import { Framework } from './types.mjs';
import { detect } from './detection/index.mjs';

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
// We want to cache detection since the framework won't change
let frameworkCache;
const frameworkChangeObservers = [];
// Setup the detection reset tracking / timeout delays
let resetTriggered = false;
const SSR_RESET_TIMEOUT = 10; // ms
const WEB_RESET_TIMEOUT = 10; // ms
const PRIME_FRAMEWORK_DELAY = 1000; // ms
const detectFramework = () => {
    if (!frameworkCache) {
        frameworkCache = detect();
        if (resetTriggered) {
            // The final run of detectFramework:
            // Starting from this point, the `frameworkCache` becomes "final".
            // So we don't need to notify the observers again so the observer
            // can be removed after the final notice.
            while (frameworkChangeObservers.length) {
                frameworkChangeObservers.pop()?.();
            }
        }
        else {
            // The first run of detectFramework:
            // Every time we update the cache, call each observer function
            frameworkChangeObservers.forEach(fcn => {
                fcn();
            });
        }
        // Retry once for either Unknown type after a delay (explained below)
        resetTimeout(Framework.ServerSideUnknown, SSR_RESET_TIMEOUT);
        resetTimeout(Framework.WebUnknown, WEB_RESET_TIMEOUT);
    }
    return frameworkCache;
};
/**
 * @internal Setup observer callback that will be called everytime the framework changes
 */
const observeFrameworkChanges = (fcn) => {
    // When the `frameworkCache` won't be updated again, we ignore all incoming
    // observers.
    if (resetTriggered) {
        return;
    }
    frameworkChangeObservers.push(fcn);
};
function clearCache() {
    frameworkCache = undefined;
}
// For a framework type and a delay amount, setup the event to re-detect
//   During the runtime boot, it is possible that framework detection will
//   be triggered before the framework has made modifications to the
//   global/window/etc needed for detection. When no framework is detected
//   we will reset and try again to ensure we don't use a cached
//   non-framework detection result for all requests.
function resetTimeout(framework, delay) {
    if (frameworkCache === framework && !resetTriggered) {
        setTimeout(() => {
            clearCache();
            resetTriggered = true;
            setTimeout(detectFramework, PRIME_FRAMEWORK_DELAY);
        }, delay);
    }
}

export { clearCache, detectFramework, frameworkChangeObservers, observeFrameworkChanges };
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