package jwt

import (
	"errors"
	"fmt"
	"strings"
	"time"

	"go.ipao.vip/atom/container"
	"go.ipao.vip/atom/opt"

	jwt "github.com/golang-jwt/jwt/v4"
	"golang.org/x/sync/singleflight"
)

const (
	CtxKey     = "claims"
	HTTPHeader = "Authorization"
)

var ErrTokenInvalidType = errors.New("token cache returned non-string value")

type BaseClaims struct {
	OpenID   string `json:"open_id,omitempty"`
	Tenant   string `json:"tenant,omitempty"`
	UserID   int64  `json:"user_id,omitempty"`
	TenantID int64  `json:"tenant_id,omitempty"`
}

// Custom claims structure
type Claims struct {
	BaseClaims
	jwt.RegisteredClaims
}

const TokenPrefix = "Bearer "

type JWT struct {
	singleflight *singleflight.Group
	config       *Config
	SigningKey   []byte
}

var (
	ErrTokenExpired     = errors.New("Token is expired")
	ErrTokenNotValidYet = errors.New("Token not active yet")
	ErrTokenMalformed   = errors.New("That's not even a token")
	ErrTokenInvalid     = errors.New("Couldn't handle this token")
)

func Provide(opts ...opt.Option) error {
	options := opt.New(opts...)
	var config Config
	if err := options.UnmarshalConfig(&config); err != nil {
		return fmt.Errorf("unmarshal jwt config: %w", err)
	}
	if err := container.Container.Provide(func() (*JWT, error) {
		return &JWT{
			singleflight: &singleflight.Group{},
			config:       &config,
			SigningKey:   []byte(config.SigningKey),
		}, nil
	}, options.DiOptions()...); err != nil {
		return fmt.Errorf("provide jwt: %w", err)
	}

	return nil
}

func (jwtProvider *JWT) CreateClaims(baseClaims BaseClaims) *Claims {
	expiresDuration, _ := time.ParseDuration(jwtProvider.config.ExpiresTime)

	claims := Claims{
		BaseClaims: baseClaims,
		RegisteredClaims: jwt.RegisteredClaims{
			NotBefore: jwt.NewNumericDate(time.Now().Add(-time.Second * 10)), // 签名生效时间
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(expiresDuration)),   // 过期时间 7天  配置文件
			Issuer:    jwtProvider.config.Issuer,                             // 签名的发行者
		},
	}

	return &claims
}

// 创建一个token
func (jwtProvider *JWT) CreateToken(claims *Claims) (string, error) {
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)

	return token.SignedString(jwtProvider.SigningKey)
}

// CreateTokenByOldToken 旧token 换新token 使用归并回源避免并发问题
func (jwtProvider *JWT) CreateTokenByOldToken(oldToken string, claims *Claims) (string, error) {
	value, err, _ := jwtProvider.singleflight.Do("JWT:"+oldToken, func() (interface{}, error) {
		return jwtProvider.CreateToken(claims)
	})

	tokenString, ok := value.(string)
	if !ok {
		return "", ErrTokenInvalidType
	}

	if err != nil {
		return "", fmt.Errorf("create token by old token: %w", err)
	}

	return tokenString, nil
}

// 解析 token
func (jwtProvider *JWT) Parse(tokenString string) (*Claims, error) {
	tokenString = strings.TrimPrefix(tokenString, TokenPrefix)
	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(_ *jwt.Token) (interface{}, error) {
		return jwtProvider.SigningKey, nil
	})
	if err != nil {
		var validationErr *jwt.ValidationError
		if errors.As(err, &validationErr) {
			if validationErr.Errors&jwt.ValidationErrorMalformed != 0 {
				return nil, ErrTokenMalformed
			}

			if validationErr.Errors&jwt.ValidationErrorExpired != 0 {
				// Token is expired
				return nil, ErrTokenExpired
			}

			if validationErr.Errors&jwt.ValidationErrorNotValidYet != 0 {
				return nil, ErrTokenNotValidYet
			}

			return nil, ErrTokenInvalid
		}
	}

	if token != nil {
		if claims, ok := token.Claims.(*Claims); ok && token.Valid {
			return claims, nil
		}

		return nil, ErrTokenInvalid
	}

	return nil, ErrTokenInvalid
}