import Promise = require("bluebird");

import {Location, Locator, LocatorFactory} from "./common";

const integerRegExp = /^\d+$/;

export interface SimpleLocatorParameters {
    resource : string;
    defaultPort? : number;
}

export class SimpleLocator {
    public static getLocatorFactory() : LocatorFactory {
        return function simpleLocator(parameters : string | SimpleLocatorParameters) : Locator {
            let resource : string = null;
            let defaultPort : number = null;

            if (typeof parameters === "string") {
                resource = parameters;
            } else if (parameters) {
                resource = parameters.resource;
                defaultPort = parameters.defaultPort;
            }

            if (!resource) {
                throw new Error("must have resource");
            }

            const locations = resource.split(";").map((locationString) => {
                const prefix = locationString.indexOf('https') === 0 ?
                    'https://' : locationString.indexOf('http') === 0 ? 'http://' : '';

                const temp = locationString.replace(prefix, '');
                const parts = temp.split(":");
                if (parts.length > 2) {
                    throw new Error(`invalid resource part '${temp}'`);
                }
                const location : Location = {host: `${prefix}${parts[0]}`};
                if (parts.length === 2) {
                    if (!integerRegExp.test(parts[1])) {
                        throw new Error(`invalid port in resource '${parts[1]}'`);
                    }
                    location.port = Number(parts[1]);
                } else if (defaultPort) {
                    location.port = defaultPort;
                }

                return location;
            });

            return () => {
                return Promise.resolve<Location>(locations[Math.floor(Math.random() * locations.length)]);
            };
        };
    }
}