package jwt

import (

	"sync"

)

var signingMethods = map[string]func() SigningMethod{}

var signingMethodLock = new(sync.RWMutex)

// Implement SigningMethod to add new methods for signing or verifying tokens.

type SigningMethod interface {

	Verify(signingString, signature string, key interface{}) error // Returns nil if signature is valid

	Sign(signingString string, key interface{}) (string, error)    // Returns encoded signature or error

	Alg() string                                                   // returns the alg identifier for this method (example: 'HS256')

}

// Register the "alg" name and a factory function for signing method.

// This is typically done during init() in the method's implementation

func RegisterSigningMethod(alg string, f func() SigningMethod) {

	signingMethodLock.Lock()

	defer signingMethodLock.Unlock()

	signingMethods[alg] = f

}

// Get a signing method from an "alg" string

func GetSigningMethod(alg string) (method SigningMethod) {

	signingMethodLock.RLock()

	defer signingMethodLock.RUnlock()

	if methodF, ok := signingMethods[alg]; ok {

		method = methodF()

	}

	return

}