Basic login for Pokemon Showdown Bot - Golang

package main

import (
    "encoding/json"
    "flag"
    "fmt"
    "io"
    "net/http"
    "net/url"
    "strings"

    "github.com/gorilla/websocket"
)

const (
    Server              = "sim.psim.us"
    WebsocketURL string = "wss://sim3.psim.us/showdown/websocket"
    ActionURL    string = "https://play.pokemonshowdown.com/~~" + Server + "/action.php"
)

// flags
var (
    name     = flag.String("name", "", "bot name")
    password = flag.String("pass", "", "bot password")
)

type Login struct {
    ActionSuccess bool        `json:"actionsuccess"`
    Assertion     string      `json:"assertion"`
    CurUser       CurrentUser `json:"curuser"`
}

type CurrentUser struct {
    LoggedIn bool   `json:"loggedin"`
    Username string `json:"username"`
    UserID   string `json:"userid"`
}

func main() {
    flag.Parse()

    conn, _, err := websocket.DefaultDialer.Dial(WebsocketURL, nil)
    if err != nil {
        panic(err)
    }
    defer conn.Close()

    fmt.Println("Connecting to Showdown...")
    for {
        _, b, err := conn.ReadMessage()
        if err != nil {
            panic(err)
        }

        fmt.Println(string(b))

        chunks := strings.Split(string(b), "|")
        switch chunks[1] {
        case "challstr":
            id, data := chunks[2], chunks[3]
            u, _ := url.Parse(ActionURL)
            q := u.Query()
            q.Set("act", "login")
            q.Set("name", *name)
            q.Set("pass", *password)
            q.Set("challengekeyid", id)
            q.Set("challstr", data)
            u.RawQuery = q.Encode()

            fmt.Println(u.String())

            res, err := http.Post(u.String(), "application/x-www-form-urlencoded", nil)
            if err != nil {
                panic(err)
            }

            fmt.Println("Response:", res.Status)

            body, err := io.ReadAll(res.Body)
            if err != nil {
                panic(err)
            }

            var login Login
            if err = json.Unmarshal(body[1:], &login); err != nil {
                panic(err)
            }

            fmt.Println(login)
            d := []byte(fmt.Sprintf("|/trn %s,0,%s", *name, login.Assertion))
            err = conn.WriteMessage(websocket.TextMessage, d)
            if err != nil {
                panic(err)
            }
        }
    }
}