package v1

import (
	"errors"
	"strings"
	"time"

	"git.jamestombleson.com/jtom38/newsbot-api/internal/domain"
	"github.com/golang-jwt/jwt/v5"
)

const (
	ErrJwtMissing       = "auth token is missing"
	ErrJwtClaimsMissing = "claims missing on token"
	ErrJwtExpired       = "auth token has expired"
	ErrJwtScopeMissing  = "required scope is missing"
)

type JwtToken struct {
	Exp        time.Time `json:"exp"`
	Iss        string    `json:"iss"`
	Authorized bool      `json:"authorized"`
	UserName   string    `json:"username"`
	Scopes     []string  `json:"scopes"`
	jwt.RegisteredClaims
}

func (j JwtToken) IsValid(scope string) error {
	err := j.hasExpired()
	if err != nil {
		return err
	}

	err = j.hasScope(scope)
	if err != nil {
		return err
	}

	return nil
}

func (j JwtToken) GetUsername() string {
	return j.UserName
}

func (j JwtToken) hasExpired() error {
	// Check to see if the token has expired
	hasExpired := j.Exp.Compare(time.Now())
	if hasExpired == -1 {
		return errors.New(ErrJwtExpired)
	}
	return nil
}

func (j JwtToken) hasScope(scope string) error {
	// they have the scope to access everything, so let them pass.
	if strings.Contains(domain.ScopeAll, scope) {
		return nil
	}

	for _, s := range j.Scopes {
		if strings.Contains(s, scope) {
			return nil
		}
	}
	return errors.New(ErrJwtScopeMissing)
}

func (h *Handler) generateJwt(username, issuer string) (string, error) {
	return h.generateJwtWithExp(username, issuer, time.Now().Add(10*time.Minute))
}

func (h *Handler) generateJwtWithExp(username, issuer string, expiresAt time.Time) (string, error) {
	secret := []byte(h.config.JwtSecret)

	// Anyone who wants to decrypt the key needs to use the same method
	token := jwt.New(jwt.SigningMethodHS256)
	claims := token.Claims.(jwt.MapClaims)
	claims["exp"] = expiresAt
	claims["authorized"] = true
	claims["username"] = username
	claims["iss"] = issuer

	var scopes []string
	if username == "admin" {
		scopes = append(scopes, domain.ScopeAll)
		claims["scopes"] = scopes
	} else {
		scopes = append(scopes, domain.ScopeRead)
		claims["scopes"] = scopes
	}

	tokenString, err := token.SignedString(secret)
	if err != nil {
		return "", err
	}

	return tokenString, nil
}