auth.go

package main

import (
	"fmt"
	"log"
	"net/http"

	"github.com/joho/godotenv"
	"github.com/zmb3/spotify/v2"
	spotifyauth "github.com/zmb3/spotify/v2/auth"
)

const redirectURI = "http://localhost:8090/callback"

var (
	auth  *spotifyauth.Authenticator
	ch    = make(chan *spotify.Client)
	state = "abc123"
)

func init() {
	err := godotenv.Load()
	if err != nil {
		log.Fatal(err)
	}
	auth = spotifyauth.New(
		spotifyauth.WithRedirectURL(redirectURI),
		spotifyauth.WithScopes(spotifyauth.ScopePlaylistModifyPrivate),
	)
}

func completeAuth(w http.ResponseWriter, r *http.Request) {
	tok, err := auth.Token(r.Context(), state, r)
	if err != nil {
		http.Error(w, "Couldn't get token", http.StatusForbidden)
		log.Fatal(err)
	}
	if st := r.FormValue("state"); st != state {
		http.NotFound(w, r)
		log.Fatalf("State mismatch: %s != %s\n", st, state)
	}
	client := spotify.New(auth.Client(r.Context(), tok), spotify.WithRetry(true))
	w.Header().Set("Content-Type", "text/html")
	fmt.Fprintf(w, "Login completed!")
	ch <- client
}