import { Action } from './Action';

/**

* Container options.

*/

export interface UseContainerOptions {

/**

* If set to true, then default container will be used in the case if given container haven't returned anything.

*/

fallback?: boolean;

/**

* If set to true, then default container will be used in the case if given container thrown an exception.

*/

fallbackOnErrors?: boolean;

}

export type ClassConstructor<T> = { new (...args: any[]): T };

/**

* Container to be used by this library for inversion control. If container was not implicitly set then by default

* container simply creates a new instance of the given class.

*/

const defaultContainer: { get<T>(someClass: ClassConstructor<T> | Function): T } = new (class {

private instances: { type: Function; object: any }[] = [];

get<T>(someClass: ClassConstructor<T>): T {

let instance = this.instances.find(instance => instance.type === someClass);

if (!instance) {

instance = { type: someClass, object: new someClass() };

this.instances.push(instance);

}

return instance.object;

}

})();

let userContainer: { get<T>(someClass: ClassConstructor<T> | Function, action?: Action): T };

let userContainerOptions: UseContainerOptions;

/**

* Allows routing controllers to resolve objects using your IoC container

*/

export interface IocAdapter {

/**

* Return

*/

get<T>(someClass: ClassConstructor<T>, action?: Action): T;

}

/**

* Sets container to be used by this library.

*/

export function useContainer(iocAdapter: IocAdapter, options?: UseContainerOptions) {

userContainer = iocAdapter;

userContainerOptions = options;

}

/**

* Gets the IOC container used by this library.

* @param someClass A class constructor to resolve

* @param action The request/response context that `someClass` is being resolved for

*/

export function getFromContainer<T>(someClass: ClassConstructor<T> | Function, action?: Action): T {

if (userContainer) {

try {

const instance = userContainer.get(someClass, action);

if (instance) return instance;

if (!userContainerOptions || !userContainerOptions.fallback) return instance;

} catch (error) {

if (!userContainerOptions || !userContainerOptions.fallbackOnErrors) throw error;

}

}

return defaultContainer.get<T>(someClass);

}