'use strict';

const $RAW = Symbol("state-raw");
function isWrappable(obj) {
  return obj != null && typeof obj === "object" && (Object.getPrototypeOf(obj) === Object.prototype || Array.isArray(obj));
}
function unwrap(item) {
  return item;
}
function setProperty(state, property, value, force) {
  if (!force && state[property] === value) return;
  if (value === undefined) {
    delete state[property];
  } else state[property] = value;
}
function mergeStoreNode(state, value, force) {
  const keys = Object.keys(value);
  for (let i = 0; i < keys.length; i += 1) {
    const key = keys[i];
    setProperty(state, key, value[key], force);
  }
}
function updateArray(current, next) {
  if (typeof next === "function") next = next(current);
  if (Array.isArray(next)) {
    if (current === next) return;
    let i = 0,
      len = next.length;
    for (; i < len; i++) {
      const value = next[i];
      if (current[i] !== value) setProperty(current, i, value);
    }
    setProperty(current, "length", len);
  } else mergeStoreNode(current, next);
}
function updatePath(current, path, traversed = []) {
  let part,
    next = current;
  if (path.length > 1) {
    part = path.shift();
    const partType = typeof part,
      isArray = Array.isArray(current);
    if (Array.isArray(part)) {
      for (let i = 0; i < part.length; i++) {
        updatePath(current, [part[i]].concat(path), traversed);
      }
      return;
    } else if (isArray && partType === "function") {
      for (let i = 0; i < current.length; i++) {
        if (part(current[i], i)) updatePath(current, [i].concat(path), traversed);
      }
      return;
    } else if (isArray && partType === "object") {
      const {
        from = 0,
        to = current.length - 1,
        by = 1
      } = part;
      for (let i = from; i <= to; i += by) {
        updatePath(current, [i].concat(path), traversed);
      }
      return;
    } else if (path.length > 1) {
      updatePath(current[part], path, [part].concat(traversed));
      return;
    }
    next = current[part];
    traversed = [part].concat(traversed);
  }
  let value = path[0];
  if (typeof value === "function") {
    value = value(next, traversed);
    if (value === next) return;
  }
  if (part === undefined && value == undefined) return;
  if (part === undefined || isWrappable(next) && isWrappable(value) && !Array.isArray(value)) {
    mergeStoreNode(next, value);
  } else setProperty(current, part, value);
}
function createStore(state) {
  const isArray = Array.isArray(state);
  function setStore(...args) {
    isArray && args.length === 1 ? updateArray(state, args[0]) : updatePath(state, args);
  }
  return [state, setStore];
}
function createMutable(state) {
  return state;
}
function reconcile(value, options = {}) {
  return state => {
    if (!isWrappable(state) || !isWrappable(value)) return value;
    const targetKeys = Object.keys(value);
    for (let i = 0, len = targetKeys.length; i < len; i++) {
      const key = targetKeys[i];
      setProperty(state, key, value[key]);
    }
    const previousKeys = Object.keys(state);
    for (let i = 0, len = previousKeys.length; i < len; i++) {
      if (value[previousKeys[i]] === undefined) setProperty(state, previousKeys[i], undefined);
    }
    return state;
  };
}
function produce(fn) {
  return state => {
    if (isWrappable(state)) fn(state);
    return state;
  };
}
const DEV = undefined;

exports.$RAW = $RAW;
exports.DEV = DEV;
exports.createMutable = createMutable;
exports.createStore = createStore;
exports.isWrappable = isWrappable;
exports.produce = produce;
exports.reconcile = reconcile;
exports.setProperty = setProperty;
exports.unwrap = unwrap;
exports.updatePath = updatePath;