package gfit

import (
	"context"
	"fmt"
	"net/http"

	"github.com/octo/gfitsync/app"
	"golang.org/x/oauth2"
	oauth2google "golang.org/x/oauth2/google"
	fitness "google.golang.org/api/fitness/v1"
)

var oauthConfig = &oauth2.Config{
	ClientID:     "@GOOGLE_CLIENT_ID@",
	ClientSecret: "@GOOGLE_CLIENT_SECRET@",
	Endpoint:     oauth2google.Endpoint,
	RedirectURL:  "https://fitbit-gfit-sync.appspot.com/google/grant",
	Scopes: []string{
		fitness.FitnessActivityWriteScope,
		fitness.FitnessBodyWriteScope,
	},
}

const csrfToken = "@CSRFTOKEN@"

func AuthURL() string {
	return oauthConfig.AuthCodeURL(csrfToken, oauth2.AccessTypeOffline)
}

func ParseToken(ctx context.Context, r *http.Request, u *app.User) error {
	if state := r.FormValue("state"); state != csrfToken {
		return fmt.Errorf("invalid state parameter: %q", state)
	}

	tok, err := oauthConfig.Exchange(ctx, r.FormValue("code"))
	if err != nil {
		return err
	}

	return u.SetToken(ctx, "Google", tok)
}

type Client struct {
	*fitness.Service
}

func NewClient(ctx context.Context, u *app.User) (*Client, error) {
	c, err := u.OAuthClient(ctx, "Google", oauthConfig)
	if err != nil {
		return nil, err
	}

	service, err := fitness.New(c)
	if err != nil {
		return nil, err
	}

	return &Client{
		Service: service,
	}, nil
}