package client

import (
	"bytes"
	"fmt"
	"io"
	"net"
	"time"
)

const PicomapPort = 28781

type udpTransport struct {
	conn *net.UDPConn
	buf  bytes.Buffer
}

func NewUDP(addr string, timeout time.Duration) (*Client, error) {
	raddr, err := net.ResolveUDPAddr("udp4", fmt.Sprintf("%s:%d", addr, PicomapPort))
	if err != nil {
		return nil, fmt.Errorf("resolve %s: %w", addr, err)
	}
	conn, err := net.DialUDP("udp4", nil, raddr)
	if err != nil {
		return nil, fmt.Errorf("dial %s: %w", addr, err)
	}
	return &Client{transport: &udpTransport{conn: conn}, timeout: timeout}, nil
}

func (t *udpTransport) Send(data []byte) error {
	_, err := t.conn.Write(data)
	return err
}

func (t *udpTransport) SetReadTimeout(timeout time.Duration) {
	t.conn.SetReadDeadline(time.Now().Add(timeout))
}

func (t *udpTransport) Reader() io.Reader {
	for {
		if t.buf.Len() > 0 {
			return &t.buf
		}
		pkt := make([]byte, 1500)
		n, err := t.conn.Read(pkt)
		if err != nil {
			return &t.buf
		}
		t.buf.Write(pkt[:n])
	}
}

func (t *udpTransport) Close() error {
	return t.conn.Close()
}