'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

// @todo Add logger on options to debug when caches go wrong.
function createFallbackableCache(options) {
    const caches = [...options.caches];
    const current = caches.shift(); // eslint-disable-line functional/immutable-data
    if (current === undefined) {
        return createNullCache();
    }
    return {
        get(key, defaultValue, events = {
            miss: () => Promise.resolve(),
        }) {
            return current.get(key, defaultValue, events).catch(() => {
                return createFallbackableCache({ caches }).get(key, defaultValue, events);
            });
        },
        set(key, value) {
            return current.set(key, value).catch(() => {
                return createFallbackableCache({ caches }).set(key, value);
            });
        },
        delete(key) {
            return current.delete(key).catch(() => {
                return createFallbackableCache({ caches }).delete(key);
            });
        },
        clear() {
            return current.clear().catch(() => {
                return createFallbackableCache({ caches }).clear();
            });
        },
    };
}

function createNullCache() {
    return {
        get(_key, defaultValue, events = {
            miss: () => Promise.resolve(),
        }) {
            const value = defaultValue();
            return value
                .then(result => Promise.all([result, events.miss(result)]))
                .then(([result]) => result);
        },
        set(_key, value) {
            return Promise.resolve(value);
        },
        delete(_key) {
            return Promise.resolve();
        },
        clear() {
            return Promise.resolve();
        },
    };
}

exports.createFallbackableCache = createFallbackableCache;
exports.createNullCache = createNullCache;