import express, {IRouter, RequestHandler, Router} from "express";
import {PathParams} from "express-serve-static-core";
import config from "config";
import {logger} from "./Logger";
import FileUploadMiddleware from "./FileUploadMiddleware";
import * as querystring from "querystring";
import {ParsedUrlQueryInput} from "querystring";
import Middleware, {MiddlewareType} from "./Middleware";
import Application from "./Application";

export default abstract class Controller {
    private static readonly routes: { [p: string]: string | undefined } = {};

    public static route(
        route: string,
        params: RouteParams = [],
        query: ParsedUrlQueryInput = {},
        absolute: boolean = false,
    ): string {
        let path = this.routes[route];
        if (path === undefined) throw new Error(`Unknown route for name ${route}.`);

        if (typeof params === 'string' || typeof params === 'number') {
            path = path.replace(/:[a-zA-Z_-]+\??/g, '' + params);
        } else if (Array.isArray(params)) {
            let i = 0;
            for (const match of path.matchAll(/:[a-zA-Z_-]+(\(.*\))?\??/g)) {
                if (match.length > 0) {
                    path = path.replace(match[0], typeof params[i] !== 'undefined' ? params[i] : '');
                }
                i++;
            }
            path = path.replace(/\/+/g, '/');
        } else {
            for (const key of Object.keys(params)) {
                path = path.replace(new RegExp(`:${key}\\??`), params[key]);
            }
        }

        const queryStr = querystring.stringify(query);
        return `${absolute ? config.get<string>('public_url') : ''}${path}` + (queryStr.length > 0 ? '?' + queryStr : '');
    }

    private readonly router: Router = express.Router();
    private readonly fileUploadFormRouter: Router = express.Router();
    private app?: Application;

    public getGlobalMiddlewares(): Middleware[] {
        return [];
    }

    public hasGlobalMiddlewares(): boolean {
        return this.getGlobalMiddlewares().length > 0;
    }

    public setupGlobalHandlers(router: Router): void {
        for (const middleware of this.getGlobalMiddlewares()) {
            router.use(this.wrap(middleware.getRequestHandler()));
        }
    }

    public getRoutesPrefix(): string {
        return '/';
    }

    public abstract routes(): void;

    public setupRoutes(): { mainRouter: Router, fileUploadFormRouter: Router } {
        this.routes();
        return {
            mainRouter: this.router,
            fileUploadFormRouter: this.fileUploadFormRouter,
        };
    }

    protected use(handler: RequestHandler): void {
        this.router.use(this.wrap(handler));
        logger.info('Installed anonymous middleware on ' + this.getRoutesPrefix());
    }

    protected useMiddleware(...middlewares: MiddlewareType<Middleware>[]): void {
        for (const middleware of middlewares) {
            const instance = new middleware(this.getApp());
            if (instance instanceof FileUploadMiddleware) {
                this.fileUploadFormRouter.use(this.wrap(instance.getRequestHandler()));
            } else {
                this.router.use(this.wrap(instance.getRequestHandler()));
            }

            logger.info('Installed ' + middleware.name + ' on ' + this.getRoutesPrefix());
        }
    }

    protected get(
        path: PathParams,
        handler: RequestHandler,
        routeName?: string,
        ...middlewares: (MiddlewareType<Middleware>)[]
    ): void {
        this.handle('get', path, handler, routeName, ...middlewares);
    }

    protected post(
        path: PathParams,
        handler: RequestHandler,
        routeName?: string,
        ...middlewares: (MiddlewareType<Middleware>)[]
    ): void {
        this.handle('post', path, handler, routeName, ...middlewares);
    }

    protected put(
        path: PathParams,
        handler: RequestHandler,
        routeName?: string,
        ...middlewares: (MiddlewareType<Middleware>)[]
    ): void {
        this.handle('put', path, handler, routeName, ...middlewares);
    }

    protected delete(
        path: PathParams,
        handler: RequestHandler,
        routeName?: string,
        ...middlewares: (MiddlewareType<Middleware>)[]
    ): void {
        this.handle('delete', path, handler, routeName, ...middlewares);
    }

    private handle(
        action: Exclude<keyof IRouter, 'stack' | 'param' | 'route' | 'use'>,
        path: PathParams,
        handler: RequestHandler,
        routeName?: string,
        ...middlewares: (MiddlewareType<Middleware>)[]
    ): void {
        this.registerRoutes(path, handler, routeName);
        for (const middleware of middlewares) {
            const instance = new middleware(this.getApp());
            if (instance instanceof FileUploadMiddleware) {
                this.fileUploadFormRouter[action](path, this.wrap(instance.getRequestHandler()));
            } else {
                this.router[action](path, this.wrap(instance.getRequestHandler()));
            }
        }
        this.router[action](path, this.wrap(handler));
    }

    private wrap(handler: RequestHandler): RequestHandler {
        return async (req, res, next) => {
            try {
                await handler.call(this, req, res, next);
            } catch (e) {
                next(e);
            }
        };
    }

    private registerRoutes(path: PathParams, handler: RequestHandler, routeName?: string) {
        if (typeof routeName !== 'string') {
            routeName = handler.name
                .replace(/(?:^|\.?)([A-Z])/g, (x, y) => '_' + y.toLowerCase())
                .replace(/(^_|get_|post_)/g, '');
        }

        if (routeName.length === 0) return;

        let routePath = null;
        if (path instanceof Array && path.length > 0) {
            path = path[0];
        }
        if (typeof path === 'string') {
            const prefix = this.getRoutesPrefix();
            routePath = (prefix !== '/' ? prefix : '') + path;
        }

        if (!Controller.routes[routeName]) {
            if (typeof routePath === 'string') {
                logger.info(`Route ${routeName} has path ${routePath}`);
                Controller.routes[routeName] = routePath;
            } else {
                logger.warn(`Cannot assign path to route ${routeName}.`);
            }
        }
    }

    protected getApp(): Application {
        if (!this.app) throw new Error('Application not initialized.');
        return this.app;
    }

    public setApp(app: Application): void {
        this.app = app;
    }
}

export type RouteParams = { [p: string]: string } | string[] | string | number;