lambda-service/src/utils/setConfig.js

import { readFileSync, writeFileSync } from 'fs'
import * as parser from '@babel/parser'
import traverse from '@babel/traverse'
import generate from '@babel/generator'
import template from '@babel/template'
import * as t from '@babel/types'
import assert from 'assert'

export default function({ key, value, file }) {
  const newContent = update({
    key,
    value,
    content: readFileSync(file, 'utf-8')
  })
  writeFileSync(file, `${newContent}\n`, 'utf-8')
}

function buildExpression(str) {
  if (str.startsWith('{')) {
    // do nothing
  } else if (str === 'true' || str === 'false') {
    // do nothing
  } else {
    str = `'${str}'`
  }
  return template(`(${str})`)().expression
}

export function update({ key, value, content }) {
  const ast = parser.parse(content, {
    sourceType: 'module'
  })
  traverse(ast, {
    ExportDefaultDeclaration(path) {
      assert(
        t.isObjectExpression(path.node.declaration),
        `config file must export default a Plain Object`
      )
      if (t.isObjectExpression(path.node.declaration)) {
        const { properties } = path.node.declaration
        let hasFound
        for (const property of properties) {
          if (
            t.isIdentifier(property.key, {
              name: key
            })
          ) {
            property.value = buildExpression(value)
            hasFound = true
            break
          }
        }
        if (!hasFound) {
          properties.push(
            t.objectProperty(t.identifier(key), buildExpression(value))
          )
        }
      }
    }
  })
  return generate(ast, {}).code
}