package auth

import (
	"crypto/rand"
	"encoding/hex"
	"errors"
	"os"
	"strings"
	"time"

	"github.com/golang-jwt/jwt/v5"
	"golang.org/x/crypto/bcrypt"
	"gorm.io/gorm"

	"server/internal/models"
)

const staffCtxKey = "staffId"

type StaffClaims struct {
	StaffID uint   `json:"staffId"`
	Email   string `json:"email"`
	jwt.RegisteredClaims
}

func JWTSecret() string {
	if s := os.Getenv("JWT_SECRET"); s != "" {
		return s
	}
	return "simple-care-staff-jwt-change-me-in-production"
}

func HashPassword(password string) (string, error) {
	b, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	return string(b), err
}

func CheckPassword(hash, password string) bool {
	return bcrypt.CompareHashAndPassword([]byte(hash), []byte(password)) == nil
}

func RandomPassword(n int) string {
	if n < 8 {
		n = 8
	}
	b := make([]byte, n)
	_, _ = rand.Read(b)
	return hex.EncodeToString(b)[:n]
}

func RandomToken(n int) string {
	b := make([]byte, n)
	_, _ = rand.Read(b)
	return hex.EncodeToString(b)
}

func IssueToken(staff *models.StaffAccount) (string, error) {
	claims := StaffClaims{
		StaffID: staff.ID,
		Email:   staff.Email,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(7 * 24 * time.Hour)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
		},
	}
	t := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return t.SignedString([]byte(JWTSecret()))
}

func ParseToken(tokenStr string) (*StaffClaims, error) {
	t, err := jwt.ParseWithClaims(tokenStr, &StaffClaims{}, func(t *jwt.Token) (any, error) {
		return []byte(JWTSecret()), nil
	})
	if err != nil {
		return nil, err
	}
	claims, ok := t.Claims.(*StaffClaims)
	if !ok || !t.Valid {
		return nil, errors.New("invalid token")
	}
	return claims, nil
}

func EmailDomainPart(email string) string {
	parts := strings.Split(strings.ToLower(strings.TrimSpace(email)), "@")
	if len(parts) != 2 {
		return ""
	}
	return parts[1]
}

func IsEmailDomainAllowed(db *gorm.DB, email string) bool {
	domain := EmailDomainPart(email)
	if domain == "" {
		return false
	}
	var count int64
	db.Model(&models.EmailDomain{}).Where("is_active = ?", true).Count(&count)
	if count == 0 {
		return true
	}
	var found int64
	db.Model(&models.EmailDomain{}).Where("domain = ? AND is_active = ?", domain, true).Count(&found)
	return found > 0
}