import express, { Request, Response, NextFunction } from 'express'

import morgan from 'morgan'

const app = express()

const port:number = 3000

interface Product {

name: string

price: number

brand: string

category?: string

}

interface ProductCreationResponse {

productID: string

result: string

}

class AppError extends Error{

statusCode: number;

constructor(statusCode: number, message: string) {

super(message);

Object.setPrototypeOf(this, new.target.prototype);

this.name = Error.name;

this.statusCode = statusCode;

Error.captureStackTrace(this);

}

}

const requestLogger = (request: Request, response: Response, next: NextFunction) => {

console.log(`${request.method} url:: ${request.url}`);

next()

}

app.use(express.static('images'))

app.use(express.static('htmls'))

app.use(requestLogger)

app.use(morgan('tiny'))

app.use('/products', express.json({ limit: 100 }))

// Error handling Middleware functions

const errorLogger = (error: Error, request: Request, response: Response, next: NextFunction) => {

console.log( `error ${error.message}`)

next(error) // calling next middleware

}

const errorResponder = (error: AppError, request: Request, response: Response, next: NextFunction) => {

response.header("Content-Type", 'application/json')

const status = error.statusCode || 400

response.status(status).send(error.message)

}

const invalidPathHandler = (request: Request, response: Response, next: NextFunction) => {

response.status(400)

response.send('invalid path')

}

app.get('product', (request: Request, response: Response)=>{

response.sendFile("productsample.html")

})

// handle get request for path /

app.get('/', (request: Request, response: Response) => {

response.send('response for GET request');

})

const requireJsonContent = (request: Request, response: Response, next: NextFunction) => {

if (request.headers['content-type'] !== 'application/json') {

response.status(400).send('Server requires application/json')

} else {

next()

}

}

const addProducts = (request: Request, response: Response, next: NextFunction) => {

let products: Product[] = []

const name: string = request.body.name

const brand: string = request.body.brand

const category: string = request.body.category

console.log(name + " " + brand)

products.push({name: request.body.name, brand: request.body.brand, price: request.body.price})

const productCreationResponse: ProductCreationResponse = {productID: "12345", result: "success"}

response.json(productCreationResponse)

response.status(200).json(products);

}

app.post('/products', addProducts)

app.get('/productswitherror', (request: Request, response: Response) => {

let error: AppError = new AppError(400, `processing error in request at ${request.url}`)

throw error

})

app.use(errorLogger)

app.use(errorResponder)

app.use(invalidPathHandler)

app.listen(port, () => {

console.log(`Server listening at port ${port}.`)

})