import debug from 'debug';
import reduce from 'lodash/reduce';

const log = debug('scope:storage-utils');

// localStorage detection
const storage = (typeof Storage) !== 'undefined' ? window.localStorage : null;

export function storageGet(key, defaultValue) {
  if (storage && storage.getItem(key) !== undefined) {
    return storage.getItem(key);
  }
  return defaultValue;
}

export function storageSet(key, value) {
  if (storage) {
    try {
      storage.setItem(key, value);
      return true;
    } catch (e) {
      log('Error storing value in storage. Maybe full? Could not store key.', key);
    }
  }
  return false;
}

export function storageGetObject(key, defaultValue) {
  const value = storageGet(key);
  if (value) {
    try {
      return JSON.parse(value);
    } catch (e) {
      log('Error getting object for key.', key);
    }
  }
  return defaultValue;
}

export function storageSetObject(key, obj) {
  try {
    return storageSet(key, JSON.stringify(obj));
  } catch (e) {
    log('Error encoding object for key', key);
  }
  return false;
}

function typeOf(obj) {
  return Object.prototype.toString.call(obj).slice(8, -1).toLowerCase();
}

// Checks the shape of an object. Ignores the signature of elements in arrays.
function shapeOf(obj) {
  return reduce(obj, (result, val, key) => {
    const type = typeOf(val);
    if (type === 'null' || type === 'undefined') {
      // Do nothing
      return result;
    } else if (type === 'object') {
      result[key] = shapeOf(val);
    } else {
      result[key] = type;
    }
    return result;
  }, {});
}

export function isCompatibleShape(object, target) {
  const shape = JSON.stringify(shapeOf(object));
  const targetString = JSON.stringify(shapeOf(target));
  return shape === targetString;
}