/*
 * Copyright © 2015-2018 Aeneas Rekkas <aeneas+oss@aeneas.io>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @author		Aeneas Rekkas <aeneas+oss@aeneas.io>
 * @copyright 	2015-2018 Aeneas Rekkas <aeneas+oss@aeneas.io>
 * @license 	Apache-2.0
 *
 */

package oauth2

import (
	"context"
	"time"

	"github.com/ory/x/errorsx"

	"github.com/ory/fosite"
	enigma "github.com/ory/fosite/token/hmac"
)

type HMACSHAStrategy struct {
	Enigma                *enigma.HMACStrategy
	AccessTokenLifespan   time.Duration
	RefreshTokenLifespan  time.Duration
	AuthorizeCodeLifespan time.Duration
}

func (h HMACSHAStrategy) AccessTokenSignature(token string) string {
	return h.Enigma.Signature(token)
}
func (h HMACSHAStrategy) RefreshTokenSignature(token string) string {
	return h.Enigma.Signature(token)
}
func (h HMACSHAStrategy) AuthorizeCodeSignature(token string) string {
	return h.Enigma.Signature(token)
}

func (h HMACSHAStrategy) GenerateAccessToken(_ context.Context, _ fosite.Requester) (token string, signature string, err error) {
	return h.Enigma.Generate()
}

func (h HMACSHAStrategy) ValidateAccessToken(_ context.Context, r fosite.Requester, token string) (err error) {
	var exp = r.GetSession().GetExpiresAt(fosite.AccessToken)
	if exp.IsZero() && r.GetRequestedAt().Add(h.AccessTokenLifespan).Before(time.Now().UTC()) {
		return errorsx.WithStack(fosite.ErrTokenExpired.WithHintf("Access token expired at '%s'.", r.GetRequestedAt().Add(h.AccessTokenLifespan)))
	}
	if !exp.IsZero() && exp.Before(time.Now().UTC()) {
		return errorsx.WithStack(fosite.ErrTokenExpired.WithHintf("Access token expired at '%s'.", exp))
	}
	return h.Enigma.Validate(token)
}

func (h HMACSHAStrategy) GenerateRefreshToken(_ context.Context, _ fosite.Requester) (token string, signature string, err error) {
	return h.Enigma.Generate()
}

func (h HMACSHAStrategy) ValidateRefreshToken(_ context.Context, r fosite.Requester, token string) (err error) {
	var exp = r.GetSession().GetExpiresAt(fosite.RefreshToken)
	if exp.IsZero() {
		// Unlimited lifetime
		return h.Enigma.Validate(token)
	}
	if !exp.IsZero() && exp.Before(time.Now().UTC()) {
		return errorsx.WithStack(fosite.ErrTokenExpired.WithHintf("Refresh token expired at '%s'.", exp))
	}
	return h.Enigma.Validate(token)
}

func (h HMACSHAStrategy) GenerateAuthorizeCode(_ context.Context, _ fosite.Requester) (token string, signature string, err error) {
	return h.Enigma.Generate()
}

func (h HMACSHAStrategy) ValidateAuthorizeCode(_ context.Context, r fosite.Requester, token string) (err error) {
	var exp = r.GetSession().GetExpiresAt(fosite.AuthorizeCode)
	if exp.IsZero() && r.GetRequestedAt().Add(h.AuthorizeCodeLifespan).Before(time.Now().UTC()) {
		return errorsx.WithStack(fosite.ErrTokenExpired.WithHintf("Authorize code expired at '%s'.", r.GetRequestedAt().Add(h.AuthorizeCodeLifespan)))
	}
	if !exp.IsZero() && exp.Before(time.Now().UTC()) {
		return errorsx.WithStack(fosite.ErrTokenExpired.WithHintf("Authorize code expired at '%s'.", exp))
	}

	return h.Enigma.Validate(token)
}