/*
	Copyright NetFoundry, Inc.

	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

	https://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.
*/

package model

import (
	"encoding/base64"
	"errors"
	"fmt"
	"github.com/openziti/edge/controller/apierror"
	"github.com/openziti/edge/controller/persistence"
	"github.com/openziti/edge/crypto"
	cert2 "github.com/openziti/edge/internal/cert"
	"github.com/openziti/fabric/controller/models"
	"github.com/openziti/foundation/storage/ast"
	"github.com/openziti/foundation/storage/boltz"
	"go.etcd.io/bbolt"
	"reflect"
	"strings"
)

type AuthenticatorHandler struct {
	baseHandler
	authStore persistence.AuthenticatorStore
}

func (handler AuthenticatorHandler) Delete(id string) error {
	return handler.deleteEntity(id)
}

func (handler AuthenticatorHandler) IsUpdated(field string) bool {
	return !strings.EqualFold(field, "method") && !strings.EqualFold(field, "identityId")
}

func NewAuthenticatorHandler(env Env) *AuthenticatorHandler {
	handler := &AuthenticatorHandler{
		baseHandler: newBaseHandler(env, env.GetStores().Authenticator),
		authStore:   env.GetStores().Authenticator,
	}

	handler.impl = handler
	return handler
}

func (handler AuthenticatorHandler) newModelEntity() boltEntitySink {
	return &Authenticator{}
}

func (handler AuthenticatorHandler) IsAuthorized(authContext AuthContext) (*Identity, error) {

	authModule := handler.env.GetAuthRegistry().GetByMethod(authContext.GetMethod())

	if authModule == nil {
		return nil, apierror.NewInvalidAuthMethod()
	}

	identityId, err := authModule.Process(authContext)

	if err != nil {
		return nil, err
	}

	if identityId == "" {
		return nil, apierror.NewInvalidAuth()
	}

	return handler.env.GetHandlers().Identity.Read(identityId)
}

func (handler AuthenticatorHandler) ReadFingerprints(authenticatorId string) ([]string, error) {
	var authenticator *persistence.Authenticator

	err := handler.env.GetStores().DbProvider.GetDb().View(func(tx *bbolt.Tx) error {
		var err error
		authenticator, err = handler.authStore.LoadOneById(tx, authenticatorId)
		return err
	})

	if err != nil {
		return nil, err
	}

	return authenticator.ToSubType().Fingerprints(), nil
}

func (handler *AuthenticatorHandler) Read(id string) (*Authenticator, error) {
	modelEntity := &Authenticator{}
	if err := handler.readEntity(id, modelEntity); err != nil {
		return nil, err
	}
	return modelEntity, nil
}

func (handler *AuthenticatorHandler) Create(authenticator *Authenticator) (string, error) {
	queryString := fmt.Sprintf(`method = "%s"`, authenticator.Method)
	query, err := ast.Parse(handler.GetStore(), queryString)
	if err != nil {
		return "", err
	}
	result, err := handler.ListForIdentity(authenticator.IdentityId, query)

	if err != nil {
		return "", err
	}

	if result.GetMetaData().Count > 0 {
		return "", apierror.NewAuthenticatorMethodMax()
	}

	if authenticator.Method == persistence.MethodAuthenticatorUpdb {
		if updb, ok := authenticator.SubType.(*AuthenticatorUpdb); ok {
			hashResult := handler.HashPassword(updb.Password)
			updb.Password = hashResult.Password
			updb.Salt = hashResult.Salt
		}
	}
	return handler.createEntity(authenticator)
}

func (handler AuthenticatorHandler) ReadByUsername(username string) (*Authenticator, error) {
	query := fmt.Sprintf("%s = \"%v\"", persistence.FieldAuthenticatorUpdbUsername, username)

	entity, err := handler.readEntityByQuery(query)

	if err != nil {
		return nil, err
	}

	if entity == nil {
		return nil, nil
	}

	authenticator, ok := entity.(*Authenticator)

	if !ok {
		return nil, fmt.Errorf("could not cast from %v to authenticator", reflect.TypeOf(entity))
	}

	return authenticator, nil
}

func (handler AuthenticatorHandler) ReadByFingerprint(fingerprint string) (*Authenticator, error) {
	query := fmt.Sprintf("%s = \"%v\"", persistence.FieldAuthenticatorCertFingerprint, fingerprint)

	entity, err := handler.readEntityByQuery(query)

	if err != nil {
		return nil, err
	}

	if entity == nil {
		return nil, nil
	}

	authenticator, ok := entity.(*Authenticator)

	if !ok {
		return nil, fmt.Errorf("could not cast from %v to authenticator", reflect.TypeOf(entity))
	}

	return authenticator, nil
}

func (handler AuthenticatorHandler) Update(authenticator *Authenticator) error {
	if updb := authenticator.ToUpdb(); updb != nil {
		hashResult := handler.HashPassword(updb.Password)
		updb.Password = hashResult.Password
		updb.Salt = hashResult.Salt
	}

	if cert := authenticator.ToCert(); cert != nil && cert.Pem != "" {
		cert.Fingerprint = cert2.NewFingerprintGenerator().FromPem([]byte(cert.Pem))
	}

	return handler.updateEntity(authenticator, handler)
}

func (handler AuthenticatorHandler) UpdateSelf(authenticatorSelf *AuthenticatorSelf) error {
	authenticator, err := handler.ReadForIdentity(authenticatorSelf.IdentityId, authenticatorSelf.Id)

	if err != nil {
		return err
	}

	if authenticator == nil {
		return boltz.NewNotFoundError(handler.authStore.GetSingularEntityType(), "id", authenticatorSelf.Id)
	}

