import idb from './idb';

function isIndexedDBValid() {
    try {
        // Initialize IndexedDB; fall back to vendor-prefixed versions
        // if needed.
        if (!idb) {
            return false;
        }
        // We mimic PouchDB here;
        //
        // We test for openDatabase because IE Mobile identifies itself
        // as Safari. Oh the lulz...
        var isSafari = typeof openDatabase !== 'undefined' &&
        /(Safari|iPhone|iPad|iPod)/.test(navigator.userAgent) &&
        !/Chrome/.test(navigator.userAgent) &&
        !/BlackBerry/.test(navigator.platform);

        var hasFetch = typeof fetch === 'function' &&
        fetch.toString().indexOf('[native code') !== -1;

        // Safari <10.1 does not meet our requirements for IDB support (#5572)
        // since Safari 10.1 shipped with fetch, we can use that to detect it
        return (!isSafari || hasFetch) &&
        typeof indexedDB !== 'undefined' &&
        // some outdated implementations of IDB that appear on Samsung
        // and HTC Android devices <4.4 are missing IDBKeyRange
        typeof IDBKeyRange !== 'undefined';
    } catch (e) {
        return false;
    }
}

export default isIndexedDBValid;