package crypto

import (
	"bytes"
	"testing"
)

func key32() []byte {
	k := make([]byte, 32)
	for i := range k {
		k[i] = byte(i + 1)
	}
	return k
}

func TestEncryptDecryptRoundTrip(t *testing.T) {
	c, err := NewCipher(key32())
	if err != nil {
		t.Fatal(err)
	}
	plain := []byte("selectel-api-secret-token")
	enc, err := c.Encrypt(plain)
	if err != nil {
		t.Fatal(err)
	}
	if enc == string(plain) {
		t.Fatal("ciphertext must differ from plaintext")
	}
	dec, err := c.Decrypt(enc)
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(dec, plain) {
		t.Fatalf("round-trip mismatch: %q != %q", dec, plain)
	}
}

func TestEncryptNonDeterministic(t *testing.T) {
	c, _ := NewCipher(key32())
	a, _ := c.Encrypt([]byte("same"))
	b, _ := c.Encrypt([]byte("same"))
	if a == b {
		t.Fatal("nonce must randomize ciphertext")
	}
}

func TestDecryptTamperFails(t *testing.T) {
	c, _ := NewCipher(key32())
	enc, _ := c.Encrypt([]byte("data"))
	// испортить последний символ base64
	tampered := enc[:len(enc)-1] + "A"
	if tampered == enc {
		tampered = enc[:len(enc)-1] + "B"
	}
	if _, err := c.Decrypt(tampered); err == nil {
		t.Fatal("GCM must reject tampered ciphertext")
	}
}

func TestNewCipherRejectsBadKey(t *testing.T) {
	if _, err := NewCipher([]byte("short")); err == nil {
		t.Fatal("expected error for non-32-byte key")
	}
}