// Copyright 2023 Woodpecker Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package encryption

import (
	"encoding/base64"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"github.com/tink-crypto/tink-go/v2/subtle/random"
)

func TestShortMessageLongKey(t *testing.T) {
	aes := &aesEncryptionService{}
	err := aes.loadCipher(string(random.GetRandomBytes(32)))
	assert.NoError(t, err)

	input := string(random.GetRandomBytes(4))
	cipher, err := aes.Encrypt(input, "")
	assert.NoError(t, err)

	output, err := aes.Decrypt(cipher, "")
	assert.NoError(t, err)
	assert.Equal(t, input, output)
}

func TestLongMessageShortKey(t *testing.T) {
	aes := &aesEncryptionService{}
	err := aes.loadCipher(string(random.GetRandomBytes(12)))
	assert.NoError(t, err)

	input := string(random.GetRandomBytes(1024))
	cipher, err := aes.Encrypt(input, "")
	assert.NoError(t, err)

	output, err := aes.Decrypt(cipher, "")
	assert.NoError(t, err)
	assert.Equal(t, input, output)
}

func TestEncryptDecryptWithAssociatedData(t *testing.T) {
	aes := &aesEncryptionService{}
	err := aes.loadCipher(string(random.GetRandomBytes(32)))
	require.NoError(t, err)

	plaintext := "secret-value-12345"
	associatedData := "repo:123"

	ciphertext, err := aes.Encrypt(plaintext, associatedData)
	require.NoError(t, err)

	// Decrypt with correct associated data should succeed
	decrypted, err := aes.Decrypt(ciphertext, associatedData)
	require.NoError(t, err)
	assert.Equal(t, plaintext, decrypted)

	// Decrypt with wrong associated data should fail
	_, err = aes.Decrypt(ciphertext, "repo:456")
	assert.Error(t, err, "decryption should fail with wrong associated data")

	// Decrypt with empty associated data should fail
	_, err = aes.Decrypt(ciphertext, "")
	assert.Error(t, err, "decryption should fail with missing associated data")
}

func TestEncryptProducesUniqueCiphertexts(t *testing.T) {
	aes := &aesEncryptionService{}
	err := aes.loadCipher(string(random.GetRandomBytes(32)))
	require.NoError(t, err)

	plaintext := "same-message"
	ciphertexts := make(map[string]bool)

	// Encrypt the same message multiple times
	for range 100 {
		ct, err := aes.Encrypt(plaintext, "")
		require.NoError(t, err)
		assert.False(t, ciphertexts[ct], "ciphertext should be unique due to random nonce")
		ciphertexts[ct] = true
	}
}

func TestDecryptTamperedCiphertext(t *testing.T) {
	aes := &aesEncryptionService{}
	err := aes.loadCipher(string(random.GetRandomBytes(32)))
	require.NoError(t, err)

	plaintext := "sensitive-data"
	ciphertext, err := aes.Encrypt(plaintext, "")
	require.NoError(t, err)

	// Decode, tamper, re-encode
	decoded, err := base64.StdEncoding.DecodeString(ciphertext)
	require.NoError(t, err)

	// Tamper with the ciphertext (flip a bit in the middle)
	if len(decoded) > AES_GCM_SIV_NonceSize+1 {
		decoded[AES_GCM_SIV_NonceSize+1] ^= 0xFF
	}
	tampered := base64.StdEncoding.EncodeToString(decoded)

	_, err = aes.Decrypt(tampered, "")
	assert.Error(t, err, "decryption of tampered ciphertext should fail")
}

func TestDecryptInvalidBase64(t *testing.T) {
	aes := &aesEncryptionService{}
	err := aes.loadCipher(string(random.GetRandomBytes(32)))
	require.NoError(t, err)

	_, err = aes.Decrypt("not-valid-base64!!!", "")
	assert.Error(t, err, "decryption of invalid base64 should fail")
}

func TestDecryptTruncatedCiphertext(t *testing.T) {
	aes := &aesEncryptionService{}
	err := aes.loadCipher(string(random.GetRandomBytes(32)))
	require.NoError(t, err)

	plaintext := "test-message"
	ciphertext, err := aes.Encrypt(plaintext, "")
	require.NoError(t, err)

	// Truncate the ciphertext
	decoded, err := base64.StdEncoding.DecodeString(ciphertext)
	require.NoError(t, err)

	truncated := base64.StdEncoding.EncodeToString(decoded[:len(decoded)/2])
	_, err = aes.Decrypt(truncated, "")
	assert.Error(t, err, "decryption of truncated ciphertext should fail")
}

func TestRandomBytesUniqueness(t *testing.T) {
	seen := make(map[string]bool)

	for range 1000 {
		bytes := random.GetRandomBytes(32)
		key := string(bytes)
		assert.False(t, seen[key], "random bytes should be unique")
		seen[key] = true
	}
}

func TestRandomBytesLength(t *testing.T) {
	tests := []uint32{1, 12, 16, 32, 64, 128, 256}

	for _, length := range tests {
		bytes := random.GetRandomBytes(length)
		assert.Len(t, bytes, int(length), "random bytes should have requested length")
	}
}