) {
      files.push({ absolute, relative: path.relative(root, absolute).split(path.sep).join('/') })
    }
  }
  return files
}

function packageJson(directory) {
  const file = path.join(directory, 'package.json')
  return existsSync(file) ? JSON.parse(readFileSync(file, 'utf8')) : null
}

function nativeDependencyVersions(root, hostPackage) {
  const dependencies = { ...hostPackage.dependencies, ...hostPackage.devDependencies }
  const native = []
  for (const name of Object.keys(dependencies).sort()) {
    const directory = path.join(root, 'node_modules', ...name.split('/'))
    const manifest = packageJson(directory)
    if (!manifest) continue
    const hasNativeCode =
      existsSync(path.join(directory, 'android')) ||
      existsSync(path.join(directory, 'react-native.config.js')) ||
      manifest.codegenConfig !== undefined
    if (hasNativeCode || name === 'react-native') {
      native.push(`${name}@${manifest.version ?? dependencies[name]}`)
    }
  }
  return native
}

/** Deterministic identity of code and dependencies that can only change through a full APK. */
export function computeNativeBaseline(root = process.cwd()) {
  const hostPackage = packageJson(root)
  if (!hostPackage) throw new Error('package.json is missing')
  const hash = createHash('sha256')
  for (const dependency of nativeDependencyVersions(root, hostPackage)) {
    hash.update(`dependency\0${dependency}\0`)
  }
  for (const file of walkNativeFiles(path.join(root, 'android')).sort((a, b) =>
    a.relative.localeCompare(b.relative),
  )) {
    hash.update(`file\0${file.relative}\0`)
    hash.update(readFileSync(file.absolute))
    hash.update('\0')
  }
  return `android-sha256:${hash.digest('hex')}`
}