const fs = require('fs')
const path = require('path')
const { execSync } = require('child_process')

// When executing the "postinstall" script, the "process.cwd" equals
// the package directory, not the parent project where the package is installed.
// NPM stores the parent project directory in the "INIT_CWD" env variable.
const parentPackageCwd = process.env.INIT_CWD

function postinstall() {
  // 1. Check if "package.json" has "msw.workerDirectory" property set.
  const packageJson = JSON.parse(
    fs.readFileSync(path.resolve(parentPackageCwd, 'package.json'), 'utf8'),
  )

  if (!packageJson.msw || !packageJson.msw.workerDirectory) {
    return
  }

  // 2. Check if the worker directory is an existing path.
  const { workerDirectory } = packageJson.msw
  const absoluteWorkerDirectory = path.resolve(
    parentPackageCwd,
    workerDirectory,
  )

  if (!fs.existsSync(absoluteWorkerDirectory)) {
    return console.error(
      `[MSW] Failed to automatically update the worker script at "%s": given path does not exist.`,
      workerDirectory,
    )
  }

  // 3. Update the worker script.
  const cliExecutable = path.resolve(process.cwd(), 'cli/index.js')

  try {
    execSync(`node ${cliExecutable} init ${absoluteWorkerDirectory}`, {
      cwd: parentPackageCwd,
    })
  } catch (error) {
    console.error(
      `[MSW] Failed to automatically update the worker script:\n${error}`,
    )
  }
}

postinstall()