/*
  The following function creates a Proxy object with event methods attached.
  This might be useful for adding api calls or data checks whenever your object changes.

  Example use case:
    On the client side you keep a data object which stores user or app data,
    whenever a key is changed you make an api call to write this new object to your database.
*/

export const watchObj = <T extends {}, V extends T[keyof T]>(
  /** Base Object to attach watchers */
  obj: T,

  /** Event that triggers pre get */
  preGet?: (
    targetRef?: T,
    property?: keyof T
  ) => void ,

  /** Event that fires after setting key value pair in object */
  afterSet?: (
    targetRef?: T,
    property?: keyof T,
    value?: V,
    beforeSetValue?: V | undefined
  ) => void,

  /** Event that triggers after delete attempt */
  afterDelete?: (
    targetRef?: T,
    property?: keyof T,
    deletedValue?: V | undefined
  ) => void
) => {

  const get = (targetRef: T, property: keyof T) => {
    if (preGet) {
      preGet(targetRef, property);
    }
    return targetRef[property];
  };

  const set = (targetRef: T, property: keyof T, value: V) => {
    const currentValue = targetRef[property] as V | undefined;
    targetRef[property] = value;
    if (afterSet) {
      afterSet(targetRef, property, value, currentValue);
    }
    return true;
  };

  const deleteProperty = (targetRef: T, property: keyof T) => {
    const valToDelete = targetRef[property] as V | undefined;
    if (property in targetRef) {
      delete targetRef[property];
    }
    if (afterDelete) {
      afterDelete(targetRef, property, valToDelete);
    }
    return true;
  };

  return new Proxy(obj, { get, set, deleteProperty });
};





// Example Code

type testObj = {
  test?: string;
};
const t: testObj = {};
const onGet = (targetRef?: testObj, property?: keyof testObj) => {
  console.log(property); // prints test since this is the property being looked up
};

const x = watchObj<testObj, testObj[keyof testObj]>(t, onGet);
console.log(x.test); // prints undefined since there is no test key in the object