import { Response, Request } from "express";
import { APIHelper } from "../helpers/APIHelper";
import { APIClient } from "./APIClient";

/**
 * Response to a request
 * 
 * @author Pierre HUBERT
 */

export class RequestHandler {

	private client : APIClient = null;

	public constructor(private req : Request, private response : Response) {}

	/**
	 * Get a parameter included in the post request
	 * 
	 * @param name Name of the parameter to get
	 */
	private getPostParam(name : string) : any {
		return this.req.body[name];
	}

	/**
	 * Get a String from the request
	 * 
	 * @param name The name of the string to get
	 * @param minLength Minimal required size of the string
	 * @param required If set to true (true by default), an error will
	 * be thrown if the string is not included in the request
	 */
	public getString(name : string, minLength : number = 1, required : boolean = true) : string {
		const param = this.getPostParam(name);

		// Check if parameter was not found
		if(param == undefined) {
			if(required)
				this.error(400, "Could not find required string: '"+name+"'");
			return "";
		}

		if(param.length < minLength)
			this.error(400, "Parameter "+name+" is too short!");

		return param;
	}


	/**
	 * Validate API tokens
	 * 
	 * @throws If the tokens could not be validated
	 */
	public async checkAPITokens() {

		// Extract API name & token from request
		const apiName = this.getString("serviceName");
		const apiToken = this.getString("serviceToken");
		
		// Validate the client
		const client = await APIHelper.GetClient(apiName, apiToken);

		if(client == null)
			this.error(400, "Client not recognized!");
		
		if(client.domain) {
			
			const allowedOrigin = "http://" + client.domain;

			const referer = this.req.get("Referer");
			if(!referer || !referer.startsWith(allowedOrigin))
				this.error(401, "Use of this client is prohibited from this domain!");
			
			this.response.set("Access-Control-Allow-Origin", allowedOrigin);
		}

		// Save client information for latter access
		this.client = client;
	}

	/**
	 * Output an error code
	 * 
	 * @param code HTTP Status code
	 * @param message The message to send
	 */
	public error(code : number, message : string) {
		this.response.status(code).send({
			code: code,
			message: message
		});

		throw Error("Could not complete request!");
	}

	/**
	 * Return a successful operation
	 * 
	 * @param message Message associated to success
	 */
	public success(message: string) {
		this.response.send({
			success: message
		});
	}

	/**
	 * Send some data to the server
	 * 
	 * @param data The data to send back to the server
	 */
	public send(data: any) {
		this.response.send(data);
	}
}