package main

import (
	"errors"
	"fmt"
	"strconv"
	"time"

	"github.com/golang-jwt/jwt/v5"
)

var secretKey = []byte("replace-with-env-variable")

type UserClaims struct {
	Name  string  `json:"name"`
	Color [3]byte `json:"color"`
	jwt.RegisteredClaims
}

func GetToken(client *Client) (string, error) {
	token := jwt.NewWithClaims(jwt.SigningMethodHS256,
		UserClaims{
			Name:  client.Name,
			Color: client.Color,
			RegisteredClaims: jwt.RegisteredClaims{
				Subject:   strconv.Itoa(int(client.Id)),
				ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour)),
				IssuedAt:  jwt.NewNumericDate(time.Now()),
			},
		},
	)
	return token.SignedString(secretKey)
}

func SetClientFromToken(client *Client, tokenString string) error {
	token, err := jwt.ParseWithClaims(tokenString, &UserClaims{}, func(t *jwt.Token) (interface{}, error) {
		if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", t.Header["alg"])
		}
		return secretKey, nil
	})
	if err != nil {
		return err
	}

	claims, ok := token.Claims.(*UserClaims)
	if !ok || !token.Valid {
		return errors.New("invalid token")
	}

	id, err := strconv.ParseUint(claims.Subject, 10, 32)
	if err != nil {
		return fmt.Errorf("invalid subject: %w", err)
	}

	client.Id = uint32(id)
	client.Name = claims.Name
	client.Color = claims.Color

	return nil
}