cookie.go

package seven5

import (
	"errors"
	"fmt"
	"net/http"
	"strings"
)

const (
	SESSION_COOKIE = "%s-seven5-session"
)

var (
	NO_SUCH_COOKIE = errors.New("Cannot find cookie")
)

//CookieMapper mediates the interaction between requests and cookies. Most applications probably
//want to implement the SessionManager not the CookieMapper.  CookieMapper is primarily of interest
//for those who need to interact with the Set-Cookie and Cookie headers from/to the browser.
type CookieMapper interface {
	CookieName() string
	Value(*http.Request) (string, error)
	AssociateCookie(http.ResponseWriter, Session)
	RemoveCookie(http.ResponseWriter)
}

//SimpleCookieMapper is a default, cookie mapper that maps UDID strings to Session
//objects and uses a simple cookie scheme to extract the UDIDs from requests generated by the
//browser.
type SimpleCookieMapper struct {
	cook string
}

//NewSimpleCookieMapper creates an instance of CookieMapper with the given application name.
func NewSimpleCookieMapper(appName string) CookieMapper {
	result := &SimpleCookieMapper{
		cook: fmt.Sprintf(SESSION_COOKIE, appName),
	}
	return result
}

//AssociateCookie is used to effectively "Log in" a particular user by associating a session
//with a response w that will be sent back to their browser.
func (self *SimpleCookieMapper) AssociateCookie(w http.ResponseWriter, s Session) {
	cookie := &http.Cookie{
		Name:  self.CookieName(),
		Value: s.SessionId(),
		Path:  "/",
	}
	http.SetCookie(w, cookie)
}

//RemoveCookie is used to effectively "Log out" a particular user by removing the association of a session
//with a response w that will be sent back to their browser.
func (self *SimpleCookieMapper) RemoveCookie(w http.ResponseWriter) {
	cookie := &http.Cookie{
		Name:   self.CookieName(),
		Value:  "",
		Path:   "/",
		MaxAge: -1,
	}
	http.SetCookie(w, cookie)
}

//Value returns the cookie value associated with a given request or an error if that cookie is not
//present.  Usually the value is the UDID of the session.
func (self *SimpleCookieMapper) Value(r *http.Request) (string, error) {
	c, err := r.Cookie(self.CookieName())
	if err == http.ErrNoCookie {
		return "", NO_SUCH_COOKIE
	}
	return strings.TrimSpace(c.Value), nil
}

//CookieName returns the name of the cookie used for this application by this session manager.
func (self *SimpleCookieMapper) CookieName() string {
	return self.cook
}