V match-expression web routing

api.v

module main

import (
	os
	net
	net.http
	net.urllib
	strings
)

pub const (
	methods_with_form = ['POST', 'PUT', 'PATCH']
	method_all = ['GET','POST','PUT','PATCH','DELETE']
	HEADER_SERVER = 'Server: VWeb\r\n'
	HEADER_CONNECTION_CLOSE = 'Connection: close\r\n'
	HEADERS_CLOSE = '${HEADER_SERVER}${HEADER_CONNECTION_CLOSE}\r\n'
	HTTP_404 = 'HTTP/1.1 404 Not Found\r\nContent-Type: text/plain\r\n${HEADERS_CLOSE}404 Not Found'
	HTTP_500 = 'HTTP/1.1 500 Internal Server Error\r\nContent-Type: text/plain\r\n${HEADERS_CLOSE}500 Internal Server Error'
	MAX_HTTP_POST_SIZE = 1024 * 1024
	Default_Port = 8080
)

pub struct Context {
pub:
	req http.Request
	conn net.Socket
	// TODO Response
mut:
	headers string // response headers
	done bool
}

fn (ctx mut Context) send_response_to_client(mimetype string, res string) bool {
	if ctx.done { return false }
	ctx.done = true
	mut sb := strings.new_builder(1024)
	sb.write('HTTP/1.1 200 OK\r\nContent-Type: ') sb.write(mimetype)
	sb.write('\r\nContent-Length: ')              sb.write(res.len.str())
	sb.write(ctx.headers)
	sb.write('\r\n')
	sb.write(HEADERS_CLOSE)
	sb.write(res)
	ctx.conn.send_string(sb.str()) or { return false }
	sb.free()
	return true
}

pub fn (ctx mut Context) html(s string) {
	ctx.send_response_to_client('text/html', s)
}

pub fn (ctx mut Context) text(s string) {
	ctx.send_response_to_client('text/plain', s)
}

pub fn (ctx mut Context) json(s string) {
	ctx.send_response_to_client('application/json', s)
}

pub fn (ctx mut Context) redirect(url string) {
	if ctx.done { return }
	ctx.done = true
	ctx.conn.send_string('HTTP/1.1 302 Found\r\nLocation: ${url}${ctx.headers}\r\n${HEADERS_CLOSE}') or { return }
}

pub fn (ctx mut Context) not_found(s string) {
	if ctx.done { return }
	ctx.done = true
	ctx.conn.send_string(HTTP_404) or { return }
}

pub fn (ctx mut Context) add_header(key, val string) {
	//println('add_header($key, $val)')
	ctx.headers = ctx.headers + '\r\n$key: $val'
	//println(ctx.headers)
}

pub fn (ctx &Context) get_header(key string) string {
	return ctx.req.headers[key]
}

struct App {
pub mut:
	vweb Context // TODO embed
	cnt int
}

pub fn run(port int) {
	println('Running a Vweb app on http://localhost:$port ...')
	l := net.listen(port) or { panic('failed to listen') }
	mut app := App{}
	app.vweb = Context{}
	app.init()
	for {
		conn := l.accept() or { panic('accept() failed') }
		handle_conn(conn, mut app)
	}
}

fn handle_conn<T>(conn net.Socket, app mut T) {
	first_line := conn.read_line()
	println('firstline="$first_line"')
	$if debug { println(first_line) }
	vals := first_line.split(' ')
	if vals.len < 2 {
		println('no vals for http')
		conn.send_string(HTTP_500) or {}
		conn.close() or {}
		return
	}
	mut headers := []string
	mut body := ''
	mut in_headers := true
	mut len := 0
	mut body_len := 0
	for j := 0; j < 100; j++ {
		line := conn.read_line()
		sline := strip(line)
		if sline == '' {
				if len == 0 {
					break
				}
			in_headers = false
		}
		if in_headers {
			headers << sline
			if sline.starts_with('Content-Length') {
				len = sline.all_after(': ').int()
			}
		} else {
			body += sline + '\r\n'
			body_len += body.len
			if body_len >= len {
				break
			}
		}
	}

	req := http.Request{
		headers: http.parse_headers(headers) //s.split_into_lines())
		ws_func: 0
		user_ptr: 0
		method: vals[0]
		url: vals[1]
	}
	if true {
		println('req.headers = ')
		println(req.headers)
	}

	app.vweb = Context{
		req: req
		conn: conn
	}

	if vals.len < 2 {
		$if debug {
			println('no vals for http')
		}
		conn.close() or {}
		return
	}

	handle_route(req.url, req.method)
	conn.close() or {}
	app.reset()
}


fn strip(s string) string {
	// strip('\nabc\r\n') => 'abc'
	return s.trim('\r\n')
}

fn main() {
	println('noice')
	run(8082)
}

pub fn (app mut App) init() {
		println('init')
}

pub fn (app mut App) reset() {
}

pub fn handle_route(route string, method string) {
	match route {

	  '/example' { 
			match method {
				'GET'    { println('example GET') 		 }
				'POST'   { println('example POST') 		 } 
				'PUT'    { println('example PUT') 		 }
				'PATCH'  { println('example PATCH') 	 }
				 else 	 { println('example no match') }
			}
		}

		'/another' { 
			match method {
				'GET'    { println('another GET') 		 }
				'POST'   { println('another POST') 		 } 
				'PUT'    { println('another PUT') 		 }
				'PATCH'  { println('another PATCH') 	 }
				 else 	 { println('another no match') }
			}
		}

		else { println('no match') }
	}
}