Case Conversion with Irregular Schema

import type { PascalCaseOptions } from "change-case"
import { camelCase, pascalCase } from "change-case"

function changeKeysFactory<TOptions>(changeCase: (input: string, options?: TOptions) => string) {
  return function changeKeys(object: unknown, depth = 1, options?: TOptions | undefined): unknown {
    if (depth === 0 || !isObject(object)) {
      return object
    }
    if (Array.isArray(object)) {
      return object.map((item) => changeKeys(item, depth - 1, options))
    }
    const result = Object.create(Object.getPrototypeOf(object))
    Object.keys(object).forEach((key) => {
      const value = object[key]
      const changedKey = changeCase(key, options)
      const changedValue = changeKeys(value, depth - 1, options)
      result[changedKey] = changedValue
    })
    return result
  }
}

const camelCaseKeys = changeKeysFactory(camelCase)
const pascalCaseKeysExceptions = (exceptions: Record<string, string>) =>
  changeKeysFactory((key: string, options?: PascalCaseOptions | undefined) =>
    exceptions[key] ? exceptions[key]! : pascalCase(key, options)
  )
const pascalCaseKeys = pascalCaseKeysExceptions({
  zipCode: "ZIPCode",
  email: "eMail",
  contactId: "ContactID"
})