github.go

package github

import (
	"errors"
	"net/http"
	"time"

	"github.com/nsheridan/cashier/server/auth"
	"github.com/nsheridan/cashier/server/config"

	githubapi "github.com/google/go-github/github"
	"golang.org/x/oauth2"
	"golang.org/x/oauth2/github"
)

const (
	name = "github"
)

// Config is an implementation of `auth.Provider` for authenticating using a
// Github account.
type Config struct {
	config       *oauth2.Config
	organization string
}

// New creates a new Github provider from a configuration.
func New(c *config.Auth) (auth.Provider, error) {
	if c.ProviderOpts["organization"] == "" {
		return nil, errors.New("github_opts organization must not be empty")
	}
	return &Config{
		config: &oauth2.Config{
			ClientID:     c.OauthClientID,
			ClientSecret: c.OauthClientSecret,
			RedirectURL:  c.OauthCallbackURL,
			Endpoint:     github.Endpoint,
			Scopes: []string{
				string(githubapi.ScopeUser),
				string(githubapi.ScopeReadOrg),
			},
		},
		organization: c.ProviderOpts["organization"],
	}, nil
}

// A new oauth2 http client.
func (c *Config) newClient(token *oauth2.Token) *http.Client {
	return c.config.Client(oauth2.NoContext, token)
}

// Name returns the name of the provider.
func (c *Config) Name() string {
	return name
}

// Valid validates the oauth token.
func (c *Config) Valid(token *oauth2.Token) bool {
	if !token.Valid() {
		return false
	}
	client := githubapi.NewClient(c.newClient(token))
	member, _, err := client.Organizations.IsMember(c.organization, c.Username(token))
	if err != nil {
		return false
	}
	return member
}

// GitHub doesn't seem to allow token revocation - tokens are indefinite and