auru / unity-cache

const EXPIRE_BIN = '___expire___';

const EXPIRE_GLUE = '::';

const DEFAULT_NAME = 'unity';

const DEFAULT_DESCRIPTION = 'Unity cache';

let cacheBins = {};

function createCacheBins(bins, name, description, driver) {

    bins = [].concat(bins, EXPIRE_BIN);

    return bins.reduce((result, storeName) => {

        if (!RE_BIN.test(storeName)) {

            throw new UnityCacheError(`Store names can only be alphanumeric, '${storeName}' given`);

        }

        result[storeName] = localforage.createInstance({

            storeName,

            name,

            description,

            driver

        });

        return result;

    }, {});

}

function getExpireKey(bin, key) {

    return bin + EXPIRE_GLUE + key;

}

async function get(bin, key, validate = true) {

    const expired = await cacheBins[EXPIRE_BIN].getItem(getExpireKey(bin, key));

    const isValid = validate && cacheBins[bin] ? expired > Date.now() : true;

    if (!isValid) {

        await cacheBins[EXPIRE_BIN].removeItem(getExpireKey(bin, key));

    }

    return isValid ? await cacheBins[bin].getItem(key) : null; // localForage return null if item doesn't exist

}

async function set(bin, key, data, expire = Number.MAX_SAFE_INTEGER) {

    return await Promise.all([

        cacheBins[EXPIRE_BIN].setItem(getExpireKey(bin, key), Date.now() + Number(expire)),

        cacheBins[bin].setItem(key, data)

    ]);

}

async function remove(bin, key) {

    return await Promise.all([

        cacheBins[EXPIRE_BIN].removeItem(getExpireKey(bin, key)),

        cacheBins[bin].removeItem(key)

    ]);

}

function drop(bins) {

    bins = [].concat(bins);

    bins.map(bin => cacheBins[bin].clear());

}

function createCache(bins, name = DEFAULT_NAME, description = DEFAULT_DESCRIPTION, driver = DB_DRIVER) {

    cacheBins = createCacheBins(bins, name, description, driver);

    return {

        get,

        set,

        remove,

        drop

    };

}

export default createCache;