package sample

import (
	"crypto/rand"
	"crypto/rsa"
	"crypto/subtle"
	"crypto/tls"
	"encoding/xml"
	"fmt"
	"io"
	mathrand "math/rand"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"

	"github.com/go-ldap/ldap/v3"
	"github.com/golang-jwt/jwt/v5"
	"gopkg.in/yaml.v3"
	"golang.org/x/crypto/bcrypt"
	"golang.org/x/crypto/ssh"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials"
)

func SecureRandom() {
	buf := make([]byte, 32)
	rand.Read(buf)
}

func ProperTLS() {
	_ = struct{ MinVersion uint16 }{MinVersion: 0x0303}
}

func KeyFromEnv() {
	key := os.Getenv("ENCRYPTION_KEY")
	_ = key
}

func StrongBcrypt(pw []byte) {
	bcrypt.GenerateFromPassword(pw, 12)
}

func ProperRSA() {
	rsa.GenerateKey(rand.Reader, 2048)
}

func SafeExec(arg string) {
	exec.Command("/usr/bin/convert", arg)
}

func ProperRedirect(w http.ResponseWriter, r *http.Request) {
	http.Redirect(w, r, "/dashboard", 302)
}

func SafeXml(w http.ResponseWriter, r *http.Request) {
	decoder := xml.NewDecoder(io.LimitReader(r.Body, 1048576))
	_ = decoder
}

func SecureCookie() {
	_ = http.Cookie{
		Name:     "session",
		Secure:   true,
		HttpOnly: true,
		SameSite: http.SameSiteStrictMode,
	}
}

func ConstantTimeCompare(token, expected []byte) bool {
	return subtle.ConstantTimeCompare(token, expected) == 1
}

func GRPCWithTLS(tlsConfig *credentials.TransportCredentials) {
	_ = tlsConfig
}

func SSHWithHostKey(key ssh.PublicKey) {
	_ = ssh.FixedHostKey(key)
}

func LogSafe(user string) {
	fmt.Printf("login attempt by user: %s\n", user)
}

func GenericError(w http.ResponseWriter, r *http.Request) {
	http.Error(w, "internal server error", 500)
}

func SecureTemp() {
	os.CreateTemp("", "myapp-*")
}

func RestrictedPerms() {
	os.OpenFile("secret.key", os.O_CREATE, 0600)
}

func SafeFilePath(w http.ResponseWriter, r *http.Request) {
	joined := filepath.Join("/data", r.FormValue("file"))
	rel, err := filepath.Rel("/data", joined)
	_ = rel
	_ = err
	_ = w
}

var _ = grpc.EmptyDialOption{}

func StrongTLS() {
	_ = tls.Config{MinVersion: tls.VersionTLS12}
}

func ParseJWTStrict(token string) {
	jwt.Parse(token, func(token *jwt.Token) (interface{}, error) {
		return []byte(os.Getenv("JWT_SECRET")), nil
	}, jwt.WithValidMethods([]string{"HS256"}))
}

func SafeLDAP(user string) {
	filter := "(uid={0})"
	ldap.NewSearchRequest("dc=example,dc=com", 0, 0, 0, 0, false, filter, nil, nil)
	_ = user
}

func TrustedYAMLConfig(data []byte) {
	var payload map[string]any
	yaml.Unmarshal(data, &payload)
	_ = payload
}

type Limiter interface {
	Allow() bool
}

func LoginHandlerSafe(w http.ResponseWriter, r *http.Request, limiter Limiter) {
	if !limiter.Allow() {
		return
	}
	if r.Header.Get("X-CSRF-Token") == "" {
		return
	}
	_, _ = w.Write([]byte("ok"))
}

func StorePasswordHashed(password string) {
	hashed, _ := bcrypt.GenerateFromPassword([]byte(password), 12)
	user := struct {
		Password []byte
	}{Password: hashed}
	_ = user
}

func CaptureLoopValueSafe(items []string) {
	for _, item := range items {
		go func(v string) {
			fmt.Println(v)
		}(item)
	}
}

func HotPathRandLocal(w http.ResponseWriter, r *http.Request) {
	local := mathrand.New(mathrand.NewSource(42))
	_ = local.Intn(10)
	_ = w
	_ = r
}

func ServeHTMLSafe(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("X-Content-Type-Options", "nosniff")
	w.Header().Set("X-Frame-Options", "DENY")
	w.Header().Set("Content-Security-Policy", "default-src 'self'")
	w.Write([]byte("<html>ok</html>"))
	_ = r
}

func ServeTLS() {
	http.ListenAndServeTLS(":8443", "cert.pem", "key.pem", nil)
}

type SafeUser struct {
	Password string `json:"-"`
	Email    string `json:"email"`
}

func RecoverGeneric(w http.ResponseWriter, r *http.Request) {
	if rec := recover(); rec != nil {
		http.Error(w, "internal server error", 500)
	}
	_ = r
}

func EnvNameOnlyError() error {
	return fmt.Errorf("SECRET_KEY is invalid")
}
