self-media-james/articles/008/claude-code-source-code/vendor/modifiers-napi-src/index.ts

import { createRequire } from 'module'
import { fileURLToPath } from 'url'
import { dirname, join } from 'path'

type ModifiersNapi = {
  getModifiers(): string[]
  isModifierPressed(modifier: string): boolean
}

let cachedModule: ModifiersNapi | null = null

function loadModule(): ModifiersNapi | null {
  if (cachedModule) {
    return cachedModule
  }

  // Only works on macOS
  if (process.platform !== 'darwin') {
    return null
  }

  try {
    if (process.env.MODIFIERS_NODE_PATH) {
      // Bundled mode - use the env var path
      // eslint-disable-next-line @typescript-eslint/no-require-imports
      cachedModule = require(process.env.MODIFIERS_NODE_PATH) as ModifiersNapi
    } else {
      // Dev mode - load from vendor directory
      const modulePath = join(
        dirname(fileURLToPath(import.meta.url)),
        '..',
        'modifiers-napi',
        `${process.arch}-darwin`,
        'modifiers.node',
      )
      cachedModule = createRequire(import.meta.url)(modulePath) as ModifiersNapi
    }
    return cachedModule
  } catch {
    return null
  }
}

export function getModifiers(): string[] {
  const mod = loadModule()
  if (!mod) {
    return []
  }
  return mod.getModifiers()
}

export function isModifierPressed(modifier: string): boolean {
  const mod = loadModule()
  if (!mod) {
    return false
  }
  return mod.isModifierPressed(modifier)
}

/**
 * Pre-warm the native module by loading it in advance.
 * Call this early (e.g., at startup) to avoid delay on first use.
 */
export function prewarm(): void {
  // Just call loadModule to cache it
  loadModule()
}