import {
    AsyncErrorCallback,
    FlowFunction,
    FlowNextCallback,
    Dictionary
} from "../interfaces";

export function flow<E>(
    start: string,
    fns: Dictionary<FlowFunction<E>>,
    final?: AsyncErrorCallback<E>
): void {

    let tmp: Dictionary<FlowFunction<E>> = {};

    for (let key in fns) {

        tmp[key] = fns[key];
    }

    fns = tmp;

    let loop = function(next: string, ...args: any[]): void {

        if (fns[next]) {

            fns[next](function(next: string, err?: E, ...args: any[]): void {

                // do not disable duplicated invocation to next callback.

                if (err !== null && err !== undefined) {

                    final && final(err);
                }
                else {

                    loop(next, ...args);
                }
            }, ...args);
        }
        else {

            final && final();
        }
    };

    loop(start);
}