	if authenticator.IdentityId != authenticatorSelf.IdentityId {
		return apierror.NewUnhandled(errors.New("authenticator does not match identity id for update"))
	}

	updbAuth := authenticator.ToUpdb()

	if updbAuth == nil {
		return apierror.NewAuthenticatorCannotBeUpdated()
	}

	curHashResult := handler.ReHashPassword(authenticatorSelf.CurrentPassword, updbAuth.DecodedSalt())

	if curHashResult.Password != updbAuth.Password {
		apiErr := apierror.NewUnauthorized()
		apiErr.Cause = apierror.NewFieldError("invalid current password", "currentPassword", authenticatorSelf.CurrentPassword)
		return apiErr
	}

	updbAuth.Username = authenticatorSelf.Username
	updbAuth.Password = authenticatorSelf.NewPassword
	updbAuth.Salt = ""
	authenticator.SubType = updbAuth

	return handler.Update(authenticator)
}

func (handler AuthenticatorHandler) Patch(authenticator *Authenticator, checker boltz.FieldChecker) error {
	if authenticator.Method == persistence.MethodAuthenticatorUpdb {
		if updb := authenticator.ToUpdb(); updb != nil {
			if checker.IsUpdated("password") {
				hashResult := handler.HashPassword(updb.Password)
				updb.Password = hashResult.Password
				updb.Salt = hashResult.Salt
			}
		}
	}

	if authenticator.Method == persistence.MethodAuthenticatorCert {
		if cert := authenticator.ToCert(); cert != nil {
			if checker.IsUpdated("certPem") {
				if cert.Fingerprint = cert2.NewFingerprintGenerator().FromPem([]byte(cert.Pem)); cert.Fingerprint == "" {
					return apierror.NewCouldNotParsePem()
				}
			}
		}
	}
	combinedChecker := &AndFieldChecker{first: handler, second: checker}
	return handler.patchEntity(authenticator, combinedChecker)
}

func (handler AuthenticatorHandler) PatchSelf(authenticatorSelf *AuthenticatorSelf, checker boltz.FieldChecker) error {
	if checker.IsUpdated("password") {
		checker = NewOrFieldChecker(checker, "salt", "password")
	}

	authenticator, err := handler.ReadForIdentity(authenticatorSelf.IdentityId, authenticatorSelf.Id)

	if err != nil {
		return err
	}

	if authenticator == nil {
		return boltz.NewNotFoundError(handler.authStore.GetSingularEntityType(), "id", authenticatorSelf.Id)
	}

	if authenticator.IdentityId != authenticatorSelf.IdentityId {
		return apierror.NewUnhandled(errors.New("authenticator does not match identity id for patch"))
	}

	updbAuth := authenticator.ToUpdb()

	if updbAuth == nil {
		return apierror.NewAuthenticatorCannotBeUpdated()
	}

	curHashResult := handler.ReHashPassword(authenticatorSelf.CurrentPassword, updbAuth.DecodedSalt())

	if curHashResult.Password != updbAuth.Password {
		apiErr := apierror.NewUnauthorized()
		apiErr.Cause = apierror.NewFieldError("invalid current password", "currentPassword", authenticatorSelf.CurrentPassword)
		return apiErr
	}

	updbAuth.Username = authenticatorSelf.Username
	updbAuth.Password = authenticatorSelf.NewPassword
	updbAuth.Salt = ""
	authenticator.SubType = updbAuth

	return handler.Patch(authenticator, checker)
}

func (handler AuthenticatorHandler) HashPassword(password string) *HashedPassword {
	newResult := crypto.Hash(password)
	b64Password := base64.StdEncoding.EncodeToString(newResult.Hash)
	b64Salt := base64.StdEncoding.EncodeToString(newResult.Salt)

	return &HashedPassword{
		RawResult: newResult,
		Salt:      b64Salt,
		Password:  b64Password,
	}
}

func (handler AuthenticatorHandler) ReHashPassword(password string, salt []byte) *HashedPassword {
	newResult := crypto.ReHash(password, salt)
	b64Password := base64.StdEncoding.EncodeToString(newResult.Hash)
	b64Salt := base64.StdEncoding.EncodeToString(newResult.Salt)

	return &HashedPassword{
		RawResult: newResult,
		Salt:      b64Salt,
		Password:  b64Password,
	}
}

func (handler AuthenticatorHandler) ListForIdentity(identityId string, query ast.Query) (*AuthenticatorListQueryResult, error) {
	filterString := fmt.Sprintf(`identity = "%s"`, identityId)
	filter, err := ast.Parse(handler.Store, filterString)
	if err != nil {
		return nil, err
	}
	query.SetPredicate(ast.NewAndExprNode(query.GetPredicate(), filter))
	result, err := handler.BasePreparedList(query)

	if err != nil {
		return nil, err
	}

	var authenticators []*Authenticator

	for _, entity := range result.GetEntities() {
		if auth, ok := entity.(*Authenticator); ok {
			authenticators = append(authenticators, auth)
		}
	}

	return &AuthenticatorListQueryResult{
		EntityListResult: result,
		Authenticators:   authenticators,
	}, nil
}

func (handler AuthenticatorHandler) ReadForIdentity(identityId string, authenticatorId string) (*Authenticator, error) {
	authenticator, err := handler.Read(authenticatorId)

	if err != nil {
		return nil, err
	}

	if authenticator.IdentityId == identityId {
		return authenticator, err
	}

	return nil, nil
}

type HashedPassword struct {
	RawResult *crypto.HashResult //raw byte hash results
	Salt      string             //base64 encoded hash
	Password  string             //base64 encoded hash
}

type AuthenticatorListQueryResult struct {
	*models.EntityListResult
	Authenticators []*Authenticator
}