import fs from "fs"

// stateFromJSON returns a JSON file backed object. When object mutates, will
// serialize the object as JSON to the specified path.
//
// with recursive proxy support similar to:
//
// https://stackoverflow.com/questions/41299642/how-to-use-javascript-proxy-for-nested-objects
export function stateFromJSON<T extends Object>(
  filepath: string,
  defaultObject: T,
  opts: {
    replacer?: Function
    reviver?: Function
  } = {}
): T {
  let root = defaultObject

  try {
    const data = fs.readFileSync(filepath, "utf8")
    // TODO: support custom revive
    root = JSON.parse(data, opts.reviver as any)
  } catch (err) {}

  function save() {
    // should be sync to avoid write races
    fs.writeFileSync(filepath, JSON.stringify(root, opts.replacer as any, 2))
  }

  const proxy = {
    get(target, key) {
      if (typeof target[key] === "object" && target[key] !== null) {
        return new Proxy(target[key], proxy)
      } else {
        return target[key]
      }
    },

    set(obj, prop, val) {
      obj[prop] = val
      save()
      return true
    },
  }

  return new Proxy(root, proxy) as T
}

// import { BigNumber } from "ethers";
// function jsonRevive(_key: string, val: any) {
//   if (val && typeof val == "object") {
//     if (val["type"] == "BigNumber") {
//       return BigNumber.from(val["hex"]);
//     }
//   }
//   return val;
// }