package redis

import (
	"crypto/rsa"
	"fmt"
	"io/ioutil"
	"strings"
	"time"

	"github.com/dgrijalva/jwt-go.git"
	"github.com/google/uuid"
	"src.dualinventive.com/go/authentication-service/internal/domain"
	"src.dualinventive.com/go/authentication-service/internal/storage"
	"src.dualinventive.com/go/lib/dilog"
	"src.dualinventive.com/go/lib/kv"
)

const tokenExpirationDuration = time.Hour * 24

//TokenRepository contains functions to manage tokens
type TokenRepository struct {
	kvstore    kv.KV
	privateKey *rsa.PrivateKey
	publicKey  *rsa.PublicKey
	logger     dilog.Logger
}

//NewTokenRepository returns a new instance of a redis (or ram) backed repository
func NewTokenRepository(
	host, port, privateKeyFile, publicKeyFile string,
	logger dilog.Logger) (storage.TokenRepository, error) {
	repo := &TokenRepository{}
	repo.logger = logger

	privateKey, err := configurePrivateKey(privateKeyFile)
	if err != nil {
		return nil, err
	}

	publicKey, err := configurePublicKey(publicKeyFile)
	if err != nil {
		return nil, err
	}

	repo.privateKey = privateKey
	repo.publicKey = publicKey

	kvstore, err := kv.New(kv.TypeRedis, fmt.Sprintf("%s:%s", host, port))
	if err != nil {
		return nil, NewErr(err)
	}

	repo.kvstore = kvstore
	return repo, nil
}

//CreateToken creates and stores token
func (tr *TokenRepository) CreateToken(
	userName string,
	companyCode string,
	userAgent string,
	rights ...string) (*domain.Token, error) {
	secret, err := tr.generateSecret(userName, userAgent, uuid.New().String(), rights)
	if err != nil {
		return nil, NewErr(err)
	}

	err = tr.kvstore.Set("token:"+secret, userName+"::"+companyCode)
	if err != nil {
		return nil, NewErr(err)
	}
	return &domain.Token{Secret: secret}, nil
}

//GetTokens returns tokens, if exists and is not expired, for given user name
func (tr *TokenRepository) GetTokens(userName string, companyCode string) ([]*domain.Token, error) {
	var keys []*domain.Token
	iter, err := tr.kvstore.Keys("token:*")
	if err != nil {
		return nil, NewErr(err)
	}
	for _, key := range iter {
		val, err := tr.kvstore.Get(key)
		if err != nil {
			continue
		}
		if val == userName+"::"+companyCode {
			keys = tr.processKey(key, keys)
		}
	}

	return keys, nil
}

//GetUserNameByToken returns a username that is bound to the given token.
func (tr *TokenRepository) GetUserNameByToken(token *domain.Token) (string, string, error) {
	value, err := tr.kvstore.Get("token:" + token.Secret)
	if err != nil {
		return "", "", NewErr(err)
	}

	split := strings.Split(value, "::")
	return split[0], split[1], nil
}

//IsValid checks if token is stored and not expired
func (tr *TokenRepository) IsValid(token *domain.Token, rights ...string) (valid bool, authorized bool, err error) {
	exists, err := tr.kvstore.Exists("token:" + token.Secret)
	if err != nil {
		return false, false, NewErr(err)
	}
	if !exists {
		return false, false, storage.ErrTokenNotFound
	}
	valid, authorized = tr.validateToken(token, rights)
	if !valid {
		return false, false, storage.ErrTokenInvalid
	}
	return valid, authorized, nil
}

//DeleteToken removes token if exists
func (tr *TokenRepository) DeleteToken(token *domain.Token) error {
	ok, err := tr.kvstore.Del("token:" + token.Secret)
	if err != nil {
		// TODO same shit as above
		return NewErr(err)
	}
	if !ok {
		return storage.ErrTokenNotFound
	}

	return nil
}

//GetTokenPayload returns encoded token data.
func (tr *TokenRepository) GetTokenPayload(token *domain.Token) (opaqueID string, userAgent string, err error) {
	var claims Claims
	_, err = jwt.ParseWithClaims(token.Secret, &claims, func(token *jwt.Token) (interface{}, error) {
		return tr.publicKey, nil
	})
	if err != nil {
		return "", "", err
	}

	return claims.OpaqueID, claims.UserAgent, nil
}

func configurePrivateKey(filepath string) (*rsa.PrivateKey, error) {
	//jwt takes care of key parsing
	f, err := ioutil.ReadFile(filepath) //nolint:gosec
	if err != nil {
		return nil, err
	}

	return jwt.ParseRSAPrivateKeyFromPEM(f)
}

func configurePublicKey(filepath string) (*rsa.PublicKey, error) {
	//jwt takes care of key parsing
	f, err := ioutil.ReadFile(filepath) //nolint:gosec
	if err != nil {
		return nil, err
	}

	return jwt.ParseRSAPublicKeyFromPEM(f)
}

func (tr *TokenRepository) generateSecret(
	username string,
	userAgent string,
	opaqueID string,
	rights []string) (string, error) {
	expirationTime := time.Now().Add(tokenExpirationDuration)

	claims := Claims{
		User:      username,
		UserAgent: userAgent,
		OpaqueID:  opaqueID,
		Rights:    rights,
		StandardClaims: jwt.StandardClaims{
			ExpiresAt: expirationTime.Unix(),
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodRS256, claims)
	tokenString, err := token.SignedString(tr.privateKey)
	if err != nil {
		return "", err
	}

	return tokenString, nil
}

func (tr *TokenRepository) processKey(key string, keys []*domain.Token) []*domain.Token {
	secret := string([]rune(key)[6:])
	token := &domain.Token{Secret: secret}
	valid, _ := tr.validateToken(token, []string{})
	if !valid {
		_, err := tr.kvstore.Del(key)
		if err != nil {
			tr.logger.Warning("floating key detected %s\n", key)
		}
	} else {
		keys = append(keys, token)
	}
	return keys
}

func (tr *TokenRepository) validateToken(token *domain.Token, rights []string) (valid bool, authorized bool) {
	var claims Claims
	tkn, err := jwt.ParseWithClaims(token.Secret, &claims, func(token *jwt.Token) (interface{}, error) {
		return tr.publicKey, nil
	})
	if err != nil {
		return false, false
	}
	if time.Now().Unix() > claims.ExpiresAt {
		return false, false
	}

	return tkn.Valid, claims.Rights.containsAll(rights...)

}

//Claims contains token data which will be encrypted and form the JWT token including headers and signing.
type Claims struct {
	jwt.StandardClaims
	User      string `json:"user"`
	UserAgent string `json:"userAgent"`
	OpaqueID  string `json:"opaqueId"`
	Rights    Rights `json:"rights"`
}

//Rights is a list of right-codes
type Rights []string

func (c Rights) containsAll(rights ...string) bool {
	for _, r := range rights {
		if !c.contains(r) {
			return false
		}
	}
	return true
}

func (c Rights) contains(right string) bool {
	for _, r := range c {
		if r == right {
			return true
		}
	}
	return false
}