import SystemJS from 'SystemJS';
|
|
export default class ApiFactory{
|
// @param events {EventEmitter}
|
constructor(events){
|
this.events = events;
|
}
|
|
// @param api {Object}
|
create(api){
|
// Adds two functions to obj
|
// - eventName
|
// - triggerEventName
|
// We could just use events, but methods
|
// are more robust as we can detect more easily if
|
// things break
|
|
const addEndpoint = (obj, eventName, preTrigger = () => {}) => {
|
const emitResponse = response => {
|
// Timeout needed for modules that have no dependencies
|
// and load synchronously. Gives time to setup the listeners.
|
setTimeout(() => {
|
this.events.emit(`${api.namespace}::${eventName}::Response`, response);
|
}, 0);
|
};
|
|
obj[eventName] = (callbackOrDeps, callbackOrUndef) => {
|
if (Array.isArray(callbackOrDeps)){
|
// Deps
|
// Load dependencies, then raise event as usual
|
// by appending the dependencies to the argument list
|
this.events.addListener(`${api.namespace}::${eventName}`, args => {
|
Promise.all(callbackOrDeps.map(dep => SystemJS.import(dep)))
|
.then((...deps) => {
|
|
// For each dependency, see if it exports a default module (ES6 style)
|
// if it does, export just the default module, otherwise export all modules
|
deps = deps.map(dep => {
|
return dep.map(exp => exp.default ? exp.default : exp);
|
});
|
|
const response = {
|
result: callbackOrUndef(...(Array.from([args]).concat(...deps))),
|
placeholder: args._placeholder
|
};
|
emitResponse(response);
|
});
|
});
|
}else{
|
// Callback
|
this.events.addListener(`${api.namespace}::${eventName}`, args => {
|
const response = {
|
result: callbackOrDeps(args),
|
placeholder: args._placeholder
|
};
|
emitResponse(response);
|
});
|
}
|
}
|
|
const triggerEventName = "trigger" + eventName[0].toUpperCase() + eventName.slice(1);
|
|
obj[triggerEventName] = (args, responseCb) => {
|
if (!args) args = {};
|
args._placeholder = {};
|
|
preTrigger(args, responseCb);
|
if (responseCb){
|
this.events.addListener(`${api.namespace}::${eventName}::Response`, response => {
|
// Give time to all listeners to receive the replies
|
// then remove the listener to avoid sending duplicate responses
|
const curSub = this.events._currentSubscription;
|
|
setTimeout(() => {
|
curSub.remove();
|
}, 0);
|
|
if (response.placeholder === args._placeholder) responseCb(response.result);
|
});
|
}
|
this.events.emit(`${api.namespace}::${eventName}`, args);
|
};
|
}
|
|
let obj = {};
|
api.endpoints.forEach(endpoint => {
|
if (!Array.isArray(endpoint)) endpoint = [endpoint];
|
addEndpoint(obj, ...endpoint);
|
});
|
|
if (api.helpers){
|
obj = Object.assign(obj, api.helpers);
|
}
|
|
// Handle syncronous function on/off/export
|
(api.functions || []).forEach(func => {
|
let callbacks = [];
|
obj[func] = (...args) => {
|
for (let i = 0; i < callbacks.length; i++){
|
if ((callbacks[i])(...args)) return true;
|
}
|
return false;
|
};
|
|
const onName = "on" + func[0].toUpperCase() + func.slice(1);
|
const offName = "off" + func[0].toUpperCase() + func.slice(1);
|
obj[onName] = f => {
|
callbacks.push(f);
|
};
|
obj[offName] = f => {
|
callbacks = callbacks.filter(cb => cb !== f);
|
};
|
});
|
|
return obj;
|
}
|
|
}
|
