package auth

import (
	"context"
	"net/http"
	"time"

	jwtmiddleware "github.com/auth0/go-jwt-middleware"
	"github.com/golang-jwt/jwt"
	"github.com/pkg/errors"
	"go.signoz.io/signoz/pkg/query-service/model"
	"go.uber.org/zap"
	"google.golang.org/grpc/metadata"
)

var (
	JwtSecret  string
	JwtExpiry  = 30 * time.Minute
	JwtRefresh = 30 * 24 * time.Hour
)

func ParseJWT(jwtStr string) (jwt.MapClaims, error) {
	token, err := jwt.Parse(jwtStr, func(token *jwt.Token) (interface{}, error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, errors.Errorf("unknown signing algo: %v", token.Header["alg"])
		}
		return []byte(JwtSecret), nil
	})

	if err != nil {
		return nil, errors.Wrapf(err, "failed to parse jwt token")
	}

	claims, ok := token.Claims.(jwt.MapClaims)
	if !ok || !token.Valid {
		return nil, errors.Errorf("Not a valid jwt claim")
	}
	return claims, nil
}

func validateUser(tok string) (*model.UserPayload, error) {
	claims, err := ParseJWT(tok)
	if err != nil {
		return nil, err
	}
	now := time.Now().Unix()
	if !claims.VerifyExpiresAt(now, true) {
		return nil, model.ErrorTokenExpired
	}
	return &model.UserPayload{
		User: model.User{
			Id:      claims["id"].(string),
			GroupId: claims["gid"].(string),
			Email:   claims["email"].(string),
		},
	}, nil
}

// AttachJwtToContext attached the jwt token from the request header to the context.
func AttachJwtToContext(ctx context.Context, r *http.Request) context.Context {
	token, err := ExtractJwtFromRequest(r)
	if err != nil {
		zap.S().Debugf("Error while getting token from header, %v", err)
		return ctx
	}

	if len(token) > 0 {
		md, ok := metadata.FromIncomingContext(ctx)
		if !ok {
			md = metadata.New(nil)
		}

		md.Append("accessJwt", token)
		ctx = metadata.NewIncomingContext(ctx, md)
	}
	return ctx
}

func ExtractJwtFromContext(ctx context.Context) (string, error) {
	md, ok := metadata.FromIncomingContext(ctx)
	if !ok {
		return "", errors.New("No JWT metadata token found")
	}
	accessJwt := md.Get("accessJwt")
	if len(accessJwt) == 0 {
		return "", errors.New("No JWT token found")
	}

	return accessJwt[0], nil
}

func ExtractJwtFromRequest(r *http.Request) (string, error) {
	return jwtmiddleware.FromAuthHeader(r)
}