import { Response, Request } from "express";
import { APIHelper } from "../helpers/APIHelper";
import { APIClient } from "./APIClient";
import { checkMail } from "../utils/StringUtils";
import { AccountHelper } from "../helpers/AccountHelper";
import { UploadedFile } from "express-fileupload";

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

export class RequestHandler {

	private client : APIClient = null;
	private userID : number = -1;
	
	private responseSent = false;

	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 postString(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;
	}

	/**
	 * Check out whether a post parameter is present into the request or not
	 * 
	 * @param name The name of the post field to check
	 */
	public hasPostParameter(name: string) : boolean {
		return this.getPostParam(name) != undefined;
	}

	/**
	 * Get an email address included in a post request
	 * 
	 * @param name The name of the POST filed
	 */
	public postEmail(name: string) : string {
		const email = this.postString(name, 3);

		if(!checkMail(email))
			this.error(400, email + " is not a valid email address!");
		
		return email;
	}

	/**
	 * Get an integer included in the request
	 * 
	 * @param name Name of POST field
	 * @param fallback Fallback value (if none, throw an error)
	 * @returns The number (throws in case of error)
	 */
	public postInt(name: string, fallback ?: number) : number {
		const param = this.getPostParam(name);

		if(param == undefined) {
			if(!fallback)
				this.error(400, "Missing integer '"+name+"' in the request!");
			return fallback;
		}

		// Check number
		if(Number.parseInt(param).toString() !== param.toString())
			this.error(400, "'"+name+"' is an invalid integer!");

		return Number.parseInt(param);
	}


	/**
	 * Get a list of integeres included in the request
	 * 
	 * @param name The name of the post field
	 * @param minEntries Specify the minimum number of entries required
	 */
	public postNumbersList(name: string,  minEntries : number = 1) : Array<number> {
		const param = this.postString(name, minEntries < 1 ? 0 : minEntries, minEntries > 0);
		let list = [];
		for (const el of param.split(",")) {
			
			if(el == "")
				continue;

			if(Number.parseInt(el).toString() != el)
				this.error(400, "Invalid number detected in '"+name+"'!");

			list.push(Number.parseInt(el));
			
		}

		if(list.length < minEntries)
			this.error(400, "Not enough entries in '" + name + "'!")

		return list;
	}

	/**
	 * Turn a list of string into a Set object
	 * 
	 * @param name Name of POST field
	 * @param minEntries Minimum number of entries to specify
	 */
	public postNumbersSet(name : string, minEntries : number = 1) : Set<number> {
		return new Set(this.postNumbersList(name, minEntries));
	}

	/**
	 * Attempt to decode JSON included in a POST request
	 * 
	 * @param name Name of POST field
	 */
	public postJSON(name: string) : any {
		const src = this.getPostParam(name);

		if(src == undefined)
			this.error(400, "Missing JSON '" + name + "' in the request!");
		
		try {
			const response = JSON.parse(src);
			return response;
		} catch(e) {
			this.error(500, "'" + name + "' is not a valid JSON !");
		}
	}

	/**
	 * Get a boolean included in the request
	 * 
	 * @param name The name of the POST field
	 */
	public postBool(name: string) : boolean {
		const param = this.getPostParam(name);

		if(param == undefined)
			this.error(400, "Missing boolean '" + name + "' in the request!");
		
		return param === "true" || param === true;
	}

	/**
	 * Get information about an uploaded file
	 * 
	 * @param name The name of the posted file
	 */
	private GetUploadedFile(name: string) : undefined | UploadedFile {
		
		if(!this.req.files)
			return undefined;

		if(this.req.files[name] instanceof Array)
			this.error(500, "Multiple upload are not supported!");
		
		return <UploadedFile|undefined>this.req.files[name];
	}

	/**
	 * Check out whether a file has been included in the request or not
	 * 
	 * @param name The name of the file to check
	 */
	public hasFile(name: string) : boolean {
		return this.GetUploadedFile(name) != undefined;
	}


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

		// Extract API name & token from request
		const apiName = this.postString("serviceName");
		const apiToken = this.postString("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;
	}

	/**
	 * Validate user tokens
	 *
	 * @param required Specify whether the user MUST be authenticated or not
	 */
	public async checkUserTokens(required ?: boolean) {

		const token1 = this.postString("userToken1", 0, false);
		const token2 = this.postString("userToken2", 0, false);

		if(token1.length < 1 || token2.length < 1) {
			if(required !== false)
				this.error(401, "This method requires the user to be signed in!");
			return;
		}
		
		
		// Validate user tokens
		this.userID = await AccountHelper.GetUserIdFromTokens(this.getClientInfo(), token1, token2);

		if(this.userID < 1)
			this.error(412, "Please check your login tokens!");
	}

	/**
	 * Get information about API client
	 */
	public getClientInfo() : APIClient {

		if(!this.client)
			throw Error("Try to get information about client but client has not been authenticated!");

		return this.client;
	}

	/**
	 * Get information about current user
	 */
	public getUserId() : number {
		if(this.userID < 1)
			throw Error("Trying to get user ID but none are available!");
		
		return this.userID;
	}

	/**
	 * Check out whether user is signed in or not
	 */
	public get signedIn() : boolean {
		return this.userID > 0;
	}

	/**
	 * Output an error code and throws an error
	 * 
	 * @param code HTTP Status code
	 * @param message The message to send
	 */
	public error(code : number, message : string, should_throw: boolean = true) {

		if(this.responseSent)
			return;

		this.response.status(code).send({
			error: {
				code: code,
				message: message
			}
		});

		this.responseSent = true;

		if(should_throw)
			throw Error("Could not complete request! ("+ message +")");
	}

	/**
	 * Return a successful operation
	 * 
	 * @param message Message associated to success
	 */
	public success(message: string) {

		this.responseSent = true;

		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.responseSent = true;

		this.response.send(data);
	}
}