package auth

import (
	"context"
	"errors"
	"fmt"
	"os"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/google"
)

type OAuthConfig struct {
	*oauth2.Config
}

const (
	base         = "https://www.googleapis.com"
	scopeEmail   = base + "/auth/userinfo.email"
	scopeProfile = base + "/auth/userinfo.profile"
)

func NewOauthConfig(path string) (OAuthConfig, error) {
	key, err := os.ReadFile(path)
	if err != nil {
		return OAuthConfig{}, fmt.Errorf("could not open file: %w", err)
	}

	config, err := google.ConfigFromJSON(key, scopeEmail, scopeProfile)
	if err != nil {
		return OAuthConfig{}, fmt.Errorf("could not load config: %w", err)
	}

	return OAuthConfig{
		Config: config,
	}, nil
}

var ErrInvalidState = errors.New("invalid ouath state provided")

type OAuthManager interface {
	Create(callback string) (code string)
	Validate(code string) (callback string, valid bool)
}

func (cfg OAuthConfig) AuthCodeURL(manager OAuthManager, callback string) string {
	state := manager.Create(callback)
	fmt.Printf("state: %v\n", state)

	return cfg.Config.AuthCodeURL(state, oauth2.AccessTypeOffline)
}

func (cfg OAuthConfig) Exchange(ctx context.Context, manager OAuthManager, state, code string) (string, *oauth2.Token, error) {
	var ok bool
	var callback string
	if callback, ok = manager.Validate(state); !ok {
		return "", nil, ErrInvalidState
	}

	tk, err := cfg.Config.Exchange(ctx, code, oauth2.AccessTypeOffline)
	return callback, tk, err
}