session.go

// package sessionmdl provides APIs to Add, Validate and Delete user sessions. These APIs must be used along with JWT Auth.
// If you want to use this functionality, a jwt token must contain `userId` and `sessionId` fields.
// A user can have multiple active sessions for different use cases. To check if user has an active session for particular usecase use `CheckForSessionAvailability()`.
// And to check user session on each request use `ValidateSessionFromToken()`.
//
// An in memory cache is used to store sessions. It automatically falls back to redis cache if -gridmode=1 is set.
//
// The expiraion of session must be same as of token expiration.

package sessionmdl

import (
	"errors"

	"corelab.mkcl.org/MKCLOS/coredevelopmentplatform/corepkgv2/cachemdl"
)

type Session struct {
	SessionFor string
	SessionId  string
}

// store is used to store sessions in memory, falls back to redis cache on grid mode.
var store cachemdl.Cacher

var (
	ErrUserNotFound            = errors.New("user not found")
	ErrSessionNotFound         = errors.New("session not found")
	ErrInvalidSessionInstance  = errors.New("got invalid session instance id")
	ErrSessionValidationFailed = errors.New("session validation failed")
)

// Init initializes sessions with provided cache. Subsequent calls will not have any effect after first initialization.
func Init(cache cachemdl.Cacher) {
	if store != nil {
		return
	}

	store = cache
}

// Set stores the sessions for provided userId. Session is appended to the list. It does not check if the same session exists or not.
func Set(userId string, s ...Session) {
	i, ok := store.Get(userId)
	if !ok || i == nil {
		set(userId, s)
		return
	}

	sessions, ok := i.([]Session)
	if !ok {
		set(userId, s)
		return
	}

	set(userId, append(sessions, s...))
}

func set(key string, val interface{}) {
	// Set the user sessions with no expiry as each session can have different expiry depending on the JWT token expiry.
	store.SetNoExpiration(key, val)
}

// Get returns all the available sessions for the user. This may contain expired but not deleted sessions.
func Get(userId string) ([]Session, error) {
	var (
		s  []Session
		i  interface{}
		ok bool
	)