// Copyright 2020 The OpenZipkin Authors; licensed to You under the Apache License, Version 2.0.

const cls = require('continuation-local-storage');

const clsHooked = require('cls-hooked');

module.exports = class CLSContext {

constructor(namespace = 'zipkin', supportAsyncAwait = false) {

if (supportAsyncAwait) {

this._session = clsHooked.getNamespace(namespace) || clsHooked.createNamespace(namespace);

} else {

this._session = cls.getNamespace(namespace) || cls.createNamespace(namespace);

}

const defaultContext = this._session.createContext();

this._session.enter(defaultContext);

}

setContext(ctx) {

this._session.set('zipkin', ctx);

}

getContext() {

const currentCtx = this._session.get('zipkin');

if (currentCtx != null) {

return currentCtx;

} else {

return null; // explicitly return null (not undefined)

}

}

scoped(callable) {

let result;

this._session.run(() => {

result = callable();

});

return result;

}

letContext(ctx, callable) {

return this.scoped(() => {

this.setContext(ctx);

return callable();

});

}

// _bindEmitter is exposed but not meant to be used.

// It was introduced in the aim to test the async/await support

// for CLSContext.

// See https://github.com/openzipkin/zipkin-js/pull/499 for more

// context

_bindEmitter(emitter) {

this._session.bindEmitter(emitter);

}

};